GB2056094A - Earth leakage circuit breaker tester - Google Patents
Earth leakage circuit breaker tester Download PDFInfo
- Publication number
- GB2056094A GB2056094A GB8005083A GB8005083A GB2056094A GB 2056094 A GB2056094 A GB 2056094A GB 8005083 A GB8005083 A GB 8005083A GB 8005083 A GB8005083 A GB 8005083A GB 2056094 A GB2056094 A GB 2056094A
- Authority
- GB
- United Kingdom
- Prior art keywords
- current
- circuit breaker
- earth leakage
- leakage circuit
- tripping
- 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.)
- Granted
Links
Classifications
-
- 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
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3277—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
-
- 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
- H02H3/26—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 difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—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 difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/33—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 difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors using summation current transformers
- H02H3/334—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 difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors using summation current transformers with means to produce an artificial unbalance for other protection or monitoring reasons or remote control
- H02H3/335—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 difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors using summation current transformers with means to produce an artificial unbalance for other protection or monitoring reasons or remote control the main function being self testing of the device
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The tester provides means for determining the tripping current and time to trip for an earth leakage circuit breaker (ELCB) (16) which ELCB is connected to a current source for producing an alternating current of a predetermined amplitude (14, 60a-60n) to simulate application for a predetermined period of an earth fault current. Tripping of the ELCB (16) in response to the current is detected by a zero-volts detector (42), disabling a timing oscillator (38) whose output is fed to a counter (54a, 54b). In a preferred embodiment the output of the counter (54a, 54b) drives a display (58a, 58b) giving the time for which the current is applied, and a secondary display (58c, 58d) gives the amplitude of the current prior to the tripping, the ELCB (16) having fault current steps of increasing amplitude applied automatically. The point on the alternating current waveform at which the fault current is applied may be controlled by a monostable (44) having an adjustable period. <IMAGE>
Description
SPECIFICATION
Earth leakage circuit breaker tester
The present invention relates to test apparatus for, and a method of testing, an earth leakage circuit breaker, or a circuit including an earth leakage circuit breaker.
According to the present invention there is provided apparatus for testing an earth leakage circuit breaker, or a circuit including an earth leakage circuit breaker, comprising a current source for producing an alternating current of a predetermined amplitude, connecting means for connecting the current from the current source to an earth leakage circuit breaker, or a circuit including same, to be tested, so as to simulate an earth fault current therein, a detector for detecting the tripping of the earth leakage circuit breaker in response to the current and a timer for timing the period between the connection of the current and the tripping of the earth leakage circuit breaker in response thereto, so as to detect tripping of the earth leakage circuit breaker within a predetermined period.
Preferably the current source is programmed to provide current in a series of steps each lasting for the predetermined period and increasing in amplitude.
The apparatus may include a display of the period times and/or of the amplitude of the current.
Preferably the apparatus is arranged for operation in an automatic mode, where the current is provided from the programmed current source until a current is applied whose amplitude is such as cause tripping of a connected earth leakage circuit breaker or circuit including same.
In one embodiment the apparatus may include phase control means whereby the point on the waveform of an applied alternating current from the current source at which the current is connected may be varied.
Preferably the connecting means connects an alternating current power supply to the apparatus through the earth leakage circuit breaker and the tripping of the earth leakage circuit breaker is detected by detecting loss of the alternating current power supply to the apparatus.
The detector preferably includes a delay triggered at the zero-crossing point of the alternating current waveform in inhibit detection of the zero-crossing point thereof at tripping of the earth leakage circuit breaker.
There is further provided a method of testing an earth leakage circuit breaker or a circuit including same, comprising applying an alternating current of a predetermined amplitude to the earth leakage circuit breaker, or circuit including same, so as to simulate an earth fault current therein, and detecting the tripping of the earth leakage circuit breaker in response to the current, and timing the period between applying the current and detecting the tripping of the earth leakage circuit breaker, so as to detect tripping of the earth leakage circuit breaker within a predetermined period.
Preferably in said method the current is applied in a programmed series of steps each lasting for the predetermined period and increasing in amplitude.
The method may be carried out in an automatic mode, wherein the programmed current steps are applied until a current is applied whose amplitude is such as to cause tripping of the earth leakage circuit breaker.
Preferably the point on the waveform of the alternating current at which the current is applied is adjustable.
The present invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a graph of current/time in relation to its effect on human adults;
Fig. 2 is a block diagram showing an apparatus according to the present invention;
Figs. 3a-3e show typical waveforms at various points in the apparatus of Fig. 2;
Fig. 4 is a schematic illustration of a calibration rig for use in setting up the apparatus;
Fig. 5 shows a detailed example of any oscilloscope display obtained using the calibration rig of Fig. 4; and
Fig. 6 shows a typical oscilloscope display using the calibration rig of Fig. 4 in the automatic mode of operation of the apparatus.
It is generally accepted that the effect of an electric current passing through a human body is related to the magnitude and frequency of that current and the time period for which it lasts.
International Electrotechnical Commission (IEC) Publication 479 (1974) provides 50 Hz current/time zones related to the expected severity of shock for human adults. A graph illustrating this is shown in Fig. 1, and the importance of the time element may be seen.
Taking as an example the case where a shock current of 100 mA was received, depending on the time taken for a protective device to interrupt the circuit, the shock could be classified as:
Zone 2 - "Usually no pathophysiologically dangerous effect", or
Zone 3 - "Usually no danger of fibrillation", or
Zone 4 -- "Fibrillation possible (up to 50% probability)".
There is also a misconception that a sensitive earth leakage circuit breaker (ELCB) rated to trip at say 30 mA, will limit the magnitude of shock current to this value. This is not the case. The current that will actually flow depends upon the touch voltage of the shock source and the total impedance (including the victim's body resistance, skin resistance etc.) between this point and the earth point of the supply transformer.
Thus, the magnitude of the fault current is only one of the factors to be taken into account, and a second important factor is the time taken to interrupt the circuit.
An object of the present invention is to enable tests to be carried out on an ELCB to determine the minimum tripping current and the time to trip at that current. Testing of the ELCB may be carried out on an ELCB connected into a supply circuit.
Considering operation in an automatic mode, in
Fig. 2 a double wound isolating transformer 10 has its primary winding 12 connected to a mains supply 14 through an earth leakage circuit breaker 1 6 which is to be tested. The 48 volt output of the secondary winding 1 8 of the transformer 10 is connected to a bridge rectifier 20, one terminal of the output of the bridge 20 being earthed, and the other (see waveforms Figs. 3a and 3b) being connected to an amplifier 22. Fig. 3a shows the waveform of the output from the bridge rectifier 22, and Fig. 3b shows an enlargement of one near zero-voltage part of the waveform. In the amplifier 22 the output of the bridge rectifier 20 is amplified and clipped at 8.4 volts.This reduces the zerovoltage gap of 2 milliseconds shown in Fig. 3a to 0.2 milliseconds shown in Fig. 3c due to amplification of the near zero-voltage part of the waveform shown in Fig. 3b.
The output from the amplifier 22 is applied to a zero-volts detector 24 the output of which is a logic 1 when a voltage is applied to its input. The output of the zero-volts detector 24 is delayed by a delay 26 and the delayed output is combined with the undelayed output to eliminate the 0.2 millisecond zero-voltage gaps. The combined output is then applied to the reset input of a flipflop 28.
A 'Start Test' switch 30 is connected to a debounce circuit 32 whose output is connected to a monostable 34 giving a logic 1 output for 1 second which triggers a monostable 36 to give a 10 microsecond pulse to the set input of the flipflop 28, which removes a "disable" input from a 10 kHz oscillator 38.
To the secondary winding 18 is connected a rectifier 40, which half-wave rectifies the output to give an output waveform as Fig. 3d. The halfwave rectified output is taken to a zero-volts detector 42 where it is clipped and amplified to provide a series of pulses as shown in Fig. 3e, which trigger a monostable 44 the period of which is adjustable by a variable resistor 46, to vary the point on the alternating current waveform at which the simulated earth fault current is applied to the earth leakage circuit breaker. The falling edge of the output from the monostable 44 triggers a monostable 48 having a period of 10 microseconds, the output of which is applied to the reset input of a flip-flop 50.
The output of the flip-flop 50 provides an "enable" input to the 10 kHz oscillator 38 which now commences to run, firstly to clear the counters 54a, 54b, 54c, 54d and secondly to set the apparatus in its starting condition. The 10 kHz output is divided by ten in a divider 52, which consequently has an output having a period of one millisecond, which output is applied to a chain of decimal counters 54a 54b, 54c, 54d.
Each counter 54a, 54b, 54c, 54d is connected to a respective driver 56a, 56b, 56c, 56dand thence to a respective liquid crystal digital display 58a, 58b, 58c, 58d. Counters 54a and 54b divide the count into units of 100 milliseconds, while counters 54c and 54d increment the simulated earth fault current in steps of 1 mA, each step being applied for a unit of 100 milliseconds.
The simulated earth fault current is produced by current generators 60a, - - - 60n (not shown in detail) each comprising a resistor connected to a 24 volt supply line from an auto-transformer (not shown) connected to the mains supply 14 through the earth leakage circuit breaker 1 6. Each resistor is coupled to earth through a triac triggered from the oscillator 38 through a gate 62 connected to the appropriate output of the counters 54c, 54d.
The 80 millisecond point is detected by an 80 millisecond detector 64, connected to the 80 millisecond output of the counter 54b. The output of the detector 64 inhibits the monostables 44 and 48 preventing the application of a reset signal to the flip-flop 50. The end of a 100 millisecond count is detected by an output from the counter 54b to a 100 millisecond detector 66 which is applied to a set input of the flip-flop 50, which inhibits the oscillator 38.
At the next zero voltage point on the alternating current waveform at the detector 42, the trigger point delay 44 is again operative to reset the flipflop 50 and hence restart the oscillator 38 at the next current increment.
If the ELCB 1 6 trips then the supply to the zerovolts detector 24 is interrupted and after a 0.4 millisecond delay caused by the delay 26, the flipflop 28 is then reset which disables the oscillator 38. The display 58c, 58d, will then show the current at which the ELCB tripped, and the displays 58a, 58b will display the length of time for which that current was applied prior to the tripping.
Where the ELCB fails to trip at a current of 99 ma, an output from the counter 54d is applied to a 100 milliamp detector 68 which triggers a set input of a flip-flop 70. The output of the flip-flop 70 switches a fail indicator 72 and inhibits the oscillator 38, terminating the test.
The apparatus may also be operated in a preset current mode. Operation of the "Start Test" switch 30 enables the oscillator 38 as before to clear the counters 54a, 54b, 54c, 54d, and set the apparatus in its starting condition. The oscillator 38 is theh again inhibited by the flip-flop 50 until the flip-flop 50 is reset when the trigger point on the alternating current waveform is reached; oscillator 38 is restarted and the appropriate current generators 60a - - - 60n, selected by a preset current switch 74 through the counters 54c, 54d, are energized.
If the ELCB does not trip within 100 milliseconds of the application of the preset current, then a 200 millisecond detector 76 operates and sets the flip-flop 70, inhibiting the oscillator 38 and switching the fail indicator 72.
The detector 76 is inhibited in the automatic mode of operation.
In the calibration rig shown in Fig. 4, a resistor 100 is inserted in series in the earth connection between the ELCB 1 6 and the set apparatus 10, a suitabie value being 0.47 ohm, and thus any earth current will appear as a voltage across the resistor 100. One channel 102 of a two-channel oscillosdope 104 is connected across the resistor 100, and the second channel 106 is connected to the output of the oscillator 38. Preferably the oscilloscope 104 is a storage oscilloscope or has some other recording means associated with it such as an ultraviolet recorder.
Figure 5 shows a typical display on the oscilloscope 104 with a preset current. The upper trace represents the fault current, and the lower trace is the envelope of the waveform of the oscillator 38. The time scan of the oscillator waveform may be compared with the time displayed by the apparatus 10.
Figure 6 shows a typical display on the oscilloscope 104 in the auto mode, the upper trace again representing the fault current, and the lower trace the envelope of the waveform of the oscillator 38.
The starting point in this display is at 0 on the alternating current waveform. The ELCB 1 6 under test tripped with a current of 11 milliamps after a period of about 60 milliseconds. The lower trace is a series of 100 millisecond blocks of 10 kHz waveform, the oscillator 38 being switched on at the appropriate point on the alternating current waveform, and switched off 100 milliseconds, or less, later. The width of the 10 kHz block under the
11 milliamp current is approximately 60
milliseconds.
As the power supply to the apparatus 10 is
removed when the ELCB is tripped, the circuitry is
preferably powered by an internal battery, though an alternative mains supply not protected by the
ELCB 1 6 under test may be used.
The battery may be rechargeable, and the
apparatus 10 may include a charging circuit.
The power consumption, size and weight of the
apparatus 10 may be reduced by the employment
of switching mode power supplies to replace transformer 10 and to produce the earth fault
currents, and a microprocesser may be used to
carry out many of the functions.
The apparatus 10 may include a battery
condition monitor whose output is included in the
display.
The voltages, currents and timings referred to in
the described embodiment are not intended to be
limiting and alternative values may be selected to
suit particular applications.
Claims (14)
1. Apparatus for testing an earth leakage circuit breaker, or a circuit including an earth leakage circuit breaker, comprising a current source for producing an alternating current of a predetermined amplitude, connecting means for connecting the current from the current source to an earth leakage circuit breaker, or a circuit including same, to be tested, so as to simulate an earth fault current therein, a detector for detecting the tripping of the earth leakage circuit breaker in response to the current and a timer for timing the period between the connection of the current and the tripping of the earth leakage circuit breaker in response thereto, so as to detect tripping of the earth leakage circuit breaker within a predetermined period.
2. Apparatus as claimed in Claim 1, wherein the current source is programmed to provide current in a series of steps each lasting for the predetermined period and increasing in amplitude.
3. Apparatus as claimed in Claim 1 or 2, including a display of the period times.
4. Apparatus as claimed in Claim 1, 2 or 3 including a display of the amplitude of the current.
5. Apparatus as claimed in Claim 1, 2, 3 or 4 arranged for operation in an automatic mode, where the current is provided from the programmed current source until a current is applied whose amplitude is such as cause tripping of a connected earth leakage circuit breaker or circuit including same.
6. Apparatus as claimed in any preceding claim including phase control means whereby the point on the waveform of an applied alternating current from the current source at which the current is connected may be varied.
7. Apparatus as claimed in any preceding claim wherein the connecting means connects an alternating current power supply to the apparatus through the earth leakage circuit breaker and the tripping of the earth leakage circuit breaker is detected by detecting loss of the alternating current power supply to the apparatus.
8. Apparatus as claimed in any preceding claim wherein the detector includes a delay triggered at the zero-crossing point of the alternating current waveform to inhibit detection of the zero-crossing point thereof at tripping of the earth leakage circuit breaker.
9. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
10. A method of testing an earth leakage circuit breaker or a circuit including same, comprising applying an alternative current of a predetermined amplitude to the earth leakage circuit breaker, or circuit including same, so as to simulate an earth fault current therein, and detecting the tripping of the earth leakage circuit breaker in response to the current, and timing the period between applying the current and detecting the tripping of the earth leakage circuit breaker, so as to detect tripping of the earth leakage circuit breaker within a predetermined period.
11. A method as claimed in Claim 10 wherein the current is applied in a programmed series of steps each lasting for the predetermined period and increasing in amplitude.
12. A method as claimed in Claim 10 or 11 carried out in an automatic mode, wherein the programmed current steps are applied until a current is applied whose amplitude is such as to cause tripping of the earth leakage circuit breaker.
13. A method as claimed in Claim 10, 11 or 12 wherein the point on the waveform of the alternating current at which the current is applied is adjustable.
14. A method as claimed in Claim 10 substantially as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8005083A GB2056094B (en) | 1979-07-26 | 1980-02-14 | Earth leakage circuit breaker tester |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7926022 | 1979-07-26 | ||
| GB8005083A GB2056094B (en) | 1979-07-26 | 1980-02-14 | Earth leakage circuit breaker tester |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2056094A true GB2056094A (en) | 1981-03-11 |
| GB2056094B GB2056094B (en) | 1983-08-03 |
Family
ID=26272325
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8005083A Expired GB2056094B (en) | 1979-07-26 | 1980-02-14 | Earth leakage circuit breaker tester |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2056094B (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2480523A1 (en) * | 1980-04-15 | 1981-10-16 | Westinghouse Electric Corp | CIRCUIT DISPLAY APPARATUS AND MULTI-PARAMETER INPUT |
| EP0080857A1 (en) * | 1981-11-26 | 1983-06-08 | British Nuclear Fuels PLC | A device for testing circuit breakers |
| GB2118310A (en) * | 1982-04-08 | 1983-10-26 | Avo Limited | An instrument for testing circuit breakers |
| GB2197491A (en) * | 1986-11-10 | 1988-05-18 | Electricity Council | Electrical circuit breaker monitoring apparatus |
| EP0506602A2 (en) * | 1991-03-27 | 1992-09-30 | Amit Electronics And Engineering Ltd. | Device and method for GFCI time response and ground test |
| EP0676844A1 (en) * | 1994-04-09 | 1995-10-11 | Rainer Berthold | Self-monitoring ground fault circuit interrupter |
| WO1996006475A1 (en) * | 1994-08-24 | 1996-02-29 | Rainer Berthold | Earth-leakage circuit breaker with automatic monitoring facility |
| WO1998009360A1 (en) * | 1996-08-30 | 1998-03-05 | Siemens Aktiengesellschaft | Circuit arrangement for monitoring of an electronic tripping device for low voltage switches |
| FR2774173A1 (en) * | 1998-01-23 | 1999-07-30 | Ainf Sa | Procedure and device for testing of domestic and industrial differential circuit breakers |
| CN104198931A (en) * | 2014-08-18 | 2014-12-10 | 国家电网公司 | Circuit breaker anti-jumping test instrument and method |
| CN108710080A (en) * | 2018-08-10 | 2018-10-26 | 江苏创能电器有限公司 | Leakage analog trial jump apparatus and system |
-
1980
- 1980-02-14 GB GB8005083A patent/GB2056094B/en not_active Expired
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2480523A1 (en) * | 1980-04-15 | 1981-10-16 | Westinghouse Electric Corp | CIRCUIT DISPLAY APPARATUS AND MULTI-PARAMETER INPUT |
| EP0080857A1 (en) * | 1981-11-26 | 1983-06-08 | British Nuclear Fuels PLC | A device for testing circuit breakers |
| WO1983002041A1 (en) * | 1981-11-26 | 1983-06-09 | Wilbraham, Paul, Kevin | A device for testing circuit breakers |
| GB2118310A (en) * | 1982-04-08 | 1983-10-26 | Avo Limited | An instrument for testing circuit breakers |
| GB2197491A (en) * | 1986-11-10 | 1988-05-18 | Electricity Council | Electrical circuit breaker monitoring apparatus |
| GB2197491B (en) * | 1986-11-10 | 1990-08-22 | Electricity Council | Electrical circuit breaker monitoring apparatus |
| EP0506602A2 (en) * | 1991-03-27 | 1992-09-30 | Amit Electronics And Engineering Ltd. | Device and method for GFCI time response and ground test |
| EP0506602A3 (en) * | 1991-03-27 | 1993-10-13 | Amit Electronics And Engineering Ltd. | Device and method for gfci time response and ground test |
| EP0676844A1 (en) * | 1994-04-09 | 1995-10-11 | Rainer Berthold | Self-monitoring ground fault circuit interrupter |
| WO1996006475A1 (en) * | 1994-08-24 | 1996-02-29 | Rainer Berthold | Earth-leakage circuit breaker with automatic monitoring facility |
| US5956218A (en) * | 1994-08-24 | 1999-09-21 | Aeg Niederspannungstechnik Gmbh & Co. Kg | Earth-leakage circuit breaker with automatic monitoring capability |
| WO1998009360A1 (en) * | 1996-08-30 | 1998-03-05 | Siemens Aktiengesellschaft | Circuit arrangement for monitoring of an electronic tripping device for low voltage switches |
| FR2774173A1 (en) * | 1998-01-23 | 1999-07-30 | Ainf Sa | Procedure and device for testing of domestic and industrial differential circuit breakers |
| CN104198931A (en) * | 2014-08-18 | 2014-12-10 | 国家电网公司 | Circuit breaker anti-jumping test instrument and method |
| CN108710080A (en) * | 2018-08-10 | 2018-10-26 | 江苏创能电器有限公司 | Leakage analog trial jump apparatus and system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2056094B (en) | 1983-08-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |