CA2550997C - Arc fault detector - Google Patents
Arc fault detector Download PDFInfo
- Publication number
- CA2550997C CA2550997C CA2550997A CA2550997A CA2550997C CA 2550997 C CA2550997 C CA 2550997C CA 2550997 A CA2550997 A CA 2550997A CA 2550997 A CA2550997 A CA 2550997A CA 2550997 C CA2550997 C CA 2550997C
- Authority
- CA
- Canada
- Prior art keywords
- inductor
- conductor
- coupled
- current
- arc
- 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.)
- Active
Links
- 239000004020 conductor Substances 0.000 claims abstract description 120
- 238000001514 detection method Methods 0.000 claims description 32
- 230000007935 neutral effect Effects 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 26
- 230000004907 flux Effects 0.000 claims description 21
- 238000009826 distribution Methods 0.000 claims description 10
- 238000004804 winding Methods 0.000 claims description 7
- 230000004044 response Effects 0.000 claims description 5
- 238000007654 immersion Methods 0.000 claims description 2
- 230000008878 coupling Effects 0.000 abstract description 14
- 238000010168 coupling process Methods 0.000 abstract description 14
- 238000005859 coupling reaction Methods 0.000 abstract description 14
- 239000003990 capacitor Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 8
- 238000009413 insulation Methods 0.000 description 7
- 230000007246 mechanism Effects 0.000 description 7
- 230000035945 sensitivity Effects 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- 230000001939 inductive effect Effects 0.000 description 5
- 239000000654 additive Substances 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- 239000000696 magnetic material Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 230000001976 improved effect Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000008033 biological extinction Effects 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
- H02H1/0015—Using arc detectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/44—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to the rate of change of electrical quantities
Abstract
An arc fault detector, as a stand alone device or in combination with a circuit interrupting device such as a ground fault interrupter (GFCI), protects from potentially dangerous arc fault conditions. The device utilizes a line side (16) or load side series connected inductance (20) having an air or magnetic core to generate the derivative di/dt signal of the arc current in the conductor (16). The derivative signal is fed to an arc fault detector (24) where it is analyzed for the presence of arcing. The device can have two series connected inductors (20, 30) inductively coupled to each other such that the signal from one inductor is inductively coupled into the other inductor for coupling to the arc fault detector.
Description
ARC FAULT DETECTOR
Inventors: Ross MERNYK
Roger M. BRADLEY
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for arc fault detection and more particularly relates to an apparatus and method for both a stand alone arc fault detector and an arc fault detector combined with a circuit interrupter device.
BACKGROUND OF THE INVENTION
Circuit breakers, fuses and ground fault circuit interrupters (GFCIs) are commonly used devices for protecting people and property from dangerous electrical faults. Fatalities and loss of property caused by electrical faults that go undetected by these protective devices still occur. One such type of electrical fault that typically goes undetected are arc faults. Arcs are potentially dangerous due to the high temperatures contained within them.
Thus, they have a high potential of creating damage, mostly through the initiation of fires. An arc, however, will trip a GFCI only if it produces sufficient current leakage to ground. In addition, an arc will trip a breaker only if the current flowing through the arc exceeds the trip parameters of the thermal/magnetic mechanism of the breaker. Therefore, an additional type of protection device is needed to detect and interrupt arcs. An arc detector whose output is used to trigger a circuit interrupting mechanism is referred to as an Arc Fault Circuit Interrupter (AFCI).
The causes of arcing are numerous, for example: aged or worn insulation and wiring;
mechanical and electrical stress caused by overuse, over currents or lightning strikes; loose connections; and mechanical damage to insulation and wires. Two types of arcing can occur in residential and commercial buildings: contact arcing and line arcing.
Contact or series arcing occurs between two contacts in series with a load. Therefore, the load controls the current flowing in the arc. Line or parallel arcing occurs between the conductors of a circuit or from a conductor to ground. In this case the arc is in parallel with any load present and the source impedance provides the only limit to the current flowing in the arc.
An example of contact arcing is illustrated in Figure 1. The conductors 114, comprising the cable 110, are separated and surrounded by an insulator 112. A
portion of the conductor 114 is broken, creating a series gap 118 in conductor 114. Under certain conditions, arcing will occur across this gap, producing a large amount of localized heat. The heat generated by the arcing might be sufficient to break down and carbonize the insulation close to the arc 119. If the arc is allowed to continue, enough heat will be generated to start a fire.
A schematic diagram illustrating an example of line arcing is shown in Figure 2.
Cable 120 comprises electrical conductors 124, 126 covered by outer insulation 122 and separated by inner insulation 128. Deterioration or damage to the inner insulation at 121 may cause line fault arcing 123 to occur between the two conductors 124, 126. The inner insulation could have been carbonized by an earlier lightning strike to the wiring system, or it could have been cut by mechanical action such as a metal chair leg cutting into an extension cord.
The potentially devastating results of arcing are widely known and a number of methods of detecting arcs have been developed in the prior art. A large percentage of the prior art refers to detecting high frequency signals generated on the AC line by arcs.
A wide range of prior art exists in the field of arc detection. Some of the prior art refer to specialized instances of arcing. For example, U.S. Patent No. 4,376,243, issued to Renn, et al., teaches a device that operates with DC current. U.S. Patent No.
4,658,322, issued to Rivera, teaches a device that detects arcing within an enclosed unit of electrical equipment.
U.S. Patent No. 4,878,144, issued to Nebon, teaches a device that detects the light produced by an arc between the contacts of a circuit breaker.
In addition, there are several patents that refer to detecting arcs on AC
power lines that disclose various methods of detecting high frequency arcing signals. For example, U.S. Patent Nos. 5,185,684 and 5,206,596, both issued to Beihoff et al., employ a complex detection means that separately detects the electric field and the magnetic field produced around a wire.
Inventors: Ross MERNYK
Roger M. BRADLEY
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for arc fault detection and more particularly relates to an apparatus and method for both a stand alone arc fault detector and an arc fault detector combined with a circuit interrupter device.
BACKGROUND OF THE INVENTION
Circuit breakers, fuses and ground fault circuit interrupters (GFCIs) are commonly used devices for protecting people and property from dangerous electrical faults. Fatalities and loss of property caused by electrical faults that go undetected by these protective devices still occur. One such type of electrical fault that typically goes undetected are arc faults. Arcs are potentially dangerous due to the high temperatures contained within them.
Thus, they have a high potential of creating damage, mostly through the initiation of fires. An arc, however, will trip a GFCI only if it produces sufficient current leakage to ground. In addition, an arc will trip a breaker only if the current flowing through the arc exceeds the trip parameters of the thermal/magnetic mechanism of the breaker. Therefore, an additional type of protection device is needed to detect and interrupt arcs. An arc detector whose output is used to trigger a circuit interrupting mechanism is referred to as an Arc Fault Circuit Interrupter (AFCI).
The causes of arcing are numerous, for example: aged or worn insulation and wiring;
mechanical and electrical stress caused by overuse, over currents or lightning strikes; loose connections; and mechanical damage to insulation and wires. Two types of arcing can occur in residential and commercial buildings: contact arcing and line arcing.
Contact or series arcing occurs between two contacts in series with a load. Therefore, the load controls the current flowing in the arc. Line or parallel arcing occurs between the conductors of a circuit or from a conductor to ground. In this case the arc is in parallel with any load present and the source impedance provides the only limit to the current flowing in the arc.
An example of contact arcing is illustrated in Figure 1. The conductors 114, comprising the cable 110, are separated and surrounded by an insulator 112. A
portion of the conductor 114 is broken, creating a series gap 118 in conductor 114. Under certain conditions, arcing will occur across this gap, producing a large amount of localized heat. The heat generated by the arcing might be sufficient to break down and carbonize the insulation close to the arc 119. If the arc is allowed to continue, enough heat will be generated to start a fire.
A schematic diagram illustrating an example of line arcing is shown in Figure 2.
Cable 120 comprises electrical conductors 124, 126 covered by outer insulation 122 and separated by inner insulation 128. Deterioration or damage to the inner insulation at 121 may cause line fault arcing 123 to occur between the two conductors 124, 126. The inner insulation could have been carbonized by an earlier lightning strike to the wiring system, or it could have been cut by mechanical action such as a metal chair leg cutting into an extension cord.
The potentially devastating results of arcing are widely known and a number of methods of detecting arcs have been developed in the prior art. A large percentage of the prior art refers to detecting high frequency signals generated on the AC line by arcs.
A wide range of prior art exists in the field of arc detection. Some of the prior art refer to specialized instances of arcing. For example, U.S. Patent No. 4,376,243, issued to Renn, et al., teaches a device that operates with DC current. U.S. Patent No.
4,658,322, issued to Rivera, teaches a device that detects arcing within an enclosed unit of electrical equipment.
U.S. Patent No. 4,878,144, issued to Nebon, teaches a device that detects the light produced by an arc between the contacts of a circuit breaker.
In addition, there are several patents that refer to detecting arcs on AC
power lines that disclose various methods of detecting high frequency arcing signals. For example, U.S. Patent Nos. 5,185,684 and 5,206,596, both issued to Beihoff et al., employ a complex detection means that separately detects the electric field and the magnetic field produced around a wire.
U.S. Patent No. 5,590,012, issued to Dollar, teaches measuring the high frequency current in a shunted path around an inductor placed in the line, which can be the magnetic trip mechanism of a breaker. In a second detection circuit, proposed by Dollar, high frequency voltage signal is extracted from the line via a high pass filter placed in parallel with any load.
Various methods can be found in the prior art to authenticate arcing and to differentiate arcing from other sources of noise. Much of the prior art involves complicated signal processing and analysis. U.S. Patent No. 5,280,404, issued to Ragsdale, teaches looking for series arcing by converting the arcing signals to pulses and counting the pulses.
In addition, several patents detect arcing by taking the first derivative or second derivative of the detected signal. For example, U.S. Patent No. 5,224,006, issued to MacKenzie et al., and U.S. Patent Nos. 5,185,684 and 5,206,596, issued to Beihoff et al, disclose such a device.
Blades uses several methods to detect arcs as disclosed in U.S. Patent Nos.
5,223,795, 5,432,455 and 5,434,509. The Blades device is based on the fact that detected high frequency noise must include gaps at each zero crossing, i.e., half cycle, of the AC
line. To differentiate arcing from other sources of noise, the Blades device measures the randomness and/or wide bandwidth characteristics of the detected high frequency signal. The device taught by U.S.
Patent No. 5,434,509 uses the fast rising edges of arc signals as a detection criterion and detects the short high frequency bursts associated with intermittent arcs.
U.S. Patent No. 5,561,505, issued to Zuercher et al., discloses a method of detecting arcing by sensing cycle to cycle changes in the AC line current. Differences in samples taken at the same point in the AC cycle are then processed to determine whether arcing is occurring.
A characteristic of arcing on a conductor is the occurrence of high frequency signals which are different from the frequency (normally 60 cycles) of the current for which the conductor is intended to carry. Electrical arcing produced by alternating voltage will extinguish each time the voltage across the arc drops below a value sufficient to sustain the arc, and will re-ignite each tine the voltage across the arc exceeds the arc's minimum ignition voltage. The ignition voltage is substantially proportional to the size of the physical gap that the arc must traverse.
Various methods can be found in the prior art to authenticate arcing and to differentiate arcing from other sources of noise. Much of the prior art involves complicated signal processing and analysis. U.S. Patent No. 5,280,404, issued to Ragsdale, teaches looking for series arcing by converting the arcing signals to pulses and counting the pulses.
In addition, several patents detect arcing by taking the first derivative or second derivative of the detected signal. For example, U.S. Patent No. 5,224,006, issued to MacKenzie et al., and U.S. Patent Nos. 5,185,684 and 5,206,596, issued to Beihoff et al, disclose such a device.
Blades uses several methods to detect arcs as disclosed in U.S. Patent Nos.
5,223,795, 5,432,455 and 5,434,509. The Blades device is based on the fact that detected high frequency noise must include gaps at each zero crossing, i.e., half cycle, of the AC
line. To differentiate arcing from other sources of noise, the Blades device measures the randomness and/or wide bandwidth characteristics of the detected high frequency signal. The device taught by U.S.
Patent No. 5,434,509 uses the fast rising edges of arc signals as a detection criterion and detects the short high frequency bursts associated with intermittent arcs.
U.S. Patent No. 5,561,505, issued to Zuercher et al., discloses a method of detecting arcing by sensing cycle to cycle changes in the AC line current. Differences in samples taken at the same point in the AC cycle are then processed to determine whether arcing is occurring.
A characteristic of arcing on a conductor is the occurrence of high frequency signals which are different from the frequency (normally 60 cycles) of the current for which the conductor is intended to carry. Electrical arcing produced by alternating voltage will extinguish each time the voltage across the arc drops below a value sufficient to sustain the arc, and will re-ignite each tine the voltage across the arc exceeds the arc's minimum ignition voltage. The ignition voltage is substantially proportional to the size of the physical gap that the arc must traverse.
The extinction voltage tends to be lower than the ignition voltage. When the arc gap is very large, the arc will be intermittent and unstable and will tend to extinguish itself and re-ignite as conditions permit. As the gap becomes smaller, the arc becomes more persistent and eventually self-sustaining. When the gap becomes much smaller, the arc tends to self-extinguish by completing the current path. When the arc conducts current, it produces high frequency signals on the electrical conductors.
A number of systems that have been developed to detect arcing in buildings do so by monitoring high frequency signals present on the conductors. One such method of detecting arcing is by an arc detector that detects the derivative of the signal on the conductor.
Typically, such arc detectors employ, for example, current transformers to produce signals representative of the high frequency signals on the wiring being monitored.
Current transformers both add to the manufacturing cost of the arc fault detector and, because of the size of the components, creates packaging difficulties. In addition, current transformers have a limited high frequency response and poor signal-to-noise ratio.
Accordingly, there is a need for an arc fault detector that provides improved signal to noise ratio, improve high frequency response, that is relatively economical to build and that is relatively small in size.
SUMMARY OF THE INVENTION
The arc fault detector of the present invention can operate either as a stand alone Arc Fault Circuit Interrupter (AFCI) or in combination with a Ground Fault Circuit Interrupter (GFCI) to interrupt the flow of current to a load when an arc is detected. The combination device, known as an arc fault circuit interrupter/ground fault circuit interrupter (AFCl/GFCI), can be realized by the addition of arc detection circuitry to a standard GFCI.
An AFCl/GFCI
device is a combination arc fault and ground fault detector, which has the ability to interrupt a circuit and thereby prevent both dangerous arcing and ground fault conditions from harming personnel or property. The term 'circuit interrupting device' is defined to Triean any electrical device used to interrupt current flow to a load and includes, but is not limited to devices such as Ground Fault Circuit Interrupters (GFCIs), Immersion Detection Circuit Interrupters (IDCIs) or Appliance Leakage Circuit Interrupters (ALCIs).
In the arc detector here disclosed, an inductor connected in series with at least the phase or neutral conductor monitors the current in the at least one conductor to detect arcing such as line-to-line, line-to ground, line-to-neutral or contact arcing. The signal from the inductor is the derivative( di/dt) of the current monitored and is fed to arc detection circuitry which comprises a peak detector with decay, a microcontroller with edge timing logic and a circuit interrupter. The series inductor can vary from a wire having a partial loop or bend to six or more full loops and a core that is either of air or a magnetic material for generating the derivative signal, the di/dt signal, of the current flowing through the conductor.
The present invention is capable of detecting arc faults on the line and/or load sides of the device. Once processed, the peak amplitudes of the sensed di/dt signals are directed to a microcontroller which analyzes the signal for the presence of arcing characteristics. Upon identifying a signal which indicates that arcing is present in a conductor, a trip signal is generated and fed to an interrupting mechanism which interrupts the flow of electricity to the load.
The circuit for the microcontroller can be placed on its own chip or on the chip typically used in today's GFCI. When a single chip is used for arc detection and ground fault protection, it can be powered from the same power supply that is used to provide power to the GFCI and, in addition other components of the GFCI such as the mechanism for interrupting the flow of current to the load when a fault occurs. This combined approach results in reduced manufacturing costs as mechanical parts of the GFCI device such as the trip relay and the mechanical contact closure mechanisms now serve dual purposes. In addition, adding the arc detection circuitry to an existing GFCI is a logical enhancement of present day GFCIs.
BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects, features, and advantages of the present invention will become more fully apparent from the following detailed description, the appended claim, and the accompanying drawings in which similar elements have similar reference numerals.
Fig. 1 is a mechanical diagram illustrating an example of contact arcing in a current carrying conductor;
Fig. 2 is a mechanical diagram illustrating an example of line arcing between two current carrying conductors;
Fig. 3 is a block diagram of an arc detection system in accordance with the principles of the invention;
Fig. 4 is a block diagram of another embodiment of an arc detection system in accordance with the principles of the invention;
Fig. 5 is a circuit diagram of an arc detectiOn circuit of the invention;
Fig. 6 is a side view of the series inductor(s) and microcontroller positioned orthogonal to each other on a circuit board;
Fig. 7 is a top view of the series inductor(s) and microcontroller positioned orthogonal to each other on a circuit board; and Fig. 8 is a circuit diagram of the second embodiment arc detection circuit in combination with a ground fault detector.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Fig. 4, there is disclosed an arc detection circuit configured to detect arcing such as neutral-to-ground, line-to-ground, line-to-neutral and/or contact arcing. Arc detection is based upon using a series inductor to monitor the current for the occurrence of arcs in at least one of the conductors of an alternating current electrical circuit such as shown in Figs. 3 and 4. The circuit for monitoring arcs includes a source of current (not shown) coupled to terminals 12 and 16. An inductor 20, normally of the same gauge wire as the conductor 18 is coupled in series with conductor 18. The inductance of series connected inductor 20 can be formed from a wire having as little inductance as would occur from a bend of 15 degrees, to as much inductance as would occur from six or more turns of 360 degrees each, and having an air or magnetic core. The inductance of series connected inductor 20 is dependent, in part, on the magnitude of the potential required to operate the arc detector circuit 24. A typical series inductor having about four complete turns each with a diameter of about 1.8 centimeters was found to provide a voltage of about 5 volts in the presence of arcing without adding any significant series impedance to the circuit. If desired, a clamp circuit 22 can be coupled in parallel with the inductor 20 to limit the maximum voltage that will appear across the inductor 20. A power supply 15 connected across the phase and neutral conductors 14, 18 upstream of the series inductor provides the low voltage power required to operate the various components of the circuit. Arc detector circuit 24 powered by power supply 15 is connected to receive the di/dt potential from series inductor 20. More specifically, arc detector circuit 24 is coupled to receive the di/dt signal of the current in the neutral conductor 18 from inductor 20 and analyze it to determine if arcing is present. Upon determining that arcing is occurring, a trip signal is generated by an appropriate control circuit within arc detector circuit ,24 and applied via conductor 26 to circuit interrupter 28.
Accordingly, when arc detector circuit 24 detects the occurrence of an arc based upon the signal produced by series connected current sensing inductor 20, a trip signal is applied to circuit interrupter 28, which disconnects power to the load.
In addition, the trip signal can be fed to annunciation apparatus such as an LED, a light emitting means such as a lamp, an audio means such as a horn or siren, a graphical or alphanumeric display, etc. to indicate the occurrence of an arc.
Referring to Fig. 4, there is shown a circuit which is similar to that of Fig.
3 with the addition of a second inductor connected in series with the phase conductor and a clamp connected in parallel with the inductor to limit the maximum voltage across the inductor. An inductor 30, which may be of the same or different gauge wire as that of inductor 20, is connected in series with phase conductor 14. Series connected inductor 30 can be formed from a wire having as little inductance as would occur from a bend of 15 degrees to as much inductance as would occur from six or more turns of 360 degrees each, and having an air or magnetic core. When the series inductor is comprised of a conductor having a bend of 15 degrees, or a portion of a full turn, the diameter of the bend or portion of the turn can be, more or less, about three-quarters to one and a half Cm. The actual inductance that inductor 30 (and inductor 20) has is determined, mainly, by the magnitude of the output potential needed to operate the arc detector circuit 24, while, at the same time, minimizing the impedance that is added to the conductor. Inductor 30 is positioned to be in close proximity to inductor 20 and inductively coupled, either through air or magnetically, to inductor 20. An inductive coupling of about 20 percent between the inductors 20, 30 was found to provide good results.
However, an inductive coupling from 5 percent to as close to 100 percent as is possible can be used.
In the embodiment of Fig. 4, inductor 30 is similar to inductor 20 and inductor 20 is inductively coupled to inductor 30. The inductive coupling between the two inductors is about 20 percent. The signal in inductor 30 which is inductively coupled into inductor 20 is fed to arc detector circuit 24. Other than inductor 30 and clamp 32 located on conductor 14, the circuit of Fig. 4 is similar to the circuit of Fig. 3. However, in the embodiment here disclosed, about 20 percent of the signal generated by inductor 30 is inductively coupled into inductor 20 and then fed to arc detection circuit 24. In those instances where a larger signal is required, inductor 30 can have an inductance that is larger than that of inductor 20, the inductive coupling between the inductors can be increased, or a second arc detector circuit similar to 24 can be coupled to phase conductor 14. A clamp circuit 32 can be coupled in parallel with inductor 30 to limit the maximum voltage across the inductor 30.
Coupling between the inductors 20, 30 can be achieved through air or by magnetic material such as a magnetic core or a magnetic circuit. With either of these techniques, inductive coupling between the two inductors can be enhanced or reduced and, if desired, the overall inductance can be increased or decreased. In addition, to minimize undesired coupling effects between the inductors, the microcontroller and the circuit board electronics, the inductors, the microcontroller and circuit board can be positioned orthogonally, as shown in Figs. 6 (side view) and 7 (top view).
As noted above, the derivative (di/dt) signal of the current in the neutral conductor generated by the series inductor 20 is fed to arc detector circuit 24 via conductor 34, and the derivative (di/dt) signal of the current in the phase conductor generated by the series inductor 30 is inductively coupled into inductor 20 from which it is then fed to arc detector circuit 24 via conductor 34. Thus, arc detector circuit 24 receives signals from inductor 20 and inductor 30 and, therefore, monitors the current in both the neutral and the phase conductors. For purposes of alternate channel sensitivity, the inductances of the two inductors 20, 30 can be coupled to be either inductively additive or canceling.
Also, the inductors 20, 30 can have inductances that are of equal or diffe,rent values.
Thus, depending of the requirements of the circuit, the inductance of inductor 20 can be less than, equal to or greater than the inductance of inductor 30.
In another embodiment of the invention the series inductor 20 of Fig. 3 is in the phase conductor 14 and ground is used as the return current path. In still another embodiment the series inductor is at least one winding of a transformer.
Referring to Fig. 5, there is shown a circuit diagram of the embodiment shown in Fig.
4. Inductor 20 is connected in series with conductor 18 and inductor 30 is connected in series with conductor 14. Power supply 15 which receives power from the phase 14 and neutral 18 conductors supplies the required potential to the arc detector circuit 24. The power supply shown has a capacitor 41 connected in series with a diode 42, and this series network is connected across the phase 14 and neutral 18 conductors upstream of the series connected inductors 20, 30. The junction of capacitor 41 and diode 42 is connected through diode 43 to an output terminal provided to supply the required potential to the arc detector circuit 24.
Connected between the output terminal of the power supply and the neutral terminal is a capacitor 44 in parallel with a Zener diode 45.
The arc detector circuit 24 includes a peak detector with decay 50 and a microcontroller with edge timing logic 60. The Peak detector includes a diode 51 connected between an input terminal of the microcontroller with edge timing logic 60 and the neutral conductor 18 at a point downstream of the inductors 20 and 30. A parallel circuit of a resistor 52 and a capacitor 54 is connected between the cathode terminal of diode 51 and a neutral terminal. The diode 51 of the peak detector provides a charging path for capacitor 54. The peak detector with decay provides signals that are representative of the derivative (di/dt) of the current in conductor 18 and conductor 14 and also serves to stretch any high speed pulses detected by the series connected inductors.
The microcontroller with edge timing logic 60 may be of the type disclosed in U.S.
Pat. No. 5,223,795. Microcontroller with edge logic 60 produces a trip signal when a signal which represents an arc is received from the peak detector 50. More specifically, microcontroller 60 analyzes the signal received from the peak detector to determine if arcing is present and, upon finding that arcing is present, generates a trip signal which is fed to circuit interrupter 28. Crystal 62 provides timing for the operation of the microprocessor.
The trip signal generated by the microcontroller is fed via conductor 65 to the gate terminal of a triac 74 in circuit interrupter 28. Circuit interrupter 28 includes a relay having two separate sets of contacts 71, 72 and a coil 73. Contacts 71 are series connected with phase conductor 14 and contacts 72 are series connected with the neutral conductor. The coil 73 of the relay is connected in series with the triac and this series network is connected between the phase conductor 14 and a neutral terminal. The gate terminal of the triac is connected through resistor 75 to conductor 65 to receive the trip signals from the microcontroller 60. A trip signal from the microcontroller primes the triac to conduct which allows current to flow through the relay coil and open the contacts 71, 72.
Referring to FIG. 8, there is shown an arc fault detector in accordance with the principles of this invention in combination with a Ground Fault Circuit Interrupter (GFCI).
The circuit 182, commonly referred to as Arc Fault Circuit Interrupter/Ground Fault Circuit Interrupter (AFCl/GFCI) comprises two current transformers having magnetic cores 233, 234 and coils 235, 236, respectively, coupled to integrated circuit (IC) 225 which may comprise the LM1851 manufactured by National Semiconductor or the RA9031 manufactured by Raytheon. AC power from the phase 14 and neutral 18 conductors is input to power supply circuit 15 which generates power for the internal circuitry of the AFCl/GFCI
device.
The series circuit of relay coil 218 and SCR 224 is connected between power supply 15 and a neutral terminal, and the gate terminal of the SCR is coupled to the output terminal of SCR trigger circuit 216. The output of pin 1 of IC 225 is the input to the SCR
trigger circuit 216.
A diode 245 is coupled in parallel with coil 235 which is coupled to pins 2 and 3 via resistor 247 and capacitors 239, 249. Pin 3 is also coupled to neutral via capacitor 251. Coil 236 is coupled to pins 4 and 5 of IC 225 via capacitors 237, 238, and pin 4 is also coupled to neutral. Pin 6 of IC 225 is coupled to pin 8 via sensitivity resistor 241 and pin 7 is coupled to neutral via time delay capacitor 243. Pin 8 is also coupled to capacitor 222 and to resistor 221 and is connected to power supply 15.
Line side electrical conductors, phase conductor 14 and neutral conductor 18, pass through the transformers 233, 234 to the load side phase and neutral conductors. Relay coil 218 is coupled to operate contacts 231, 232, associated with the phase and neutral conductors, respectively, which function to open the circuit in the event a fault is detected. The coil 218 of the relay is energized when the SCR 224 is turned on by a signal from the trigger circuit 216. In addition, the circuit comprises a test circuit comprised of momentary push button switch 228 connected in series with resistor 230. When switch 228 is pressed, a temporary simulated ground fault from load phase to line neutral is created to test the operation of the device.
Inductors 20, 30 are coupled in series with conductors 14, 18 and downstream of the input to the power supply 36. The two inductors are inductively coupled to each other and inductor 20 is connected to feed a signal representative of the derivative (di/dt) current in the conductors to the arc fault detector 24 as described above. The microcontroller of the arc fault detector can be a stand alone component or it can be a part of the IC 225 of the ground fault circuit interrupter. If the microcontroller is a stand alone component, the trip signal generated by the microcontroller is fed to the SCR trigger circuit 216. If the microcontroller is a part of IC 225, the trip signal is the TRIG-GFCI signal from IC 225.
In the description of the embodiments of the invention here disclosed, either one or both of the series inductors 20, 30 can be primary windings inductively coupled either through air or a magnetic core to a common secondary winding or separate secondary windings connected to feed received signals to the microcontroller. Thus, the series inductors provide the derivative (di/dt) of current flow and are the primary of at least one current transformer. An inductor of the invention here disclosed can be formed from a conductor having as little inductance as would occur from a bend of 15 degrees to as much inductance as would occur from six or more turns of 360 degrees each, and having an air or magnetic core.
The series inductance is connected in series with all or part of the current flowing in the conductor, where the individual or combined inductances of the windings are used to obtain direct measurement of the derivative of current flowing in the conductor(s).
The two series inductors 20, 30 can have an inductance of between .1 and 1,000,000 nanohenrys. Inductors having an inductance of between .1 and 100 nanohenrys were made by putting a loop having a turn of less than 45 degrees in a 12 gauge wire. A
loop having a turn of approximately 45 degrees in the conductor produced an inductance of approximately one nanohenry and, a loop of about four turns of 360 degrees each having a diameter of about 1 Cm. formed an inductor having an inductance of approximately 1,000,000 nanohenrys.
There is here disclosed a method and apparatus for detecting the occurrence of arcing of a conductor. Improved resolution, signal to noise ratio, derivative accuracy and high frequency response is obtained from a direct measurement of the derivative of current flow.
In the invention, the inductor is connected in series with the line current to measure the derivative di/dt of the current flow. Low noise measurement is achieved by referencing the electronics to one side of the inductor, and having the electronics monitor the voltage on the other side of the inductor.
Line current surges generate magnetic flux through the series inductor which, in turn, can induce a magnetic flux in the surrounding electronic material. Surface and sheet currents can also be induced in the surrounding material, in response to the magnetic flux. By orienting the inductor to be orthogonal to the printed circuit board having the electronics of the arc fault detector, the surface and sheet currents on the circuit board itself, and in the electronics mounted on or coplaner with the circuit board can be minimized.
If the derivative di/dt of the current becomes very high in magnitude, there may be an undesirable large drop of line voltage across the inductor. This can be avoided by clamping the maximum voltage drop across the inductor with one of more diodes, Zener diodes, avalanche diodes, diacs, mov's, sidacs, transorbs, gas tubes, etc.
In those instances where sensitivity to the derivative of current flow on both the phase and neutral power lines is desired, a second inductor can be located in close proximity and orientation to the first inductor such that flux coupling is achieved between the two inductors.
Coupling can also be achieved, enhanced or reduced by using magnetic material either in a core or a magnetic circuit, either of which will effectively modify the overall inductance.
Thus, there is also disclosed a second inductor flux coupled to the first inductor for alternate channel sensitivity where the two inductors can be either additive or canceling and can be of different magnitudes.
In those instances where the electrical power distribution network is three phase, a third series inductor can be coupled in series with the third conductor to produce a voltage across itself related to the derivative of current flow in the third conductor and positioned to achieve flux coupling with the inductor in the first and/or second series inductor(s).
In devices that employ current measurements, space, which is usually at a premium in many device designs, can be saved by combining the series inductor that is sensitive to the derivative of current flow with the primary of a current measuring transformer. In this manner, the same inductor which provides direct measurement of the derivative of the current flow can also function as the primary of the current transformer.
Where alternate channel sensitivity and current measurement are both required, the two inductors can act as the primaries of a current transformer. In this embodiment, the flux induced in the transformer core from each of the two inductors should be either additive or subtractive but, when subtractive, they should not fully cancel each other.
Where alternate channel sensitivity and ground fault detection are both required, the two inductors can together act as the primaries on a ground fault differential transformer. In this embodiment, the coupling provided by the transformer may or may not be the only coupling between the two inductors and the flux induced in the transformer core for a given current, from each of the inductors, must either fully of nearly fully cancel.
Where alternate channel sensitivity and ground fault detection are both required, the two inductors can together act as the primaries on a ground fault transformer.
In this embodiment, the coupling provided by the transformer may or may not be the only coupling between the two inductors. Therefore, the flux induced in the transformer core for a given current, from each of the inductors, should be additive or subtractive.
The arc detector here disclosed can be combined with other types of circuit interrupting devices such a GFCI, IDCI or ALCI to create a multipurpose device. In the case of a GFCI, the arc detection circuitry can be placed onboard the same silicon chip typically used in today's GFCI devices. In some instances, some of the pins of commonly used GFCI
integrated circuits can be converted for multifunction operation. The AFCI can be powered from the same power supply that provides power to the circuit interrupting device. This combined approach can result in reduced manufacturing costs as the mechanical parts of the circuit interrupting device such as the trip relay and the mechanical contact closure mechanisms will serve dual purposes. In addition, adding AFCI circuitry to an existing circuit interrupting device is a logical enhancement of such present day devices. In particular, it is logical to enhance a GFCI with AFCI circuitry since a GFCI can detect arcing in certain situations including any condition whereby an arc produces leakage current to ground.
The foregoing has outlined, rather broadly, the preferred feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention and that such other structures do not depart from the spirit and scope of the invention is its broadest form.
A number of systems that have been developed to detect arcing in buildings do so by monitoring high frequency signals present on the conductors. One such method of detecting arcing is by an arc detector that detects the derivative of the signal on the conductor.
Typically, such arc detectors employ, for example, current transformers to produce signals representative of the high frequency signals on the wiring being monitored.
Current transformers both add to the manufacturing cost of the arc fault detector and, because of the size of the components, creates packaging difficulties. In addition, current transformers have a limited high frequency response and poor signal-to-noise ratio.
Accordingly, there is a need for an arc fault detector that provides improved signal to noise ratio, improve high frequency response, that is relatively economical to build and that is relatively small in size.
SUMMARY OF THE INVENTION
The arc fault detector of the present invention can operate either as a stand alone Arc Fault Circuit Interrupter (AFCI) or in combination with a Ground Fault Circuit Interrupter (GFCI) to interrupt the flow of current to a load when an arc is detected. The combination device, known as an arc fault circuit interrupter/ground fault circuit interrupter (AFCl/GFCI), can be realized by the addition of arc detection circuitry to a standard GFCI.
An AFCl/GFCI
device is a combination arc fault and ground fault detector, which has the ability to interrupt a circuit and thereby prevent both dangerous arcing and ground fault conditions from harming personnel or property. The term 'circuit interrupting device' is defined to Triean any electrical device used to interrupt current flow to a load and includes, but is not limited to devices such as Ground Fault Circuit Interrupters (GFCIs), Immersion Detection Circuit Interrupters (IDCIs) or Appliance Leakage Circuit Interrupters (ALCIs).
In the arc detector here disclosed, an inductor connected in series with at least the phase or neutral conductor monitors the current in the at least one conductor to detect arcing such as line-to-line, line-to ground, line-to-neutral or contact arcing. The signal from the inductor is the derivative( di/dt) of the current monitored and is fed to arc detection circuitry which comprises a peak detector with decay, a microcontroller with edge timing logic and a circuit interrupter. The series inductor can vary from a wire having a partial loop or bend to six or more full loops and a core that is either of air or a magnetic material for generating the derivative signal, the di/dt signal, of the current flowing through the conductor.
The present invention is capable of detecting arc faults on the line and/or load sides of the device. Once processed, the peak amplitudes of the sensed di/dt signals are directed to a microcontroller which analyzes the signal for the presence of arcing characteristics. Upon identifying a signal which indicates that arcing is present in a conductor, a trip signal is generated and fed to an interrupting mechanism which interrupts the flow of electricity to the load.
The circuit for the microcontroller can be placed on its own chip or on the chip typically used in today's GFCI. When a single chip is used for arc detection and ground fault protection, it can be powered from the same power supply that is used to provide power to the GFCI and, in addition other components of the GFCI such as the mechanism for interrupting the flow of current to the load when a fault occurs. This combined approach results in reduced manufacturing costs as mechanical parts of the GFCI device such as the trip relay and the mechanical contact closure mechanisms now serve dual purposes. In addition, adding the arc detection circuitry to an existing GFCI is a logical enhancement of present day GFCIs.
BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects, features, and advantages of the present invention will become more fully apparent from the following detailed description, the appended claim, and the accompanying drawings in which similar elements have similar reference numerals.
Fig. 1 is a mechanical diagram illustrating an example of contact arcing in a current carrying conductor;
Fig. 2 is a mechanical diagram illustrating an example of line arcing between two current carrying conductors;
Fig. 3 is a block diagram of an arc detection system in accordance with the principles of the invention;
Fig. 4 is a block diagram of another embodiment of an arc detection system in accordance with the principles of the invention;
Fig. 5 is a circuit diagram of an arc detectiOn circuit of the invention;
Fig. 6 is a side view of the series inductor(s) and microcontroller positioned orthogonal to each other on a circuit board;
Fig. 7 is a top view of the series inductor(s) and microcontroller positioned orthogonal to each other on a circuit board; and Fig. 8 is a circuit diagram of the second embodiment arc detection circuit in combination with a ground fault detector.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Fig. 4, there is disclosed an arc detection circuit configured to detect arcing such as neutral-to-ground, line-to-ground, line-to-neutral and/or contact arcing. Arc detection is based upon using a series inductor to monitor the current for the occurrence of arcs in at least one of the conductors of an alternating current electrical circuit such as shown in Figs. 3 and 4. The circuit for monitoring arcs includes a source of current (not shown) coupled to terminals 12 and 16. An inductor 20, normally of the same gauge wire as the conductor 18 is coupled in series with conductor 18. The inductance of series connected inductor 20 can be formed from a wire having as little inductance as would occur from a bend of 15 degrees, to as much inductance as would occur from six or more turns of 360 degrees each, and having an air or magnetic core. The inductance of series connected inductor 20 is dependent, in part, on the magnitude of the potential required to operate the arc detector circuit 24. A typical series inductor having about four complete turns each with a diameter of about 1.8 centimeters was found to provide a voltage of about 5 volts in the presence of arcing without adding any significant series impedance to the circuit. If desired, a clamp circuit 22 can be coupled in parallel with the inductor 20 to limit the maximum voltage that will appear across the inductor 20. A power supply 15 connected across the phase and neutral conductors 14, 18 upstream of the series inductor provides the low voltage power required to operate the various components of the circuit. Arc detector circuit 24 powered by power supply 15 is connected to receive the di/dt potential from series inductor 20. More specifically, arc detector circuit 24 is coupled to receive the di/dt signal of the current in the neutral conductor 18 from inductor 20 and analyze it to determine if arcing is present. Upon determining that arcing is occurring, a trip signal is generated by an appropriate control circuit within arc detector circuit ,24 and applied via conductor 26 to circuit interrupter 28.
Accordingly, when arc detector circuit 24 detects the occurrence of an arc based upon the signal produced by series connected current sensing inductor 20, a trip signal is applied to circuit interrupter 28, which disconnects power to the load.
In addition, the trip signal can be fed to annunciation apparatus such as an LED, a light emitting means such as a lamp, an audio means such as a horn or siren, a graphical or alphanumeric display, etc. to indicate the occurrence of an arc.
Referring to Fig. 4, there is shown a circuit which is similar to that of Fig.
3 with the addition of a second inductor connected in series with the phase conductor and a clamp connected in parallel with the inductor to limit the maximum voltage across the inductor. An inductor 30, which may be of the same or different gauge wire as that of inductor 20, is connected in series with phase conductor 14. Series connected inductor 30 can be formed from a wire having as little inductance as would occur from a bend of 15 degrees to as much inductance as would occur from six or more turns of 360 degrees each, and having an air or magnetic core. When the series inductor is comprised of a conductor having a bend of 15 degrees, or a portion of a full turn, the diameter of the bend or portion of the turn can be, more or less, about three-quarters to one and a half Cm. The actual inductance that inductor 30 (and inductor 20) has is determined, mainly, by the magnitude of the output potential needed to operate the arc detector circuit 24, while, at the same time, minimizing the impedance that is added to the conductor. Inductor 30 is positioned to be in close proximity to inductor 20 and inductively coupled, either through air or magnetically, to inductor 20. An inductive coupling of about 20 percent between the inductors 20, 30 was found to provide good results.
However, an inductive coupling from 5 percent to as close to 100 percent as is possible can be used.
In the embodiment of Fig. 4, inductor 30 is similar to inductor 20 and inductor 20 is inductively coupled to inductor 30. The inductive coupling between the two inductors is about 20 percent. The signal in inductor 30 which is inductively coupled into inductor 20 is fed to arc detector circuit 24. Other than inductor 30 and clamp 32 located on conductor 14, the circuit of Fig. 4 is similar to the circuit of Fig. 3. However, in the embodiment here disclosed, about 20 percent of the signal generated by inductor 30 is inductively coupled into inductor 20 and then fed to arc detection circuit 24. In those instances where a larger signal is required, inductor 30 can have an inductance that is larger than that of inductor 20, the inductive coupling between the inductors can be increased, or a second arc detector circuit similar to 24 can be coupled to phase conductor 14. A clamp circuit 32 can be coupled in parallel with inductor 30 to limit the maximum voltage across the inductor 30.
Coupling between the inductors 20, 30 can be achieved through air or by magnetic material such as a magnetic core or a magnetic circuit. With either of these techniques, inductive coupling between the two inductors can be enhanced or reduced and, if desired, the overall inductance can be increased or decreased. In addition, to minimize undesired coupling effects between the inductors, the microcontroller and the circuit board electronics, the inductors, the microcontroller and circuit board can be positioned orthogonally, as shown in Figs. 6 (side view) and 7 (top view).
As noted above, the derivative (di/dt) signal of the current in the neutral conductor generated by the series inductor 20 is fed to arc detector circuit 24 via conductor 34, and the derivative (di/dt) signal of the current in the phase conductor generated by the series inductor 30 is inductively coupled into inductor 20 from which it is then fed to arc detector circuit 24 via conductor 34. Thus, arc detector circuit 24 receives signals from inductor 20 and inductor 30 and, therefore, monitors the current in both the neutral and the phase conductors. For purposes of alternate channel sensitivity, the inductances of the two inductors 20, 30 can be coupled to be either inductively additive or canceling.
Also, the inductors 20, 30 can have inductances that are of equal or diffe,rent values.
Thus, depending of the requirements of the circuit, the inductance of inductor 20 can be less than, equal to or greater than the inductance of inductor 30.
In another embodiment of the invention the series inductor 20 of Fig. 3 is in the phase conductor 14 and ground is used as the return current path. In still another embodiment the series inductor is at least one winding of a transformer.
Referring to Fig. 5, there is shown a circuit diagram of the embodiment shown in Fig.
4. Inductor 20 is connected in series with conductor 18 and inductor 30 is connected in series with conductor 14. Power supply 15 which receives power from the phase 14 and neutral 18 conductors supplies the required potential to the arc detector circuit 24. The power supply shown has a capacitor 41 connected in series with a diode 42, and this series network is connected across the phase 14 and neutral 18 conductors upstream of the series connected inductors 20, 30. The junction of capacitor 41 and diode 42 is connected through diode 43 to an output terminal provided to supply the required potential to the arc detector circuit 24.
Connected between the output terminal of the power supply and the neutral terminal is a capacitor 44 in parallel with a Zener diode 45.
The arc detector circuit 24 includes a peak detector with decay 50 and a microcontroller with edge timing logic 60. The Peak detector includes a diode 51 connected between an input terminal of the microcontroller with edge timing logic 60 and the neutral conductor 18 at a point downstream of the inductors 20 and 30. A parallel circuit of a resistor 52 and a capacitor 54 is connected between the cathode terminal of diode 51 and a neutral terminal. The diode 51 of the peak detector provides a charging path for capacitor 54. The peak detector with decay provides signals that are representative of the derivative (di/dt) of the current in conductor 18 and conductor 14 and also serves to stretch any high speed pulses detected by the series connected inductors.
The microcontroller with edge timing logic 60 may be of the type disclosed in U.S.
Pat. No. 5,223,795. Microcontroller with edge logic 60 produces a trip signal when a signal which represents an arc is received from the peak detector 50. More specifically, microcontroller 60 analyzes the signal received from the peak detector to determine if arcing is present and, upon finding that arcing is present, generates a trip signal which is fed to circuit interrupter 28. Crystal 62 provides timing for the operation of the microprocessor.
The trip signal generated by the microcontroller is fed via conductor 65 to the gate terminal of a triac 74 in circuit interrupter 28. Circuit interrupter 28 includes a relay having two separate sets of contacts 71, 72 and a coil 73. Contacts 71 are series connected with phase conductor 14 and contacts 72 are series connected with the neutral conductor. The coil 73 of the relay is connected in series with the triac and this series network is connected between the phase conductor 14 and a neutral terminal. The gate terminal of the triac is connected through resistor 75 to conductor 65 to receive the trip signals from the microcontroller 60. A trip signal from the microcontroller primes the triac to conduct which allows current to flow through the relay coil and open the contacts 71, 72.
Referring to FIG. 8, there is shown an arc fault detector in accordance with the principles of this invention in combination with a Ground Fault Circuit Interrupter (GFCI).
The circuit 182, commonly referred to as Arc Fault Circuit Interrupter/Ground Fault Circuit Interrupter (AFCl/GFCI) comprises two current transformers having magnetic cores 233, 234 and coils 235, 236, respectively, coupled to integrated circuit (IC) 225 which may comprise the LM1851 manufactured by National Semiconductor or the RA9031 manufactured by Raytheon. AC power from the phase 14 and neutral 18 conductors is input to power supply circuit 15 which generates power for the internal circuitry of the AFCl/GFCI
device.
The series circuit of relay coil 218 and SCR 224 is connected between power supply 15 and a neutral terminal, and the gate terminal of the SCR is coupled to the output terminal of SCR trigger circuit 216. The output of pin 1 of IC 225 is the input to the SCR
trigger circuit 216.
A diode 245 is coupled in parallel with coil 235 which is coupled to pins 2 and 3 via resistor 247 and capacitors 239, 249. Pin 3 is also coupled to neutral via capacitor 251. Coil 236 is coupled to pins 4 and 5 of IC 225 via capacitors 237, 238, and pin 4 is also coupled to neutral. Pin 6 of IC 225 is coupled to pin 8 via sensitivity resistor 241 and pin 7 is coupled to neutral via time delay capacitor 243. Pin 8 is also coupled to capacitor 222 and to resistor 221 and is connected to power supply 15.
Line side electrical conductors, phase conductor 14 and neutral conductor 18, pass through the transformers 233, 234 to the load side phase and neutral conductors. Relay coil 218 is coupled to operate contacts 231, 232, associated with the phase and neutral conductors, respectively, which function to open the circuit in the event a fault is detected. The coil 218 of the relay is energized when the SCR 224 is turned on by a signal from the trigger circuit 216. In addition, the circuit comprises a test circuit comprised of momentary push button switch 228 connected in series with resistor 230. When switch 228 is pressed, a temporary simulated ground fault from load phase to line neutral is created to test the operation of the device.
Inductors 20, 30 are coupled in series with conductors 14, 18 and downstream of the input to the power supply 36. The two inductors are inductively coupled to each other and inductor 20 is connected to feed a signal representative of the derivative (di/dt) current in the conductors to the arc fault detector 24 as described above. The microcontroller of the arc fault detector can be a stand alone component or it can be a part of the IC 225 of the ground fault circuit interrupter. If the microcontroller is a stand alone component, the trip signal generated by the microcontroller is fed to the SCR trigger circuit 216. If the microcontroller is a part of IC 225, the trip signal is the TRIG-GFCI signal from IC 225.
In the description of the embodiments of the invention here disclosed, either one or both of the series inductors 20, 30 can be primary windings inductively coupled either through air or a magnetic core to a common secondary winding or separate secondary windings connected to feed received signals to the microcontroller. Thus, the series inductors provide the derivative (di/dt) of current flow and are the primary of at least one current transformer. An inductor of the invention here disclosed can be formed from a conductor having as little inductance as would occur from a bend of 15 degrees to as much inductance as would occur from six or more turns of 360 degrees each, and having an air or magnetic core.
The series inductance is connected in series with all or part of the current flowing in the conductor, where the individual or combined inductances of the windings are used to obtain direct measurement of the derivative of current flowing in the conductor(s).
The two series inductors 20, 30 can have an inductance of between .1 and 1,000,000 nanohenrys. Inductors having an inductance of between .1 and 100 nanohenrys were made by putting a loop having a turn of less than 45 degrees in a 12 gauge wire. A
loop having a turn of approximately 45 degrees in the conductor produced an inductance of approximately one nanohenry and, a loop of about four turns of 360 degrees each having a diameter of about 1 Cm. formed an inductor having an inductance of approximately 1,000,000 nanohenrys.
There is here disclosed a method and apparatus for detecting the occurrence of arcing of a conductor. Improved resolution, signal to noise ratio, derivative accuracy and high frequency response is obtained from a direct measurement of the derivative of current flow.
In the invention, the inductor is connected in series with the line current to measure the derivative di/dt of the current flow. Low noise measurement is achieved by referencing the electronics to one side of the inductor, and having the electronics monitor the voltage on the other side of the inductor.
Line current surges generate magnetic flux through the series inductor which, in turn, can induce a magnetic flux in the surrounding electronic material. Surface and sheet currents can also be induced in the surrounding material, in response to the magnetic flux. By orienting the inductor to be orthogonal to the printed circuit board having the electronics of the arc fault detector, the surface and sheet currents on the circuit board itself, and in the electronics mounted on or coplaner with the circuit board can be minimized.
If the derivative di/dt of the current becomes very high in magnitude, there may be an undesirable large drop of line voltage across the inductor. This can be avoided by clamping the maximum voltage drop across the inductor with one of more diodes, Zener diodes, avalanche diodes, diacs, mov's, sidacs, transorbs, gas tubes, etc.
In those instances where sensitivity to the derivative of current flow on both the phase and neutral power lines is desired, a second inductor can be located in close proximity and orientation to the first inductor such that flux coupling is achieved between the two inductors.
Coupling can also be achieved, enhanced or reduced by using magnetic material either in a core or a magnetic circuit, either of which will effectively modify the overall inductance.
Thus, there is also disclosed a second inductor flux coupled to the first inductor for alternate channel sensitivity where the two inductors can be either additive or canceling and can be of different magnitudes.
In those instances where the electrical power distribution network is three phase, a third series inductor can be coupled in series with the third conductor to produce a voltage across itself related to the derivative of current flow in the third conductor and positioned to achieve flux coupling with the inductor in the first and/or second series inductor(s).
In devices that employ current measurements, space, which is usually at a premium in many device designs, can be saved by combining the series inductor that is sensitive to the derivative of current flow with the primary of a current measuring transformer. In this manner, the same inductor which provides direct measurement of the derivative of the current flow can also function as the primary of the current transformer.
Where alternate channel sensitivity and current measurement are both required, the two inductors can act as the primaries of a current transformer. In this embodiment, the flux induced in the transformer core from each of the two inductors should be either additive or subtractive but, when subtractive, they should not fully cancel each other.
Where alternate channel sensitivity and ground fault detection are both required, the two inductors can together act as the primaries on a ground fault differential transformer. In this embodiment, the coupling provided by the transformer may or may not be the only coupling between the two inductors and the flux induced in the transformer core for a given current, from each of the inductors, must either fully of nearly fully cancel.
Where alternate channel sensitivity and ground fault detection are both required, the two inductors can together act as the primaries on a ground fault transformer.
In this embodiment, the coupling provided by the transformer may or may not be the only coupling between the two inductors. Therefore, the flux induced in the transformer core for a given current, from each of the inductors, should be additive or subtractive.
The arc detector here disclosed can be combined with other types of circuit interrupting devices such a GFCI, IDCI or ALCI to create a multipurpose device. In the case of a GFCI, the arc detection circuitry can be placed onboard the same silicon chip typically used in today's GFCI devices. In some instances, some of the pins of commonly used GFCI
integrated circuits can be converted for multifunction operation. The AFCI can be powered from the same power supply that provides power to the circuit interrupting device. This combined approach can result in reduced manufacturing costs as the mechanical parts of the circuit interrupting device such as the trip relay and the mechanical contact closure mechanisms will serve dual purposes. In addition, adding AFCI circuitry to an existing circuit interrupting device is a logical enhancement of such present day devices. In particular, it is logical to enhance a GFCI with AFCI circuitry since a GFCI can detect arcing in certain situations including any condition whereby an arc produces leakage current to ground.
The foregoing has outlined, rather broadly, the preferred feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention and that such other structures do not depart from the spirit and scope of the invention is its broadest form.
Claims (67)
1. Apparatus for detecting arcs on an electrical power distribution network having at least one conductor comprising:
a first inductor adapted to be coupled with a conductor of the network producing a voltage across the first inductor having a waveform which relates to the derivative of current flow in the conductor; and an arc detector coupled to identify when the waveform of the voltage across the first inductor is representative of arcing on the network and to generate an arc detection signal when the waveform is representative of arcing on the network.
a first inductor adapted to be coupled with a conductor of the network producing a voltage across the first inductor having a waveform which relates to the derivative of current flow in the conductor; and an arc detector coupled to identify when the waveform of the voltage across the first inductor is representative of arcing on the network and to generate an arc detection signal when the waveform is representative of arcing on the network.
2. The apparatus of claim 1 wherein the at least one conductor comprises a neutral conductor and a phase conductor.
3. The apparatus of claim 1 wherein the at least one conductor comprises a neutral conductor and two phase conductors.
4. The apparatus of claim 1 wherein the at least one conductor comprises a neutral conductor and three phase conductors.
5. The apparatus of claim 1 wherein the at least one conductor comprises two phase conductors.
6. The apparatus of claim 1 wherein the at least one conductor comprises a single conductor with return current carried through a ground or frame.
7. The apparatus of claim 1 wherein the first inductor is adapted to be coupled to be in series with all current in the at least one conductor.
8. The apparatus of claim 1 wherein the first inductor is adapted to be coupled in series with part of the current in the at least one conductor.
9. The apparatus of claim 1 wherein the first inductor is at least one winding of a transformer.
10. The apparatus of claim 9 wherein the transformer is coupled to a current circuit to measure current in at least one conductor of the network.
11. The apparatus of claim 9 wherein the transformer forms part of a ground fault circuit to measure ground fault differential current flow in at least two conductors of the network.
12. The apparatus of claim 9 wherein the transformer forms part of a ground fault circuit to measure ground fault grounded neutral current flow in at least one conductor of the network.
13. The apparatus of claim 1 wherein the first inductor has an inductance of between 0.1 and 1,000,000 nanohenries.
14. The apparatus of claim 1 wherein the first inductor comprises a conductor having a bend between 15 degrees and a turn of 360 degrees.
15. The apparatus of claim 1 wherein the first inductor comprises a conductor having between one and six turns.
16. The apparatus of claim 1 further comprising a clamping circuit coupled in parallel with the first inductor.
17. The apparatus of claim 16 wherein the clamping circuit comprises at least one diode.
18. The apparatus of claim 16 wherein the at least one diode comprises a first diode coupled in parallel with a second diode head-to-toe.
19. The apparatus of claim 16 wherein the clamping circuit comprises at least one Zener diode.
20. The apparatus of claim 16 wherein the at least one diode comprises first and second Zener diodes coupled in parallel head-to-toe.
21. The apparatus of claim 16 wherein the at least one diode comprises first and second Zener diodes coupled back-to-back.
22. The apparatus of claim 16 wherein the clamping circuit comprises an avalanche diode.
23. The apparatus of claim 16 wherein the clamping circuit comprises a diac.
24. The apparatus of claim 16 wherein the clamping circuit comprises an MOV.
25. The apparatus of claim 16 wherein the clamping circuit comprises a sidac.
26. The apparatus of claim 16 wherein the clamping circuit comprises a transorb.
27. The apparatus of claim 16 wherein the clamping circuit comprises a gas tube.
28. The apparatus of claim 1 wherein the inductor is oriented orthogonally to the electronics circuitry of the arc detector.
29. The apparatus of claim 1 wherein the inductor is oriented orthogonally to the electronics circuitry of a device the apparatus is coupled to.
30. The apparatus of claim 9 wherein the at least one winding of the transformer is oriented orthogonally to the electronics circuitry of the arc detector.
31. The apparatus of claim 1 further comprising:
a trip assembly coupled to the arc detection signal from the arc detector to interrupt current flow in at least one conductor of the electrical power distribution network.
a trip assembly coupled to the arc detection signal from the arc detector to interrupt current flow in at least one conductor of the electrical power distribution network.
32. The apparatus of claim 1 further comprising:
an annunciator coupled to the arc detector to indicate the status of the arc detection signal.
an annunciator coupled to the arc detector to indicate the status of the arc detection signal.
33. The apparatus of claim 32 wherein the annunciator is at least one LED.
34. The apparatus of claim 32 wherein the annunciator is at least one lamp.
35. The apparatus of claim 32 wherein the annunciator is at least one audio generating means.
36. The apparatus of claim 32 wherein the annunciator is a graphical or alphanumeric display.
37. Apparatus according to claim 1 wherein the electrical power distribution network having at least two conductors, the apparatus further comprises:
a second inductor adapted to be coupled with a second of the at least two conductors to produce a voltage across itself related to the derivative of current flow in the second conductor;
wherein said arc detector is responsive to the waveforms of the voltages across each of the first and second inductors to determine when a waveform indicative of arcing on the network is present and to generate an arc detection signal when arcing is present.
a second inductor adapted to be coupled with a second of the at least two conductors to produce a voltage across itself related to the derivative of current flow in the second conductor;
wherein said arc detector is responsive to the waveforms of the voltages across each of the first and second inductors to determine when a waveform indicative of arcing on the network is present and to generate an arc detection signal when arcing is present.
38. The apparatus of claim 37 further comprising:
a third inductor coupled in series with a third conductor of the network to produce a voltage across itself related to the derivative of current flow in the third conductor.
a third inductor coupled in series with a third conductor of the network to produce a voltage across itself related to the derivative of current flow in the third conductor.
39. The apparatus of claim 37, wherein the waveforms are referenced to one side of the respective inductors.
40. The apparatus of claim 37, wherein the first and the second inductors are untapped.
41. Apparatus according to claim 1, the electrical power distribution network having at least two conductors, the apparatus further comprises:
a second inductor adapted to be coupled to a second of the at least two conductors to generate magnetic flux related to the derivative of current flow in the second conductor; and a flux coupler to link the magnetic flux of the second inductor to the first inductor.
a second inductor adapted to be coupled to a second of the at least two conductors to generate magnetic flux related to the derivative of current flow in the second conductor; and a flux coupler to link the magnetic flux of the second inductor to the first inductor.
42. The apparatus of claim 41 further comprising:
a third inductor coupled to a third conductor of the network to generate magnetic flux related to the derivative of current flow in the third conductor and coupled to link the magnetic flux of the third inductor to the first inductor through the flux coupler.
a third inductor coupled to a third conductor of the network to generate magnetic flux related to the derivative of current flow in the third conductor and coupled to link the magnetic flux of the third inductor to the first inductor through the flux coupler.
43. The apparatus of claim 41 or 42 wherein the flux coupler is a magnetic core.
44. The apparatus of claim 41 or 42 wherein the flux coupler is an air core.
45. The apparatus of claim 41 further comprising:
a ground fault current measuring circuit to measure the ground fault current in at least two of the conductors of the network; and a ground fault current detector responsive to the ground fault current measuring circuit to generate a ground fault detection signal when a ground fault is present.
a ground fault current measuring circuit to measure the ground fault current in at least two of the conductors of the network; and a ground fault current detector responsive to the ground fault current measuring circuit to generate a ground fault detection signal when a ground fault is present.
46. The apparatus of claim 45 further comprising:
a trip assembly responsive to the arc detection signal and the ground fault detection signal to interrupt current flow in at least one conductor of the electrical power distribution network.
a trip assembly responsive to the arc detection signal and the ground fault detection signal to interrupt current flow in at least one conductor of the electrical power distribution network.
47. The apparatus of claim 43 further comprising:
an annunciator coupled to the arc detector and the ground fault current detector to indicate the status of the arc detection signal and/or ground fault detection signal.
an annunciator coupled to the arc detector and the ground fault current detector to indicate the status of the arc detection signal and/or ground fault detection signal.
48. Apparatus according to claim 1 further comprising:
a second inductor adapted to be coupled to a second of the at least two conductors and disposed to generate magnetic flux related to the derivative of current flow in the second conductor; and a current measuring circuit coupled to at least one of said first and second inductors and disposed to measure the current flowing in at least one of said at least two conductors from a waveform of the voltage across said at least one inductor.
a second inductor adapted to be coupled to a second of the at least two conductors and disposed to generate magnetic flux related to the derivative of current flow in the second conductor; and a current measuring circuit coupled to at least one of said first and second inductors and disposed to measure the current flowing in at least one of said at least two conductors from a waveform of the voltage across said at least one inductor.
49. The apparatus of any one of claims 1 to 48, further comprising a circuit board and a microcontroller coupled to the circuit board, wherein at least one inductor comprises a circuit coupled to the circuit board.
50. A method for detecting an arc fault on a power distribution network comprising:
producing a voltage across an inductor, said voltage having a waveform which relates to a derivative of current flow in a conductor;
determining a change in current over time (di/dt) via said series inductor;
applying a trip signal in response to the presence of a sufficient voltage produced across said series inductor.
producing a voltage across an inductor, said voltage having a waveform which relates to a derivative of current flow in a conductor;
determining a change in current over time (di/dt) via said series inductor;
applying a trip signal in response to the presence of a sufficient voltage produced across said series inductor.
51. The method of claim 50, further comprising the step of determining when said waveform of said voltage across said inductor is representative of an arc fault.
52. The method of claim 50, further comprising the step of generating a detection signal from said waveform when said waveform is representative of arcing on the network.
53. The method of claim 50, further comprising the step of clamping excess voltage across said inductor to limit excess voltage across said inductor.
54. The method of claim 50, further comprising the step of determining the presence of a ground fault.
55. The method of claim 50 wherein the electrical power distribution network has at least two conductors, the method further comprising:
producing a voltage across a second inductor adapted to be coupled to a second of the at least two conductors to generate magnetic flux related to the derivative of current flow in the second conductor;
linking the magnetic flux of the second inductor to the first inductor; and determining when a waveform indicative of arcing on the network is present and generating an arc detection signal when a waveform indicative of arcing is present.
producing a voltage across a second inductor adapted to be coupled to a second of the at least two conductors to generate magnetic flux related to the derivative of current flow in the second conductor;
linking the magnetic flux of the second inductor to the first inductor; and determining when a waveform indicative of arcing on the network is present and generating an arc detection signal when a waveform indicative of arcing is present.
56. The method of claim 55, further comprising the step of determining the presence of a ground fault.
57. The method of claim 50 wherein the electrical power distribution network has at least two conductors, the method further comprising:
producing a voltage across a second inductor adapted to be coupled to a second of the at least two conductors to generate magnetic flux related to the derivative of current flow in the second conductor;
measuring a current in at least one of said first and second inductors to measure the current flowing in at least one of said at least two conductors from said waveform of the voltage across said at least one inductor.
producing a voltage across a second inductor adapted to be coupled to a second of the at least two conductors to generate magnetic flux related to the derivative of current flow in the second conductor;
measuring a current in at least one of said first and second inductors to measure the current flowing in at least one of said at least two conductors from said waveform of the voltage across said at least one inductor.
58. The method of claim 57, further comprising the step of determining the presence of a ground fault.
59. The method of claim 50 wherein the electrical power distribution network has a line side phase conductor and a line side neutral conductor wherein the inductor being coupled to at least one of a line side phase conductor and a line side neutral conductor, the method further comprising:
reading the voltage across the inductor;
wherein if the change in current over time (di/dt) exceeds a predetermined magnitude, then the trip signal is applied to a fault interrupter to open a set of contacts.
reading the voltage across the inductor;
wherein if the change in current over time (di/dt) exceeds a predetermined magnitude, then the trip signal is applied to a fault interrupter to open a set of contacts.
60. The method of claim 59, further comprising the step of determining when said waveform of said voltage across said inductor is representative of an arc fault.
61. The method of claim 60, wherein said step of determining occurs using a microcontroller to determine whether said waveform of said voltage across said inductor is representative of an arc fault.
62. The method of claim 61 wherein said waveform of said voltage across said inductor is representative of an arc fault if the detected change in current over time (di/dt) exceeds a predetermined magnitude.
63. Apparatus according to claim 1 wherein:
the waveform relating to the derivative of current flow in the conductor is a single waveform; and a current measuring transformer coupled to the series inductor to measure the current flowing in the at least one conductor from the single waveform of the voltage across the series inductor.
the waveform relating to the derivative of current flow in the conductor is a single waveform; and a current measuring transformer coupled to the series inductor to measure the current flowing in the at least one conductor from the single waveform of the voltage across the series inductor.
64. The apparatus of claim 63 wherein the at least one conductor comprises a neutral conductor and a phase conductor.
65. The apparatus of claim 63 comprising a ground fault circuit interrupter.
66. The apparatus of claim 63 comprising an immersion detection circuit interrupter.
67. The apparatus of claim 63 comprising an appliance leakage circuit interrupter.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/743,248 US6972572B2 (en) | 2003-12-22 | 2003-12-22 | Arc fault detector |
US10/743,248 | 2003-12-22 | ||
PCT/US2004/043272 WO2005062917A2 (en) | 2003-12-22 | 2004-12-20 | Arc fault detector |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2550997A1 CA2550997A1 (en) | 2005-07-14 |
CA2550997C true CA2550997C (en) | 2014-03-18 |
Family
ID=34678617
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA2550997A Active CA2550997C (en) | 2003-12-22 | 2004-12-20 | Arc fault detector |
Country Status (5)
Country | Link |
---|---|
US (4) | US6972572B2 (en) |
CN (1) | CN1918680A (en) |
CA (1) | CA2550997C (en) |
MX (1) | MXPA06007196A (en) |
WO (1) | WO2005062917A2 (en) |
Families Citing this family (65)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7400477B2 (en) | 1998-08-24 | 2008-07-15 | Leviton Manufacturing Co., Inc. | Method of distribution of a circuit interrupting device with reset lockout and reverse wiring protection |
US7003435B2 (en) | 2002-10-03 | 2006-02-21 | Leviton Manufacturing Co., Inc. | Arc fault detector with circuit interrupter |
US6972572B2 (en) | 2003-12-22 | 2005-12-06 | Leviton Manufacturing Co., Inc. | Arc fault detector |
US7476823B2 (en) * | 2004-02-27 | 2009-01-13 | Ssi Power Llc | Current pause device for an electric power circuit interrupter |
US7952360B2 (en) * | 2007-03-14 | 2011-05-31 | General Electric Company | Method and system for passively detecting and locating wire harness defects |
US20070132531A1 (en) * | 2005-12-14 | 2007-06-14 | Eaton Corporation | Two pole circuit interrupter employing a single arc fault or ground fault trip circuit |
CN1988099B (en) * | 2005-12-23 | 2010-05-05 | 通领科技集团有限公司 | Leakage current detection breaker with fire-proof shield |
CN1328591C (en) * | 2005-12-26 | 2007-07-25 | 通领科技集团有限公司 | Earth-fault circuit breaker life termination detecting-protecting method and its circuit |
CN1328588C (en) * | 2005-12-27 | 2007-07-25 | 通领科技集团有限公司 | Life-stopping intelligent inspection and inspector for leakage protector |
CN1319101C (en) * | 2005-12-27 | 2007-05-30 | 通领科技集团有限公司 | Lift stop intelligent detection and detector for leakage protector |
CN1328587C (en) * | 2005-12-27 | 2007-07-25 | 通领科技集团有限公司 | Life-stopping intelligent inspection and inspector for leakage protector |
WO2007088588A1 (en) * | 2006-01-31 | 2007-08-09 | Mitsubishi Denki Kabushiki Kaisha | Residual magnetic flux determining apparatus |
CN100349345C (en) * | 2006-02-21 | 2007-11-14 | 通领科技集团有限公司 | Intelligent detecting method and appliance for service stop of electricity leakage protector |
CN1321430C (en) | 2006-03-06 | 2007-06-13 | 通领科技集团有限公司 | Earthing fault breaker actuator having pressure balance auto compensation |
US7492171B2 (en) * | 2006-06-29 | 2009-02-17 | Intel Corporation | Systems and arrangements for sensing current with a low loss sense element |
MX2008016072A (en) * | 2006-06-30 | 2009-02-25 | Leviton Manufacturing Co | Circuit interrupter with live ground detector. |
US9127534B2 (en) | 2006-10-31 | 2015-09-08 | Halliburton Energy Services, Inc. | Cable integrity monitor for electromagnetic telemetry systems |
US20080180866A1 (en) * | 2007-01-29 | 2008-07-31 | Honor Tone, Ltd. | Combined arc fault circuit interrupter and leakage current detector interrupter |
WO2009004607A2 (en) * | 2007-07-03 | 2009-01-08 | Mainnet Communications Ltd. | Remote detection of discharge on a power line network |
US7580232B2 (en) * | 2007-12-21 | 2009-08-25 | General Electric Company | Arc detection system and method |
WO2009097469A1 (en) | 2008-01-29 | 2009-08-06 | Leviton Manufacturing Co., Inc. | Self testing fault circuit interrupter apparatus and method |
US8076943B2 (en) * | 2008-02-21 | 2011-12-13 | Genesis Medical Imaging, Inc. | Impedance-based arc detector for computed tomography scanner and method of use thereof |
US7924537B2 (en) | 2008-07-09 | 2011-04-12 | Leviton Manufacturing Company, Inc. | Miswiring circuit coupled to an electrical fault interrupter |
US8436625B2 (en) * | 2008-09-05 | 2013-05-07 | Radar Engineers | Identification of power system primary arcs based on pulse density |
US8004418B2 (en) * | 2008-09-08 | 2011-08-23 | Eaton Corporation | Communication interface apparatus for an electrical distribution panel, and system and electrical distribution panel including the same |
AT507102B1 (en) * | 2009-02-23 | 2010-02-15 | Moeller Gebaeudeautomation Gmb | BREAKERS |
US8267562B2 (en) * | 2009-03-18 | 2012-09-18 | Siemens Industry, Inc. | Multi-pole circuit breaker light guide trip indicator and installation method |
US8228649B2 (en) * | 2009-06-04 | 2012-07-24 | Eaton Corporation | Impedance-based current sensor |
US8279573B2 (en) * | 2009-07-30 | 2012-10-02 | General Electric Company | Circuit protection device and system |
US8325504B2 (en) * | 2009-09-18 | 2012-12-04 | Power Distribution, Inc. | Direct current power supply for mission critical applications |
CN101718834B (en) * | 2009-12-01 | 2012-07-04 | 湖南大学 | Method for analysing analog circuit fault propagation characteristic |
US20110141635A1 (en) * | 2009-12-10 | 2011-06-16 | Fabian Steven D | Thermally protected GFCI |
US8289664B2 (en) * | 2010-03-08 | 2012-10-16 | Pass & Seymour, Inc. | Protective device for an electrical supply facility |
US8405939B2 (en) * | 2010-03-08 | 2013-03-26 | Pass & Seymour, Inc. | Protective device for an electrical supply facility |
US8335062B2 (en) * | 2010-03-08 | 2012-12-18 | Pass & Seymour, Inc. | Protective device for an electrical supply facility |
US9948087B2 (en) | 2010-03-08 | 2018-04-17 | Pass & Seymour, Inc. | Protective device for an electrical supply facility |
EP2577826A2 (en) * | 2010-06-03 | 2013-04-10 | Shakira Limited | An arc fault detector for ac or dc installations |
CN103004049B (en) * | 2010-06-14 | 2017-03-29 | Abb研究有限公司 | The circuit breaker failure protection of HVDC circuit-breakers |
US8373570B2 (en) | 2010-10-26 | 2013-02-12 | Cooper Technologies Company | ARC fault detection method and apparatus |
CN102043115B (en) * | 2010-11-02 | 2013-02-20 | 深圳市双合电气股份有限公司 | Network on-line live line measurement method for line parameter of power system |
CN102136248B (en) * | 2010-12-10 | 2016-03-23 | 深圳市中庆微科技开发有限公司 | A kind of LED control device of intelligent newspapers barrier and LED control system |
GB201102031D0 (en) | 2011-02-07 | 2011-03-23 | Rolls Royce Plc | Protection system for an electrical power network |
CN102116787A (en) * | 2011-02-23 | 2011-07-06 | 河南科技大学 | Device for testing electric arc in high-speed electric sliding contact state |
US8717718B2 (en) | 2011-04-11 | 2014-05-06 | Leviton Manufacturing Company, Inc. | Electrical load control with fault protection |
US9551751B2 (en) | 2011-06-15 | 2017-01-24 | Ul Llc | High speed controllable load |
US8599523B1 (en) | 2011-07-29 | 2013-12-03 | Leviton Manufacturing Company, Inc. | Arc fault circuit interrupter |
US8995098B2 (en) * | 2011-10-14 | 2015-03-31 | True-Safe Technologies, Inc. | Miswire protection and annunciation of system conditions for arc fault circuit interrupters and other wiring devices |
US9945894B2 (en) | 2012-02-29 | 2018-04-17 | Innovative Scientific Solutions, Inc. | Arc fault detection |
CN103376372A (en) * | 2012-04-23 | 2013-10-30 | 福建俊豪电子有限公司 | Three-phase AFCI detecting device |
US9025287B2 (en) | 2012-12-19 | 2015-05-05 | Stmicroelectronics S.R.L. | Arc fault detection equipment and method using low frequency harmonic current analysis |
EP3044599B8 (en) * | 2013-09-13 | 2021-12-08 | Schneider Electric USA, Inc. | Arc-fault and ground fault interrupter using a single ground fault sensor and single adc |
WO2015100577A1 (en) | 2013-12-31 | 2015-07-09 | Siemens Aktiengesellschaft | Devices and methods for arc fault detection |
DE102014202533A1 (en) * | 2014-02-12 | 2015-08-13 | Siemens Aktiengesellschaft | Test device and test method for a fire protection switch |
US9759758B2 (en) | 2014-04-25 | 2017-09-12 | Leviton Manufacturing Co., Inc. | Ground fault detector |
CN105223427B (en) * | 2014-06-17 | 2019-05-17 | 西门子公司 | The detection method and detection device of fault electric arc |
CN104090233B (en) * | 2014-07-24 | 2017-06-06 | 珠海格力电器股份有限公司 | The detection means and detection method of fault electric arc breaker |
US10162008B2 (en) * | 2014-08-29 | 2018-12-25 | James J. Kinsella | Manual and automated non-destructive testing for short-circuit and ground fault conditions in branch motor circuits |
CN105372558A (en) * | 2015-12-14 | 2016-03-02 | 王永妍 | Substation power grid detection system |
GB2546743B (en) * | 2016-01-26 | 2019-02-13 | Shakira Ltd | An arc fault current detector |
CN105823963B (en) * | 2016-05-17 | 2018-11-13 | 中国科学院电工研究所 | A kind of DC grid fault detect positioning device |
US10223906B2 (en) | 2017-01-23 | 2019-03-05 | Florida Power & Light Company | Open neutral detection |
CN109188189B (en) * | 2018-07-11 | 2020-04-28 | 天津大学 | Method for identifying permanent fault of ultra/ultra-high voltage transmission line based on arc characteristic |
CN110018401B (en) * | 2019-05-20 | 2021-03-16 | 国网甘肃省电力公司天水供电公司 | Distribution line single-phase earth fault positioning method |
CN110850229A (en) * | 2019-11-06 | 2020-02-28 | 天津大学 | Power distribution network single-phase earth fault line selection method |
CN114755546B (en) * | 2022-06-14 | 2022-08-26 | 锦浪科技股份有限公司 | Method and device for detecting direct-current fault arc of photovoltaic system and photovoltaic system |
Family Cites Families (111)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2247746C3 (en) * | 1972-09-29 | 1975-11-27 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Method of measuring a line impedance |
US5202662A (en) * | 1978-09-07 | 1993-04-13 | Leviton Manufacturing Company, Inc. | Resettable circuit breaker for use in ground fault circuit interrupters and the like |
US4356443A (en) * | 1980-08-26 | 1982-10-26 | Westinghouse Electric Corp. | Detection of arcing faults in polyphase electric machines |
US4376243A (en) * | 1981-01-26 | 1983-03-08 | General Motors Corporation | Arc detector for electric rod furnace |
US4466071A (en) * | 1981-09-28 | 1984-08-14 | Texas A&M University System | High impedance fault detection apparatus and method |
US4658322A (en) * | 1982-04-29 | 1987-04-14 | The United States Of America As Represented By The Secretary Of The Navy | Arcing fault detector |
US4709293A (en) * | 1983-12-05 | 1987-11-24 | Leviton Manufacturing Company, Inc. | Shock hazard protection system |
US4618907A (en) * | 1985-01-29 | 1986-10-21 | Eagle Electric Mfg. Co., Inc. | Desensitized ground fault interrupter |
US4851782A (en) * | 1987-01-15 | 1989-07-25 | Jeerings Donald I | High impedance fault analyzer in electric power distribution |
FR2621748B1 (en) * | 1987-10-09 | 1996-07-05 | Merlin Gerin | STATIC TRIGGER OF A MOLDED CASE CIRCUIT BREAKER |
FR2634897A1 (en) * | 1988-07-26 | 1990-02-02 | Alsthom | DEVICE FOR MEASURING PHASE CURRENTS OF A THREE-PHASE INSTALLATION |
US4931894A (en) * | 1989-09-29 | 1990-06-05 | Technology Research Corporation | Ground fault current interrupter circuit with arcing protection |
US4939495A (en) * | 1989-12-19 | 1990-07-03 | Texas Instruments Incorporated | Circuit breaker with auxiliary status indicating switch |
US5121282A (en) * | 1990-03-30 | 1992-06-09 | White Orval C | Arcing fault detector |
US5185686A (en) * | 1991-03-28 | 1993-02-09 | Eaton Corporation | Direction sensing arc detection |
US5206596A (en) * | 1991-03-28 | 1993-04-27 | Eaton Corporation | Arc detector transducer using an e and b field sensor |
US5185684A (en) * | 1991-03-28 | 1993-02-09 | Eaton Corporation | Frequency selective arc detection |
US5224006A (en) * | 1991-09-26 | 1993-06-29 | Westinghouse Electric Corp. | Electronic circuit breaker with protection against sputtering arc faults and ground faults |
US5280404A (en) * | 1992-05-15 | 1994-01-18 | Bio-Rad Laboratories, Inc. | Arc detection system |
US5434509A (en) * | 1992-07-30 | 1995-07-18 | Blades; Frederick K. | Method and apparatus for detecting arcing in alternating-current power systems by monitoring high-frequency noise |
US5223795A (en) * | 1992-07-30 | 1993-06-29 | Blades Frederick K | Method and apparatus for detecting arcing in electrical connections by monitoring high frequency noise |
US5729145A (en) * | 1992-07-30 | 1998-03-17 | Siemens Energy & Automation, Inc. | Method and apparatus for detecting arcing in AC power systems by monitoring high frequency noise |
US5432455A (en) * | 1992-07-30 | 1995-07-11 | Blades; Frederick K. | Method and apparatus for detecting arcing in alternating current power systems by monitoring high-frequency noise |
US5536980A (en) * | 1992-11-19 | 1996-07-16 | Texas Instruments Incorporated | High voltage, high current switching apparatus |
ZA941138B (en) | 1993-02-26 | 1994-08-29 | Westinghouse Electric Corp | Circuit breaker responsive to repeated in-rush currents produced by a sputtering arc fault. |
US5383799A (en) * | 1993-03-26 | 1995-01-24 | Fladung; Philip E. | Multi-purpose plug-in electrical outlet adaptor |
US5452223A (en) * | 1993-08-20 | 1995-09-19 | Eaton Corporation | Arc detection using current variation |
US5459630A (en) * | 1993-09-15 | 1995-10-17 | Eaton Corporation | Self testing circuit breaker ground fault and sputtering arc trip unit |
US5519561A (en) * | 1994-11-08 | 1996-05-21 | Eaton Corporation | Circuit breaker using bimetal of thermal-magnetic trip to sense current |
US5682101A (en) * | 1995-03-13 | 1997-10-28 | Square D Company | Arcing fault detection system |
US6259996B1 (en) | 1998-02-19 | 2001-07-10 | Square D Company | Arc fault detection system |
US6246556B1 (en) | 1995-03-13 | 2001-06-12 | Square D Company | Electrical fault detection system |
US6313641B1 (en) * | 1995-03-13 | 2001-11-06 | Square D Company | Method and system for detecting arcing faults and testing such system |
US5825598A (en) * | 1997-02-11 | 1998-10-20 | Square D Company | Arcing fault detection system installed in a panelboard |
US5590012A (en) * | 1995-03-30 | 1996-12-31 | Siemens Energy & Automation, Inc. | Electric arc detector sensor circuit |
US5600524A (en) * | 1995-05-04 | 1997-02-04 | Leviton Manufacturing Co., Inc. | Intelligent ground fault circuit interrupter |
US5561505A (en) * | 1995-11-01 | 1996-10-01 | Xerox Corporation | Mechanically sealable liquid charging apparatus |
US5886606A (en) * | 1995-11-14 | 1999-03-23 | Fuji Electric Co., Ltd. | Circuit breaker |
US5689180A (en) * | 1995-12-13 | 1997-11-18 | Carlson; Curt S. | Isolated electrical power supply |
US5818237A (en) * | 1996-06-10 | 1998-10-06 | Eaton Corporation | Apparatus for envelope detection of low current arcs |
US5835321A (en) | 1996-08-02 | 1998-11-10 | Eaton Corporation | Arc fault detection apparatus and circuit breaker incorporating same |
US5834940A (en) * | 1996-09-24 | 1998-11-10 | Brooks; Stanley J. | Arcing fault detector testing and demonstration system |
US5818671A (en) * | 1996-10-04 | 1998-10-06 | General Electric Company | Circuit breaker with arcing fault detection module |
US5847913A (en) | 1997-02-21 | 1998-12-08 | Square D Company | Trip indicators for circuit protection devices |
US5946179A (en) | 1997-03-25 | 1999-08-31 | Square D Company | Electronically controlled circuit breaker with integrated latch tripping |
US5839092A (en) | 1997-03-26 | 1998-11-17 | Square D Company | Arcing fault detection system using fluctuations in current peaks and waveforms |
US5999384A (en) | 1997-08-25 | 1999-12-07 | Square D Company | Circuit interrupter with arcing fault protection and PTC (positive temperature coefficient resistivity) elements for short circuit and overload protection |
US5906517A (en) | 1997-09-11 | 1999-05-25 | Fiskars Inc. | Power strip |
US6359745B1 (en) | 1997-09-26 | 2002-03-19 | Iomega Corporation | Latent illuminance discrimination marker system for data storage cartridges |
US5805398A (en) * | 1997-09-29 | 1998-09-08 | Eaton Corporation | Arc fault detector with immunity to tungsten bulb burnout and circuit breaker incorporating same |
US5815352A (en) * | 1997-09-29 | 1998-09-29 | Eaton Corporation | Arc fault detector with limiting of sensed signal to shape response characteristic and circuit breaker incoprorating same |
US5805397A (en) * | 1997-09-29 | 1998-09-08 | Eaton Corporation | Arcing fault detector with multiple channel sensing and circuit breaker incorporating same |
US6088205A (en) | 1997-12-19 | 2000-07-11 | Leviton Manufacturing Co., Inc. | Arc fault detector with circuit interrupter |
US6128169A (en) * | 1997-12-19 | 2000-10-03 | Leviton Manufacturing Co., Inc. | Arc fault detector with circuit interrupter and early arc fault detection |
US5963406A (en) | 1997-12-19 | 1999-10-05 | Leviton Manufacturing Co., Inc. | Arc fault detector with circuit interrupter |
US6567250B1 (en) * | 1998-02-19 | 2003-05-20 | Square D Company | Arc fault protected device |
US6782329B2 (en) * | 1998-02-19 | 2004-08-24 | Square D Company | Detection of arcing faults using bifurcated wiring system |
US5986860A (en) | 1998-02-19 | 1999-11-16 | Square D Company | Zone arc fault detection |
US6266219B1 (en) | 1998-06-02 | 2001-07-24 | Pass & Seymour, Inc. | Combination ground fault and arc fault circuit interrupter |
US6275044B1 (en) | 1998-07-15 | 2001-08-14 | Square D Company | Arcing fault detection system |
US6040967A (en) | 1998-08-24 | 2000-03-21 | Leviton Manufacturing Co., Inc. | Reset lockout for circuit interrupting device |
US6373257B1 (en) * | 1998-12-09 | 2002-04-16 | Pass & Seymour, Inc. | Arc fault circuit interrupter |
US6218844B1 (en) | 1998-12-16 | 2001-04-17 | Square D Company | Method and apparatus for testing an arcing fault circuit interrupter |
US6362628B2 (en) | 1998-12-21 | 2002-03-26 | Pass & Seymour, Inc. | Arc fault circuit detector device detecting pulse width modulation of arc noise |
US6191589B1 (en) * | 1999-03-29 | 2001-02-20 | George A. Spencer | Test circuit for an AFCI/GFCI circuit breaker |
US6426634B1 (en) * | 1999-03-29 | 2002-07-30 | George A. Spencer | Circuit breaker with integrated self-test enhancements |
US6426632B1 (en) | 1999-03-29 | 2002-07-30 | George A. Spencer | Method and apparatus for testing an AFCI/GFCI circuit breaker |
US6433977B1 (en) * | 1999-04-16 | 2002-08-13 | Pass & Seymour, Inc. | Combo AFCI/GFCI with single test button |
US6295190B1 (en) * | 1999-10-26 | 2001-09-25 | Electric Boat Corporation | Circuit breaker arrangement with integrated protection, control and monitoring |
US6421214B1 (en) * | 2000-03-03 | 2002-07-16 | Pass & Seymour, Inc. | Arc fault or ground fault detector with self-test feature |
US6876528B2 (en) * | 2000-03-04 | 2005-04-05 | Passi Seymour, Inc. | Two winding resonating arc fault sensor which boosts arc fault signals while rejecting arc mimicking noise |
US6628486B1 (en) * | 2000-03-06 | 2003-09-30 | Pass & Seymour, Inc. | Fault detection device with line-load miswire protection |
US7035066B2 (en) * | 2000-06-02 | 2006-04-25 | Raytheon Company | Arc-default detecting circuit breaker system |
US6747859B2 (en) * | 2000-07-11 | 2004-06-08 | Easyplug Inc. | Modular power line network adapter |
US6417671B1 (en) * | 2000-11-07 | 2002-07-09 | General Electric Company | Arc fault circuit breaker apparatus and related methods |
US6807035B1 (en) | 2000-11-28 | 2004-10-19 | Hubbell Incorporated | Fault interrupter using microcontroller for fault sensing and automatic self-testing |
US6642832B2 (en) | 2000-12-08 | 2003-11-04 | Texas Instruments Incorporated | ARC responsive thermal circuit breaker |
US6577484B1 (en) | 2000-12-12 | 2003-06-10 | Pass & Seymour, Inc. | Arc fault detector device utilizing the di/dt and 60 Hz components of an arcing waveform |
US6807036B2 (en) | 2001-04-26 | 2004-10-19 | Hubbell Incorporated | Digital fault interrupter with self-testing capabilities |
US20030151478A1 (en) * | 2001-10-02 | 2003-08-14 | Dejan Radosavljevic | Protection device with lockout test |
US7068480B2 (en) * | 2001-10-17 | 2006-06-27 | Square D Company | Arc detection using load recognition, harmonic content and broadband noise |
US6538862B1 (en) | 2001-11-26 | 2003-03-25 | General Electric Company | Circuit breaker with a single test button mechanism |
US6545574B1 (en) | 2001-12-17 | 2003-04-08 | General Electric Company | Arc fault circuit breaker |
US6785104B2 (en) | 2002-03-05 | 2004-08-31 | Eaton Corporation | Low energy pulsing device and method for electrical system arc detection |
RU2316090C2 (en) * | 2002-04-04 | 2008-01-27 | Кьюн Тей КИМ | Low-voltage power distribution circuit |
KR100464596B1 (en) * | 2002-04-09 | 2005-01-03 | 휴먼엘텍 주식회사 | Circuit Breaker for Detecting Overload |
US7180717B2 (en) * | 2002-07-12 | 2007-02-20 | Cooper Technologies Company | Electrical network protection system |
US6810069B2 (en) * | 2002-07-12 | 2004-10-26 | Mcgraw-Edison Company | Electrical arc furnace protection system |
US6720872B1 (en) | 2002-07-16 | 2004-04-13 | Eaton Corporation | Ground fault/arc fault circuit interrupter and method of testing the same with a test button and a reset button |
JP3863828B2 (en) * | 2002-08-26 | 2006-12-27 | 富士通株式会社 | Disk medium positioning method |
US7003435B2 (en) | 2002-10-03 | 2006-02-21 | Leviton Manufacturing Co., Inc. | Arc fault detector with circuit interrupter |
AU2003267842A1 (en) | 2002-10-10 | 2004-05-04 | Hanyang Hak Won Co., Ltd. | Hybrid type sensor for detecting high frequency partial discharge |
US7009406B2 (en) * | 2003-04-24 | 2006-03-07 | Delphi Technologies, Inc. | Arc fault detector and method |
US7149065B2 (en) * | 2003-06-16 | 2006-12-12 | Hubbell Incorporated | Self testing digital fault interrupter |
US6943558B2 (en) | 2003-09-15 | 2005-09-13 | The Boeing Company | System and method for remotely detecting electric arc events in a power system |
US7180299B2 (en) | 2003-12-22 | 2007-02-20 | Leviton Manufacturing Co., Inc. | Arc fault detector |
US6972572B2 (en) | 2003-12-22 | 2005-12-06 | Leviton Manufacturing Co., Inc. | Arc fault detector |
DE102004011023A1 (en) * | 2004-03-04 | 2005-09-15 | Siemens Ag | Three or four-pole low-voltage circuit breaker, has output signals from Rogowski coils fed via low-pass filters to measuring amplifier and via resistances to integrating capacitor |
US20050286184A1 (en) * | 2004-06-22 | 2005-12-29 | Steve Campolo | Electrical power outlet strip |
US7215520B2 (en) * | 2004-07-20 | 2007-05-08 | Eaton Corporation | Circuit interrupter including arc fault test and/or ground fault test failure indicator |
US7190562B2 (en) * | 2004-09-09 | 2007-03-13 | Sensata Technologies, Inc. | Method for detecting arc faults |
US7253603B2 (en) * | 2005-01-06 | 2007-08-07 | S & C Electric Co. | Current sensor arrangement |
US20060171085A1 (en) * | 2005-01-21 | 2006-08-03 | Thomas Keating | Arc fault detection |
US7227441B2 (en) * | 2005-02-04 | 2007-06-05 | Schweitzer Engineering Laboratories, Inc. | Precision Rogowski coil and method for manufacturing same |
US7268989B2 (en) * | 2005-04-11 | 2007-09-11 | Eaton Corporation | Arc fault circuit interrupter for a compressor load |
DE102005016996B4 (en) * | 2005-04-13 | 2014-10-23 | TRUMPF Hüttinger GmbH + Co. KG | Current measurement device |
US7319574B2 (en) * | 2005-05-23 | 2008-01-15 | Eaton Corporation | Arc fault detection apparatus, method and system for an underground electrical conductor |
US7253637B2 (en) * | 2005-09-13 | 2007-08-07 | Square D Company | Arc fault circuit interrupter system |
EP1793235A1 (en) * | 2005-11-30 | 2007-06-06 | ABB Technology AG | Monitoring System for High-Voltage Switch Gears |
US7443644B2 (en) * | 2006-02-09 | 2008-10-28 | Sam Kyoung Sung | Circuit for preventing malfunction of arc fault detection device |
US7403129B2 (en) * | 2006-05-10 | 2008-07-22 | Eaton Corporation | Electrical switching apparatus and method employing acoustic and current signals to distinguish between parallel and series arc faults |
-
2003
- 2003-12-22 US US10/743,248 patent/US6972572B2/en not_active Expired - Lifetime
-
2004
- 2004-12-20 CN CNA2004800417391A patent/CN1918680A/en active Pending
- 2004-12-20 WO PCT/US2004/043272 patent/WO2005062917A2/en active Application Filing
- 2004-12-20 CA CA2550997A patent/CA2550997C/en active Active
- 2004-12-20 MX MXPA06007196A patent/MXPA06007196A/en active IP Right Grant
-
2005
- 2005-12-05 US US11/295,277 patent/US7259568B2/en not_active Expired - Lifetime
-
2007
- 2007-04-23 US US11/738,783 patent/US7535234B2/en not_active Expired - Fee Related
-
2009
- 2009-04-13 US US12/422,435 patent/US7986148B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
US20070262780A1 (en) | 2007-11-15 |
MXPA06007196A (en) | 2006-09-04 |
WO2005062917A2 (en) | 2005-07-14 |
WO2005062917A3 (en) | 2005-11-03 |
CA2550997A1 (en) | 2005-07-14 |
US20060226852A1 (en) | 2006-10-12 |
CN1918680A (en) | 2007-02-21 |
US6972572B2 (en) | 2005-12-06 |
US20050134285A1 (en) | 2005-06-23 |
US20090207535A1 (en) | 2009-08-20 |
US7535234B2 (en) | 2009-05-19 |
US7259568B2 (en) | 2007-08-21 |
US7986148B2 (en) | 2011-07-26 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2550997C (en) | Arc fault detector | |
US7180299B2 (en) | Arc fault detector | |
CA2320859C (en) | Electrical fault detection system | |
US9347978B2 (en) | Arc fault detector with circuit interrupter | |
US9638738B2 (en) | Apparatus and method to detect a series arc fault of an electrical circuit | |
US8189307B2 (en) | Composite type electric circuit breaker and method thereof | |
US6195241B1 (en) | Arcing fault detection system | |
US5834940A (en) | Arcing fault detector testing and demonstration system | |
US5986860A (en) | Zone arc fault detection | |
US20030156367A1 (en) | Arc fault circuit interrupter with upstream impedance detector | |
US6556397B2 (en) | Device and method for detecting arc fault | |
WO1997030501A9 (en) | Arcing fault detection system | |
CA2560791A1 (en) | Arc fault detector | |
US6785104B2 (en) | Low energy pulsing device and method for electrical system arc detection | |
CA2503472A1 (en) | Electrical fault detection system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request |