US 3197723 A
Description (OCR text may contain errors)
July 27 1965 l. K. DOR-rom' 3,197,723
CASCADED COAXIAL CABLE TRANSFORMER Filed April 26, 1961 4 Sheets-Sheet 1 g2 EI- f5..
Mirra/@ri July 27, 1965 l. K. Dom-0R1- 3,197,723
` CASGADED COAXIAL CABLE TRANSFORMER Filed April 26. 1961 4 sheets-sneet 2 wQQQQQ QQQQ Jly 2.7, 1965 l. K. DoR'roR-r- 3,197,723 n cAscAnED coAxIAL CABLE TRANsFoRMER Filed April` 2e, 1961- 4 sheets-sheet s IWI @Mummia/M0@ l. K. DORTORT CASCADED COAXIAL CABLE TRANSFORMER July 27, 1965 Filed April 26, 1961 4 Sheets-Sheet 4 INVENTOR United States Patent O M 3,197,723 CASCADED CGAXIAL CABLE 'IRANSFURMER Isadore K. Dortort, Philadelphia, Pa., assigner to EJE-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Apr. 26, 1961., Ser. No. 165,690 3 Claims. (Cl. 336-I95) My invention relates to a novel cascaded coaxial cable transformer construction for obtaining a very high ratio transformer having a substantially zero leakage reactance where multi-conductor coaxial cables are used for the windings, and more specifically relates to a novel cascading arrangement which minimizes the number of coaxial conductors required for the cable.
In copending application (C4588) Serial No. 808,520 now abandoned, led Apr. 23, 1959, entitled Zero Reactance Transformer, in the name of Jensen and Dortort, and assigned to the assignee of the present invention, a transformer construction is disclosed where, by making the transformer windings of coaxial cable, the reactance of the transformer is made substantially zero. Such transformers are highly desirable in applications of pulse transformers to high energy pulse generators, and transformers for short circuit generators for testing high power circuit breakers.
When such coaxial cable transformers are manufactured, in order to obtain very high voltages, the coaxial cable must either contain a large number of conductors which makes it dilicult and expensive to manufacture, or very high voltages must exist between a limited number of adjacent conductors which also leads to great expense and diiculty in manufacturing because of difficult insulation problems. Which ever of the methods is used to obtain the high output voltage, it becomes necessary to increase the outer diameter of the cable, since either more turns or more insulation is necessary. This increases the bending radius of the cable and, therefore, increases the internal diameter of the coil.
The principle of the present invention is to provide a novel transformer construction using the coaxial cable concept of the above noted application where a limited number of coaxial conductors may be used with a relatively -low voltage appearing between adjacent conductors, although very high voltages are obtained from the system. More specifically, I have found that by cascading a plurality of such transformers, I can obtain extremely high voltages while the construction of the individual transformer cables is kept within reasonable limits. By way of example, in cascading two transformers, the input voltage is applied to a primary winding portion of the first transformer. An end portion of the secondary winding of the first transformer, which has the same voltage appearing thereacross as the primary voltage, is then connected to the primary winding of the second transformer. The total voltage output is then taken from the secondary winding of the first transformer and the secondary winding of the second transformer whereby, a voltage equal to the full voltage output of the second transformer plus the voltage across the secondary winding of the iirst transformer, less that portion used as an input for the second transformer, is obtained.
This increased voltage ratio between the total output of the combined transformers to the voltage input of the first transformer is thus achieved without requiring an excessive number of turns kfor the coaxial cable of either of the transformers, and without requiring excessive voltages between the adjacent conductors of the individual transformers.
In order to increase the voltage level to whatever value is required, it will be apparent that as many transformers as necessary can be cascaded with one another Caf) lflz Patented July 27, 1965 ICC where the input to each successive transformer is derived from a portion of the secondary output of a preceding transformer.
Accordingly, a primary object of this invention is to provide a novel high voltage transformer system.
Another object of this invention is to provide a novel arrangement of cascaded coaxial cable transformers which reduces the required diameter of the coaxial cable.
Another object of this invention is to provide a novel, relatively inexpensive high Voltage transformer.
A further object of this invention is to provide a novel high voltage transformer system having substantially zero reactance wherein the diameter of the coaxial cable used is relatively independent of the voltage ratio to be obtained.
These and other objects of this invention will become apparent from the following description when taken in connection with the drawings in which:
FIGURE 1 illustrates a typical two-winding transformer formed of coaxial cable.
FIGURE 2 illustrates the coaxial cable transformer of FIGURE l as an auto-transformer.
FIGURE 3 illustrates the composite cable to be used in the embodiments of FIGURES 1 or 2 when formed of spiral wound, round conductors.
FIGURE 4 illustrates the manner in which the coaxial winding can be formed by metallic tapes.
FIGURE 5 illustrates the manner in which the conductors of FIGURES 3 and 4 can be modified with a central tubular conductor which is adapted to conduct a cooling medium.
FIGURE 6 shows another manner in which the cable of FIGURE 3 could be formed so as to conduct a coolant therethrough.
FIGURE 7 schematically illustrates the novel cascading arrangement of the present invention for transformers of the type shown in FIGURE 2.
FIGURE 8 schematically illustrates the manner in which the three transformers of FIGURE 7 can be formed on a common core.
FIGURE 9 shows an enlarged view of the cascaded circuit portion of FIGURE 7 where a portion of the secondary winding of a preceding transformer is connected to the primary winding of a succeeding transformer.
FIGURE 10 illustrates the manner in which the invention may be applied to a unitary package of conductors not coaxial with one another for applications where some minimum leakage ield is permissible.
FIGURE 1l schematically illustrates a modification of the arrangement of FIGURE l0.
FIGURE 12 schematically illustrates a further embodiment of the invention using a multi-layered sandwich of sheet metal and foil separated by sheets of insulating material where the primary and secondary windings are interleaved.
FIGURE 13 schematically illustrates a typical prior art type of .autotransformer construction.
FIGUR-E 14 schematically illustrates the novel transformer of the invention ,as shown, `for example, in FIG- URES 7 and 9 for purposes of comparison with the prior art type of autotransformer construction of FIGURE 13.
Referring now to FIGURE 1, a transformer core 20, which is constructed in accordance with the usual techniques, has a window 22 which receives composite winding 24 which is formed in accordance with the Iteachings of above noted .application Serial No. 808,502.
The composite winding 24, as is schematically illustrated, has seven turns and is formed of four physically parallel `conductors 26, 28, 30 and 32. These individual physically parallel conductors 26 Athrough 32 are contained in an insulating -medium 34 and are insulated from one another, as will be seen more fully hereinafter, andsa are surrounded by a hollow conductive sheath 36 which acts as a primary winding for the transformer. The sheath 36 is then covered with an insulating sheath 3S which insulates adjacent turns ofwinding 24 from one another.
As schematically illust-rated to the left of FIGURE 1, an A.C. generator 40 is connected across the primary winding 36. The physically parallel conductors 26 through 32 form the secondary winding and are externally sequentially connected in series so that the secondary winding is comprised of four times seven, or twenty-eight turns. Therefore, if the generator voltage is V, the output secondary voltage is 4V. This connection of the individual conductors of the secondary winding is more specifically seen in FIGURE 1 to runas follows:
The first terminal of conductor 26 forms the lower ter- -minal 42 of the secon-dary winding. Conductor 26 then is taken through the seven-turn winding and emerges at the top of the winding and is then externally connected to thelower end of conductor 281 Conductor 23 then runs through the seven turns of the winding and emerges at the lupper port-ion of the winding, and is then connected to the lower end of conductor 3f). Conductor 30 then 'runs through the seven-turn winding and emerges at the upper part of the coil, and is thereafter connected to the lower end lof conductor 32. Conductor 32 finally runs through the seven-.turn winding to complete the twentyeight turn secondary and thereafter emerges at the top of the winding, and is terminated at upper terminal 44.
Accordingly, a step-up transformer is provided in which the leakage reactance, because of the configuration of the windings, issubstantially zero.
The above FIGURE 1 schematically illustrates the transformer structure as a two-winding transformer. If desired, Ian auto-transformer connection may be used to increase the economy of the unit. This is illustrated in FIGURE 2 which further specifically illust-rates the preferred winding as formed of concentric conductors for the physically parallel conductors of the Winding.
In FIGURE 2, winding 24V is. formed of concentric conductor elements 46, 48, 50 and 52 which correspond to conductors 26, 28, 30 and `32 respectively of FIGURE 1. The generator 50 in FIGURE 2 is connected across the first tubular conductor 46 which serves `as the primary of the auto-transformer shown. The secondary winding is formed by the external connections between conductors 46 through 52 and starts at the lower end of conductor 46 and runs to the upper end of conductor 46 to form the i-rst seven turns. The upper end of winding 46 is then connected .to the 4lower end of winding 48, and the connection then again goes through the seven-turn Winding to the upper end of winding 48. T-he upper end of winding 48 is then connected to the lower end of winding 50 which again goes 4through the seven turns to emerge at the upper end of winding 5t). The upper end of winding 50 is then connected `to the lower end of winding 52 which goes through the seven-turn winding to complete the twenty-eight turns, and the conductor emerges at the upper end of winding 52.
As was the case in FIGURE 1, the upper end of winding 52 emerges to terminal 44, while the lower end of winding 46 emerges as terminal 42. Similarly, the complete composite cable is covered with an insulating sheath 38, while the various concentric conductors are insulated from one another in any desired manner.
In forming lthe composite conductors of FIGURES 1 and 2, many techniques may be employed.
In FIGURE 3 a typical possible construction is shown where the cable is made of spiral wound, round conductors. In this case, the innermost conductor 52 of FIG- URE 2 is seen in FIGURE 3 as being formed by the innermost group of spiral wound, round conductors 52. Innermost conductor 52 is then covered with an insulation medium 54, and a second layer of spiral wound, round conductors 50 forms the conductor 50 of. FIG- URE 2. Once aga-in, an insulating sheath 56 is wound on conductor Sil, and the concentric wound, round conductor layer 43 is wound on insulation `|56. A further sheath of insulation -53 is wound on top of conductors 4S, and sheath 5S supports the final layer of conductors 46 which form the outermost tubular conductor 46 -of FIGURE 2. The complete assembly is then covered by insulation sheath 69 so that the complete composite conductor is formed.
While FIGURE 3 shows the use of spiral wound, round conductors for forming the conductive elements, a metallic tape may be used instead of the round wires, as is schematically illustrated lin FIGURE 4.
In FIGURE 4, the conductive elements 46, 48 and 50 are of metallic tape, while the innermost conductor 52 may be a round conductor. As was the case in FIG- URE 3, the conductive layers are insulated from one an-` other by insulator layers 54, 56 and 58 with insulating sheath 64B completing the cable.
FIGURE 5, which is a cross-sectional View of a conductor similar to the `conductor of FIGURE 3, further illustrates that the central conductor 52 can be formed of a tubular conductor where the tube may be used to conduct a cooling mediumv such as oil to carry away the internal heat of the conductor.
The `insulation between the various conductive layers of FIGURES 3, 4 and 5 has been described as being of any desired type. Thus, it may be in the form of an extruded plastic jacket, a wound paper tape, or a cloth or plastic tape, or any of the well known and commonly used insulating materials. Certain plastic materials, such as polyethylene, can be irradiated after the coil is formed to provide greater electrical strength. Insulation over the sheath conductor to `form layer 60 can be in the form of `an extruded plastic, varnish, enamel, glass or cloth tape. It need only be sufficient to withstand the turnto -turn voltage of the transformer :secondary winding, and have sufficient mechanical strength to withstand the coil winding operation.
For very high voltages, it has been found that paper insulated cable in combination with high or low pressure loil systems is suitable for the loperation of the system. This `lends itself, as is shown in FIGURE 6, to using a sheath 62 which may be of aluminum over the type of cable shown in FIGURE 3. The composite conductor may then be impregnated with -oil which is contained by lsheath 62. The aluminum sheath is subsequently surrounded by another insulating wrapping 64 to prevent short circuiting of the -turns when the winding is wound. The transformer may then be made essentially a dry type transformer even for very high voltages, with the oil being contained within the cable. The central conductor can readily be `formed with channels to permit the rapid equalization of oil pressures.
Since the jacket 62 isa conductive member, it is clear that it could be used as another winding of the secondary, or as a primary winding. Furthermore, instead of being formed as a sheath, it may bedesirable that it be formed of a -stranded conductor with the entire core and coil immersed in a tank of insulating oil, as is well known in the a-rt. completely dry, it is clear that it can be enclosed in a hermetically sealed case which would contain some inert gas, or some high dielectric gas, such as sulphur hexa uoride.
It is obvious that the low voltage primary winding will have the largest cross-section. If, as in most cases, it is desirable to tap the high voltage winding, the current ratings of the internal conductors will be graded according to the current they will deliver at their tap. If a tap is provided at each conductor terminal, the grading will be uniform and achieved naturally by the increasing.
diameter of the conductor.
In the case of a test transformer, the duty cycle is extremely short and the cross-section of each conductor is so dimensioned that the total heat generated in the Still further, if the transformer is to be made conductor during the test will raise the temperature of the conductor to a maximum safe value.
In accordance with the present invention, and in order to reduce the number of conductors in the coaxial cable as well as the voltage between the conductors, I have discovered that I can cascade several coaxial cable transformers, as shown in FIGURE 7. Referring to FIGURE 7, I have schematically illustrated three transformers 100, 101 and 102 which may each be of the type shown in FIGURE 2.
The full output voltage of the system is VN, while the input voltage is V. The bottom line 103 schematically illustrates the reference potential of the system. It is seen that transformer 101 must be insulated from this reference, as schematically illustrated byinsulator 104, which is capable of withstanding somewhat less than the full output voltage of transformer 100, and is approximately one-third of the full output voltage. Transformer 102 must be insulated from ground 103, as schematically illustrated by the two insulators S and 106 which are capable of insulating apotential of the order of twothirds of the full output voltage of the system.
Each of the auto-transformers 100, 101 and 102 have respective primary or input winding portions 107, 108 and 109. The outer end of the secondary windings of transformers 100 and 101 have output portions 110 and 111 respectively which are connected to the primary windings or input winding portion of the succeeding transformers, whereby output winding portion 110 is connected to input winding 108, while output winding portion 111 is connected to input winding 109.
The winding portions 110 and 111 are arranged to have a voltage thereacross equal to the primary voltage V of the system, whereby each of the cascaded transformers 100, 101 and 102 sees the same primary voltage.
Assuming, for the embodiment 0f FIGURE 7, that the conductor used in winding transformers 100, 101 and 102 is a four-conductor coaxial cable, there will be provided a transformation ratio of ten to one between the output voltage VN and input voltage V. That is to say, the output voltage VN is equal to the sum of the full winding voltage of transformer 102 which is four times as great as its input voltage plus the voltage appearing across the winding of transformer 101 up to and excluding winding portion 111, which is equal to three times the input Voltage plus the voltage appearing across transformer winding 100 up to and excluding winding portion 110 which is again equal to three times the input voltage V.
Moreover, the transformation ratio, shown above to be ten to one, is achieved with only one-tenth of the output voltage appearing between the adjacent conductors of -any of the transformers. It will be noted that had a single transformer having a four-conductor cable been used, the voltage between conductors would necessarily be one-fourth of the output voltage rather than the onetenth obtained with the novel cascaded system.
Again, if a single transformer were used and were designed so that only one-tenth of the total voltage between conductors appears as in the novel system of FIGURE 7, it would require the use of a ten-conductor coaxial cable. Thus, in the case of attempting to use a single transformer of the type shown in FIGURE 2, an attempt to achieve the results of the system of FIGURE 7 would require a substantially increased diameter for the coaxial cable, due either to a required increase in insulation between the cable conductors because of the increased voltage between conductors or an increased number of turns, due to the required turns ratio which must be met.
In FIGURE 7, I show the result of a ten to one ratio using only three transformers which are cascaded with one another. It will be apparent that other cascading arrangements could be used. By way of example, twoconductor coaxial cable transformers can be used where nine transformers of this type are cascaded so that only one-tenth of the output voltage appears between adjacent conductors. The determination of the size of the transformers may be begun here by considering the total rating of all of the transformers expressed in terms of an equivalent two-winding transformer. Thus, the total KVA expressed as KVAT will be equal to VI iiNet-DWH) KVATooo Ntn-nM-l-i where V is the input voltage of the primary Winding of transformer 100,
I is the input primary current of transformer 100,
N is the total number of transformers, and
n is the number of conductors in each of the coaxial cables In the generalized situation, it will be seen that the VA rating of the Kth transformer is VI (ri-1) (N-K-I-l) KVM-1000 Noz-n+1 From the above, it is seen that the total KVA parts of the cascaded transformers expressed in terms of an equivalent two-winding transformer increases as the number of transformers increase.
While in FIGURE 7 I have illustrated my novel cascading system for the case of three independent transformers, the same results may be obtained in a unitary transformer construction wherein a common core is used for all of the transformers to form a multi-Winding transformer. Such a construction is schematically illustrated in FIGURE 8 where a transformer core 120 receives six layers of Windings schematically illustrated by layers 121 through 126. Each of layers 121 through 126 as shown in FIGURE 8 is formed of the four coaxial cable conductor which is used here for purposes of illustration. Equating this to FIGURE 7, layers 121 and 122 serve as a first transformer system, layers 123 and 124 serve as a second transformer system, and layers 125 and 126 serve as the third transformer system. These three transformer systems are, of course, fully equivalent to transformers 100, 101, and 102, respectively of FIGURE 7.
Clearly, each of the transformer systems can be formed of any desired number of layers, two layers being selected here for purposes of illustration. In the event that an odd number of layers are used for each section, it would be preferable to make the cable terminations outside of the coil area so that the cable ends or the cross connections between the ends need not be carried through the coil to produce unnecessary complications in the insulation structure.
The inter-connections between the various coils are schematically illustrated in FIGURE 8 where the circuit diagram achieved through such connections is identical to that previously shown in FIGURE 7.
It will be noted that the layer insulation between sections such as the insulating layers 127, 128 and 129 illustrated in dotted lines for the layer insulation between the layers of given sections or transformer groups, may be calculated in the standard manner on the basis of the outside conductor voltage only. The barrier insulation illustrated by the double dotted lines, such as barrier insulation layers 130 and 131, are equivalent to insulators 104 and insulators 105, respectively of FIGURE 7, and are designed to withstand approximately volts. The insulation equivalent of insulator 106 is not required.
As is illustrated in FIGURE 7 and reproduced on an enlarged scale in FIGURE 9, there is a closed circuit at the point at which adjacent transformer sections are connected. Thus, in FIGURE 9, winding portion 110 is connected in closed circuit arrangement with respect to winding portion 108. It has at least partially been this closed winding portion which for many years has led those skilled in the art to not adopt such an arrangement in low reactance applications, since it was felt that this arrangement would lend itself to substantial leakage fields. I have, however, found that this is not the case and have demonstrated that practically all leakage fields are cancelled in this area.
More specitically,V if the current divides between winding portions 110 and 108 merely as a function of their respective resistances, the magnetic ields of these currents in a given coaxial cable would not be cancelled. Such a current distribution is shown in FIGURE 9 as 1/zIn based on the assumption that the two conductors have equal resistances and their currents are equal. The circulating current i is caused, by reactance and proxmer winding currents in the two connected sections which cause all the llux to Vcancel if so that X is again O.
These currents, however, will not divide merely according to the resistances of the windings, but there will be a circulating current between them which is equivalent to the eddy current elfects found in multiple strands of conductors of standard transformers, if wound without transpositions. In this particular instance, these eddy currents are desired and necessary. They are more specilically produced by the resultant leakage field, and will produce winding currents as specifically shown in FIG- URE 7 with only a slight error due to the resistance drop ofthe cable in the sections involved, thereby causing the leakage fields to be essentially cancelled.
It can be demonstrated that in coaxial cables with relatively small insulation thickness between the conductors, this error is negligible. As a result, the coaxial currents are completely balanced just as in the cascaded transformers of FIGURE 7, so that substantially all of the leakage fields are cancelled out again to retain the exceedingly low or substantially zero reactance vof the cascaded transformer system.
The foregoing discussion of the operation of the novel transformer of the invention can be further facilitated by the comparison shown in FIGURES 13 and 14 of a standard prior art type of autotransformer and the novel transformer of the invention schematically shown in FIGURE 14.
In each of the figures, there is illustrated a common magnetic core 200 which receives a plurality of series connected windings, each of which is composed of a plurality of turns.
Referring first to FIGURE 13, the voltage source E is connected across the primary winding section 201, while the output voltage 9E is derived lfrom the nine series connected turns illustrated. Clearly, a current of the magniture 91 must be drawn from the voltage source E. This current less the magnitude 1I flows in the primary winding 201, thus causing a net current 8l for driving flux in core`200. The two additional turns of the first section will each have an upwardly directed current I so that for the rst group of three turns, there is a net downwardly directed current 6I.
In the next two groups of three turns each, each turn supplies the magnitude 1I in an upward direction, thus providing the opposing current 6I for a net zero value of ampere turns for the core 200. That is, the net current for each group of turns is not zero, but is some discrete value.
As indicated in FIGURE 13, a leakage liux will be created by the current magnitude 6nI where n is the total number of turns.
With the arrangement of the invention, and illustrated in FIGURE 14, leakage flux will be canceled within each of the groups of turns so that there will be smaller leakage g flux and thus a lower reactance for the transformer system. Thus, FIGURE 14 illustrates four groups of windings which are cascaded in accordance with the invention on the common core 260.
In the first and lower group of turns, the central conductors provide 7I and 1I, respectively, to counterbalance the 3l of the input winding 11. Thus, there is a net zero current for the first group of windings. In a similar manner, the net current in each of the additional Winding groups is zero, as shown in FIGURE 14.
Accordingly, the invention provides cancellation within each winding group so that the leakage flux around the core is substantially reduced, thus leading tota much lower reactance device.
Where coaxial cable is used to define the windings of FIGURE 14, it will be apparent that the coupling between adjacent turns is much tighter and the induced current between winding sections will be much more exact. Therefore, the net current will be more nearly zero than when using a standard transformer winding.
While the present invention is particularly applicable to cases where the transformer System is to have a substantially zero leakage reactance, it is to be understood that the invention is additionally applicable to those cases wherein some minimum leakage reactance is permissible so that coaxial cable is not necessary. That is to say, the invention is applicable to other types of conductor arrangements other than coaxial arrangements.
By way of example, and as is Vschematically shown in FIGURE 10, a transformer corel may have a winding formed of adjacently positioned axially elongated or sheet conductors 151 through 161 where conductor 161 is the nth conductor or middle conductor of the pack, corresponding to the middle conductor of a coaxial cable. Conductors 151 and 160 correspond to the sheath.
The windings 151 and 160 may, for example, be primary windings, while windings 152 through 159 and 161 are secondary windings with the complete schematically illustrated group of windings being wound at one and the same time, as is the case in the coaxial type of conductor. Note that in FIGURE 10 I show an equivalent of a cross-sectional view through the combined conductor forming six windings, and that this group will be wound around a transformer core such ascore 150.
The conductors 151 through 155 are further connected in parallel with conductors 160, 159, 158, IS7 and 156 respectively with transportations being used throughout the Winding, if desired. To assure a more uniform distribution of current, although the distribution of current obtained from a continuous winding of the type of FIG- URE 10 will be suicient for most cases.
When the transformer conductor is constructed in the manner shown in FIGURE l0, a transformer system may be seen to be formed in the manner illustrated in FIG- URES 7 and 8, whereby a high voltage ratio may be provided for the system without requiring either an excessively large number of parallel conductors within the cable or without requiring an excessively large voltage between the adjacent conductors of the unitary conductor bundle.
Where requirements are less stringent so far as leakage reactance is concerned, a one-sided arrangement, schematically illustrated in FIGURE 11, may be used where the cable is composed, as schematically illustrated for the cable cross-section, of only conductors 151 through 155 and 161.
FIGURE 12 illustrates one manner in which a stepdown transformer can be made using a winding of the type shown in FIGURE 11, and applying the concepts of cascaded systems, as described in FIGURE 8. Thus, in FIGURE 12, a common transformer core 162 is Wound with three sections of windings, 163, 164 and 165 respectively which are each, in turn, formed of three layers of windings, as contrasted to the two layers shown in FIGURE 8. Thus, section 163 is formed of three layers 166, 167 and 16S which are, in turn, composed of five layers of sheet metal or foil separated by sheets of insulatinfr material (not shown).
Each of the groups of layers, such as layers idd, M7 and ldd, are wound as a unitary conductor bundle to simultaneously form the primary and secondary windings of the transformer. Clearly, there will be an inter-layer insulation between layers, as indicated by dotted lines la@ and i7@ for section M3, while section insulation is provided as illustrated in the double dotted lines such as lines il'l between sections 163 and ldd.
lt will be noted that FGURE l2 results in a transformer that resembles one having interleaved primary and secondary windings. lt differs, however, in that the full voltage of the primary winding of the transformer does not appear across the insulation between primary and secondary windings.
These spaces need only be sufficient for a relatively small portion of the voltage, and for ventilation purposes. Therefore, they do not contribute appreciably to the irnpedance as in the standard interleaved transformer.
The sheet-type conductor construction of FIGURE 12 is particularly useful for moderate and low voltage transformers having large turns ratios, as, for example, is required in spot-welding type transformers. ln such application, the input AC. generator E72 is connected, as illustrated, with the load V13 being connected as shown. The load f7.3, for example, can be the electrodes of a spotwelding transformer.
Although l have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specic disclosure herein but only by the appended claims.
1. A high voltage transformer system; said high voltage transfer.; er system comprising a plurality or" Windings and a common magnetic core receiving said plurality of windings; each of said plurality of windings comprising a plurality of turns; each of said plurality of windings having an input winding portieri; each of said plurality of windings except the last of said plurality of windings having an output winding portion; the said input winding portion of each of said plurality of windings being connected in series with the said output winding portion of the next adjacent winding of said plurality of windings.
The device substantially as set forth in claim l, wherein said input winding portion of the iirst of said plurality of serially arranged windings defines the input connection for said system; the outer ends of said plurality of windings dening the output terminals of said system.
3. rl`he device substantially set forth in claim l. wherein each of said windings comprise coaxially arranged conductors; each of said coaxially arranged conductors sequentially connected to one another to denne a plurality of turns equal in number to the number of turns of said winding around said core times the number of coaxially arranged conductors.
References Cited bythe Examiner UNITED STATE-S PATENTS l,ll7,293 ll/l4 Wilson 307-17 X 1,523,367 1/25 Petersen et al. 307-17 1,868,483 7/32 Austin 307-17 3,995,965 10/61 Wertanen 336-195 10i-IN F. BURNS, Primary Examiner.
MlLTON O. HRSHFIELD, LLOYD M. MCCOLLUM,