CA2279414A1 - Synchronous machine - Google Patents
Synchronous machine Download PDFInfo
- Publication number
- CA2279414A1 CA2279414A1 CA002279414A CA2279414A CA2279414A1 CA 2279414 A1 CA2279414 A1 CA 2279414A1 CA 002279414 A CA002279414 A CA 002279414A CA 2279414 A CA2279414 A CA 2279414A CA 2279414 A1 CA2279414 A1 CA 2279414A1
- Authority
- CA
- Canada
- Prior art keywords
- stator
- temperature
- stator current
- synchronous machine
- machine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
- H02P9/26—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices
- H02P9/30—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices
- H02P9/305—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices controlling voltage
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S174/00—Electricity: conductors and insulators
- Y10S174/13—High voltage cable, e.g. above 10kv, corona prevention
- Y10S174/14—High voltage cable, e.g. above 10kv, corona prevention having a particular cable application, e.g. winding
- Y10S174/19—High voltage cable, e.g. above 10kv, corona prevention having a particular cable application, e.g. winding in a dynamo-electric machine
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S174/00—Electricity: conductors and insulators
- Y10S174/13—High voltage cable, e.g. above 10kv, corona prevention
- Y10S174/29—High voltage cable, e.g. above 10kv, corona prevention having a semiconductive layer
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
- Control Of Ac Motors In General (AREA)
- Insulation, Fastening Of Motor, Generator Windings (AREA)
- Control Of Multiple Motors (AREA)
Abstract
A synchronous machine for power and/or voltage control comprises a stator with a stator winding and a rotor with a field winding. The stator winding comprises a high-voltage cable with solid insulation. A rotor has a thermally based rotor current limit intersecting with a thermally based stator current limit in a capability graph at a power factor considerably below the rated power factor or has the thermally based rotor current limit above the thermally based stator current limit in the capability graph. Means are provided for limiting the currents in order to avoid thermal damage. In a method for power and/or voltage control of such a synchronous machine, the machine operates with the stator current exceeding the thermally based stator current limit for a certain time period less than the maximum permissible time limit, whereafter the overload is reduced by reduction of either the active power or the field current or a combination of both.
Description
2 PCTISE98/00174 SYNCHRONOUS MACHINE
The present invention relates to a method for power and/or voltage control in a synchronous machine, and a synchronous machine for power and/or voltage control.
In the following "synchronous machine" shall be taken to mean synchronous generator. Synchronous generators are used in electric power networks in the first place to supply active and reactive power in the "hour scale". Ac:tive power can also be controlled in the "second-minute scale" (frequency control), as well as reactive power (voltage control). Synchronous machines also provide suitable contributions in the "millisecond scale" to the fault currents, so that error states in the network can be quickly resolved in selective man-ner.
Synchronous machines are important production sources of reactive power in power systems. When the reactive power requirement increases in the system, this tends to lower the terminal voltage on the synchronous ma-chine. To keep the voltage constant, the field current is normally increased by means of the voltage regulator of the synchronous machine. The synchronous machine will thus produce the reactive power required to achieve rea~~tive power balance at the desired terminal voltage.
The above-mentioned process applies as long as the power production corresponds to one point in the per-missible area in the capability graph of the synchro-nous machine, i.e. the graph of limits as regards reac-tive and active power, see Figure 1 showing the rela-tionship at overexcited operation. At overexcited op-eration, i.e. when the synchronous machine is producing reactive power, the permissible operating area is lim-ited by thermally based rotor and stator current lim-its. The synchronous machines of today are normally dimensioned so that rotor and stator current limits in-tersect each other at a point in the capability graph corresponding to rated power at rated power factor, see Figure 1. The rated power factor for synchronous gen-erators is typically 0.8 - 0.95. At overexcited opera-tion, where the power factor is greater than the rated power factor, the limit for the capability graph of the synchronous machine consists of the stator current limit and, at overexcited operation, where the power factor is less than the rated power factor, the limit consists of the rotor current limit.
In conventional technology, if the stator or rotor cur-rent limits are exceeded current limiters, if such are installed and used, come into operation. These limiters reduce the currents by lowering the excitation. Since it takes a certain time before damaging temperatures are obtained, intervention of the current limiters of the stator or rotor is delayed several seconds before the current is lowered. The delay typically depends on the size of the current but it is usually less than one minute, see e.g. VERIFICATION OF LIMITER PERFORMANCE IN
MODERN EXCITATION CONTROL SYSTEMS in IEEE Transaction on Energy Conversion, Vol. 10, No. 3, September 1995.
The current reduction is achieved by a decrease in the field current which results in a decrease in the termi-nal voltage and reactive power production of the gen-erator. The consequences for the part of the system in the vicinity of the machine are that the local reactive power production decreases and that it is more diffi-cult to import power from adjacent parts of the system, when the voltage drops.
The present invention relates to a method for power and/or voltage control in a synchronous machine, and a synchronous machine for power and/or voltage control.
In the following "synchronous machine" shall be taken to mean synchronous generator. Synchronous generators are used in electric power networks in the first place to supply active and reactive power in the "hour scale". Ac:tive power can also be controlled in the "second-minute scale" (frequency control), as well as reactive power (voltage control). Synchronous machines also provide suitable contributions in the "millisecond scale" to the fault currents, so that error states in the network can be quickly resolved in selective man-ner.
Synchronous machines are important production sources of reactive power in power systems. When the reactive power requirement increases in the system, this tends to lower the terminal voltage on the synchronous ma-chine. To keep the voltage constant, the field current is normally increased by means of the voltage regulator of the synchronous machine. The synchronous machine will thus produce the reactive power required to achieve rea~~tive power balance at the desired terminal voltage.
The above-mentioned process applies as long as the power production corresponds to one point in the per-missible area in the capability graph of the synchro-nous machine, i.e. the graph of limits as regards reac-tive and active power, see Figure 1 showing the rela-tionship at overexcited operation. At overexcited op-eration, i.e. when the synchronous machine is producing reactive power, the permissible operating area is lim-ited by thermally based rotor and stator current lim-its. The synchronous machines of today are normally dimensioned so that rotor and stator current limits in-tersect each other at a point in the capability graph corresponding to rated power at rated power factor, see Figure 1. The rated power factor for synchronous gen-erators is typically 0.8 - 0.95. At overexcited opera-tion, where the power factor is greater than the rated power factor, the limit for the capability graph of the synchronous machine consists of the stator current limit and, at overexcited operation, where the power factor is less than the rated power factor, the limit consists of the rotor current limit.
In conventional technology, if the stator or rotor cur-rent limits are exceeded current limiters, if such are installed and used, come into operation. These limiters reduce the currents by lowering the excitation. Since it takes a certain time before damaging temperatures are obtained, intervention of the current limiters of the stator or rotor is delayed several seconds before the current is lowered. The delay typically depends on the size of the current but it is usually less than one minute, see e.g. VERIFICATION OF LIMITER PERFORMANCE IN
MODERN EXCITATION CONTROL SYSTEMS in IEEE Transaction on Energy Conversion, Vol. 10, No. 3, September 1995.
The current reduction is achieved by a decrease in the field current which results in a decrease in the termi-nal voltage and reactive power production of the gen-erator. The consequences for the part of the system in the vicinity of the machine are that the local reactive power production decreases and that it is more diffi-cult to import power from adjacent parts of the system, when the voltage drops.
3 _ If the trar..smission network is unable to transmit the power required at prevailing voltages there is a risk of the pow~sr system being subjected to voltage col-lapse. To avoid this it is advantageous for the power to be produced locally, close to the load. If this is not possible, and the power must be transmitted from other parts of the system, it is, as known, advanta-geous if this can be done at as high a voltage level as possible. When the voltage drops, the reactive power production (shunt capacitances) of the transmission lines decrease. Transformer tap-changers act in order to keep the voltages to the loads constant, and thus the power of the loads constant. If the power consump-tion of the loads is constant and the transmission voltage is lower than normally, the currents in the transmission lines will be higher and the reactive power consumption of the transmission lines will be greater (series inductances), see Cigre brochure 101, October 1995.
In many power systems, if current limiters come into operation for certain synchronous machines as described above, the reactive power production is limited and this may lead to a voltage collapse of the system.
In normal operation of the power system, with an essen-tially intact network, these situations are normally avoided by the installation of additional reactive power production resources, e.g. mechanically switched shunt capacitors and/or thyristor controlled static var compenstors (SVC), if necessary. However, as a wide-w spread voltage collapse usually has severe consequences for the society, also abnormal operating conditions needs to be considered. If the network is weakened, due to e.g. faults or maintenance on important elements of
In many power systems, if current limiters come into operation for certain synchronous machines as described above, the reactive power production is limited and this may lead to a voltage collapse of the system.
In normal operation of the power system, with an essen-tially intact network, these situations are normally avoided by the installation of additional reactive power production resources, e.g. mechanically switched shunt capacitors and/or thyristor controlled static var compenstors (SVC), if necessary. However, as a wide-w spread voltage collapse usually has severe consequences for the society, also abnormal operating conditions needs to be considered. If the network is weakened, due to e.g. faults or maintenance on important elements of
4 the network, the installed reactive power producing re-sources may no longer be sufficient, resulting in the above described situation which may lead to voltage collapse. The cost of installing additional controlla-ble reactive power producing resources, e.g. SVC de-vices, such that also these abnormal operating condi-tions can be handled is considerable. There is conse-quently a need for inexpensive controllable reactive power production reserves. These reserve resources should be capable of delivering reactive power such that voltage can be maintained at prescribed levels for at least 10 to 20 minutes giving the system operators a chance to take preventive actions, such as e.g. start-ing gas turbines or shedding load.
In power systems known today, or in power plants, the energy conversion usually occurs in two stages, using a step-up transformer. The rotating synchronous machine and the transformer, each have a magnetic circuit. It is known that manufacturers of such equipment are cau-tious and conservative in their recommendations for the set values in the limit devices, see Cigre brochure 101, October 1995, section 4.5.4., page 60. Coordina-tion is required and a certain risk of conflict thus exists in dimensioning and protecting generators and transformers. The step-up transformer has no air gap and is therefore sensitive to saturation as a result of high voltage or geomagnetic currents. The transformer also consumes part of the reactive power of the genera-tor, both at normal and abnormal operation. The major-ity of the active losses appear in the conductors of the armature circuit and the step-up transformer, while the core losses are relatively small in both devices.
One complication here is that the losses are normally developed at medium and high voltage and are therefore more difficult to cool away than if they had been de-veloped at earth potential.
The object of the present invention is to achieve a
In power systems known today, or in power plants, the energy conversion usually occurs in two stages, using a step-up transformer. The rotating synchronous machine and the transformer, each have a magnetic circuit. It is known that manufacturers of such equipment are cau-tious and conservative in their recommendations for the set values in the limit devices, see Cigre brochure 101, October 1995, section 4.5.4., page 60. Coordina-tion is required and a certain risk of conflict thus exists in dimensioning and protecting generators and transformers. The step-up transformer has no air gap and is therefore sensitive to saturation as a result of high voltage or geomagnetic currents. The transformer also consumes part of the reactive power of the genera-tor, both at normal and abnormal operation. The major-ity of the active losses appear in the conductors of the armature circuit and the step-up transformer, while the core losses are relatively small in both devices.
One complication here is that the losses are normally developed at medium and high voltage and are therefore more difficult to cool away than if they had been de-veloped at earth potential.
The object of the present invention is to achieve a
5 synchronous machine for power and/or voltage control and a method for power and/or voltage control in order to avoid voltage collapse in power systems.
This object is achieved by a method and a synchronous machine of t=he type described in the introduction, with the features defined in claims 1, 26 and claim 30, re-spectively.
According to the invention, thus, the synchronous ma-chine is designed so that the thermally based rotor current limit is raised with respect to the thermally based stator- current limit such that either the inter-section with the thermally based stator current limit in the capability graph is at a power factor value con-siderably below the rated power factor value, or the rotor current limit is raised above the stator current limit such that the two limits do not intersect. If the rotor and stator. current limits intersect at the power factor zero in the capability graph as shown in Fig-ure 2, or if the rotor current limit is raised above the stator current limit, the stator current limit will be limiting for all overexcited operation.
In the following "cable" shall refer to high-voltage, insulated electric conductors comprising a core having ~ a number of strand parts of conducting material such as copper, for instance, an inner semiconducting layer surrounding the core, a high-voltage insulating layer surrounding the inner semiconducting layer, and an outer semi-conducting layer surrounding the insulating layer. A synchronous machine with a stator winding
This object is achieved by a method and a synchronous machine of t=he type described in the introduction, with the features defined in claims 1, 26 and claim 30, re-spectively.
According to the invention, thus, the synchronous ma-chine is designed so that the thermally based rotor current limit is raised with respect to the thermally based stator- current limit such that either the inter-section with the thermally based stator current limit in the capability graph is at a power factor value con-siderably below the rated power factor value, or the rotor current limit is raised above the stator current limit such that the two limits do not intersect. If the rotor and stator. current limits intersect at the power factor zero in the capability graph as shown in Fig-ure 2, or if the rotor current limit is raised above the stator current limit, the stator current limit will be limiting for all overexcited operation.
In the following "cable" shall refer to high-voltage, insulated electric conductors comprising a core having ~ a number of strand parts of conducting material such as copper, for instance, an inner semiconducting layer surrounding the core, a high-voltage insulating layer surrounding the inner semiconducting layer, and an outer semi-conducting layer surrounding the insulating layer. A synchronous machine with a stator winding
6 -which comprises this type of cable can be designed for direct connection to the power network at higher volt-ages than with conventional machines, thus eliminating the need for a step-up transformer. In the case of re-active power production it is advantageous to use a ma chine designed for direct connection to transmission level, since the reactive power consumed in the step-up transformer in the conventional plant instead can be delivered to the power network with a machine according to the invention.
The advantages of the invention are particularly no-ticeable in a machine wound with a cable of the type described above, particularly a cable having a diameter within the interval 20-200 mm and a conducting area within the interval 80-3000 mm2. Such applications of the invention thus constitute preferred embodiments thereof .
Raising the rotor current limit has a number of advan-tages for a synchronous machine. It enables direct measurement of limiting stator temperatures, for in-stance. This is considerably more difficult if the limiting temperatures are located in the rotor since it is difficult to measure, or in any other way communi-cate with a rotating object. ~ Furthermore, reducing ac-tive power enables more reactive power to be produced.
This is also possible with conventional rotor dimen-sioning but more MVAr per reduced MW results in this case, as can be seen in the curves in Figures 1 and 2.
A number of other advantages are also gained by raising the rotor current limit, specific to this type of ma-chine. The time constants for heating (and cooling) the stator are large in comparison with a conventional machine. This means that the machine, with conven-
The advantages of the invention are particularly no-ticeable in a machine wound with a cable of the type described above, particularly a cable having a diameter within the interval 20-200 mm and a conducting area within the interval 80-3000 mm2. Such applications of the invention thus constitute preferred embodiments thereof .
Raising the rotor current limit has a number of advan-tages for a synchronous machine. It enables direct measurement of limiting stator temperatures, for in-stance. This is considerably more difficult if the limiting temperatures are located in the rotor since it is difficult to measure, or in any other way communi-cate with a rotating object. ~ Furthermore, reducing ac-tive power enables more reactive power to be produced.
This is also possible with conventional rotor dimen-sioning but more MVAr per reduced MW results in this case, as can be seen in the curves in Figures 1 and 2.
A number of other advantages are also gained by raising the rotor current limit, specific to this type of ma-chine. The time constants for heating (and cooling) the stator are large in comparison with a conventional machine. This means that the machine, with conven-
7 _ tional stator current limiters, can be run overloaded for longer than a conventional machine without damaging temperatures. being reached. Simulations indicate that the stator ~;afely can be overloaded 80 o for 15 minutes in some cas~=s. This extended time period can be util-ized to take' action either to reduce the system's need for reactive power, or to increase the production of reactive power. It is also easier to implement forced cooling of the stator of the machine. A machine of this type has a degree of efficiency comparable with that of a c~anventional machine, i . a . the stator losses are approximately equivalent. While a conventional ma-chine has primarily conductor losses, this type of ma-chine has less conductor losses and more core losses.
Since the core losses are developed at earth potential they are easier to cool away. A cooling machine can be used, for instance, for forced cooling in situations with high core temperatures.
With conventional current limiters the time period con-tributed by the time constant for heating, can be util-ized to reduce the active power and thus enable in-creased and/or prolonged production of reactive power.
The need for reducing the field is thus less and, in the best care, is eliminated.
With direct temperature measurement or temperature es-timation (or a combination thereof) we can pass from using the term "stator current limit" to talking about stator temperature limit(s). Since it is the stator temperature (in critical points), and not the stator current, that is limiting, this offers a number of ad-- vantages. 'rhe general tendency to set the limiter con servatively can thus be lessened since it is the pri mary quantity that is known and not a derivative. With a conventional current limiter no consideration can be taken to the temperature of the machine when the cur-rent limit is exceeded, i.e. no consideration can be taken to the fact, for instance, that the machine was started shortly before the current limit was exceeded, or that the load was low shortly before. This can be avoided by using stator temperature limits) instead.
Cooling of the machine is dimensioned so that the sta-tor in continuous rated operation does not exceed a certain temperature - let us call this the rated tem-perature. This temperature is consciously set conser vatively, i.e. the stator (insulation) can withstand higher temperatures for long periods of time. If the temperature in the critical points is known the machine can be run above rated operation for relatively long periods.
Dimensioning the rotor with salient poles (hydro-electric generators) in synchronous machines according to the invention is facilitated by the fact that the inner diameter of the stator can be made larger than in conventional machines since the stator winding is com-posed of cable in which the insulation takes up more space. It is thus possible to design the stator for this type of synchronous machine in accordance with conventional dimensioning procedures and change only the design of the rotor so that the rotor current limit is raised in the desired manner.
For a synchronous machine incorporating an air-cooled rotor with salient poles, this can be done, for in-stance, by utilizing the extra space to wind extra turns of the field winding in order to increase the magnetic pole voltage. A certain number of turns in the field winding then consist of cooling turns, thus increasing the cooled surface of the field winding. If the extra turns are provided with the same proportion 9 _ of cooling turns, as the other turns the temperature increase in the field winding can be kept at the same level as in a conventional dimensioning procedure, de-spite the magnetic pole voltage being raised.
For a synchronous machine with cylindrical rotor (turbo-rotor) the rotor current limit can be increased by making the machine longer, for instance.
The invention will now be explained in more detail in the following with reference to the accompanying draw-ings in which Figures 1 anal 2 show capability graphs for overexcited synchronous machines with conventional dimen-sioning and in accordance with the invention, respectively, Figure 3 shows a cross section through the cable used for the stator winding in the synchronous ma chine according to the invention, Figures ~ and 5 show two embodiments of a temperature estimator in the synchronous machine according to the invention, Figure 6 shows an example of a temperature-monitoring circuit that emits an output signal for further control, and Figures 7 - 9 show various circuits for control of the synchronous machine according to the invention.
Figure 3 shows a cross section through a cable used in ' the present invention. The cable is composed of a con-ductor consp_sting of a number of strand parts 2 made of copper, for instance, and having circular cross sec-tion. This conductor is arranged in the middle of the cable 1 and around the conductor is a first semicon-ducting layer 3. Around the first semiconducting layer _ 3 is an insulating layer, e.g. XLPE-insulation, and around the insulating layer is a second semiconducting layer that is normally earthed.
5 In the machine according to the invention the windings are thus preferably cables of a type having solid, ex-truded insulation, such as those used nowadays for power distribution, e.g. XLPE-cables or cables with EPR-insulation. Such cables are flexible, which is an 10 important property in this context since the technology for the device according to the invention is based pri-marily on winding systems in which the winding is formed from cable which is bent during assembly. The flexibility of a XLPE-cable normally corresponds to a radius of curvature of approximately 20 cm for a cable 30 mm in diameter, and a radius of curvature of ap-proximately 65 cm for a cable 80 mm in diameter. In the present application the term "flexible" is used to indicate that the winding is flexible down to a radius of curvature in the order of four times the cable di-ameter, preferably eight to twelve times the cable di-ameter.
Windings in the present invention are constructed to retain their properties even when they are bent and when they are subjected to thermal stress during opera-tion. It is vital that the layers retain their adhe-sion to each other in this context. The material prop-erties of the layers are decisive here, particularly their elasticity and relative coefficients of thermal expansion. In a XLPE-cable, for instance, the insulat-ing layer consists of cross-linked, low-density poly-ethylene, and the semiconducting layers consist of polyethylene with soot and metal particles mixed in.
Changes in volume as a result of temperature fluctua-tions are completely absorbed as changes in radius in WO 9$/34312 PCT/SE98/00174 11 ._ the cable and, thanks to the comparatively slight dif-ference between the coefficients of thermal expansion in the layers in relation to the elasticity of these materials, radial expansion can take place without the adhesion between the layers being lost.
The material combinations stated above should be con-sidered only as examples. Other combinations fulfill-ing the conditions specified and also the condition of being semic:onducting, i.e. having resistivity within the range of 10-1-106 ohm-cm, e.g. 1-500 ohm-cm, or 10-200 ohm-cm, naturally also fall within the scope of the invention.
The insulating layer may consist, for example, of a solid thermoplastic material such as low-density poly-ethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polybutylene (PB), polymethyl pen-tene (PMP), cross-linked materials such as cross-linked polyethylene (XLPE), or rubber such as ethylene propyl-ene rubber (EPR) or silicon rubber.
The inner and outer semiconducting layers may be of the same basic material but with particles of conducting material such as soot or metal powder mixed in.
The mechanical properties of these materials, particu-larly their coefficients of thermal expansion, are af-fected relatively little by whether soot or metal pow-der is mixed in or not - at least in the proportions required tc> achieve the conductivity necessary accord-ing to the invention. The insulating layer and the semiconducting layers thus have substantially the same coefficients of thermal expansion.
12 _ Ethylene-vinyl-acetate copolymers/nitrile rubber, butyl graft polyethylene, ethylene-butyl-acrylate-copolymers and ethylene-ethyl-acrylate copolymers may also consti-tute suitable polymers for the semiconducting layers.
Even when different types of material are used as base in the various layers, it is desirable for their coef ficients of thermal expansion to be substantially the same. This is the case with combination of the materi als listed above.
The materials listed above have relatively good elas-ticity, with an E-modulus of E<500 MPa, preferably <200 MPa. The elasticity is sufficient for any minor differences between the coefficients of thermal expan-sion for the materials in the layers to be absorbed in the radial direction of the elasticity so that no cracks appear, or any other damage, and so that the layers are not released from each other. The material in the layers is elastic, and the adhesion between the layers is at least of the same magnitude as the weakest of the materials.
The conductivity of the two semiconducting layers is sufficient to substantially equalize the potential along each layer. The conductivity of the outer semi-conducting layer is sufficiently great to enclose the electrical field in the cable, but sufficiently small not to give rise to significant losses due to currents induced in the longitudinal direction of the layer.
Thus, each of the two semiconducting layers essentially constitutes one equipotential surface and the winding, with these layers, will substantially enclose the elec trical field within it.
There is, of course, nothing to prevent one or more ad-ditional serniconducting layers being arranged in the insulating layer.
As mentioned above, the stator current limit is ther-mally restricted in the present invention. It is the insulation ~1 that sets the limit in the first place.
If a cable with XLPE-insulation is used, the tempera-ture of the layer between the conductor and the insula-tion should not exceed 90°C, which is the maximum tem-perature at rated operation and normal location in earth, for :instance, i.a. the insulation can withstand this temperature for several hours and it may be briefly somewhat exceeded. The temperature of the sur-face layer between the insulation and the iron' in the stator should not exceed a temperature limit of typi-cally 55°C, i.e. the temperature difference over the insulation will be at least 35°C.
A synchronous machine according to the invention may be dimensioned for a temperature of 70-80°C in the conduc-tor and a core temperature of 40-50°C at rated opera-tion. These temperatures are extremely dependent on the temperature of the coolant. A cooling machine may be used to lower this temperature although in normal operation this has a negative effect on the degree of efficiency. On the other hand, connection of such a machine may be justified in an emergency situation, al-though it must be taken into consideration that it may take a relatively long time to start up.
In order to make maximum use of the thermal inertia in the stator in a synchronous machine according to the invention it. is desirable for the surrounding conductor and iron temperatures to be determined in the part of the insulation most critical from the heating aspect.
This can be achieved by direct measurement using meas uring devices, or with a temperature estimator of the type shown in Figure 9. It is also possible to combine temperature measurement and temperature estimation ac s cording to Figure 5.
In Figure 4 losses in conductors caused by the stator current, and thus dependent on the machine's loading, are represented by a current source PLE, and the core losses caused by the flux (voltage), which are more or less constant irrespective of the load, by a current source PFE. The temperature of the coolant is repre-sented by the voltage source TKy. RR+S represents thermal resistance for cooling tubes and silicon fill-ing, RISO thermal resistance for the insulation and CLE. CISO and CFE, the thermal capacitance for conduc-tor, insulation and core. TLE in point 59 represents the temperature in the conductor and TISO in point 52 the mean temperature of the insulation. The model shown in Figure 9 can be calibrated by comparison of TFE with directly measured iron temperature. The tem-perature TLE is relatively difficult and expensive to measure directly since the conductor is normally at high potential.
The model shown in Figure 4 can also be refined by di-viding the thermal resistance between conductor and iron into several resistances connected in series, which would correspond to different radii of the insu-lation. By placing a capacitance from a point between each consecutive resistance and a reference tempera-ture, 0°C, any temperature dependence of the thermal capacitance of the insulation can be modelled more pre-cisely. Since a temperature gradient exists in the in-sulation, such a division would result in a somewhat improved result.
15 _ In Figure 9 the temperatures TLE~ TISO and TFE are considered as states whereas TKy~ PLE and PFE are considered as input signals. The initial state values are needed to start the temperature estimator and the estimator is normally started simultaneously with the machine, i . E: . from cold machine .
The number of nodes can of course be increased, but the embodiments described in connection with Figure 4 and below in connection with Figure 5 are to be preferred.
Figure 5 shows a modification of the temperature esti-mator in Figure 4, in which the iron temperature TFE is IS measured directly. The iron temperature will then be represented by a voltage source TFE in the thus simpli fied diagram, and serves as input signal, together with PLE . The temperatures TISO and TLE constitute states and are obtained in the points 52 and 59 in the same way as in Figure 9.
The copper losses are dependent on the stator current and thus on how heavily loaded the machine is. The iron losses are dependent on the flux, which is more or less constant at terminal voltage, depending on the load. The time constant for the temperature increase and cooling of the core circuit is, on the other hand, extremely large in this type of machine and the machine therefore has greater overload capacity if it has just been started.
Both the iron losses and the copper losses will de-crease if the field is reduced.
An advantage of the synchronous machine according to the invention in comparison with a conventional machine is that the electric losses are more associated with the flux in the core than with currents in the conduc-tors in the armature circuit . The core losses are de-veloped at earth potential, which facilitates normal cooling and even forced cooling with cooling machines.
The conductors of the armature circuit have relatively low current density and the losses on the high-voltage potential are relatively small.
The time constant for heating - and thus cooling - the core circuit is extremely large. Calculations show that the adiabatic temperature increase occurs in the order of hundredths of oK/s. The temperature increase in the armature circuit is also somewhat elevated as a result of the great thermal resistance in the solid in sulation of the winding cable. At the current densi ties in question the adiabatic temperature increases by 1/30 to 1/100 oK/s, while conventional machines have an adiabatic temperature increase in the order of 1/10 oK/s.
Both the temperature in the conductor TLE, and in the core TFE must be monitored and Figure 6 illustrates an example of a monitoring circuit that emits an output signal for further control. This circuit thus com-prises a temperature estimator 2 according to Figure 4, to which the input magnitudes I (stator current), L3 (terminal voltage) and TKy are supplied. The output signals TLE, and TFE are obtained from the estimator 2, these being compared at 4 and 6, respectively, with pre-set limit values TL,LE, and TL, FE , as mentioned above, and the result of the comparison is supplied to a gate 8 (Lowest Value Gate). This gate emits a con-trol signal at its output constituting the temperature difference between temperature and temperature limit which is greatest in absolute terms.
If TFE is measured directly, only TLE, need be deter-mined from I and TFE with the aid of the temperature estimator. If both TFE and TLE~ are measured directly, no temperature estimator is required and the measured temperatures are instead compared directly with the limit values.
Figure 7 shows in block diagram form an example of a control circuit for reducing the active power if the stator current: exceeds a maximum permissible limit value.
A synchronous generator G is connected to a power net-IS work via a breaker 10. The generator G is excited via a thyristor-rectifier 12. The voltage U is supplied via a voltage transformer PTg to a measured value con-verter 14, a unit IL"Prod" for determining of the ac-tual stator current limit IL, and to a unit OP"Prod"
for generating a signal "0P order" for reducing the ac-tive power if the stator current exceeds the stator.
current limit. In the same way, the current I~ is supplied via a current transformer CTg to the units IL
"Prod" and ~P"Prod". In the unit IL "Prod" the direc-tion of the reactive power, voltage drop and initial time delay allowed for reducing the field are taken into consideration when determining the stator current limit. The stator current limit is based on the stator temperature at rated operation (TLE~ - 70-80oC and TFE
- 40-50oC with XLPE-insulation). The rate of reduction and maximum range for the reduction of the active power is also determined in the unit OP"Prod", as well as a function, if any, for returning to the active power production the synchronous machine had before the sta-for current limit was exceeded, if the reactive power requirement of the system again decreases.
18 _ The maximum reactive power the synchronous machine in the embodiment described can produce in steady state operation is equivalent to 100$ of rated power and is obtained when the active power has been reduced to . zero. However, there is cause to introduce a lower limit greater than zero for reducing of active power, since further reduction of active power gives little in return of increased ability to produce reactive power, see Figure 2. If more reactive power is required in steady state operation, this must be meet by a reduc-tion of the field after an appropriate time delay.
The output signal U from the network converter 14 is compared at 16 with a predetermined reference value UREF and the result of the comparison is supplied to an amplifier and signal-processing unit 18 before being supplied to a gate 20.
At 22 the stator current I is compared with the stator current limit IL generated in the unit IL"Prod", and the result of the comparison is supplied to an ampli-fier and signal-processing unit 24 and a subsequent block 26 with non-linear characteristic. The non-linear characteristic is such that a large output signal is obtained for positive input signals and an output sig-nal proportional to the input signal for negative input signals. The output signal from the block 26 is also supplied to the gate 20 which is a Lowest Value Gate, i.e. the signal that is lowest is obtained as output signal.
The output signal from the gate 20 is supplied to a signal-processing unit 28 with integrating action which is in turn connected to a trigger circuit 30 for the rectifier 12 of the excitation machine.
19 _ The control circuit in Figure 7 comprises essentially three main parts: an automatic voltage regulator, a stator current limiter and a system for reducing the active effect in order to increase the ability of the synchronous machine to meet the system's demand for re-active effect at the desired voltage level.
Reduction of the field current can be achieved in sev-eral ways according to the invention. A traditional limiter may thus be used that operates on the principle that if the stator current exceeds the stator current limit during a maximum permissible period, the field current is lowered until the stator current becomes equal to the stator current limit.
The actual control may be effected in various ways. Tn this case the initial time delay must be at least long enough to ensure that brief large currents arising out of error conditions in the system do not cause reduc-tion of the field because the current limit has been exceeded. Various methods of time delay are possible, a . g . a constant delay time irrespective of by how much the current exceeds the limit, or inverse time charac-teristic, i . a . the more the current exceeds the limit, the shorter the time delay. ~ If the stator current limit has been exceeded, a period of time must be al-lowed for cooling. The type of synchronous machine un-der consideration has large time constants with regard to heating and cooling of the stator and the time delay can therefore be large in comparison with in the case of a conventional machine. This is because time is al lowed either to reduce the system's demand for reactive power or increase the machine's ability to produce re active power.
20 _ The dimensioning of the machine, together with reduc-tion of active power increases the machine's ability to produce reactive power.
According to the invention reduction of the field cur-rent is also possible starting from the temperature at the most critical points. The temperature of the con-ductors in the stator and the core temperature in the stator at the most critical points can be determined either through direct measurement, which may be diffi-cult in the case of conductor temperature, or with the aid of a temperature estimator with copper losses (stator current), iron losses (voltage) and coolant temperature as input signals, as discussed above. Two IS modes are thus possible for control, namely:
1) if the temperatures are below their maximum permissible temperature limits the field current is controlled so that the terminal voltage becomes equal to the desired operating voltage, and 2) if the terminal voltage is less than the desired operating voltage, the field current is con trolled so that the conductor temperature or core tem perature becomes equal to the maximum permissible tem perature limit and the other temperature is below its 1 imit .
The transition point where the stator temperature is equal to the maximum permissible stator temperature and the terminal voltage is equal to the desired operation voltage can be realized with a Lowest Value Gate, as described in connection with the figure.
Mode 1 above corresponds to normal voltage control, whereas mode 2 protects the machine against high tem-peratures since terminal voltage and stator temperature decrease when the field current decreases.
21 _ . Figure 8 shows a control circuit for achieving control of the above-mentioned type.
Besides the current I~ and the voltage U~ , the unit DT"Prod" is also supplied with the temperature TKy of the coolant .. The output signal from the unit OT"Prod"
is supplied' to an amplifier and signal-processing unit 40 and the block 26 with non-linear characteristic, as described earlier, for supply to the gate 20 together with the processed and amplified output signal from comparison of the voltage U with desired operation voltage Uref. Depending on the output signal from the gate 20, control of the machine is then carried out in a manner corresponding to that described in the embodi-ment according to Figure 7.
If the limiting temperature (TLE or TFE) approaches its maximum temperature limit (e. g. TL,LE, - 90oC and TL, FE
- 55°C with x:LPE-insulation) with a time derivative greater than zero, the above control may result in an "over-swing" :in the temperature. If this over-temperature is brief, and providing it is moderate, it does not constitute a serious risk to the insulation.
However, it may result in a temporary voltage drop that may upset the stability of the~power system, as a re-sult of the control circuit attempting to counteract the over-tempe_=ature by reducing the field.
To avoid this, the control circuit may be supplemented with a temperature predicting circuit, e.g. based on the time derivative of the temperature, so that even before maximum temperature is reached, the voltage is permitted to gently start falling. The "over-swing" in temperature will then be slight, or altogether elimi-nated.
22 ._ The voltage will thus commence falling earlier, but not so quickly.
A comparison between a traditional current limiter ac-cording to Figure 7 and a stator temperature limiter according to Figure 8 shows the latter to have the ad-vantage of allowing overload over a long period of time, in the order of hours, whereas the traditional current limiter only permits overload for a short pe-riod of time, in the order of seconds - minutes.
If the machine is equipped with stator temperature lim-iters, however, a warning signal should be sent to the operating centre as soon as the temperature for rated operation is exceeded, since this indicates that an overload situation exists and should be remedied.
Figure 9 shows a further development of the control circuit in Figure 7. Here a restricted control based on the temperature, aimed at maintaining the terminal voltage at as acceptable a level as possible for as long as possible by utilizing the thermal capacity of the stator to the maximum, is combined with a control of active and reactive power.
An output signal is thus generated in the unit OT"Prod"
in the same way as in the circuit according to Figure
Since the core losses are developed at earth potential they are easier to cool away. A cooling machine can be used, for instance, for forced cooling in situations with high core temperatures.
With conventional current limiters the time period con-tributed by the time constant for heating, can be util-ized to reduce the active power and thus enable in-creased and/or prolonged production of reactive power.
The need for reducing the field is thus less and, in the best care, is eliminated.
With direct temperature measurement or temperature es-timation (or a combination thereof) we can pass from using the term "stator current limit" to talking about stator temperature limit(s). Since it is the stator temperature (in critical points), and not the stator current, that is limiting, this offers a number of ad-- vantages. 'rhe general tendency to set the limiter con servatively can thus be lessened since it is the pri mary quantity that is known and not a derivative. With a conventional current limiter no consideration can be taken to the temperature of the machine when the cur-rent limit is exceeded, i.e. no consideration can be taken to the fact, for instance, that the machine was started shortly before the current limit was exceeded, or that the load was low shortly before. This can be avoided by using stator temperature limits) instead.
Cooling of the machine is dimensioned so that the sta-tor in continuous rated operation does not exceed a certain temperature - let us call this the rated tem-perature. This temperature is consciously set conser vatively, i.e. the stator (insulation) can withstand higher temperatures for long periods of time. If the temperature in the critical points is known the machine can be run above rated operation for relatively long periods.
Dimensioning the rotor with salient poles (hydro-electric generators) in synchronous machines according to the invention is facilitated by the fact that the inner diameter of the stator can be made larger than in conventional machines since the stator winding is com-posed of cable in which the insulation takes up more space. It is thus possible to design the stator for this type of synchronous machine in accordance with conventional dimensioning procedures and change only the design of the rotor so that the rotor current limit is raised in the desired manner.
For a synchronous machine incorporating an air-cooled rotor with salient poles, this can be done, for in-stance, by utilizing the extra space to wind extra turns of the field winding in order to increase the magnetic pole voltage. A certain number of turns in the field winding then consist of cooling turns, thus increasing the cooled surface of the field winding. If the extra turns are provided with the same proportion 9 _ of cooling turns, as the other turns the temperature increase in the field winding can be kept at the same level as in a conventional dimensioning procedure, de-spite the magnetic pole voltage being raised.
For a synchronous machine with cylindrical rotor (turbo-rotor) the rotor current limit can be increased by making the machine longer, for instance.
The invention will now be explained in more detail in the following with reference to the accompanying draw-ings in which Figures 1 anal 2 show capability graphs for overexcited synchronous machines with conventional dimen-sioning and in accordance with the invention, respectively, Figure 3 shows a cross section through the cable used for the stator winding in the synchronous ma chine according to the invention, Figures ~ and 5 show two embodiments of a temperature estimator in the synchronous machine according to the invention, Figure 6 shows an example of a temperature-monitoring circuit that emits an output signal for further control, and Figures 7 - 9 show various circuits for control of the synchronous machine according to the invention.
Figure 3 shows a cross section through a cable used in ' the present invention. The cable is composed of a con-ductor consp_sting of a number of strand parts 2 made of copper, for instance, and having circular cross sec-tion. This conductor is arranged in the middle of the cable 1 and around the conductor is a first semicon-ducting layer 3. Around the first semiconducting layer _ 3 is an insulating layer, e.g. XLPE-insulation, and around the insulating layer is a second semiconducting layer that is normally earthed.
5 In the machine according to the invention the windings are thus preferably cables of a type having solid, ex-truded insulation, such as those used nowadays for power distribution, e.g. XLPE-cables or cables with EPR-insulation. Such cables are flexible, which is an 10 important property in this context since the technology for the device according to the invention is based pri-marily on winding systems in which the winding is formed from cable which is bent during assembly. The flexibility of a XLPE-cable normally corresponds to a radius of curvature of approximately 20 cm for a cable 30 mm in diameter, and a radius of curvature of ap-proximately 65 cm for a cable 80 mm in diameter. In the present application the term "flexible" is used to indicate that the winding is flexible down to a radius of curvature in the order of four times the cable di-ameter, preferably eight to twelve times the cable di-ameter.
Windings in the present invention are constructed to retain their properties even when they are bent and when they are subjected to thermal stress during opera-tion. It is vital that the layers retain their adhe-sion to each other in this context. The material prop-erties of the layers are decisive here, particularly their elasticity and relative coefficients of thermal expansion. In a XLPE-cable, for instance, the insulat-ing layer consists of cross-linked, low-density poly-ethylene, and the semiconducting layers consist of polyethylene with soot and metal particles mixed in.
Changes in volume as a result of temperature fluctua-tions are completely absorbed as changes in radius in WO 9$/34312 PCT/SE98/00174 11 ._ the cable and, thanks to the comparatively slight dif-ference between the coefficients of thermal expansion in the layers in relation to the elasticity of these materials, radial expansion can take place without the adhesion between the layers being lost.
The material combinations stated above should be con-sidered only as examples. Other combinations fulfill-ing the conditions specified and also the condition of being semic:onducting, i.e. having resistivity within the range of 10-1-106 ohm-cm, e.g. 1-500 ohm-cm, or 10-200 ohm-cm, naturally also fall within the scope of the invention.
The insulating layer may consist, for example, of a solid thermoplastic material such as low-density poly-ethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polybutylene (PB), polymethyl pen-tene (PMP), cross-linked materials such as cross-linked polyethylene (XLPE), or rubber such as ethylene propyl-ene rubber (EPR) or silicon rubber.
The inner and outer semiconducting layers may be of the same basic material but with particles of conducting material such as soot or metal powder mixed in.
The mechanical properties of these materials, particu-larly their coefficients of thermal expansion, are af-fected relatively little by whether soot or metal pow-der is mixed in or not - at least in the proportions required tc> achieve the conductivity necessary accord-ing to the invention. The insulating layer and the semiconducting layers thus have substantially the same coefficients of thermal expansion.
12 _ Ethylene-vinyl-acetate copolymers/nitrile rubber, butyl graft polyethylene, ethylene-butyl-acrylate-copolymers and ethylene-ethyl-acrylate copolymers may also consti-tute suitable polymers for the semiconducting layers.
Even when different types of material are used as base in the various layers, it is desirable for their coef ficients of thermal expansion to be substantially the same. This is the case with combination of the materi als listed above.
The materials listed above have relatively good elas-ticity, with an E-modulus of E<500 MPa, preferably <200 MPa. The elasticity is sufficient for any minor differences between the coefficients of thermal expan-sion for the materials in the layers to be absorbed in the radial direction of the elasticity so that no cracks appear, or any other damage, and so that the layers are not released from each other. The material in the layers is elastic, and the adhesion between the layers is at least of the same magnitude as the weakest of the materials.
The conductivity of the two semiconducting layers is sufficient to substantially equalize the potential along each layer. The conductivity of the outer semi-conducting layer is sufficiently great to enclose the electrical field in the cable, but sufficiently small not to give rise to significant losses due to currents induced in the longitudinal direction of the layer.
Thus, each of the two semiconducting layers essentially constitutes one equipotential surface and the winding, with these layers, will substantially enclose the elec trical field within it.
There is, of course, nothing to prevent one or more ad-ditional serniconducting layers being arranged in the insulating layer.
As mentioned above, the stator current limit is ther-mally restricted in the present invention. It is the insulation ~1 that sets the limit in the first place.
If a cable with XLPE-insulation is used, the tempera-ture of the layer between the conductor and the insula-tion should not exceed 90°C, which is the maximum tem-perature at rated operation and normal location in earth, for :instance, i.a. the insulation can withstand this temperature for several hours and it may be briefly somewhat exceeded. The temperature of the sur-face layer between the insulation and the iron' in the stator should not exceed a temperature limit of typi-cally 55°C, i.e. the temperature difference over the insulation will be at least 35°C.
A synchronous machine according to the invention may be dimensioned for a temperature of 70-80°C in the conduc-tor and a core temperature of 40-50°C at rated opera-tion. These temperatures are extremely dependent on the temperature of the coolant. A cooling machine may be used to lower this temperature although in normal operation this has a negative effect on the degree of efficiency. On the other hand, connection of such a machine may be justified in an emergency situation, al-though it must be taken into consideration that it may take a relatively long time to start up.
In order to make maximum use of the thermal inertia in the stator in a synchronous machine according to the invention it. is desirable for the surrounding conductor and iron temperatures to be determined in the part of the insulation most critical from the heating aspect.
This can be achieved by direct measurement using meas uring devices, or with a temperature estimator of the type shown in Figure 9. It is also possible to combine temperature measurement and temperature estimation ac s cording to Figure 5.
In Figure 4 losses in conductors caused by the stator current, and thus dependent on the machine's loading, are represented by a current source PLE, and the core losses caused by the flux (voltage), which are more or less constant irrespective of the load, by a current source PFE. The temperature of the coolant is repre-sented by the voltage source TKy. RR+S represents thermal resistance for cooling tubes and silicon fill-ing, RISO thermal resistance for the insulation and CLE. CISO and CFE, the thermal capacitance for conduc-tor, insulation and core. TLE in point 59 represents the temperature in the conductor and TISO in point 52 the mean temperature of the insulation. The model shown in Figure 9 can be calibrated by comparison of TFE with directly measured iron temperature. The tem-perature TLE is relatively difficult and expensive to measure directly since the conductor is normally at high potential.
The model shown in Figure 4 can also be refined by di-viding the thermal resistance between conductor and iron into several resistances connected in series, which would correspond to different radii of the insu-lation. By placing a capacitance from a point between each consecutive resistance and a reference tempera-ture, 0°C, any temperature dependence of the thermal capacitance of the insulation can be modelled more pre-cisely. Since a temperature gradient exists in the in-sulation, such a division would result in a somewhat improved result.
15 _ In Figure 9 the temperatures TLE~ TISO and TFE are considered as states whereas TKy~ PLE and PFE are considered as input signals. The initial state values are needed to start the temperature estimator and the estimator is normally started simultaneously with the machine, i . E: . from cold machine .
The number of nodes can of course be increased, but the embodiments described in connection with Figure 4 and below in connection with Figure 5 are to be preferred.
Figure 5 shows a modification of the temperature esti-mator in Figure 4, in which the iron temperature TFE is IS measured directly. The iron temperature will then be represented by a voltage source TFE in the thus simpli fied diagram, and serves as input signal, together with PLE . The temperatures TISO and TLE constitute states and are obtained in the points 52 and 59 in the same way as in Figure 9.
The copper losses are dependent on the stator current and thus on how heavily loaded the machine is. The iron losses are dependent on the flux, which is more or less constant at terminal voltage, depending on the load. The time constant for the temperature increase and cooling of the core circuit is, on the other hand, extremely large in this type of machine and the machine therefore has greater overload capacity if it has just been started.
Both the iron losses and the copper losses will de-crease if the field is reduced.
An advantage of the synchronous machine according to the invention in comparison with a conventional machine is that the electric losses are more associated with the flux in the core than with currents in the conduc-tors in the armature circuit . The core losses are de-veloped at earth potential, which facilitates normal cooling and even forced cooling with cooling machines.
The conductors of the armature circuit have relatively low current density and the losses on the high-voltage potential are relatively small.
The time constant for heating - and thus cooling - the core circuit is extremely large. Calculations show that the adiabatic temperature increase occurs in the order of hundredths of oK/s. The temperature increase in the armature circuit is also somewhat elevated as a result of the great thermal resistance in the solid in sulation of the winding cable. At the current densi ties in question the adiabatic temperature increases by 1/30 to 1/100 oK/s, while conventional machines have an adiabatic temperature increase in the order of 1/10 oK/s.
Both the temperature in the conductor TLE, and in the core TFE must be monitored and Figure 6 illustrates an example of a monitoring circuit that emits an output signal for further control. This circuit thus com-prises a temperature estimator 2 according to Figure 4, to which the input magnitudes I (stator current), L3 (terminal voltage) and TKy are supplied. The output signals TLE, and TFE are obtained from the estimator 2, these being compared at 4 and 6, respectively, with pre-set limit values TL,LE, and TL, FE , as mentioned above, and the result of the comparison is supplied to a gate 8 (Lowest Value Gate). This gate emits a con-trol signal at its output constituting the temperature difference between temperature and temperature limit which is greatest in absolute terms.
If TFE is measured directly, only TLE, need be deter-mined from I and TFE with the aid of the temperature estimator. If both TFE and TLE~ are measured directly, no temperature estimator is required and the measured temperatures are instead compared directly with the limit values.
Figure 7 shows in block diagram form an example of a control circuit for reducing the active power if the stator current: exceeds a maximum permissible limit value.
A synchronous generator G is connected to a power net-IS work via a breaker 10. The generator G is excited via a thyristor-rectifier 12. The voltage U is supplied via a voltage transformer PTg to a measured value con-verter 14, a unit IL"Prod" for determining of the ac-tual stator current limit IL, and to a unit OP"Prod"
for generating a signal "0P order" for reducing the ac-tive power if the stator current exceeds the stator.
current limit. In the same way, the current I~ is supplied via a current transformer CTg to the units IL
"Prod" and ~P"Prod". In the unit IL "Prod" the direc-tion of the reactive power, voltage drop and initial time delay allowed for reducing the field are taken into consideration when determining the stator current limit. The stator current limit is based on the stator temperature at rated operation (TLE~ - 70-80oC and TFE
- 40-50oC with XLPE-insulation). The rate of reduction and maximum range for the reduction of the active power is also determined in the unit OP"Prod", as well as a function, if any, for returning to the active power production the synchronous machine had before the sta-for current limit was exceeded, if the reactive power requirement of the system again decreases.
18 _ The maximum reactive power the synchronous machine in the embodiment described can produce in steady state operation is equivalent to 100$ of rated power and is obtained when the active power has been reduced to . zero. However, there is cause to introduce a lower limit greater than zero for reducing of active power, since further reduction of active power gives little in return of increased ability to produce reactive power, see Figure 2. If more reactive power is required in steady state operation, this must be meet by a reduc-tion of the field after an appropriate time delay.
The output signal U from the network converter 14 is compared at 16 with a predetermined reference value UREF and the result of the comparison is supplied to an amplifier and signal-processing unit 18 before being supplied to a gate 20.
At 22 the stator current I is compared with the stator current limit IL generated in the unit IL"Prod", and the result of the comparison is supplied to an ampli-fier and signal-processing unit 24 and a subsequent block 26 with non-linear characteristic. The non-linear characteristic is such that a large output signal is obtained for positive input signals and an output sig-nal proportional to the input signal for negative input signals. The output signal from the block 26 is also supplied to the gate 20 which is a Lowest Value Gate, i.e. the signal that is lowest is obtained as output signal.
The output signal from the gate 20 is supplied to a signal-processing unit 28 with integrating action which is in turn connected to a trigger circuit 30 for the rectifier 12 of the excitation machine.
19 _ The control circuit in Figure 7 comprises essentially three main parts: an automatic voltage regulator, a stator current limiter and a system for reducing the active effect in order to increase the ability of the synchronous machine to meet the system's demand for re-active effect at the desired voltage level.
Reduction of the field current can be achieved in sev-eral ways according to the invention. A traditional limiter may thus be used that operates on the principle that if the stator current exceeds the stator current limit during a maximum permissible period, the field current is lowered until the stator current becomes equal to the stator current limit.
The actual control may be effected in various ways. Tn this case the initial time delay must be at least long enough to ensure that brief large currents arising out of error conditions in the system do not cause reduc-tion of the field because the current limit has been exceeded. Various methods of time delay are possible, a . g . a constant delay time irrespective of by how much the current exceeds the limit, or inverse time charac-teristic, i . a . the more the current exceeds the limit, the shorter the time delay. ~ If the stator current limit has been exceeded, a period of time must be al-lowed for cooling. The type of synchronous machine un-der consideration has large time constants with regard to heating and cooling of the stator and the time delay can therefore be large in comparison with in the case of a conventional machine. This is because time is al lowed either to reduce the system's demand for reactive power or increase the machine's ability to produce re active power.
20 _ The dimensioning of the machine, together with reduc-tion of active power increases the machine's ability to produce reactive power.
According to the invention reduction of the field cur-rent is also possible starting from the temperature at the most critical points. The temperature of the con-ductors in the stator and the core temperature in the stator at the most critical points can be determined either through direct measurement, which may be diffi-cult in the case of conductor temperature, or with the aid of a temperature estimator with copper losses (stator current), iron losses (voltage) and coolant temperature as input signals, as discussed above. Two IS modes are thus possible for control, namely:
1) if the temperatures are below their maximum permissible temperature limits the field current is controlled so that the terminal voltage becomes equal to the desired operating voltage, and 2) if the terminal voltage is less than the desired operating voltage, the field current is con trolled so that the conductor temperature or core tem perature becomes equal to the maximum permissible tem perature limit and the other temperature is below its 1 imit .
The transition point where the stator temperature is equal to the maximum permissible stator temperature and the terminal voltage is equal to the desired operation voltage can be realized with a Lowest Value Gate, as described in connection with the figure.
Mode 1 above corresponds to normal voltage control, whereas mode 2 protects the machine against high tem-peratures since terminal voltage and stator temperature decrease when the field current decreases.
21 _ . Figure 8 shows a control circuit for achieving control of the above-mentioned type.
Besides the current I~ and the voltage U~ , the unit DT"Prod" is also supplied with the temperature TKy of the coolant .. The output signal from the unit OT"Prod"
is supplied' to an amplifier and signal-processing unit 40 and the block 26 with non-linear characteristic, as described earlier, for supply to the gate 20 together with the processed and amplified output signal from comparison of the voltage U with desired operation voltage Uref. Depending on the output signal from the gate 20, control of the machine is then carried out in a manner corresponding to that described in the embodi-ment according to Figure 7.
If the limiting temperature (TLE or TFE) approaches its maximum temperature limit (e. g. TL,LE, - 90oC and TL, FE
- 55°C with x:LPE-insulation) with a time derivative greater than zero, the above control may result in an "over-swing" :in the temperature. If this over-temperature is brief, and providing it is moderate, it does not constitute a serious risk to the insulation.
However, it may result in a temporary voltage drop that may upset the stability of the~power system, as a re-sult of the control circuit attempting to counteract the over-tempe_=ature by reducing the field.
To avoid this, the control circuit may be supplemented with a temperature predicting circuit, e.g. based on the time derivative of the temperature, so that even before maximum temperature is reached, the voltage is permitted to gently start falling. The "over-swing" in temperature will then be slight, or altogether elimi-nated.
22 ._ The voltage will thus commence falling earlier, but not so quickly.
A comparison between a traditional current limiter ac-cording to Figure 7 and a stator temperature limiter according to Figure 8 shows the latter to have the ad-vantage of allowing overload over a long period of time, in the order of hours, whereas the traditional current limiter only permits overload for a short pe-riod of time, in the order of seconds - minutes.
If the machine is equipped with stator temperature lim-iters, however, a warning signal should be sent to the operating centre as soon as the temperature for rated operation is exceeded, since this indicates that an overload situation exists and should be remedied.
Figure 9 shows a further development of the control circuit in Figure 7. Here a restricted control based on the temperature, aimed at maintaining the terminal voltage at as acceptable a level as possible for as long as possible by utilizing the thermal capacity of the stator to the maximum, is combined with a control of active and reactive power.
An output signal is thus generated in the unit OT"Prod"
in the same way as in the circuit according to Figure
8. This signal is supplied to the amplifier and sig-nal-processing unit 40, block 26 and gate 20 to achieve the same limiting control as in Figure 8. The output signal from the unit OT"Prod" is also supplied to the unit ~P"Prod", together with the voltage U~ , whereupon a control signal 0P order is obtained as output signal from the unit OP"Prod" in order to reduce the active power to U=ref, i.e. the terminal voltage equal to de-sired operating voltage or until the active power reaches a predetermined minimum power limit, as men-tioned earlier.. The reduction of active power is pref-erably commenced when either the core or the conductor temperature exceeds the temperatures the machine is di-mensioned for.
Yet another control possibility is based on starting a cooling machine to lower the iron and copper tempera-tunes when eii~her a current or temperature limit is reached. This. enables the machine to be loaded fur-ther.
Yet another control possibility is based on starting a cooling machine to lower the iron and copper tempera-tunes when eii~her a current or temperature limit is reached. This. enables the machine to be loaded fur-ther.
Claims (38)
1. A synchronous machine with power and/or voltage control, comprising a stator with a stator winding and a rotor with a field winding, characterized in that the stator winding comprises a high-voltage cable with solid insulation and a rotor having a thermally based rotor current limit intersecting with a thermally based stator current limit in a capability graph at a power factor considerably below the rated power factor or having the thermally based rotor current limit above the thermally based stator current limit in the capability graph, and means for limiting the currents in order to avoid thermal damage.
2. A synchronous machine according to claim 1, characterized in that the means for limiting currents comprises temperature-determining members to determine the temperature of the stator at at least one point critical to heating and/or a current measuring device and a voltage measuring device for measuring stator current and voltage, and also a control circuit connected to the temperature-determining members and/or current-measuring and voltage-measuring devices, to reduce the active power or field current if the temperature and/or stator current or stator voltage exceeds predetermined limit values.
3. A synchronous machine as claimed in claim 2, characterized in that the temperature-determining members comprise at least one measuring device arranged at a point in the stator that is susceptible to heating, in order to measure the temperature there.
25 9. A synchronous machine as claimed in claim 3, characterized in that the measuring device is placed on the slot wall inside a winding slot in the stator.
5. A synchronous machine as claimed in claim 2, characterized in that the temperature-determining members comprise a temperature estimator arranged to determine the temperature of the stator laminations on the basis of the core losses and losses in conductors and the temperature of the coolant, at a critical point for heating, in order to induce the control circuit to reduce the field current if the temperature determined exceeds a predetermined limit value.
6. A synchronous machine as claimed in any of claims 2-5, characterized in that the temperature-determining members comprise temperature estimators arranged to determine the temperature in the conductors and in essential parts of the cable insulation, from the losses in the conductors.
7. A synchronous machine as claimed in any of claims 2-6, characterized in that the control circuit is arranged, upon increasing stator temperature, to commence reduction of the field current at a temperature below the maximum permissible stator temperature.
8. A synchronous machine as claimed in any of claims 1-7, characterized in that the control circuit is arranged to commence reduction after the temperature has been above rated operating temperature, i.e. the temperature against which the machine is dimensioned at rated operation, but below the maximum permissible stator temperature, for a predetermined period of time.
9. A synchronous machine as claimed in any of claims 1-8, characterized in that, if the stator current exceeds the stator current limit, the control circuit is arranged to control the field current so that the terminal voltage of the machine is equal to the desired operating voltage if the time during which the stator current has been above the stator current limit is shorter than the maximum permissible time, and, if the maximum permissible time has been exceeded, the control circuit is arranged to reduce the field current until the stator current becomes equal to the stator current limit.
10. A synchronous machine as claimed in claim 9, characterized in that the control circuit is arranged to commence reduction of the field current with a certain time delay after the stator current limit has been exceeded.
11. A synchronous machine as claimed in any of the preceding claims, characterized in that the field winding is designed with a number of extra turns in order to increase the magnetic pole voltage.
12. A synchronous machine as claimed in claim 11, characterized in that a certain, proportion of the extra turns are in the form of cooling turns for the winding.
13. A synchronous machine as claimed in any of the preceding claims, characterized in that the field winding is given increased conducting area in order to obtain relatively low current density in the winding.
27 19. A synchronous machine as claimed any of the preceding claims, characterized in that special cooling means are arranged for the field winding.
15. A synchronous machine as claimed in any of the preceding claims, characterized in that a cooling machine is arranged to be connected if the stator current exceeds or is predicted to exceed the stator current limit and/or the temperature measured exceeds a predetermined limit value, in order to achieve forced cooling.
16. A synchronous machine as claimed in any of the preceding claims, characterized in that the cable is a high-voltage cable and is of a type comprising a core having a plurality of strand parts, an inner semicon-ducting layer surrounding the core, an insulating layer surrounding the inner semiconducting layer, and an outer semi-conducting layer surrounding the insulating layer.
17. A synchronous machine as claimed in any of the preceding claims, characterized in that the high-voltage cable has a diameter within the interval 20-200 mm and a conducting area within the interval 80-3000 mm2.
18. A synchronous machine as claimed in any of the preceding claims, characterized in that the winding is flexible and in that said layers are in contact with each other.
19. A synchronous machine as claimed in any of the preceding claims, characterized in that said layers consist of materials with such elasticity and such a relation between the coefficients of thermal expansion of the materials that the changes in volume in the layers caused by temperature fluctuations during operation are absorbed by the elasticity of the materials so that the layers retain their adhesion to each other.
20. A synchronous machine as claimed in any of the preceding claims, characterized in that the materials in said layers have high elasticity, preferably with an E-modulus less than 500 MPa, most preferably less than 200 MPa.
21. A synchronous machine as claimed in any of the preceding claims, characterized in that the coefficients of thermal expansion for the materials in said layers are of substantially the same magnitude.
22. A synchronous machine as claimed in any of the preceding claims, characterized in that the adhesion between the layers is of at least the same magnitude as the strength of the weakest of the materials.
23. A synchronous machine as claimed in any of the preceding claims, characterized in that each of the semiconducting layers essentially constitutes one equipotential surface.
24. A synchronous machine as claimed in any of the preceding claims, characterized in that the rotor is of a type with salient poles.
25. A synchronous machine as claimed in any of claims 1-23, characterized in that the rotor is of cylindrical type.
26. A method for power and/or voltage control of a synchronous machine according to any of the previous claims, characterized in that the machine operates with the stator current exceeding the thermally based stator current limit for a certain time period less than the maximum permissible time limit, whereafter the overload is reduced by reduction of either the active power or the field current or a combination if both.
27. A method according to claims 26, characterized in that the machine is capable of operating with the stator current exceeding the thermally based stator current limit with at least 30 % for at least 3 minutes without risk of thermal damage, provided that the machine has raised temperature prior to the overload situation.
28. A method according to claim 26 or 27, characterized in that the machine is capable of operating with the stator current exceeding the thermally based stator current limit with at least 30 % for at least 5 minutes without risk of thermal damage, provided that the machine has rated temperature prior to the overload situation.
29. A method according to any of claims 26-28, characterized in that the machine is capable of operating with the stator current exceeding the thermally based stator current limit with at least 50 % for at least 5 minutes, preferably with at least 80 % for at least 15 minutes, without risk of thermal damage, provided that the machine has rated temperature prior to the overload situation.
30. A method for power and/or voltage control in a synchronous machine comprising a stator with a stator-winding and a rotor with a field winding, characterized in that the stator winding is wound of cable provided with solid high voltage insulation and in that the rotor of the machine is constructed so that the thermally based rotor and stator current limits intersect each other in the capability graph at a power factor value considerably below the rated power factor value, and in that the active power is reduced if the stator current increases so far as to incur risk of thermal damage.
31. A method as claimed in claim 30, wherein the stator current may be permitted to exceed the stator current limit for a predetermined maximum time, characterized in that if the stator current is above the stator current limit the active power is reduced until the stator current becomes equal to the stator current limit, provided that the time during which the stator current has been above the stator current limit is shorter than said maximum permissible time.
32. A method as claimed in claim 31, characterized in that if the stator current is above the stator current limit for a time exceeding the maximum permissible time, the active power and the field current are reduced until the stator current is equal to the stator current limit.
33. A method as claimed in any of claims 30-32, characterized in that the active power is reduced in accordance with a ramp function.
34. A method as claimed in any of claims 30-32, characterized in that the active power is reduced in accordance with a ramp function, if the stator current has exceeded the stator current limit but is below a predetermined second limit value above the stator current limit, and in that the active power is reduced as fast as possible if the stator current exceeds said second limit value.
35. A method as claimed in claim 33 or claim 34, characterized in that such a derivative is selected for the ramp function that power oscillations on the electric power network are avoided and that damage to turbines and other parts of the electric power production plant in which the synchronous machine is included is prevented.
36. A method as claimed in claim 33 or claim 34, characterized in that a derivative is selected for the ramp function, which is dependent on the time constant for warming up the stator.
37. A method as claimed in any of claims 33-36, characterized in that the active power is reduced so much that acceptable terminal voltage is maintained on the machine.
38. A method as claimed in any of claims 30-37, characterized in that the limit value for the power factor is zero.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9700367-7 | 1997-02-03 | ||
| SE9700367A SE510315C2 (en) | 1997-02-03 | 1997-02-03 | Synchronous machine, e.g. synchronous generator in electric power network |
| SE9704431A SE9704431D0 (en) | 1997-02-03 | 1997-11-28 | Power control of synchronous machine |
| SE9704431-7 | 1997-11-28 | ||
| PCT/SE1998/000174 WO1998034312A1 (en) | 1997-02-03 | 1998-02-02 | Synchronous machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2279414A1 true CA2279414A1 (en) | 1998-08-06 |
Family
ID=26662883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002279414A Abandoned CA2279414A1 (en) | 1997-02-03 | 1998-02-02 | Synchronous machine |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US6828701B1 (en) |
| EP (1) | EP1016179A1 (en) |
| JP (1) | JP2001510018A (en) |
| CN (1) | CN1080474C (en) |
| AU (1) | AU730760B2 (en) |
| BR (1) | BR9807131A (en) |
| CA (1) | CA2279414A1 (en) |
| NO (1) | NO993686L (en) |
| NZ (1) | NZ337069A (en) |
| PL (1) | PL334995A1 (en) |
| SE (1) | SE9704431D0 (en) |
| WO (1) | WO1998034312A1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE514068C2 (en) * | 1999-04-30 | 2000-12-18 | Abb Ab | Rotary power system stabilizer |
| US6204642B1 (en) * | 1999-08-06 | 2001-03-20 | General Electric Company | Method and apparatus for modifying limit and protection software in a synchronous generator exciter to match the capability of the turbine-generator |
| SE518216C2 (en) * | 2000-04-06 | 2002-09-10 | Abb Ab | Method of operation of synchronous compensator and such synchronous compensator. |
| US20020084655A1 (en) * | 2000-12-29 | 2002-07-04 | Abb Research Ltd. | System, method and computer program product for enhancing commercial value of electrical power produced from a renewable energy power production facility |
| RU2323512C2 (en) * | 2002-07-31 | 2008-04-27 | Э.Он Сверие Аб | Electrical machine |
| JP3992017B2 (en) * | 2004-05-18 | 2007-10-17 | 株式会社デンソー | Vehicle power generation system |
| JP4508748B2 (en) * | 2004-06-30 | 2010-07-21 | 大阪瓦斯株式会社 | In-house power generator centralized management system |
| WO2009076955A1 (en) * | 2007-12-14 | 2009-06-25 | Vestas Wind Systems A/S | Lifetime optimization of a wind turbine generator by controlling the generator temperature |
| US8129873B2 (en) * | 2010-04-05 | 2012-03-06 | General Electronic Company | Stator coil coolant flow reduction monitoring |
| EP2477325B1 (en) * | 2011-01-18 | 2019-04-24 | Vestas Wind Systems A/S | Method for operating an electromechanical generator |
| WO2012146250A2 (en) * | 2011-04-28 | 2012-11-01 | Vestas Wind Systems A/S | A variable wind turbine having a power dissipating unit; a method of operating a power dissipating unit in a wind turbine |
| CN102352815B (en) * | 2011-09-15 | 2013-08-21 | 新疆金风科技股份有限公司 | Wind generating set |
| US8901790B2 (en) | 2012-01-03 | 2014-12-02 | General Electric Company | Cooling of stator core flange |
| CN103001555B (en) * | 2012-11-16 | 2015-03-11 | 南京南瑞继保电气有限公司 | Synchronous motor armature overcurrent limiting method |
| CN104104290A (en) * | 2014-06-26 | 2014-10-15 | 刘芳彪 | Speed compensation type generator voltage stabilizing device and power-frequency permanent magnet generator set |
| CN106301130B (en) * | 2015-05-13 | 2019-04-05 | 北京和利时电机技术有限公司 | A kind of control method and system of the automatic load shedding of motor-driven dynamic overload |
| CN105515477B (en) * | 2015-12-14 | 2018-04-20 | 国电南瑞科技股份有限公司 | The implementation method of stator current limiter in a kind of excitation system |
| CN106059420B (en) * | 2016-07-07 | 2018-11-02 | 广西大学 | A kind of control method of magneto alternator for automobile |
| DE102016220536A1 (en) * | 2016-10-19 | 2018-04-19 | Volkswagen Aktiengesellschaft | Process for temperature derating of electrical machines |
| CN113141145B (en) * | 2020-01-16 | 2023-04-11 | 台达电子工业股份有限公司 | Working equipment system and control method applicable to same |
| CN111765055B (en) * | 2020-07-08 | 2023-02-03 | 中国船舶重工集团海装风电股份有限公司 | Refined safety protection method for power loop of wind turbine generator |
| KR102425497B1 (en) * | 2020-10-28 | 2022-07-27 | 주식회사 위드피에스 | Synchoronous generator, apparatus and method for monitoring of synchoronous generator, computer-readable storage medium and computer program |
| RU2755021C1 (en) * | 2021-02-17 | 2021-09-09 | Акционерное общество Специальные энергетические технологии | Generator hybrid switch |
Family Cites Families (439)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE425551C (en) | 1926-02-20 | Bbc Brown Boveri & Cie | Device for the magnetic closure of open slots in electrical machines | |
| DE426793C (en) | 1926-03-18 | Bbc Brown Boveri & Cie | Device for the magnetic closure of open slots in electrical machines | |
| DE336418C (en) | 1921-05-02 | Stanislaus Berger | Support for electrical lines to be led on walls | |
| DE568508C (en) | 1933-01-20 | Bbc Brown Boveri & Cie | AC high-voltage generator with at least two electrically separate windings | |
| DE523047C (en) | 1931-04-18 | Brown Boveir & Cie Ag | Process for the production of slot wedges with iron sheets layered transversely to the longitudinal direction of the wedge for electrical machines | |
| US1304451A (en) | 1919-05-20 | Locke h | ||
| DE435608C (en) | 1926-10-18 | Bbc Brown Boveri & Cie | Divided conductor for electrical machines | |
| DE572030C (en) | 1933-03-09 | Bbc Brown Boveri & Cie | Cooling device for the winding heads of high-voltage machines | |
| US681800A (en) | 1901-06-18 | 1901-09-03 | Oskar Lasche | Stationary armature and inductor. |
| DE372390C (en) | 1915-12-09 | 1923-03-27 | Bergmann Elek Citaets Werke Ak | Machine for the conversion or for the simultaneous generation of alternating currents of different frequencies with the same or different number of phases |
| GB123906A (en) | 1918-05-31 | 1919-03-13 | Brush Electrical Eng | Improvements in or pertaining to Windings in Electrical Apparatus. |
| US1418856A (en) | 1919-05-02 | 1922-06-06 | Allischalmers Mfg Company | Dynamo-electric machine |
| DE443011C (en) | 1919-07-19 | 1927-04-13 | Bbc Brown Boveri & Cie | Installation on high-voltage windings in electrical machines |
| US1481585A (en) | 1919-09-16 | 1924-01-22 | Electrical Improvements Ltd | Electric reactive winding |
| DE387973C (en) | 1921-06-04 | 1924-01-09 | Hellmuth Beyer | Arrangement of the coils to reduce the leakage in transformers with a disc-like winding structure |
| DE482506C (en) | 1921-07-09 | 1929-09-14 | Bbc Brown Boveri & Cie | Device for short-circuit-proof fastening of involute-shaped stator winding heads of air-cooled electrical machines |
| DE460124C (en) | 1922-10-10 | 1928-05-22 | Bbc Brown Boveri & Cie | Laminated magnetic wedge to close the winding grooves of electrical machines |
| US1756672A (en) | 1922-10-12 | 1930-04-29 | Allis Louis Co | Dynamo-electric machine |
| DE433749C (en) | 1923-11-25 | 1926-09-07 | Bbc Brown Boveri & Cie | Coil winding of alternating current machines, which carry very strong currents, with ring-shaped connecting conductors |
| DE432169C (en) | 1924-01-15 | 1926-07-26 | Bbc Brown Boveri & Cie | Device for the magnetic closure of open slots in electrical machines |
| DE435609C (en) | 1924-03-02 | 1926-10-18 | Bbc Brown Boveri & Cie | Divided conductor for electrical machines |
| DE441717C (en) | 1924-03-02 | 1927-03-11 | Bbc Brown Boveri & Cie | Divided conductor for electrical machines |
| GB268271A (en) | 1926-06-12 | 1927-03-31 | Pirelli & C | Improvements in or relating to joints for high tension electric cables |
| DE501181C (en) | 1927-02-19 | 1930-07-03 | Felten & Guilleaume Carlswerk | Process for the manufacture of cables for electrical overhead lines |
| GB292999A (en) | 1927-06-29 | 1929-04-11 | Siemens Ag | Arrangement of core segments in the casings of dynamo electric machines, rotary transformers and the like |
| GB293861A (en) | 1927-07-15 | 1928-11-08 | Westinghouse Electric & Mfg Co | Improvements in or relating to radio coupling devices and conductors therefor |
| US1728915A (en) | 1928-05-05 | 1929-09-24 | Earl P Blankenship | Line saver and restrainer for drilling cables |
| US1781308A (en) | 1928-05-30 | 1930-11-11 | Ericsson Telefon Ab L M | High-frequency differential transformer |
| US1762775A (en) | 1928-09-19 | 1930-06-10 | Bell Telephone Labor Inc | Inductance device |
| GB319313A (en) | 1928-09-20 | 1929-07-18 | Siemens Ag | The regulation of the electric potential of long lines |
| DE629301C (en) | 1929-02-28 | 1936-04-27 | Hartstoff Metall Akt Ges Hamet | Iron core for electrical machines |
| US1747507A (en) | 1929-05-10 | 1930-02-18 | Westinghouse Electric & Mfg Co | Reactor structure |
| US1742985A (en) | 1929-05-20 | 1930-01-07 | Gen Electric | Transformer |
| DE584639C (en) | 1929-12-28 | 1933-09-27 | Aeg | Corona protection for windings in electrical machines |
| US1861182A (en) | 1930-01-31 | 1932-05-31 | Okonite Co | Electric conductor |
| US1974406A (en) | 1930-12-13 | 1934-09-25 | Herbert F Apple | Dynamo electric machine core slot lining |
| DE604972C (en) | 1931-02-27 | 1934-10-12 | Otis Aufzugswerke Ges M B H | Door drive for elevators |
| DE586121C (en) | 1932-05-01 | 1933-10-18 | Felix Kleiss Dipl Ing | Process for the implementation of wires and tapes through baths |
| US2006170A (en) | 1933-05-11 | 1935-06-25 | Gen Electric | Winding for the stationary members of alternating current dynamo-electric machines |
| DE719009C (en) | 1935-05-30 | 1942-03-26 | Aeg | Equipment for the operation of electrical rail feeders |
| FR805544A (en) | 1936-04-29 | 1936-11-21 | Travail Electr Des Metaux Soc | Method and device for adjusting voltages in a static transformer |
| DE673545C (en) | 1936-07-30 | 1939-03-24 | Siemens Schuckertwerke Akt Ges | Multiphase scatter transformer made up of single-phase transformers |
| NL54036C (en) | 1937-09-15 | |||
| FR847899A (en) | 1937-12-23 | 1939-10-18 | Lignes Telegraph Telephon | Transformer |
| FR841351A (en) | 1938-01-19 | 1939-05-17 | Manufacturing process of laminated or divided magnetic circuits | |
| US2217430A (en) | 1938-02-26 | 1940-10-08 | Westinghouse Electric & Mfg Co | Water-cooled stator for dynamoelectric machines |
| US2206856A (en) | 1938-05-31 | 1940-07-02 | William E Shearer | Transformer |
| US2305153A (en) | 1938-11-26 | 1942-12-15 | Fries Eduard | Adjustable transformer with high reactance |
| FR864380A (en) | 1939-12-01 | 1941-04-25 | Entpr Chemin | Improvements to steam winches for piling piling and the like |
| GB540456A (en) | 1940-04-17 | 1941-10-17 | Austin Walters & Son Ltd | Improvements in or relating to self-regulating electric transformers |
| US2241832A (en) | 1940-05-07 | 1941-05-13 | Hugo W Wahlquist | Method and apparatus for reducing harmonics in power systems |
| US2256897A (en) | 1940-07-24 | 1941-09-23 | Cons Edison Co New York Inc | Insulating joint for electric cable sheaths and method of making same |
| US2295415A (en) | 1940-08-02 | 1942-09-08 | Westinghouse Electric & Mfg Co | Air-cooled, air-insulated transformer |
| US2251291A (en) | 1940-08-10 | 1941-08-05 | Western Electric Co | Strand handling apparatus |
| GB589071A (en) | 1942-03-27 | 1947-06-11 | Gen Electric Co Ltd | Improvements in protective shields in high-voltage apparatus |
| US2415652A (en) | 1942-06-03 | 1947-02-11 | Kerite Company | High-voltage cable |
| US2462651A (en) | 1944-06-12 | 1949-02-22 | Gen Electric | Electric induction apparatus |
| US2424443A (en) | 1944-12-06 | 1947-07-22 | Gen Electric | Dynamoelectric machine |
| US2459322A (en) | 1945-03-16 | 1949-01-18 | Allis Chalmers Mfg Co | Stationary induction apparatus |
| US2436306A (en) | 1945-06-16 | 1948-02-17 | Westinghouse Electric Corp | Corona elimination in generator end windings |
| US2446999A (en) | 1945-11-07 | 1948-08-17 | Gen Electric | Magnetic core |
| US2498238A (en) | 1947-04-30 | 1950-02-21 | Westinghouse Electric Corp | Resistance compositions and products thereof |
| DE875227C (en) | 1948-12-31 | 1953-04-30 | Siemens Ag | Rotary field machine with concentrated windings and pronounced poles with pole pieces |
| DE846583C (en) | 1949-02-18 | 1952-08-14 | Siemens Ag | Iron core for electrical devices, especially transformers, chokes or the like. |
| US2721905A (en) | 1949-03-04 | 1955-10-25 | Webster Electric Co Inc | Transducer |
| FR1011924A (en) | 1949-04-23 | 1952-07-01 | Improvements to rotating electrical machines | |
| GB685416A (en) | 1950-04-08 | 1953-01-07 | Westinghouse Electric Int Co | Improvements in or relating to stationary electrical induction apparatus |
| DE1638176U (en) | 1952-02-12 | 1952-05-15 | Bosch & Speidel | CUFF FOR BLOOD PRESSURE MEASUREMENT. |
| GB702892A (en) | 1952-02-14 | 1954-01-27 | Asea Ab | Electric railway system |
| GB715226A (en) | 1952-04-07 | 1954-09-08 | Dowty Equipment Ltd | Improvements relating to electro-magnetic coils |
| GB723457A (en) | 1952-07-07 | 1955-02-09 | Standard Telephones Cables Ltd | Joint for an electric cable |
| BE534972A (en) | 1953-03-23 | |||
| US2780771A (en) | 1953-04-21 | 1957-02-05 | Vickers Inc | Magnetic amplifier |
| NL195374A (en) | 1954-03-11 | |||
| GB827600A (en) | 1954-12-13 | 1960-02-10 | Shiro Sasaki | Electric transformers and the like |
| US2962679A (en) | 1955-07-25 | 1960-11-29 | Gen Electric | Coaxial core inductive structures |
| GB805721A (en) | 1955-10-29 | 1958-12-10 | Comp Generale Electricite | Improvements in or relating to three-phase magnetic circuits |
| US2846599A (en) | 1956-01-23 | 1958-08-05 | Wetomore Hodges | Electric motor components and the like and method for making the same |
| US2947957A (en) | 1957-04-22 | 1960-08-02 | Zenith Radio Corp | Transformers |
| US2885581A (en) | 1957-04-29 | 1959-05-05 | Gen Electric | Arrangement for preventing displacement of stator end turns |
| CA635218A (en) | 1958-01-02 | 1962-01-23 | W. Smith John | Reinforced end turns in dynamoelectric machines |
| US2943242A (en) | 1958-02-05 | 1960-06-28 | Pure Oil Co | Anti-static grounding device |
| US2975309A (en) | 1958-07-18 | 1961-03-14 | Komplex Nagyberendezesek Expor | Oil-cooled stators for turboalternators |
| GB854728A (en) | 1958-09-29 | 1960-11-23 | British Thomson Houston Co Ltd | Improvements relating to electrical transformers |
| GB870583A (en) | 1958-12-01 | 1961-06-14 | Okonite Co | Method of making electric cables |
| FR1238795A (en) | 1959-07-06 | 1960-08-19 | Fournitures Pour L Electrolyse | Improvements to electrical transformers |
| DE1807391U (en) | 1959-08-29 | 1960-03-03 | Heinrich Ungruhe | BASE RING FOR FITING STRAP. |
| CH395369A (en) | 1959-09-18 | 1965-07-15 | Asea Ab | Corona shield on an induction coil provided with insulation in a vacuum furnace and method for producing a corona shield |
| US3157806A (en) | 1959-11-05 | 1964-11-17 | Bbc Brown Boveri & Cie | Synchronous machine with salient poles |
| US3158770A (en) | 1960-12-14 | 1964-11-24 | Gen Electric | Armature bar vibration damping arrangement |
| US3098893A (en) | 1961-03-30 | 1963-07-23 | Gen Electric | Low electrical resistance composition and cable made therefrom |
| US3130335A (en) | 1961-04-17 | 1964-04-21 | Epoxylite Corp | Dynamo-electric machine |
| GB992249A (en) | 1961-08-23 | 1965-05-19 | Urho Leander Wertanen | Electrical impedance devices |
| GB1024583A (en) | 1961-10-26 | 1966-03-30 | Ass Elect Ind | Improvements in and relating to electric transformers |
| US3143269A (en) | 1961-11-29 | 1964-08-04 | Crompton & Knowles Corp | Tractor-type stock feed |
| CH391071A (en) | 1962-03-01 | 1965-04-30 | Bbc Brown Boveri & Cie | Laminated stator bodies for electrical machines, in particular turbo generators |
| GB965741A (en) | 1962-03-02 | 1964-08-06 | Core Mfg Company | Transformer core |
| SE305899B (en) | 1962-06-15 | 1968-11-11 | O Andersson | |
| NL297703A (en) | 1962-09-25 | |||
| US3268766A (en) | 1964-02-04 | 1966-08-23 | Du Pont | Apparatus for removal of electric charges from dielectric film surfaces |
| US3372283A (en) | 1965-02-15 | 1968-03-05 | Ampex | Attenuation control device |
| SE318939B (en) | 1965-03-17 | 1969-12-22 | Asea Ab | |
| US3304599A (en) | 1965-03-30 | 1967-02-21 | Teletype Corp | Method of manufacturing an electromagnet having a u-shaped core |
| US3333044A (en) | 1965-04-23 | 1967-07-25 | William A Toto | Passageway structure for liquid coolant at gun and transformer ends of welding cable having novel internal surface bearing for alternate polarity strands |
| CA812934A (en) | 1965-07-19 | 1969-05-13 | Cuny Robert | Rotary transformer for coupling multi-phase systems having a small frequency difference |
| GB1135242A (en) | 1965-09-13 | 1968-12-04 | Ass Elect Ind | Improvements in or relating to packing means for conductors in stator slots of dynamo-electric machines |
| US3365657A (en) | 1966-03-04 | 1968-01-23 | Nasa Usa | Power supply |
| GB1117433A (en) | 1966-06-07 | 1968-06-19 | English Electric Co Ltd | Improvements in alternating current generators |
| GB1103098A (en) | 1966-06-24 | 1968-02-14 | Phelps Dodge Copper Prod | Improvements in or relating to shielded electric cable |
| GB1103099A (en) | 1966-06-24 | 1968-02-14 | Phelps Dodge Copper Prod | Improvements in or relating to shielded electric cable |
| US3444407A (en) | 1966-07-20 | 1969-05-13 | Gen Electric | Rigid conductor bars in dynamoelectric machine slots |
| US3484690A (en) | 1966-08-23 | 1969-12-16 | Herman Wald | Three current winding single stator network meter for 3-wire 120/208 volt service |
| US3418530A (en) | 1966-09-07 | 1968-12-24 | Army Usa | Electronic crowbar |
| US3354331A (en) | 1966-09-26 | 1967-11-21 | Gen Electric | High voltage grading for dynamoelectric machine |
| GB1147049A (en) | 1966-09-28 | 1969-04-02 | Parsons C A & Co Ltd | Improvements in and relating to transformer windings |
| US3437858A (en) | 1966-11-17 | 1969-04-08 | Glastic Corp | Slot wedge for electric motors or generators |
| AT272436B (en) | 1967-04-10 | 1969-07-10 | Peter Dipl Ing Dr Techn Klaudy | Method of overload protection using superconductors |
| GB1174659A (en) | 1967-04-21 | 1969-12-17 | Elektromat Veb | Mechanism for Inserting Coils into Grooves of the Stators of Electric Machines |
| GB1226451A (en) | 1968-03-15 | 1971-03-31 | ||
| CH479975A (en) | 1968-08-19 | 1969-10-15 | Oerlikon Maschf | Head bandage for an electrical machine |
| GB1268770A (en) | 1968-11-21 | 1972-03-29 | Kenneth Grundy | Electrical connector |
| US3651402A (en) | 1969-01-27 | 1972-03-21 | Honeywell Inc | Supervisory apparatus |
| SE326758B (en) | 1969-10-29 | 1970-08-03 | Asea Ab | |
| US3614692A (en) | 1970-06-02 | 1971-10-19 | Magnetech Ind Inc | Variable induction device |
| FR2108171A1 (en) | 1970-09-29 | 1972-05-19 | Sumitomo Electric Industries | Insulated electric cable - incorporating an insulating layer and an easily strippable semiconductor layer |
| DE2050312A1 (en) | 1970-10-13 | 1972-04-20 | Siemens Ag | Multiple choke with damping of symmetrical interference currents |
| US3631519A (en) | 1970-12-21 | 1971-12-28 | Gen Electric | Stress graded cable termination |
| US3675056A (en) | 1971-01-04 | 1972-07-04 | Gen Electric | Hermetically sealed dynamoelectric machine |
| US3644662A (en) | 1971-01-11 | 1972-02-22 | Gen Electric | Stress cascade-graded cable termination |
| GB1395152A (en) | 1971-02-01 | 1975-05-21 | Int Research & Dev Co Ltd | Altering current dynamo-electric machine windings |
| DE2111086A1 (en) | 1971-03-09 | 1972-09-14 | Siemens Ag | Stand sheet metal cutting of electrical machines |
| US3749811A (en) | 1971-03-10 | 1973-07-31 | Siemens Ag | Superconducting cable |
| US3684821A (en) | 1971-03-30 | 1972-08-15 | Sumitomo Electric Industries | High voltage insulated electric cable having outer semiconductive layer |
| US3716719A (en) | 1971-06-07 | 1973-02-13 | Aerco Corp | Modulated output transformers |
| JPS4831403A (en) | 1971-08-27 | 1973-04-25 | ||
| US3746954A (en) | 1971-09-17 | 1973-07-17 | Sqare D Co | Adjustable voltage thyristor-controlled hoist control for a dc motor |
| US3727085A (en) | 1971-09-30 | 1973-04-10 | Gen Dynamics Corp | Electric motor with facility for liquid cooling |
| DE2155371C2 (en) | 1971-11-08 | 1982-06-24 | Appt, geb. Kirschmann, Emma, 7000 Stuttgart | Device for shaping the winding heads of electrical machines |
| US3740600A (en) | 1971-12-12 | 1973-06-19 | Gen Electric | Self-supporting coil brace |
| DE2164078A1 (en) | 1971-12-23 | 1973-06-28 | Siemens Ag | DRIVE ARRANGEMENT WITH A LINEAR MOTOR DESIGNED IN THE TYPE OF A SYNCHRONOUS MACHINE |
| BE793731A (en) | 1972-01-05 | 1973-05-02 | English Electric Co Ltd | ELECTROGENERATORS |
| SU425268A1 (en) | 1972-02-29 | 1974-04-25 | желого электромашиностроени при Лысьвенском турбогенераторном | ELECTRIC MACHINE STATOR |
| FR2175579B1 (en) | 1972-03-14 | 1974-08-02 | Thomson Brandt | |
| US3758699A (en) | 1972-03-15 | 1973-09-11 | G & W Electric Speciality Co | Apparatus and method for dynamically cooling a cable termination |
| US3716652A (en) | 1972-04-18 | 1973-02-13 | G & W Electric Speciality Co | System for dynamically cooling a high voltage cable termination |
| US3748555A (en) | 1972-05-01 | 1973-07-24 | Westinghouse Electric Corp | Protective circuit for brushless synchronous motors |
| US3968388A (en) | 1972-06-14 | 1976-07-06 | Kraftwerk Union Aktiengesellschaft | Electric machines, particularly turbogenerators, having liquid cooled rotors |
| CH547028A (en) | 1972-06-16 | 1974-03-15 | Bbc Brown Boveri & Cie | GLIME PROTECTION FILM, THE PROCESS FOR ITS MANUFACTURING AND THEIR USE IN HIGH VOLTAGE WINDINGS. |
| US3801843A (en) | 1972-06-16 | 1974-04-02 | Gen Electric | Rotating electrical machine having rotor and stator cooled by means of heat pipes |
| US3792399A (en) | 1972-08-28 | 1974-02-12 | Nasa | Banded transformer cores |
| US3778891A (en) | 1972-10-30 | 1973-12-18 | Westinghouse Electric Corp | Method of securing dynamoelectric machine coils by slot wedge and filler locking means |
| US3932791A (en) | 1973-01-22 | 1976-01-13 | Oswald Joseph V | Multi-range, high-speed A.C. over-current protection means including a static switch |
| US3995785A (en) | 1973-02-12 | 1976-12-07 | Essex International, Inc. | Apparatus and method for forming dynamoelectric machine field windings by pushing |
| CA1028440A (en) | 1973-02-26 | 1978-03-21 | Uop Inc. | Polymer compositions with treated filler |
| FR2222738B1 (en) | 1973-03-20 | 1976-05-21 | Unelec | |
| SE371348B (en) | 1973-03-22 | 1974-11-11 | Asea Ab | |
| US3781739A (en) | 1973-03-28 | 1973-12-25 | Westinghouse Electric Corp | Interleaved winding for electrical inductive apparatus |
| CH549467A (en) | 1973-03-29 | 1974-05-31 | Micafil Ag | PROCESS FOR MANUFACTURING A COMPRESSED LAYERING MATERIAL. |
| US3881647A (en) | 1973-04-30 | 1975-05-06 | Lebus International Inc | Anti-slack line handling device |
| CH560448A5 (en) | 1973-07-06 | 1975-03-27 | Bbc Brown Boveri & Cie | |
| US4084307A (en) | 1973-07-11 | 1978-04-18 | Allmanna Svenska Elektriska Aktiebolaget | Method of joining two cables with an insulation of cross-linked polyethylene or another cross linked linear polymer |
| DE2351340A1 (en) | 1973-10-12 | 1975-04-24 | Siemens Ag | TAPE REEL FOR TRANSFORMERS |
| GB1433158A (en) | 1973-11-19 | 1976-04-22 | Pirelli General Cable Works | Electric cable installations |
| US3947278A (en) | 1973-12-19 | 1976-03-30 | Universal Oil Products Company | Duplex resistor inks |
| DE2400698A1 (en) | 1974-01-08 | 1975-07-10 | Krim Samhalov Izmail | Self-excited machine with two separate stator windings - windings star-connected with second capacitively closed for excitation |
| US4109098A (en) | 1974-01-31 | 1978-08-22 | Telefonaktiebolaget L M Ericsson | High voltage cable |
| SE384420B (en) | 1974-01-31 | 1976-05-03 | Ericsson Telefon Ab L M | ELECTRICAL CABLE WITH SYNTHETIC INSULATION AND AN OUTER SEMICONDUCTIVE LAYER |
| CA1016586A (en) | 1974-02-18 | 1977-08-30 | Hubert G. Panter | Grounding of outer winding insulation to cores in dynamoelectric machines |
| US4039740A (en) | 1974-06-19 | 1977-08-02 | The Furukawa Electric Co., Ltd. | Cryogenic power cable |
| GB1525745A (en) | 1974-09-19 | 1978-09-20 | Matsushita Electric Ind Co Ltd | Synthetic resin encapsulated coil assembly |
| GB1479904A (en) | 1974-10-15 | 1977-07-13 | Ass Elect Ind | Alternating current power transmission systems |
| US3902000A (en) | 1974-11-12 | 1975-08-26 | Us Energy | Termination for superconducting power transmission systems |
| US3943392A (en) | 1974-11-27 | 1976-03-09 | Allis-Chalmers Corporation | Combination slot liner and retainer for dynamoelectric machine conductor bars |
| CH579844A5 (en) | 1974-12-04 | 1976-09-15 | Bbc Brown Boveri & Cie | |
| US3965408A (en) | 1974-12-16 | 1976-06-22 | International Business Machines Corporation | Controlled ferroresonant transformer regulated power supply |
| DE2600206C2 (en) | 1975-01-06 | 1986-01-09 | The Reluxtrol Co., Seattle, Wash. | Device for non-destructive material testing using the eddy current method |
| US4091138A (en) | 1975-02-12 | 1978-05-23 | Sumitomo Bakelite Company Limited | Insulating film, sheet, or plate material with metallic coating and method for manufacturing same |
| AT338915B (en) | 1975-02-18 | 1977-09-26 | Dukshtau Alexandr Antonovich | STAND FOR ELECTRIC MACHINERY |
| JPS51113110A (en) | 1975-03-28 | 1976-10-06 | Mitsubishi Electric Corp | Drive system for inductor type synchronous motor |
| US4008409A (en) | 1975-04-09 | 1977-02-15 | General Electric Company | Dynamoelectric machine core and coil assembly |
| US3971543A (en) | 1975-04-17 | 1976-07-27 | Shanahan William F | Tool and kit for electrical fishing |
| DE2520511C3 (en) | 1975-05-07 | 1978-11-30 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Device for supporting the rotor winding of a salient pole rotor of a four-pole or higher-pole electrical machine |
| ZA753046B (en) | 1975-05-12 | 1976-09-29 | Gec South Africa Pty | Transformer cooling |
| SE7605754L (en) | 1975-05-22 | 1976-11-23 | Reynolds Metals Co | ELECTRICAL CABLE |
| US4031310A (en) | 1975-06-13 | 1977-06-21 | General Cable Corporation | Shrinkable electrical cable core for cryogenic cable |
| US4091139A (en) | 1975-09-17 | 1978-05-23 | Westinghouse Electric Corp. | Semiconductor binding tape and an electrical member wrapped therewith |
| US4258280A (en) | 1975-11-07 | 1981-03-24 | Bbc Brown Boveri & Company Limited | Supporting structure for slow speed large diameter electrical machines |
| US4085347A (en) | 1976-01-16 | 1978-04-18 | White-Westinghouse Corporation | Laminated stator core |
| AT340523B (en) | 1976-04-27 | 1977-12-27 | Hitzinger & Co Dipl Ing | BRUSHLESS SYNC GENERATOR |
| US4047138A (en) | 1976-05-19 | 1977-09-06 | General Electric Company | Power inductor and transformer with low acoustic noise air gap |
| DE2622309C3 (en) | 1976-05-19 | 1979-05-03 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Protective device for a brushless synchronous machine |
| JPS5325886A (en) | 1976-08-21 | 1978-03-10 | Sumitomo Electric Ind Ltd | Brid ged polyolefine insulating hightension cable having outer semiconductor layers which can be treated off easily |
| US4064419A (en) | 1976-10-08 | 1977-12-20 | Westinghouse Electric Corporation | Synchronous motor KVAR regulation system |
| US4103075A (en) | 1976-10-28 | 1978-07-25 | Airco, Inc. | Composite monolithic low-loss superconductor for power transmission line |
| US4041431A (en) | 1976-11-22 | 1977-08-09 | Ralph Ogden | Input line voltage compensating transformer power regulator |
| SU625290A1 (en) | 1976-11-30 | 1978-09-25 | Специальное Конструкторское Бюро "Энергохиммаш" | Electric motor |
| US4099227A (en) | 1976-12-01 | 1978-07-04 | Square D Company | Sensor circuit |
| DE2656389C3 (en) | 1976-12-13 | 1979-11-29 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Synchronous linear motor |
| FR2376542A1 (en) | 1976-12-30 | 1978-07-28 | Aroshidze Jury | Spring mounted stator core of electrical machine - is attached to stator frame at points of maximum stiffness to form rigid structure |
| US4200817A (en) | 1977-01-20 | 1980-04-29 | Bbc Brown Boveri & Company Limited | Δ-Connected, two-layer, three-phase winding for an electrical machine |
| IT1113513B (en) | 1977-03-16 | 1986-01-20 | Pirelli | IMPROVEMENT CONCERNING THE CABLES FOR ENERGY |
| JPS53120117A (en) * | 1977-03-30 | 1978-10-20 | Hitachi Ltd | Excitation control system for generator |
| US4149101A (en) | 1977-05-12 | 1979-04-10 | Lesokhin Albert Z | Arrangement for locking slot wedges retaining electric windings |
| DE2721905C2 (en) | 1977-05-14 | 1986-02-20 | Thyssen Industrie Ag, 4300 Essen | Method of manufacturing a three-phase alternating current winding for a linear motor |
| US4134036A (en) | 1977-06-03 | 1979-01-09 | Cooper Industries, Inc. | Motor mounting device |
| US4152615A (en) | 1977-06-14 | 1979-05-01 | Westinghouse Electric Corp. | End iron axial flux damper system |
| DE2729067A1 (en) | 1977-06-28 | 1979-01-11 | Kabel Metallwerke Ghh | MEDIUM OR HIGH VOLTAGE ELECTRIC CABLE |
| US4177418A (en) | 1977-08-04 | 1979-12-04 | International Business Machines Corporation | Flux controlled shunt regulated transformer |
| US4164672A (en) | 1977-08-18 | 1979-08-14 | Electric Power Research Institute, Inc. | Cooling and insulating system for extra high voltage electrical machine with a spiral winding |
| US4184186A (en) | 1977-09-06 | 1980-01-15 | General Electric Company | Current limiting device for an electric power system |
| US4160193A (en) | 1977-11-17 | 1979-07-03 | Richmond Abraham W | Metal vapor electric discharge lamp system |
| PL123224B1 (en) | 1977-11-30 | 1982-09-30 | Inst Spawalnictwa | Welding transformer of dropping external characteristic |
| US4134146A (en) | 1978-02-09 | 1979-01-09 | General Electric Company | Surge arrester gap assembly |
| US4177397A (en) | 1978-03-17 | 1979-12-04 | Amp Incorporated | Electrical connections for windings of motor stators |
| SU792302A1 (en) | 1978-04-04 | 1980-12-30 | Предприятие П/Я В-8833 | Transformer |
| US4164772A (en) | 1978-04-17 | 1979-08-14 | Electric Power Research Institute, Inc. | AC fault current limiting circuit |
| DE2824951A1 (en) | 1978-06-07 | 1979-12-20 | Kabel Metallwerke Ghh | METHOD OF MANUFACTURING A STATOR FOR A LINEAR MOTOR |
| CH629344A5 (en) | 1978-06-08 | 1982-04-15 | Bbc Brown Boveri & Cie | DEVICE FOR SUPPORTING THE FIELD DEVELOPMENT OF A POLE WHEEL WITH EXCELLENT POLES. |
| SU694939A1 (en) | 1978-06-22 | 1982-01-07 | Научно-Исследовательский Сектор Всесоюзного Ордена Ленина Проектно-Изыскательского И Научно-Исследовательского Института "Гидропроект" Им.С.Я.Жука | Generator stator |
| US4208597A (en) | 1978-06-22 | 1980-06-17 | Westinghouse Electric Corp. | Stator core cooling for dynamoelectric machines |
| DE2925934A1 (en) | 1978-07-06 | 1980-01-24 | Vilanova Luis Montplet | MAGNETIC DEVICE, IN PARTICULAR FOR DETECTING FAULTS OF UNDERGROUND ELECTRIC CABLES |
| US4200818A (en) | 1978-08-01 | 1980-04-29 | Westinghouse Electric Corp. | Resin impregnated aromatic polyamide covered glass based slot wedge for large dynamoelectric machines |
| DE2835386A1 (en) | 1978-08-12 | 1980-02-21 | Kabel Metallwerke Ghh | Three=phase AC winding for linear motor - is made by preforming cables which are wound on drum, fastened on supports and then placed in slots |
| DE2836229C2 (en) | 1978-08-17 | 1983-12-15 | Siemens AG, 1000 Berlin und 8000 München | Stator winding of an electrical machine |
| CA1095601A (en) | 1978-08-28 | 1981-02-10 | Alfred M. Hase | Regulating transformer with magnetic shunt |
| DE2839517C2 (en) | 1978-09-11 | 1986-05-07 | Thyssen Industrie Ag, 4300 Essen | Process for the production of a prefabricated winding for linear motors |
| JPS6028226B2 (en) | 1978-09-20 | 1985-07-03 | 株式会社日立製作所 | salient pole rotor |
| JPS6044764B2 (en) * | 1978-11-09 | 1985-10-05 | 株式会社フジクラ | Cable conductor manufacturing method |
| US4207482A (en) | 1978-11-14 | 1980-06-10 | Westinghouse Electric Corp. | Multilayered high voltage grading system for electrical conductors |
| US4238339A (en) | 1978-11-27 | 1980-12-09 | Fridman Vladimir M | Arrangement for supporting stator end windings of an electric machine |
| JPS5579676A (en) | 1978-12-13 | 1980-06-16 | Toshiba Corp | Harmonic filter for electric power |
| DE2854520A1 (en) | 1978-12-16 | 1980-06-26 | Bbc Brown Boveri & Cie | ELECTRIC COIL |
| CH651975A5 (en) | 1979-01-10 | 1985-10-15 | Bbc Brown Boveri & Cie | PROTECTIVE DEVICE ON A TURBO GROUP AGAINST SUBSYNCHRONOUS RESONANCES. |
| US4317001A (en) | 1979-02-23 | 1982-02-23 | Pirelli Cable Corp. | Irradiation cross-linked polymeric insulated electric cable |
| US4281264A (en) | 1979-02-26 | 1981-07-28 | General Electric Company | Mounting of armature conductors in air-gap armatures |
| US4262209A (en) | 1979-02-26 | 1981-04-14 | Berner Charles A | Supplemental electrical power generating system |
| SE416693B (en) | 1979-03-08 | 1981-01-26 | Elmekano I Lulea Ab | DEVICE FOR PHASE COMPENSATION AND MAGNETIZATION OF AN ASYNCHRONIC MACHINE FOR OPERATING AS GENERATOR |
| SU873370A1 (en) | 1979-03-11 | 1981-10-15 | Предприятие П/Я М-5113 | Synchronous machine excitation system |
| FR2452167A1 (en) | 1979-03-20 | 1980-10-17 | Aerospatiale | PROCESS FOR THE PRODUCTION OF A MAGNETIC FRAME WITH DIVIDED STRUCTURE AND REINFORCEMENT THUS OBTAINED |
| CH641599A5 (en) | 1979-03-27 | 1984-02-29 | Streiff Mathias Ag | METHOD AND DEVICE FOR LAYING AND FASTENING HEAVY ELECTRIC CABLES IN A CABLE CHANNEL. |
| DE2913697C2 (en) | 1979-04-05 | 1986-05-22 | kabelmetal electro GmbH, 3000 Hannover | Prefabricated winding for a linear motor |
| DE2917717A1 (en) | 1979-05-02 | 1980-11-27 | Kraftwerk Union Ag | Turbogenerator stator cooling segments - have parallel channels extending from to distributor to zone of stator teeth |
| DE2920478C2 (en) | 1979-05-21 | 1986-06-26 | kabelmetal electro GmbH, 3000 Hannover | Prefabricated three-phase alternating current winding for a linear motor |
| DE2921114A1 (en) | 1979-05-25 | 1980-12-04 | Bosch Gmbh Robert | WINDING PROCESS FOR AN ELECTRIC GENERATOR AND THREE-PHASE GENERATOR PRODUCED AFTER THIS |
| US4357542A (en) | 1979-07-12 | 1982-11-02 | Westinghouse Electric Corp. | Wind turbine generator system |
| US4255684A (en) | 1979-08-03 | 1981-03-10 | Mischler William R | Laminated motor stator structure with molded composite pole pieces |
| US4292558A (en) | 1979-08-15 | 1981-09-29 | Westinghouse Electric Corp. | Support structure for dynamoelectric machine stators spiral pancake winding |
| DE2939004A1 (en) | 1979-09-26 | 1981-04-09 | Siemens AG, 1000 Berlin und 8000 München | Synchronous linear motor for rail vehicle drive - has field winding divided into switched sections with inter-looped current lines |
| US4320645A (en) | 1979-10-11 | 1982-03-23 | Card-O-Matic Pty. Limited | Apparatus for fabricating electrical equipment |
| FR2467502A1 (en) | 1979-10-11 | 1981-04-17 | Ducellier & Cie | Electric starter motor rotor winding for vehicle - has minimal depth slots with offset conductors to minimise flux distortion |
| JPS5675411U (en) | 1979-11-15 | 1981-06-19 | ||
| SU961048A1 (en) | 1979-12-06 | 1982-09-23 | Научно-Исследовательский Сектор Всесоюзного Ордена Ленина Проектно-Изыскательского И Научно-Исследовательского Института "Гидропроект" Им.С.Я.Жука | Generator stator |
| DE3002945A1 (en) | 1980-01-29 | 1981-07-30 | Anton Piller Kg, 3360 Osterode | TRANSFORMER SYSTEM |
| DE3006382C2 (en) | 1980-02-21 | 1985-10-31 | Thyssen Industrie Ag, 4300 Essen | Three-phase alternating current winding for a linear motor |
| DE3008212C2 (en) | 1980-03-04 | 1985-06-27 | Robert Bosch Gmbh, 7000 Stuttgart | Process for the production of stator windings for three-phase alternators |
| DE3008818A1 (en) | 1980-03-05 | 1981-09-10 | Siemens AG, 1000 Berlin und 8000 München | Jointing sleeve for HT cables - with plastic cylinder over metal tube and insulating tape wraps |
| EP0055779B1 (en) | 1980-04-03 | 1985-10-16 | The Fujikura Cable Works, Ltd. | Process for manufacturing stranded conductor comprising insulated conductor strands |
| DE3016990A1 (en) | 1980-05-02 | 1981-11-12 | Kraftwerk Union AG, 4330 Mülheim | DEVICE FOR FIXING WINDING RODS IN SLOTS OF ELECTRICAL MACHINES, IN PARTICULAR TURBOGENERATORS |
| US4594630A (en) | 1980-06-02 | 1986-06-10 | Electric Power Research Institute, Inc. | Emission controlled current limiter for use in electric power transmission and distribution |
| US4353612A (en) | 1980-06-06 | 1982-10-12 | The National Telephone Supply Company | Shield connector |
| DE3031866A1 (en) | 1980-08-23 | 1982-04-01 | Brown, Boveri & Cie Ag, 6800 Mannheim | LADDER BAR FOR ELECTRICAL MACHINE |
| US4330726A (en) | 1980-12-04 | 1982-05-18 | General Electric Company | Air-gap winding stator construction for dynamoelectric machine |
| CH662454A5 (en) | 1980-12-18 | 1987-09-30 | V Proektno Izyskatelskyi Nii G | Arrangement for connecting two layer cable in front part of a high voltage generators staenderwicklung. |
| US4404486A (en) | 1980-12-24 | 1983-09-13 | General Electric Company | Star connected air gap polyphase armature having limited voltage gradients at phase boundaries |
| DE3101217C2 (en) | 1981-01-16 | 1984-08-23 | Smit Transformatoren B.V., Nijmegen | Winding for a dry-type transformer with spacer arrangement |
| AT378287B (en) | 1981-01-30 | 1985-07-10 | Elin Union Ag | HIGH VOLTAGE WINDING FOR ELECTRICAL MACHINES |
| SU955369A1 (en) | 1981-03-26 | 1982-08-30 | Научно-Исследовательский Сектор Всесоюзного Ордена Ленина Проектно-Изыскательского И Научно-Исследовательского Института "Гидропроект" Им.С.Я.Жука | Electric machine stator |
| US4368418A (en) | 1981-04-21 | 1983-01-11 | Power Technologies, Inc. | Apparatus for controlling high voltage by absorption of capacitive vars |
| GB2099635B (en) | 1981-05-29 | 1985-07-03 | Harmer & Simmons Ltd | Ransformers for battery charging systems |
| US4367425A (en) | 1981-06-01 | 1983-01-04 | Westinghouse Electric Corp. | Impregnated high voltage spacers for use with resin filled hose bracing systems |
| US4449768A (en) | 1981-07-23 | 1984-05-22 | Preformed Line Products Company | Shield connector |
| GB2106306B (en) | 1981-07-28 | 1985-07-31 | Pirelli General Plc | Improvements in electric cables and installations |
| DE3129928A1 (en) | 1981-07-29 | 1983-02-24 | Anton Piller GmbH & Co KG, 3360 Osterode | ROTATING TRANSFORMER |
| US4470884A (en) | 1981-08-07 | 1984-09-11 | National Ano-Wire, Inc. | High speed aluminum wire anodizing machine and process |
| CA1164851A (en) | 1981-08-17 | 1984-04-03 | Ali Pan | Reeling of cable |
| US4368399A (en) | 1981-08-17 | 1983-01-11 | Westinghouse Electric Corp. | Rotor end turn winding and support structure |
| US4387316A (en) | 1981-09-30 | 1983-06-07 | General Electric Company | Dynamoelectric machine stator wedges and method |
| US4475075A (en) | 1981-10-14 | 1984-10-02 | Munn Robert B | Electric power generator and system |
| US4426771A (en) | 1981-10-27 | 1984-01-24 | Emerson Electric Co. | Method of fabricating a stator for a multiple-pole dynamoelectric machine |
| US4431960A (en) | 1981-11-06 | 1984-02-14 | Fdx Patents Holding Company, N.V. | Current amplifying apparatus |
| SU1019553A1 (en) | 1982-02-23 | 1983-05-23 | Харьковский Ордена Ленина Авиационный Институт Им.Н.Е.Жуковского | Electric machine stator |
| US4425521A (en) | 1982-06-03 | 1984-01-10 | General Electric Company | Magnetic slot wedge with low average permeability and high mechanical strength |
| US4546210A (en) | 1982-06-07 | 1985-10-08 | Hitachi, Ltd. | Litz wire |
| US4443725A (en) | 1982-06-14 | 1984-04-17 | General Electric Company | Dynamoelectric machine stator wedge |
| JPS5928852A (en) | 1982-08-06 | 1984-02-15 | Hitachi Ltd | Salient-pole type rotary electric machine |
| US4481438A (en) | 1982-09-13 | 1984-11-06 | Electric Power Research Institute, Inc. | High voltage electrical generator and windings for use therein |
| JPS5956825A (en) | 1982-09-21 | 1984-04-02 | 三菱電機株式会社 | Ac current limiting device |
| US4473765A (en) | 1982-09-30 | 1984-09-25 | General Electric Company | Electrostatic grading layer for the surface of an electrical insulation exposed to high electrical stress |
| JPS5986110A (en) | 1982-11-09 | 1984-05-18 | 住友電気工業株式会社 | Crosslinked polyethylene insulated cable |
| GB2140195B (en) | 1982-12-03 | 1986-04-30 | Electric Power Res Inst | Cryogenic cable and method of making same |
| CH659910A5 (en) | 1983-01-27 | 1987-02-27 | Bbc Brown Boveri & Cie | AIR THROTTLE COIL AND METHOD FOR THEIR PRODUCTION. |
| DE3305225A1 (en) | 1983-02-16 | 1984-08-16 | BBC Aktiengesellschaft Brown, Boveri & Cie., Baden, Aargau | High-voltage DC-transmission power station in a block circuit |
| GB2136214B (en) | 1983-03-11 | 1986-05-29 | British Aerospace | Pulse transformer |
| DE3309051C2 (en) | 1983-03-14 | 1986-10-02 | Thyssen Industrie Ag, 4300 Essen | Three-phase alternating current winding for a linear motor |
| EP0120154A1 (en) | 1983-03-25 | 1984-10-03 | TRENCH ELECTRIC, a Division of Guthrie Canadian Investments Limited | Continuously transposed conductor |
| US4619040A (en) | 1983-05-23 | 1986-10-28 | Emerson Electric Co. | Method of fabricating stator for a multiple pole dynamoelectric machine |
| US4510476A (en) | 1983-06-21 | 1985-04-09 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | High voltage isolation transformer |
| DE3323696A1 (en) | 1983-07-01 | 1985-01-10 | Thyssen Industrie Ag, 4300 Essen | METHOD AND DEVICE FOR LAYING A PRE-MANUFACTURED WINDING OF A LINEAR MOTOR |
| US4590416A (en) | 1983-08-08 | 1986-05-20 | Rig Efficiency, Inc. | Closed loop power factor control for power supply systems |
| US4565929A (en) | 1983-09-29 | 1986-01-21 | The Boeing Company | Wind powered system for generating electricity |
| US4510077A (en) | 1983-11-03 | 1985-04-09 | General Electric Company | Semiconductive glass fibers and method |
| US4503284A (en) | 1983-11-09 | 1985-03-05 | Essex Group, Inc. | RF Suppressing magnet wire |
| IT1195482B (en) | 1983-11-18 | 1988-10-19 | Meccanica Di Precisione Spa | PROGRAMMABLE ROBOT ABLE TO MANAGE THE FEEDING AND UNLOADING OF EMPTY SPOOLS AND FULL SPOOLS INTO AND FROM MACHINES USED FOR WINDING METAL WIRES EOD OTHER MATERIAL AT TWENTY OPERATING CHARACTERISTICS U GUALES OR DIFFERENT THAN ONE LONG THE SAME ROBOT YOU ARE LOOKING AT |
| US4622116A (en) * | 1983-11-25 | 1986-11-11 | General Electric Company | Process for electrodepositing mica on coil or bar connections and resulting products |
| FR2556146B1 (en) | 1983-12-05 | 1988-01-15 | Paris & Du Rhone | DEVICE FOR MOUNTING AND INSULATING CONDUCTORS ON ROTORS OF ELECTRIC ROTATING MACHINES |
| DE3444189A1 (en) | 1984-03-21 | 1985-09-26 | Kraftwerk Union AG, 4330 Mülheim | DEVICE FOR INDIRECT GAS COOLING OF THE STATE DEVELOPMENT AND / OR FOR DIRECT GAS COOLING OF THE STATE SHEET PACKAGE OF DYNAMOELECTRICAL MACHINES, PREFERRED FOR GAS COOLED TURBOGENERATORS |
| US4488079A (en) | 1984-03-30 | 1984-12-11 | Westinghouse Electric Corp. | Dynamoelectric machine with stator coil end turn support system |
| US4650924A (en) | 1984-07-24 | 1987-03-17 | Phelps Dodge Industries, Inc. | Ribbon cable, method and apparatus, and electromagnetic device |
| US5036165A (en) | 1984-08-23 | 1991-07-30 | General Electric Co. | Semi-conducting layer for insulated electrical conductors |
| US4853565A (en) * | 1984-08-23 | 1989-08-01 | General Electric Company | Semi-conducting layer for insulated electrical conductors |
| US5066881A (en) | 1984-08-23 | 1991-11-19 | General Electric Company | Semi-conducting layer for insulated electrical conductors |
| US5067046A (en) | 1984-08-23 | 1991-11-19 | General Electric Company | Electric charge bleed-off structure using pyrolyzed glass fiber |
| AU575681B2 (en) | 1984-09-13 | 1988-08-04 | Utdc Inc. | Linear induction motor |
| US4560896A (en) | 1984-10-01 | 1985-12-24 | General Electric Company | Composite slot insulation for dynamoelectric machine |
| DE3438747A1 (en) | 1984-10-23 | 1986-04-24 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | ELECTRONICALLY COMMUTED, COLLECTORLESS DC MOTOR |
| JPH0123900Y2 (en) | 1984-11-08 | 1989-07-20 | ||
| DE3441311A1 (en) | 1984-11-12 | 1986-05-15 | Siemens AG, 1000 Berlin und 8000 München | SPLICE PROTECTOR INSERT FOR CABLE SLEEVES MADE OF SHRINKABLE MATERIAL |
| JPS61121729A (en) | 1984-11-14 | 1986-06-09 | Fanuc Ltd | Liquid cooled motor |
| US4607183A (en) | 1984-11-14 | 1986-08-19 | General Electric Company | Dynamoelectric machine slot wedges with abrasion resistant layer |
| EP0246377A1 (en) | 1986-05-23 | 1987-11-25 | Royal Melbourne Institute Of Technology Limited | Electrically-variable inductor |
| US4588916A (en) | 1985-01-28 | 1986-05-13 | General Motors Corporation | End turn insulation for a dynamoelectric machine |
| US4868970A (en) | 1985-03-08 | 1989-09-26 | Kolimorgen Corporation | Method of making an electric motor |
| EP0198535B1 (en) | 1985-04-04 | 1990-02-07 | Koninklijke Philips Electronics N.V. | Composite wire for hf applications, coil wound from such a wire, and deflection unit comprising such a coil |
| US4618795A (en) | 1985-04-10 | 1986-10-21 | Westinghouse Electric Corp. | Turbine generator stator end winding support assembly with decoupling from the core |
| US4723104A (en) | 1985-10-02 | 1988-02-02 | Frederick Rohatyn | Energy saving system for larger three phase induction motors |
| DE3543106A1 (en) | 1985-12-06 | 1987-06-11 | Kabelmetal Electro Gmbh | ELECTRIC CABLE FOR USE AS WINDING STRING FOR LINEAR MOTORS |
| US4656379A (en) | 1985-12-18 | 1987-04-07 | The Garrett Corporation | Hybrid excited generator with flux control of consequent-pole rotor |
| FR2594271A1 (en) | 1986-02-13 | 1987-08-14 | Paris & Du Rhone | Rotor for electric rotating machine, with slots housing two overlying conductors |
| IT1190077B (en) | 1986-02-28 | 1988-02-10 | Pirelli Cavi Spa | ELECTRIC CABLE WITH IMPROVED SCREEN AND PROCEDURE FOR THE CONSTRUCTION OF THIS SCREEN |
| US5447665A (en) | 1986-03-31 | 1995-09-05 | Nupipe, Inc. | Method of removal of replacement pipe installed in an existing conduit |
| US5244624B1 (en) | 1986-03-31 | 1997-11-18 | Nu Pipe Inc | Method of installing a new pipe inside an existing conduit by progressive rounding |
| DE3612112A1 (en) | 1986-04-10 | 1987-10-15 | Siemens Ag | Bracing for the teeth of the stator of a turbogenerator |
| US4687882A (en) | 1986-04-28 | 1987-08-18 | Stone Gregory C | Surge attenuating cable |
| US4963695A (en) | 1986-05-16 | 1990-10-16 | Pirelli Cable Corporation | Power cable with metallic shielding tape and water swellable powder |
| GB8617004D0 (en) | 1986-07-11 | 1986-08-20 | Bp Chem Int Ltd | Polymer composition |
| JPS63110939A (en) | 1986-10-25 | 1988-05-16 | Hitachi Ltd | Rotor of induction motor |
| JPH0687642B2 (en) | 1986-12-15 | 1994-11-02 | 株式会社日立製作所 | Rotor winding abnormality diagnosis device for rotating electric machine |
| US4924342A (en) | 1987-01-27 | 1990-05-08 | Teledyne Inet | Low voltage transient current limiting circuit |
| EP0280759B1 (en) | 1987-03-06 | 1993-10-13 | Heinrich Dr. Groh | Arrangement for electric energy cables for protection against explosions of gas and/or dust/air mixtures, especially for underground working |
| JPH07108074B2 (en) | 1987-03-10 | 1995-11-15 | 株式会社三ツ葉電機製作所 | Slot structure of rotor core in rotating electric machine |
| CA1258881A (en) | 1987-04-15 | 1989-08-29 | Leonard Bolduc | Self-regulated transformer with gaps |
| SU1511810A1 (en) | 1987-05-26 | 1989-09-30 | Ленинградское Электромашиностроительное Объединение "Электросила" Им.С.М.Кирова | Method of repairing laminated stator core of high-power electric machine |
| US5012125A (en) | 1987-06-03 | 1991-04-30 | Norand Corporation | Shielded electrical wire construction, and transformer utilizing the same for reduction of capacitive coupling |
| SE457792B (en) | 1987-06-12 | 1989-01-30 | Kabmatik Ab | CABLE EXCHANGE DEVICE FOR APPLICATION FROM EXCHANGE FROM A FIRST ROTARY DRUM TO ANOTHER ROTARY DRUM |
| US4845308A (en) | 1987-07-20 | 1989-07-04 | The Babcock & Wilcox Company | Superconducting electrical conductor |
| DE3726346A1 (en) | 1987-08-07 | 1989-02-16 | Vacuumschmelze Gmbh | Annular core (ring core) for current sensors |
| US4800314A (en) | 1987-08-24 | 1989-01-24 | Westinghouse Electric Corp. | Deep beam support arrangement for dynamoelectric machine stator coil end portions |
| US4801832A (en) | 1987-11-04 | 1989-01-31 | General Electric Company | Stator and rotor lamination construction for a dynamo-electric machine |
| DE3737719A1 (en) | 1987-11-06 | 1989-05-24 | Thyssen Industrie | METHOD AND DEVICE FOR INSERTING A WINDING IN THE INDUCTOR OF A LINEAR MOTOR |
| US4810919A (en) | 1987-11-16 | 1989-03-07 | Westinghouse Electric Corp. | Low-torque nuts for stator core through-bolts |
| CA1318948C (en) | 1987-11-18 | 1993-06-08 | Takayuki Nimiya | Cable closure |
| US4994952A (en) | 1988-02-10 | 1991-02-19 | Electronics Research Group, Inc. | Low-noise switching power supply having variable reluctance transformer |
| NL8800832A (en) | 1988-03-31 | 1989-10-16 | Lovink Terborg Bv | METHOD FOR PROTECTING PROTECTION AGAINST MOISTURE-ENCLOSED ELEMENTS AND FILLING MASS USED IN THAT METHOD |
| US4914386A (en) | 1988-04-28 | 1990-04-03 | Abb Power Distribution Inc. | Method and apparatus for providing thermal protection for large motors based on accurate calculations of slip dependent rotor resistance |
| US4864266A (en) | 1988-04-29 | 1989-09-05 | Electric Power Research Institute, Inc. | High-voltage winding for core-form power transformers |
| DE3816652A1 (en) | 1988-05-16 | 1989-11-30 | Magnet Motor Gmbh | ELECTRIC MACHINE WITH LIQUID COOLING |
| JPH0721078Y2 (en) | 1988-07-21 | 1995-05-15 | 多摩川精機株式会社 | Electric motor |
| CH677549A5 (en) | 1988-08-02 | 1991-05-31 | Asea Brown Boveri | |
| US4847747A (en) | 1988-09-26 | 1989-07-11 | Westinghouse Electric Corp. | Commutation circuit for load-commutated inverter induction motor drives |
| US5083360A (en) | 1988-09-28 | 1992-01-28 | Abb Power T&D Company, Inc. | Method of making a repairable amorphous metal transformer joint |
| GB2223877B (en) | 1988-10-17 | 1993-05-19 | Pirelli General Plc | Extra-high-voltage power cable |
| US4926079A (en) | 1988-10-17 | 1990-05-15 | Ryobi Motor Products Corp. | Motor field winding with intermediate tap |
| US5168662A (en) | 1988-12-28 | 1992-12-08 | Fanuc Ltd. | Process of structuring stator of built-in motor |
| JPH02179246A (en) | 1988-12-28 | 1990-07-12 | Fanuc Ltd | Stator construction of built-in motor |
| US5136459A (en) | 1989-03-13 | 1992-08-04 | Electric Power Research Institute, Inc. | High speed current limiting system responsive to symmetrical & asymmetrical currents |
| US4942326A (en) | 1989-04-19 | 1990-07-17 | Westinghouse Electric Corp. | Biased securement system for end winding conductor |
| US5124607A (en) | 1989-05-19 | 1992-06-23 | General Electric Company | Dynamoelectric machines including metal filled glass cloth slot closure wedges, and methods of making the same |
| JPH0351968A (en) | 1989-07-19 | 1991-03-06 | Toshiba Corp | Linearization decision system |
| US4949001A (en) | 1989-07-21 | 1990-08-14 | Campbell Steven R | Partial discharge detection method and apparatus |
| US5355046A (en) | 1989-12-15 | 1994-10-11 | Klaus Weigelt | Stator end-winding system and a retrofitting set for same |
| US5097241A (en) | 1989-12-29 | 1992-03-17 | Sundstrand Corporation | Cooling apparatus for windings |
| JPH04212403A (en) | 1990-01-25 | 1992-08-04 | Branimir Jakovljevic | Magnetic core sheet |
| EP0440865A1 (en) | 1990-02-09 | 1991-08-14 | Asea Brown Boveri Ab | Electrical insulation |
| CA2010670C (en) | 1990-02-22 | 1997-04-01 | James H. Dymond | Salient pole rotor for a dynamoelectric machine |
| DE4022476A1 (en) | 1990-07-14 | 1992-01-16 | Thyssen Industrie | Electric cable for three=phase AC winding of linear motor - covers one phase by inner conducting layer surrounded by insulation and outer conducting layer |
| DE4023903C1 (en) | 1990-07-27 | 1991-11-07 | Micafil Ag, Zuerich, Ch | Planar insulator for electrical machine or appts. - is laminated construction withstanding high mechanical loading and with curved edges for fitting into grooves |
| DE4030236C2 (en) | 1990-09-25 | 1999-01-07 | Thyssen Industrie | Device for removing the winding of a linear motor |
| US5111095A (en) | 1990-11-28 | 1992-05-05 | Magna Physics Corporation | Polyphase switched reluctance motor |
| US5175396A (en) | 1990-12-14 | 1992-12-29 | Westinghouse Electric Corp. | Low-electric stress insulating wall for high voltage coils having roebeled strands |
| DE4100135C1 (en) | 1991-01-04 | 1992-05-14 | Loher Ag, 8399 Ruhstorf, De | |
| US5187428A (en) | 1991-02-26 | 1993-02-16 | Miller Electric Mfg. Co. | Shunt coil controlled transformer |
| US5153460A (en) | 1991-03-25 | 1992-10-06 | The United States Of America As Represented By The Secretary Of The Army | Triggering technique for multi-electrode spark gap switch |
| FR2677802B1 (en) | 1991-06-14 | 1994-09-09 | Alsthom Gec | ELECTRIC WINDING AND ITS WINDING METHOD. |
| US5246783A (en) | 1991-08-15 | 1993-09-21 | Exxon Chemical Patents Inc. | Electrical devices comprising polymeric insulating or semiconducting members |
| SE469361B (en) | 1991-11-04 | 1993-06-21 | Asea Brown Boveri | PROCEDURE AND DEVICE FOR REDUCTION OF DIFFICULTIES IN THE POWER |
| US5264778A (en) * | 1991-12-31 | 1993-11-23 | Westinghouse Electric Corp. | Apparatus protecting a synchronous machine from under excitation |
| CA2086897A1 (en) | 1992-01-13 | 1993-07-14 | Howard H. Bobry | Toroidal transformer and method for making |
| US5343139A (en) | 1992-01-31 | 1994-08-30 | Westinghouse Electric Corporation | Generalized fast, power flow controller |
| US5235488A (en) | 1992-02-05 | 1993-08-10 | Brett Products, Inc. | Wire wound core |
| US5327637A (en) | 1992-02-07 | 1994-07-12 | Kabelmetal Electro Gmbh | Process for repairing the winding of an electrical linear drive |
| JP3135338B2 (en) | 1992-02-21 | 2001-02-13 | 株式会社日立製作所 | Commutation type DC circuit breaker |
| WO1993018528A1 (en) | 1992-03-05 | 1993-09-16 | Siemens Aktiengesellschaft | Coil for high-voltage transformer |
| JP3245748B2 (en) | 1992-03-09 | 2002-01-15 | 久光製薬株式会社 | P-menthane derivative and cooling sensate containing the same |
| JPH05328681A (en) | 1992-05-18 | 1993-12-10 | Mitsuba Electric Mfg Co Ltd | Coating material for armature core in motor of electrical equipment |
| DE4218969A1 (en) | 1992-06-10 | 1993-12-16 | Asea Brown Boveri | Process for fixing winding heads of electrical machines and means for carrying out the process |
| GB2268337B (en) | 1992-07-01 | 1996-06-05 | Gec Alsthom Ltd | Electrical machine slot wedging system |
| US5304883A (en) | 1992-09-03 | 1994-04-19 | Alliedsignal Inc | Ring wound stator having variable cross section conductors |
| AT399790B (en) | 1992-09-10 | 1995-07-25 | Elin Energieversorgung | HIGH VOLTAGE WINDING |
| DE4233558C2 (en) | 1992-09-30 | 1995-07-20 | Siemens Ag | Electrical machine |
| EP0596791B1 (en) | 1992-11-05 | 1997-03-12 | Gec Alsthom T Et D Sa | Superconducting winding, in particular for current limiter and current limiter with such a winding |
| US5325008A (en) | 1992-12-09 | 1994-06-28 | General Electric Company | Constrained ripple spring assembly with debondable adhesive and methods of installation |
| GB9226925D0 (en) | 1992-12-24 | 1993-02-17 | Anglia Electronic Tech Ltd | Transformer winding |
| DE69401722T2 (en) | 1993-03-26 | 1997-07-03 | Ngk Insulators Ltd | Superconducting device for residual current limitation |
| US5341281A (en) | 1993-05-14 | 1994-08-23 | Allen-Bradley Company, Inc. | Harmonic compensator using low leakage reactance transformer |
| US5365132A (en) | 1993-05-27 | 1994-11-15 | General Electric Company | Lamination for a dynamoelectric machine with improved cooling capacity |
| JP3355700B2 (en) | 1993-06-14 | 2002-12-09 | 松下電器産業株式会社 | Rotating electric machine stator |
| US5321308A (en) * | 1993-07-14 | 1994-06-14 | Tri-Sen Systems Inc. | Control method and apparatus for a turbine generator |
| US5545853A (en) | 1993-07-19 | 1996-08-13 | Champlain Cable Corporation | Surge-protected cable |
| FR2708157B1 (en) | 1993-07-22 | 1995-09-08 | Valeo Equip Electr Moteur | Element of a rotating machine and motor vehicle starter comprising such an element. |
| DE4329382A1 (en) | 1993-09-01 | 1995-03-02 | Abb Management Ag | Method and device for detecting earth faults on the conductors of an electrical machine |
| GB2283133B (en) | 1993-10-20 | 1998-04-15 | Gen Electric | Dynamoelectric machine and method for manufacturing same |
| SE502417C2 (en) | 1993-12-29 | 1995-10-16 | Skaltek Ab | Control device for unrolling or unrolling a string, eg a cable on or from a drum |
| JP3468817B2 (en) | 1994-02-25 | 2003-11-17 | 株式会社東芝 | Field ground fault detector |
| DE4409794C1 (en) | 1994-03-22 | 1995-08-24 | Vem Elektroantriebe Gmbh | Fastening for equalising connection lines of high-power DC machines |
| US5530307A (en) | 1994-03-28 | 1996-06-25 | Emerson Electric Co. | Flux controlled permanent magnet dynamo-electric machine |
| DE4412412C2 (en) | 1994-04-11 | 1996-03-28 | Siemens Ag | Locomotive transformer and winding arrangement for this |
| DE4412761C2 (en) | 1994-04-13 | 1997-04-10 | Siemens Ag | Conductor feedthrough for an AC device with superconductivity |
| JP3623269B2 (en) | 1994-04-15 | 2005-02-23 | コールモージェン・コーポレーション | Axial air gap motor |
| US5500632A (en) | 1994-05-11 | 1996-03-19 | Halser, Iii; Joseph G. | Wide band audio transformer with multifilar winding |
| GB2289992B (en) | 1994-05-24 | 1998-05-20 | Gec Alsthom Ltd | Improvements in or relating to cooling arrangements in rotating electrical machines |
| FI942447A0 (en) | 1994-05-26 | 1994-05-26 | Abb Stroemberg Kojeet Oy | Foerfarande Foer eliminering av stoerningar i ett elkraftoeverfoeringsnaet samt koppling i ett elkraftoeverfoeringsnaet |
| DE4420322C2 (en) | 1994-06-13 | 1997-02-27 | Dresden Ev Inst Festkoerper | YBa¶2¶Cu¶3¶O¶X¶ high-temperature superconductor and method for its production |
| IT1266896B1 (en) | 1994-07-27 | 1997-01-21 | Magneti Marelli Spa | ROTOR OF AN ELECTRIC MACHINE, IN PARTICULAR OF AN ELECTRIC MOTOR FOR STARTING THE INTERNAL COMBUSTION ENGINE OF A MOTOR VEHICLE AND |
| US5550410A (en) | 1994-08-02 | 1996-08-27 | Titus; Charles H. | Gas turbine electrical power generation scheme utilizing remotely located fuel sites |
| US5612510A (en) | 1994-10-11 | 1997-03-18 | Champlain Cable Corporation | High-voltage automobile and appliance cable |
| US5510942A (en) | 1994-12-19 | 1996-04-23 | General Electric Company | Series-capacitor compensation equipment |
| ES2152489T3 (en) | 1995-01-17 | 2001-02-01 | Thomas & Betts Corp | CABLE CONNECTION BOX WITH PRESSURE COATING AND CONTAINER FOR OUTGOING COATING MATERIAL. |
| DE59604144D1 (en) | 1995-02-21 | 2000-02-17 | Siemens Ag | Hybrid excited electrical machine |
| GB9507391D0 (en) | 1995-04-10 | 1995-05-31 | Switched Reluctance Drives Ltd | Method and apparatus for reducing winding failures in switched reluctance machines |
| DE19515003C2 (en) | 1995-04-24 | 1997-04-17 | Asea Brown Boveri | Superconducting coil |
| US5663605A (en) | 1995-05-03 | 1997-09-02 | Ford Motor Company | Rotating electrical machine with electromagnetic and permanent magnet excitation |
| US5691589A (en) | 1995-06-30 | 1997-11-25 | Kaman Electromagnetics Corporation | Detachable magnet carrier for permanent magnet motor |
| US5607320A (en) | 1995-09-28 | 1997-03-04 | Osram Sylvania Inc. | Cable clamp apparatus |
| GB2308490A (en) | 1995-12-18 | 1997-06-25 | Oxford Instr Ltd | Superconductor and energy storage device |
| DE19547229A1 (en) | 1995-12-18 | 1997-06-19 | Asea Brown Boveri | Packing strips for large rotary electrical machine stator winding |
| IT1281651B1 (en) | 1995-12-21 | 1998-02-20 | Pirelli Cavi S P A Ora Pirelli | TERMINAL FOR CONNECTING A SUPERCONDUCTIVE POLYPHASE CABLE TO A ROOM TEMPERATURE ELECTRICAL SYSTEM |
| DE69709432T2 (en) | 1996-03-20 | 2002-08-22 | Nkt Cables As Broendby | High voltage cables |
| NO307354B1 (en) * | 1996-04-26 | 2000-03-20 | Norsk Subsea Cable As | Device by hydroelectric control cable |
| US5807447A (en) | 1996-10-16 | 1998-09-15 | Hendrix Wire & Cable, Inc. | Neutral conductor grounding system |
-
1997
- 1997-11-28 SE SE9704431A patent/SE9704431D0/en unknown
-
1998
- 1998-02-02 PL PL98334995A patent/PL334995A1/en unknown
- 1998-02-02 JP JP53281698A patent/JP2001510018A/en active Pending
- 1998-02-02 CN CN98802274A patent/CN1080474C/en not_active Expired - Fee Related
- 1998-02-02 BR BR9807131-9A patent/BR9807131A/en not_active IP Right Cessation
- 1998-02-02 EP EP98902371A patent/EP1016179A1/en not_active Withdrawn
- 1998-02-02 NZ NZ337069A patent/NZ337069A/en unknown
- 1998-02-02 US US09/355,728 patent/US6828701B1/en not_active Expired - Fee Related
- 1998-02-02 CA CA002279414A patent/CA2279414A1/en not_active Abandoned
- 1998-02-02 WO PCT/SE1998/000174 patent/WO1998034312A1/en not_active Application Discontinuation
- 1998-02-02 AU AU58925/98A patent/AU730760B2/en not_active Ceased
-
1999
- 1999-07-29 NO NO993686A patent/NO993686L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| NZ337069A (en) | 2001-05-25 |
| EP1016179A1 (en) | 2000-07-05 |
| JP2001510018A (en) | 2001-07-24 |
| WO1998034312A1 (en) | 1998-08-06 |
| AU5892598A (en) | 1998-08-25 |
| NO993686D0 (en) | 1999-07-29 |
| NO993686L (en) | 1999-10-04 |
| PL334995A1 (en) | 2000-03-27 |
| CN1080474C (en) | 2002-03-06 |
| US6828701B1 (en) | 2004-12-07 |
| SE9704431D0 (en) | 1997-11-28 |
| BR9807131A (en) | 2000-01-25 |
| AU730760B2 (en) | 2001-03-15 |
| CN1246969A (en) | 2000-03-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU730760B2 (en) | Synchronous machine | |
| US6525504B1 (en) | Method and device for controlling the magnetic flux in a rotating high voltage electric alternating current machine | |
| EP0901701B1 (en) | Synchronous compensator plant | |
| EP1034593B1 (en) | Power flow control | |
| WO2001078215A1 (en) | Synchronous compensation | |
| AU736277B2 (en) | Synchronous compensator plant | |
| AU737513B2 (en) | A method and device for controlling the magnetic flux in a rotating high voltage electric alternating current machine with permanent magnet rotor | |
| MXPA99006972A (en) | Synchronous machine | |
| Lindahl | Improved control of field current heating for voltage stability machine design-Powerformer/sup TM | |
| CZ262299A3 (en) | Synchronous machine | |
| AU736226B2 (en) | Rotating electric machine with magnetic circuit | |
| SE510315C2 (en) | Synchronous machine, e.g. synchronous generator in electric power network | |
| Yellagoud et al. | A Study of Power Formers and Their Impact on Power System Reliability and Environment | |
| CA2309971A1 (en) | Power flow control | |
| RU99119328A (en) | SYNCHRONOUS MACHINE | |
| MXPA00003034A (en) | Synchronous compensator plant |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |