JP2023167788A - Integrity testing device and integrity testing method of ground fault detection device - Google Patents

Abstract

To provide a device and method for testing the integrity of an entire ground fault detection device.SOLUTION: An integrity testing device for a ground fault detection device has a zero-phase current transformer arranged so that an AC line passes through it, an earth leakage relay for the AC line that operates when the output from a secondary winding of the zero-phase current transformer exceeds a predetermined value, and a circuit breaker that interrupts the AC line according to the output of the earth leakage relay. The integrity testing device also includes a test conductor that passes through the zero-phase current transformer or is arranged around the zero-phase current transformer, a portable power source that sends a pseudo-ground fault signal to the test conductor, an ammeter that measures the current value of the pseudo-ground fault signal, and a variable resistance in the circuit so that the portable power source can increase or decrease the alternating current. The integrity testing device preferably includes means for measuring the elapsed time from when the pseudo ground fault signal is issued until when the earth leakage relay outputs the predetermined signal to the circuit breaker.SELECTED DRAWING: Figure 1

Description

The present invention extracts the power from a separate circuit, steps down the voltage from the voltage actually used, and uses a pseudo leakage to check the soundness of the ground fault detection device (between the ZCT and the ground leakage relay input side) and prevent ground faults from occurring. The present invention relates to a device and method for preventing.

In factories that use power such as cranes, there are high-voltage panels that step down the transmitted high-voltage alternating current to working voltage, air circuit breakers (hereinafter also referred to as ACBs) and cranes in the electrical room that supplies power to equipment in the factory. A ground fault detection device is installed on the power panel to prevent ground fault accidents.

As illustrated in FIG. 4, the ground fault detection device 1 normally includes a zero-phase current transformer 2 (hereinafter also referred to as ZCT) arranged so that an AC line passes through it, and the zero-phase current transformer 2. an earth leakage relay 3 for the AC line that operates when the output from the secondary winding exceeds a predetermined value; and an overcurrent breaker 4 as a circuit breaker that interrupts the AC line in accordance with the output of the earth leakage relay 3. (hereinafter also referred to as NFB (no-fuse breaker)). Generally, the test button of the earth leakage relay 3 is used to test whether the output of the earth leakage relay 3 reliably operates the NFB 4 and instantly cuts off the AC line.

If the ground fault detection device does not operate properly, the ACB or high voltage panel will detect a ground fault and the power to the entire factory will be cut off. If this happens, there is a risk that the wiring will be burnt out or the factory will stop operating, and it will take time to recover from the problem while investigating the cause.

For example, Patent Document 1 discloses an earth leakage breaker including a pseudo current circuit. This earth leakage breaker has a test button that allows you to check all circuits.

Furthermore, Patent Document 2 discloses a technique in which operation can be checked by sending a pseudo signal from the earth leakage relay body to the ZCT.

Japanese Patent Application Publication No. 2007-96616 Japanese Patent Application Publication No. 2003-274550

The above conventional technology has the following problems.
The technique described in Patent Document 1 is related to an earth leakage breaker and cannot be directly applied to a ground fault detector. Further, the technique described in Patent Document 2 uses a ZCT secondary winding, and there is a problem in that it cannot be confirmed whether the ZCT can reliably detect a ground fault in an AC power line. In other words, inspection from the ZCT to the earth leakage relay input side was not possible. Furthermore, conventional inspections have not been able to ascertain the amount of time it takes from the occurrence of a ground fault to the interruption of the AC power line.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a device and method for testing the health of the entire ground fault detection device, from the ZCT to the earth leakage relay input side.

In order to solve the above-mentioned problems and achieve the purpose, a health testing device for a ground fault detection device according to the present invention includes a zero-phase current transformer arranged so that an AC line passes through it, and a zero-phase current transformer arranged so that an AC line passes through it. Earth fault detection comprising: an earth leakage relay for the alternating current line that operates when the output from the secondary winding of the current device exceeds a predetermined value; and a circuit breaker that interrupts the alternating current line according to the output of the earth leakage relay. A device health testing device, comprising a test conductor that passes through the zero-phase current transformer or is arranged around the zero-phase current transformer, and a pseudo ground fault signal that can be passed through the test conductor. It is characterized by comprising a portable power source and an ammeter for measuring the current value of the pseudo-ground fault signal, and having a variable resistance in the circuit so that the portable power source can increase or decrease the alternating current.

The integrity testing device for a ground fault detection device according to the present invention further includes means for measuring the elapsed time from when the pseudo ground fault signal is issued until when the earth leakage relay outputs a predetermined signal to the circuit breaker. It is thought that having such a system in place may be a more preferable solution.

In order to solve the above-mentioned problems and achieve the purpose, a soundness test method for a ground fault detection device according to the present invention includes a zero-phase current transformer arranged so that an AC line passes through it, and a zero-phase current transformer arranged so that an AC line passes through it. Earth fault detection comprising: an earth leakage relay for the alternating current line that operates when the output from the secondary winding of the current device exceeds a predetermined value; and a circuit breaker that interrupts the alternating current line according to the output of the earth leakage relay. A method for testing the health of a device, in which a test conductor is arranged so as to pass through the zero-phase current transformer or to be wrapped around the zero-phase current transformer, and a current is output from a portable power source as a pseudo-ground fault signal. Alternating current is passed through the test conductor while increasing the current value, and when the pseudo ground fault signal is passed at a predetermined current value, the soundness is determined by determining that the earth leakage relay outputs a predetermined signal to the circuit breaker. It is characterized by:

In addition, the soundness test method of the ground fault detection device according to the present invention is as follows:
(a) Furthermore, it is determined that the elapsed time from when the pseudo ground fault signal of a predetermined current value is issued to when the earth leakage relay outputs the predetermined signal to the circuit breaker is within a predetermined time. Judgment;
(b) confirming in advance that the pseudo ground fault signal outputs a predetermined current value;
It is thought that this could be a more preferable solution.

According to the soundness testing device and method for a ground fault detection device according to the present invention, the soundness of the entire ground fault detection device can be tested. Since accidents can be prevented from occurring, serious troubles caused by ground faults can now be suppressed. Furthermore, when replacing the earth leakage relay or ZCT of the ground fault detection device, it is possible to confirm that it operates reliably.

1 is a circuit diagram showing a schematic configuration of a health testing device for a ground fault detection device according to an embodiment of the present invention. FIG. 2 is a detailed schematic diagram showing the device configuration of a health testing device for a ground fault detection device according to the above embodiment. 3 is a graph showing measurement results of elapsed time from issuing a pseudo-ground fault signal to cutting off an AC power line using the integrity testing device for a ground fault detection device according to the above embodiment, in which (a) is a graph on the machine side; An example of the operation of the ground fault detection device in the switchboard is shown, and (b) is an example of the operation of the ACB in the electrical room. 1 is a circuit diagram showing a schematic configuration of a conventional ground fault detection device.

Embodiments of the present invention will be specifically described below. Note that each drawing is schematic and may differ from the actual drawing. Furthermore, the following embodiments are intended to exemplify devices and methods for embodying the technical idea of the present invention, and the configuration is not limited to the following. That is, the technical idea of the present invention can be modified in various ways within the technical scope described in the claims.

First, the configuration of a health testing device for a ground fault detection device according to an embodiment of the present invention will be described based on FIGS. 1 and 2. FIG. 1 is a circuit diagram showing a schematic configuration of a ground fault detection device and a test device. FIG. 2 is a detailed schematic diagram of the configuration of the test device.

The ground fault detection device 1 includes a ZCT 2, an earth leakage relay 3, and an NFB 4 as a circuit breaker for an AC line. The NFB 4 and the ZCT 2 are arranged in this order from the power supply side 5 of the AC line toward the power reception side 6 such as a crane. The output of the secondary winding of ZCT2 is connected to the input terminal of earth leakage relay 3. If a ground fault occurs in any phase of the normally balanced interphase current of a three-phase alternating current, excessive current will flow in that phase. ZCT2 detects the AC magnetic field generated by the excessive current and outputs it to earth leakage relay 3, and earth leakage relay 3 outputs to NFB4 to interrupt the AC line.

The test device 10 of this embodiment includes a test conductor 11 arranged to pass through the ZCT 2, a portable power source 20 for passing an alternating current through the test conductor, and an ammeter 12 for measuring the value of the current flowing through the test conductor 11. and. Further, in this embodiment, a stopwatch 30 is provided as a measuring means for measuring elapsed time. The test conducting wire 11 may be arranged so as to be wound around the ZCT 2 multiple times. For example, it is preferable that the portable power source 20, the ammeter 12, and the elapsed time measuring means 30 be housed together in a portable case or the like. It is also preferable that the test conductor 11 can also be accommodated.

The portable power source 20 of this embodiment includes a DC power source 21 such as a dry battery, a starting switch 22, a starting LED 23 for confirming starting, a sine wave inverter 24 for converting DC electricity into AC electricity, and a predetermined AC voltage. It has a transformer 25 for converting into an output voltage, an electric resistor 26 and a variable resistor 27 for adjusting the output current to a predetermined value, a fuse 28, and a connector 29 for connecting to the test conductor 11. It also has a push button 7 and an ammeter 12 for issuing a ground fault signal during output to the test conductor 11. For example, if the DC voltage is 12V DC, the output of the sine wave inverter 24 is 100V AC, the output voltage to the test lead 11 is 17V AC, and the electric resistor 26 is 20Ω, the output current can be 0.85A at maximum. A variable resistor 27 arranged in series with the electric resistor 26 can increase or decrease the value of the current flowing through the test conductor 11.

The stopwatch 30 of this embodiment has a start/stop terminal 30 that constitutes a circuit for starting and stopping time measurement, and a reset/wrap terminal 32 that constitutes a circuit for measuring and resetting time. . Further, the circuit for starting and stopping time measurement has a push button 7 that is linked to a pseudo ground fault signal. The reset/wrap terminal 32 is connected to the output terminal of the earth leakage relay 3 by a connector 34. Further, the stopwatch 30 can be reset by a reset push button 33. One of the connectors 34 may be an alligator clip.

A method for testing the integrity of the ground fault detection device 1 using the test device 10 described above will be described. The inspection between earth leakage relay 3 and NFB4 can be performed using the existing circuit, so it will be omitted.

To configure the test circuit, the test conductor 11 is set so as to pass through the ZCT2. It may be wound around ZCT2 multiple times.
Next, both ends of the test lead wire 11 are connected to the connector 29 of the portable power source 20. The circuit connector 34 of the reset/wrap terminal 32 of the stopwatch 30 is connected to the output terminal of the earth leakage relay 3.

Connect the startup switch 22 of the portable power source 20 and check that the startup LED 23 is lit.
While pressing the push button 7 for generating the pseudo-ground fault signal, the variable resistor 27 is operated to increase the output current flowing through the test conductor 11.
The earth leakage relay 3 outputs a ground fault detection signal to the NFB 4, and the NFB 4 confirms the current value at which the AC line is cut off. If this current value exceeds a predetermined current value, or if the earth leakage relay does not operate even if it exceeds the predetermined current value, it is determined that there is a defect between ZCT2 and earth leakage relay 3, and necessary measures are taken. For example, check for disconnection and replace the ZCT 2 and earth leakage relay 3.
Note that the above-mentioned predetermined current value is an arbitrary current setting value that is detected as a leakage in each circuit breaker. For example, if there is an abnormality in detection at the NFB, the ACB or high voltage panel will detect a ground fault. This can lead to the power being cut off to the entire factory, wiring to burn out, and factory operations to stop.

If the current value at which the earth leakage relay 3 operates is within a predetermined value, the variable resistor 27 is fixed to that current value.
Once the start switch 22 of the portable power source 20 is released, it is confirmed that the start LED 23 is turned off.
The stopwatch 30 is reset using the reset push button 33.
Bring back NFB4.
Once again, connect the startup switch 22 of the portable power source 20 and check that the startup LED is lit.
The push button 7 of the pseudo ground fault signal is pressed, and the stopwatch 30 measures the elapsed time until the NFB 4 is shut off.
If the elapsed time is within a predetermined value, it is determined that the ground fault detection device 1 is normal.

FIG. 3 shows the measurement results of elapsed time using the test device of this embodiment. In the example of FIG. 3(a), the NFB 4 cut off the AC circuit with an output current of 0.2 A to the test conductor 11. The operating time of this ground fault detection device is 0.1 s, which is shorter than the operating time until the upstream electrical room ACB is activated to cut off the power supply and the operating time until the high voltage board is cut off. In a healthy ground fault detection device, the NFB4 cuts off the AC line when the value is within the detection setting value (solid line) after issuing the pseudo ground fault signal. On the other hand, in the case indicated by an x mark (broken line), the elapsed time until the NFB 4 shuts off the AC line is longer than the time for the ACB or the high voltage board to operate, and it was determined that the ground fault detection device 1 is defective. Note that the operating time of 0.1 s of the ground fault detection device 1 described above is an example of the operating time specified by the earth leakage relay. If the time until actual detection is longer than the operating time, the upstream ACB or high-voltage panel circuit breaker will be activated, leading to a power outage for the entire factory. The purpose of this test equipment and test method is to confirm that ground fault detection works within this operating time. The operating time of this ground fault detection device is the operating time specified in JIS C8374:1991, which is the standard for earth leakage relays, specifically, high-speed type: within 0.1 s, delayed type: over 0.1 s and within 2 s. and anti-time type: preferably the operating time is determined by the rated sensitivity current and its multiple. In addition, it is preferable to apply this test device and test method not only to the inspection of the existing ground fault detection device but also to the time of replacing the ZCT 2, the earth leakage relay 3, and the NFB 4.

In the above embodiment, an overcurrent circuit breaker, that is, an NFB was used as an example of the circuit breaker of the ground fault detection device, but in the present invention, the circuit breaker is an air circuit breaker, as shown in FIG. In other words, it can also be applied to the case of ACB. The portable power source, ammeter, resistor, variable resistor, etc. may be changed to one with a desired capacity in accordance with the operating current setting value and predetermined operating time of the ACB.

According to the soundness testing device and soundness testing method for a ground fault detection device according to the present invention, it is possible to test the soundness of the entire ground fault detection device, so that it is possible to test the soundness of the whole ground fault detection device. Since ground fault accidents can be prevented, serious troubles caused by ground faults can be suppressed, which contributes to improved productivity and is industrially useful.

1 Ground fault detection device 2 Zero-phase current transformer (ZCT)
3 Earth leakage relay 4 Overcurrent breaker (NFB)
5 Power feeding side 6 Power receiving side 7 Push button (PB1) (interlocked)
10 Test device 11 Test lead wire 12 Ammeter 20 Portable power source 21 DC power source (dry battery)
22 Start switch 23 Start LED
24 Sine wave inverter 25 Transformer 26 Electrical resistor 27 Variable resistor 28 Fuse 29 Connector 30 Time measuring means (stopwatch)
31 Start/stop terminal 32 Reset/wrap terminal 33 Reset push button 34 Connector

Claims (5)

a zero-phase current transformer arranged so that an AC line passes through it;
an earth leakage relay for the AC line that operates when the output from the secondary winding of the zero-phase current transformer exceeds a predetermined value;
A health testing device for a ground fault detection device, comprising: a circuit breaker that interrupts the alternating current circuit according to the output of the earth leakage relay;
A test conductor that passes through the zero-phase current transformer or is arranged around the zero-phase current transformer;
a portable power source that sends a pseudo ground fault signal to the test conductor;
an ammeter that measures the current value of the pseudo ground fault signal,
The portable power source has a variable resistance in the circuit so that the alternating current can be increased or decreased.
Soundness testing equipment for ground fault detection equipment. The health testing device for a ground fault detection device according to claim 1, further comprising means for measuring elapsed time from when the pseudo ground fault signal is issued until when the earth leakage relay outputs a predetermined signal to the circuit breaker. . a zero-phase current transformer arranged so that an AC line passes through it;
an earth leakage relay for the AC line that operates when the output from the secondary winding of the zero-phase current transformer exceeds a predetermined value;
A method for testing the integrity of a ground fault detection device, comprising: a circuit breaker that interrupts the alternating current circuit in accordance with the output of the earth leakage relay;
Arranging a test lead so as to pass through the zero-phase current transformer or to wrap it around the zero-phase current transformer,
Applying an alternating current to the test conductor while increasing the current value as a pseudo ground fault signal from a portable power source,
A method for testing the soundness of a ground fault detection device, wherein the soundness is determined by the earth leakage relay outputting a predetermined signal to the circuit breaker when the pseudo ground fault signal is passed at a predetermined current value. Furthermore, the soundness is determined if the elapsed time from when the pseudo ground fault signal of a predetermined current value is issued until the time when the earth leakage relay outputs the predetermined signal to the circuit breaker is within a predetermined time. A method for testing the integrity of a ground fault detection device according to claim 3. 5. The soundness testing method for a ground fault detection device according to claim 3, wherein it is confirmed in advance that the portable power source outputs a predetermined current value as the pseudo ground fault signal.

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