JP2024047298A - Ground-fault circuit interrupter and distribution board - Google Patents

Abstract

To perform a test of power leakage detection without disconnecting a cable way.SOLUTION: A ground-fault circuit interrupter A1 comprises: contact points 14A, 14B, and 14C inserted into cable ways 13A, 13B, and 13C; a residual current transformer 2; a power leakage determination device 3; a lead-out device 4; and a test device 5. The residual current transformer 2 detects a leakage power current flowing in each of the cable ways 13A, 13B, and 13C. The power leakage determination device 3 determines the presence/absence of the power leakage on the basis that the leakage power current detected by the residual current transformer 2 is reached to a regulation value. The lead-out device 4 opens a path of each of the contact points 14A, 14B, and 14C when it is determined that there is the power leakage by the power leakage determination device 3. The test device 5 includes: a current generation circuit 50 that generates a test current Is detected by the residual current transformer 2; and a test determination circuit 51 that determines whether or not the test current Is detected by the residual current transformer 2 can be detected through the power leakage determination device 3.SELECTED DRAWING: Figure 1

Description

This disclosure relates to an earth leakage circuit breaker and a distribution board, and more specifically to an earth leakage circuit breaker having a test function for interrupting an earth leakage current, and a distribution board equipped with the earth leakage circuit breaker.

As a conventional example, the earth leakage circuit breaker described in Patent Document 1 is exemplified. The earth leakage circuit breaker described in Patent Document 1 (hereinafter referred to as the conventional example) includes a zero-phase current transformer whose primary winding is the AC circuit to be detected for earth leakage, and an earth leakage detection unit that determines the presence or absence of earth leakage in the AC circuit based on the secondary output of the zero-phase current transformer. The conventional example also includes a test device that supplies a simulated earth leakage current for earth leakage operation testing to a test winding wound around the zero-phase current transformer when a test switch is pressed.

JP 2015-032420 A

However, in the above conventional example, if the leakage current detection unit is normal, the AC circuit is interrupted by supplying a simulated leakage current (test current) from the test device to the AC circuit.

The objective of this disclosure is to provide a ground fault circuit interrupter and distribution board that can perform a ground fault detection test without interrupting the electrical circuit.

The earth leakage circuit breaker according to one aspect of the present disclosure includes a contact inserted into an electric circuit, a zero-phase current transformer, an earth leakage determination device, a tripping device, and a test device. The zero-phase current transformer detects an earth leakage current flowing in the electric circuit. The earth leakage determination device determines the presence or absence of an earth leakage based on whether the earth leakage current detected by the zero-phase current transformer reaches a specified value. The tripping device opens the contact when the earth leakage determination device determines that an earth leakage exists. The test device tests the earth leakage determination device. The test device includes a current generating circuit that generates a test current detected by the zero-phase current transformer, and a test determination circuit that determines whether the test current detected by the zero-phase current transformer can be detected via the earth leakage determination device.

A distribution board according to one embodiment of the present disclosure includes the earth leakage circuit breaker and a cabinet that houses internal equipment including the earth leakage circuit breaker.

The earth leakage circuit breaker and distribution board disclosed herein have the advantage of being able to perform earth leakage detection tests without interrupting the electrical circuit.

FIG. 1 is a circuit block diagram of an earth leakage circuit breaker according to an embodiment of the present disclosure. FIG. 2 is a front view of the earth leakage circuit breaker. 3A and 3B are circuit diagrams of a current generating circuit and a waveform diagram of a test current in the earth leakage circuit breaker, respectively. 4A and 4B are a front view and a right side view, respectively, of a distribution board according to an embodiment of the present disclosure.

The earth leakage circuit breaker A1 and the distribution board B1 according to the embodiments of the present disclosure will be described in detail below with reference to the drawings. However, each figure described in the following embodiments is a schematic diagram, and the ratio of the size and thickness of each component does not necessarily reflect the actual dimensional ratio. Note that the configuration described in the following embodiments is merely one example of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

(1) Overview The earth leakage circuit breaker A1 according to the embodiment includes contacts 14A, 14B, and 14C to be inserted into electric circuits 13A, 13B, and 13C, a zero-phase current transformer 2, an earth leakage determination device 3, a tripping device 4, and a test device 5 (see FIG. 1 ). The electric circuit in the embodiment is a single-phase three-wire electric circuit consisting of electric circuits 13A and 13B of two voltage poles and an electric circuit 13C of one ground pole. However, the electric circuit may be a single-phase two-wire, three-phase three-wire, or three-phase four-wire electric circuit.

One contact is inserted into each of the three electrical circuits 13A, 13B, and 13C. That is, contact 14A is inserted into electrical circuit 13A, contact 14B is inserted into electrical circuit 13B, and contact 14C is inserted into electrical circuit 13C.

The zero-phase current transformer 2 detects leakage current flowing through the electric circuits 13A, 13B, and 13C. In the embodiment, the zero-phase current transformer 2 has a resistor that converts the output current into a voltage, and outputs a detection voltage proportional to the unbalanced current (leakage current) flowing through the three electric circuits 13A, 13B, and 13C.

The leakage current determination device 3 determines whether or not there is a leakage current based on whether or not the leakage current (detection voltage) detected by the zero-phase current transformer 2 reaches a specified value. In other words, the leakage current determination device 3 determines that there is a leakage current if the leakage current detected by the zero-phase current transformer 2 reaches a specified value, and determines that there is no leakage current if the leakage current detected by the zero-phase current transformer 2 does not reach the specified value. When the leakage current determination device 3 determines that there is a leakage current, the trip device 4 opens the contacts 14A, 14B, and 14C to interrupt the electric circuits 13A, 13B, and 13C.

The test device 5 has a current generating circuit 50 and a test determination circuit 51. The current generating circuit 50 generates a test current that is detected by the zero-phase current transformer 2. The test determination circuit 51 determines whether the test current detected by the zero-phase current transformer 2 can be detected via the leakage current determination device 3.

For example, if an abnormality such as a break occurs in the line for inputting the detection voltage of the zero-phase current transformer 2 to the leakage current determination device 3, the test determination circuit 51 will not be able to detect the test current detected by the zero-phase current transformer 2. Therefore, the test device 5 can test whether the leakage current determination device 3 can normally perform leakage current determination. Moreover, unlike conventional leakage current tests, the test by the test device 5 does not operate the trip device 4. Therefore, the leakage current circuit breaker A1 according to the embodiment can perform a leakage current detection test without interrupting the electric circuits 13A, 13B, and 13C. Furthermore, in the leakage current circuit breaker A1 according to the embodiment, the leakage current determination device 3 and the test device 5 can operate independently of each other, so that the leakage current determination device 3 can determine the presence or absence of leakage current even during the test by the test device 5.

The distribution board B1 according to the embodiment also includes a ground fault circuit interrupter A1 according to the embodiment and a cabinet 70 that houses internal equipment including the ground fault circuit interrupter A1 according to the embodiment (see Figures 4A and 4B).

The distribution board B1 according to the embodiment is equipped with the earth leakage circuit breaker A1 according to the embodiment, and therefore has the advantage that earth leakage detection tests can be performed without interrupting the electric circuits 13A, 13B, and 13C.

(2) Details The earth leakage circuit breaker A1 (hereinafter abbreviated as earth leakage circuit breaker A1) according to the embodiment is used as the main switch (also called a trunk breaker) of the distribution board B1 (hereinafter abbreviated as distribution board B1) according to the embodiment.

(2-1) Details of the distribution board The distribution board B1 is a residential distribution board (so-called residential board) used in a single-phase three-wire power distribution system. However, the distribution board B1 is not limited to a residential board, and may be a cabinet-type distribution board used in a three-phase three-wire or three-phase four-wire power distribution system.

The distribution board B1 includes, as internal equipment, a ground fault circuit interrupter A1 (main switch), multiple branch switches C1 (also called branch breakers), and a primary feed branch switch D1 (see FIG. 4A). Each of the multiple branch switches C1 is configured as a circuit breaker for wiring. However, at least one of the multiple branch switches C1 may be configured as a ground fault circuit interrupter according to the embodiment.

The primary terminals of these multiple branch switches C1 are electrically connected to the secondary terminal 12 of the earth leakage circuit breaker A1 via branch lines and bus bars (not shown). In addition, the primary feed branch switch D1 is electrically connected to the primary terminal 11 (see Figure 1) of the earth leakage circuit breaker A1. However, the distribution board B1 may not be equipped with a primary feed branch switch D1.

The distribution board B1 includes a cabinet 70 that houses these internal devices (see Figures 4A and 4B). The cabinet 70 includes a box 71 and a cover 72.

The box 71 is made of electrically insulating synthetic resin and has a box shape with an open front. A metal mounting plate (not shown) is fixed to the inner bottom surface of the box 71. The earth leakage circuit breaker A1, the multiple branch switches C1, and the primary feeder branch switch D1 are attached to the front surface of the mounting plate and housed in the box 71.

The cover 72 is made of electrically insulating synthetic resin like the box 71, and is formed in a box shape with an open back. The cover 72 is attached to the box 71 so as to cover the opening on the front of the box 71 (see FIG. 4A). However, the cover 72 has two windows (a first window 721 and a second window 722) on the bottom. The first window 721 exposes a portion of the front of each of the earth leakage circuit breaker A1 and the primary feeder branch switch D1 housed in the box 71. The second window 722 exposes a portion of the front of each of the multiple branch switches C1 housed in the box 71.

The cabinet 70 is installed by directly attaching it to the wall of the house or by embedding the rear end of the box 71.

(2-2) Details of the Earth Leakage Circuit Breaker As described above, the earth leakage circuit breaker A1 includes the contacts 14A, 14B, and 14C to be inserted into the electric circuits 13A, 13B, and 13C, the zero-phase current transformer 2, the earth leakage determination device 3, the trip device 4, and the test device 5 (see FIG. 1). The earth leakage circuit breaker A1 further includes a case 10 that houses these components (see FIG. 2).

(2-2-1) Case The case 10 is made of an electrically insulating synthetic resin and has a rectangular parallelepiped shape. In the following description, the up-down and left-right directions in Fig. 2 are defined as the up-down and left-right directions of the case 10, and the direction perpendicular to the paper surface of Fig. 2 is defined as the front-rear direction (the direction toward the front of the paper surface is the front direction).

A terminal block 100 is provided at the upper end of the case 10. Three primary side terminals 11 are arranged in the left-right direction on the terminal block 100. Each of these three primary side terminals 11 has a terminal board 110 with a screw hole and a terminal screw (not shown) that is screwed into the screw hole of the terminal board 110. An insulating wall 111 is provided between each of the three terminal boards 110 adjacent to each other in the left-right direction. The terminal boards 110 at both ends of the left and right are primary side terminals 11 of the voltage pole, and the terminal board 110 in the center is the primary side terminal 11 of the neutral pole, and the terminal boards 110 at both ends of the left and right are isolated from the terminal board 110 in the center by the insulating wall 111.

A terminal mounting portion 101 protrudes upward from the upper right end of the case 10. Three secondary terminals 12 protrude from the right side surface of the terminal mounting portion 101. These three secondary terminals 12 are screwed to three conductive bars (not shown) that serve as bus bars and are electrically connected. The terminal mounting portion 101 houses three electric wires (not shown) that form part of the three electric circuits 13A, 13B, and 13C.

The case 10 contains three electrical circuits 13A, 13B, and 13C that electrically connect each pair of the three primary terminals 11 and the three secondary terminals 12, and three contacts 14A, 14B, and 14C that are inserted into each of the three electrical circuits 13A, 13B, and 13C.

The three secondary terminals 12 protrude from the upper part of the right side of the case 10, approximately parallel to the front surface of the case 10. These three secondary terminals 12 are arranged in a single row in the vertical direction when viewed from the front, and in two rows in the front-to-rear direction when viewed from the right. The two secondary terminals 12 at the top and bottom ends are voltage pole terminals, and the central secondary terminal 12 is a neutral pole terminal. The two voltage pole secondary terminals 12 are located at the rear end of the case 10, and the neutral pole secondary terminal 12 is located at the front end of the case 10.

Although not shown, the case 10 also houses an opening/closing mechanism that opens and closes the contacts 14A, 14B, and 14C together. The opening/closing mechanism opens and closes the contacts 14A, 14B, and 14C in response to the operation of the handle 15, and is configured to forcibly open the contacts 14A, 14B, and 14C using the trip device 4. The handle 15 is exposed to the outside of the case 10 through an opening 102 provided in the center of the front surface of the case 10 (see FIG. 2).

The case 10 further houses the zero-phase current transformer 2, leakage current determination device 3, test device 5, power supply circuit 6, etc. The zero-phase current transformer 2 has a zero-phase current transformer in which a secondary winding (output winding) is wound around a toroidal core with an opening in the center, and a resistor (not shown) electrically connected between the terminals of the secondary winding of the zero-phase current transformer. Three electric circuits 13A, 13B, 13C are inserted into the openings of the toroidal core of the zero-phase current transformer.

(2-2-2) Power Supply Circuit The power supply circuit 6 generates a DC voltage (control voltage Vcc) of about 3 V to 5 V from an AC voltage of effective value 100 V obtained from the voltage pole electric circuit 13A and the neutral pole electric circuit 13C. The control voltage Vcc generated by the power supply circuit 6 is supplied to the leakage current determination device 3 and the test device 5.

(2-2-3) Electric Leakage Determination Device The electric leakage determination device 3 has an A/D conversion circuit 30 and a determination circuit 31. However, the A/D conversion circuit 30 and the determination circuit 31 are configured as a single integrated circuit (for example, an application specific integrated circuit (ASIC)).

The A/D conversion circuit 30 quantizes the analog detection voltage of the zero-phase current transformer 2 and converts it into a digital detection voltage value. The digital detection voltage value (hereinafter abbreviated as the detection voltage value) output from the A/D conversion circuit 30 is recorded in a buffer memory (not shown) of the leakage current determination device 3. However, the A/D conversion circuit 30 may output the detection voltage value to the determination circuit 31 without going through the buffer memory.

The judgment circuit 31 calculates the effective value of the leakage current from the detected voltage value read from the buffer memory. Specifically, the judgment circuit 31 integrates the square of the detected voltage value (absolute value) for a time period corresponding to one cycle of the power system, and calculates the square root (effective value) of the value obtained by dividing the integral value by the time period corresponding to one cycle. In the following explanation, the effective value of the detected voltage calculated by the judgment circuit 31 is referred to as the effective value of the leakage current.

The judgment circuit 31 compares the effective value of the leakage current with a threshold value. If the effective value of the leakage current is equal to or greater than the threshold value, the judgment circuit 31 determines that the leakage current is equal to or greater than a preset value and determines that there is a leakage current. If the effective value of the leakage current is less than the threshold value, the judgment circuit 31 determines that there is no leakage current.

By the way, there are thought to be three main causes of leakage current:

The first is poor insulation of the load connected to the electric circuits 13A, 13B, and 13C via the branch switch C1. A leakage current caused by poor insulation of the load is an alternating current (hereinafter referred to as normal leakage current) with a frequency approximately equal to the power supply frequency (50 Hz or 60 Hz, which is the frequency of the power system). Note that normal leakage current continues to flow unless the poor insulation of the load is eliminated.

The second type is a lightning surge caused by induced lightning. The leakage current caused by a lightning surge is much larger than normal leakage current, and only flows for a short period of time.

The third is when the load is a device that uses switching elements, such as an inverter or converter. The leakage current caused by a switching element is an alternating current with a frequency approximately equal to the switching frequency and its harmonic frequencies (hereafter referred to as switching leakage current). Note that the switching leakage current continues to flow as long as the load causing it is operating.

Therefore, when earth leakage circuit breaker A1 detects a normal leakage current and determines that there is an earth leakage, it is desirable to open contacts 14A, 14B, and 14C to cut off electric circuits 13A, 13B, and 13C. On the other hand, when an earth leakage current due to a lightning surge is flowing or when a switching earth leakage current is flowing, it is desirable for earth leakage circuit breaker A1 to determine that there is no earth leakage and not cut off electric circuits 13A, 13B, and 13C.

Therefore, when the judgment circuit 31 calculates the effective value of the leakage current from the detected voltage value read from the buffer memory, it is desirable to use a digital filter (low-pass filter) to remove the detected voltage value having a frequency higher than the cutoff frequency. The cutoff frequency is desirably a frequency (e.g., 200 Hz) three to four times higher than the power supply frequency (50 Hz or 60 Hz).

The determination circuit 31 calculates the effective value of the detected voltage value filtered by the digital filter, and compares the effective value with a threshold value to determine whether or not there is a leakage current. As a result, the leakage current determination device 3 can avoid determining that there is a leakage current due to a lightning surge and a switching leakage current.

When the leakage current determination device 3 determines that a leakage current exists, it outputs a leakage current detection signal to the tripping device 4.

(2-2-4) Tripping Device The tripping device 4 opens the contacts 14A, 14B, 14C to interrupt the electric circuits 13A, 13B, 13C when it receives a leakage current detection signal from the leakage current determination device 3. For example, the tripping device 4 is equipped with a solenoid, and energizes an exciting coil of the solenoid to move a plunger, thereby driving an opening/closing mechanism to open the contacts 14A, 14B, 14C.

(2-2-5) Testing Device The testing device 5 includes a current generating circuit 50 and a test determination circuit 51. The testing device 5 further includes a control circuit 52 and a notification circuit 53.

The control circuit 52 mainly comprises a microcontroller. The control circuit 52 controls the current generating circuit 50, the test determination circuit 51, and the notification circuit 53 to perform a test (operation test) of the leakage current determination device 3. The control circuit 52 receives a trigger input when the test button 16 provided on the front of the case 10 is pressed, and starts a test when the control circuit 52 receives the trigger input. However, the control circuit 52 may also perform tests periodically according to a time schedule, as described below. The specific control operation of the control circuit 52 will be described later.

The notification circuit 53 has the role of notifying the result of the test performed by the test device 5. For example, the notification circuit 53 has a display element that selectively emits red light and green light. The display element is configured, for example, by housing an LED that emits red light and an LED that emits green light in a single package.

The notification circuit 53 causes the display element to emit red light if the test result is bad, and causes the display element to emit green light if the test result is good. In other words, the notification circuit 53 visually notifies the test result by the color of light emitted by the display element. The light emitted by the display element is emitted outside the case 10 through a display window 103 (see Figure 2) provided on the front of the case 10.

The current generating circuit 50 generates a test current Is that is detected by the zero-phase current transformer 2. The current generating circuit 50 has two switching elements Q1 and Q2, a plurality of resistors R1, R2, and R3, and a capacitor C2 (see FIG. 3A). The first switching element Q1 is a PNP-type bipolar transistor, and the second switching element Q2 is an NPN-type bipolar transistor. A control voltage Vcc is applied to the emitter of the first switching element Q1. The collector of the first switching element Q1 is electrically connected to the collector of the second switching element Q2. The base of the first switching element Q1 is electrically connected to one end of the resistor R1. The emitter of the second switching element Q2 is grounded to ground. The base of the second switching element Q2 is electrically connected to one end of the resistor R2. The other ends of the two resistors R1 and R2 are electrically connected to the control circuit 52.

The connection point between the collector of the first switching element Q1 and the collector of the second switching element Q2 is electrically connected to one end of the output line 500 via a resistor R3. The other end of the output line 500 is electrically connected to one end of the capacitor C2. The other end of the capacitor C2 is grounded. The output line 500 is inserted into an opening in the toroidal core of the zero-phase current transformer 2.

The current generating circuit 50 is driven by a control signal Vs input from the control circuit 52. The control signal Vs is a square pulse with a duty ratio of 50% (see FIG. 3A). When the control signal Vs is at a low level, the first switching element Q1 is turned on and the second switching element Q2 is turned off. As a result, a charging current (positive test current Is) flows from the first switching element Q1 to the capacitor C2 via the resistor R3 and the output line 500 due to the control voltage Vcc. The positive test current Is has a waveform that is a differentiated square pulse that falls from a high level to a low level (see FIG. 3B).

When the control signal Vs changes from low to high, the first switching element Q1 turns off and the second switching element Q2 turns on. As a result, the charge in the capacitor C2 is discharged through the output line 500, the resistor R3, and the second switching element Q2, so that a discharge current (negative test current Is) flows in the opposite direction to the charging current. The negative test current Is has a waveform obtained by differentiating a square pulse that falls from a high level to a low level (see FIG. 3B). The frequency of the control signal Vs is preferably sufficiently higher than the power supply frequency and sufficiently lower than the frequency of the switching leakage current (e.g., 50 kHz), e.g., 300 Hz to 500 Hz.

The detection voltage output from the zero-phase current transformer 2 includes a voltage whose frequency and magnitude correspond to the frequency and magnitude of the test current Is flowing through the output line 500. In particular, when the currents flowing through the three electric circuits 13A, 13B, and 13C are balanced (when no leakage current occurs), the detection voltage is a voltage whose frequency and magnitude correspond to the frequency and magnitude of the test current Is flowing through the output line 500.

The test judgment circuit 51 calculates the effective value of the detected voltage value output from the A/D conversion circuit 30, and compares the calculated effective value with a reference value. If the effective value is equal to or greater than the reference value, the test judgment circuit 51 determines that the test current Is has been detected (the test result is good). On the other hand, if the detected voltage value is less than the reference value, the test judgment circuit 51 determines that the test current Is has not been detected (the test result is bad). Then, the test judgment circuit 51 controls the notification circuit 53, causing it to emit light (green light or red light) corresponding to the test result (good or bad).

In addition, in the earth leakage circuit breaker A1, it is preferable that the test determination circuit 51 and the earth leakage determination device 3 are configured as a single integrated circuit IC1 (see Figure 1).

(2-2-6) Description of Testing of the Earth Leakage Determination Device Next, a description will be given of testing of the earth leakage determination device 3 by the test device 5. Note that the earth leakage determination device 3 operates continuously while the contacts 14A, 14B, and 14C are closed and current is flowing through the electric circuits 13A, 13B, and 13C.

When the test button 16 is pressed and a trigger input is received, the control circuit 52 of the test device 5 outputs a control signal Vs to the current generation circuit 50 and instructs the test judgment circuit 51 to start the judgment process. The current generation circuit 50 passes a test current Is through the output line 500 in response to the control signal Vs.

The frequency of the test current Is is set to a frequency (e.g., 300 Hz) that is sufficiently higher than the power supply frequency. Therefore, the detection voltage of the zero-phase current transformer 2 that detects the test current Is is filtered by a digital filter in the judgment circuit 31 of the leakage current judgment device 3, so that the effective value of the detected voltage value does not exceed the threshold value. Therefore, the leakage current judgment device 3 judges that there is no leakage. Therefore, the leakage current breaker A1 can prevent the leakage current judgment device 3 from erroneously judging the test current Is to be a normal leakage current.

When the test judgment circuit 51 receives an instruction from the control circuit 52, it calculates the effective value of the detected voltage value (detected voltage value of the test current Is) output from the A/D conversion circuit 30 and compares the calculated effective value with a reference value. If the effective value is equal to or greater than the reference value, the test judgment circuit 51 determines that the test current Is has been detected (the test result is good). On the other hand, if the detected voltage value is less than the reference value, the test judgment circuit 51 determines that the test current Is cannot be detected (the test result is bad).

For example, if the line (electric wire) for inputting the detection voltage of the zero-phase current transformer 2 to the A/D conversion circuit 30 is broken or short-circuited, the test judgment circuit 51 cannot detect the test current Is, and the test result is bad. Alternatively, if the line (copper foil for printed wiring) for outputting the detection voltage value from the A/D conversion circuit 30 is broken or short-circuited, and if the A/D conversion circuit 30 is faulty, the test judgment circuit 51 cannot detect the test current Is, and the test result is bad. Here, if the test judgment circuit 51 and the leakage current judgment device 3 are configured as one integrated circuit IC1, the test judgment circuit 51 can indirectly determine whether or not the judgment circuit 31 is faulty. In other words, if the test judgment circuit 51 and the judgment circuit 31 are configured as one integrated circuit IC1, the possibility of only one of the test judgment circuit 51 and the judgment circuit 31 failing is considered to be significantly lower than the possibility of the entire integrated circuit IC1 including both failing. Therefore, the test judgment circuit 51 can practically determine whether or not the entire leakage current judgment device 3 is abnormal (failed). Therefore, the earth leakage circuit breaker A1 can improve the reliability of the test results of the test device 5.

The test determination circuit 51 then controls the notification circuit 53 to selectively emit green or red light, thereby notifying the test result (good or bad) of the earth leakage determination device 3. By having the notification circuit 53 notify the test result of the test device 5, the earth leakage circuit breaker A1 can prompt the implementation of measures, particularly for bad test results.

In addition, a normal leakage current may flow through the electrical circuits 13A, 13B, and 13C while the test device 5 is performing a test. In this case, the leakage current determination device 3 can determine the presence or absence of a leakage current based on the detection voltage of the zero-phase current transformer 2 without being affected by the test current Is flowing through the output line 500.

However, a load that generates harmonic noise (for example, an electronic device equipped with a switching power supply, such as a personal computer) may be connected to a branch circuit of the distribution board B1. In this case, harmonic noise in a frequency band that includes the frequency of the test current Is may flow into the electrical circuits 13A, 13B, and 13C of the earth leakage circuit breaker A1. If harmonic noise from the load flows into the electrical circuits 13A, 13B, and 13C during testing by the test device 5, the test judgment circuit 51 may erroneously judge the harmonic noise to be the test current Is.

In response to this, the control circuit 52 of the test device 5 operates the test judgment circuit 51 within a predetermined time after operating the current generation circuit 50. Note that the "predetermined time" is, for example, a time period corresponding to the operating frequency (clock frequency) of the microcontroller, which is the main component of the control circuit 52, and is preferably, for example, several microseconds to several tens of microseconds.

The earth leakage circuit breaker A1 thus reduces the possibility that the test judgment circuit 51 will erroneously judge harmonic noise to be the test current Is, thereby improving the reliability of the test results.

In addition, in the earth leakage circuit breaker A1, the control circuit 52 of the test device 5 may periodically operate the current generating circuit 50 and the test determination circuit 51. For example, the control circuit 52 may use a timer mounted on the microcontroller to cause the test device 5 to execute a test at a predetermined time interval (e.g., 23 hours).

The earth leakage circuit breaker A1 can improve the reliability of the earth leakage determination by periodically testing the earth leakage determination device 3 while eliminating the need for a person to operate the test button 16 by having the control circuit 52 periodically operate the current generating circuit 50 and the test determination circuit 51. Also, by having the control circuit 52 execute the test at time intervals of 23 hours (or an integer multiple of 23 hours), the time at which the test is executed can be advanced by one hour each time. As a result, the earth leakage circuit breaker A1 can improve the reliability of the test results by being less susceptible to the effects of harmonic noise and the like, compared to when the test is executed every time at a specific time (hour) of the day.

(3) Modifications of the earth leakage circuit breaker according to the embodiment Next, several modifications of the earth leakage circuit breaker A1 according to the embodiment will be described. However, the basic configuration of the earth leakage circuit breaker A1 of each modification described below is common to the basic configuration of the earth leakage circuit breaker A1 according to the embodiment. Therefore, the same reference numerals are used for the configurations common to the basic configuration of the earth leakage circuit breaker A1 according to the embodiment, and illustrations and descriptions are omitted as appropriate.

(3-1) Modification 1
The earth leakage circuit breaker A1 of the first modification is characterized by the configurations of the earth leakage determination device 3 and the test device 5.

In the first modification, the leakage current determination device 3 compares the period during which the leakage current is equal to or greater than a specified value with a first time, instead of comparing the detected voltage value filtered by the digital filter of the determination circuit 31 with a threshold value, and determines whether or not there is a leakage current.

To explain in more detail, the judgment circuit 31 judges whether or not there is a leakage current based on the number of times the detection voltage of the zero-phase current transformer 2 reverses between positive and negative (the number of waves in the leakage current waveform) as well as the result of comparing the effective value of the leakage current with the threshold value. That is, the judgment circuit 31 judges that there is a leakage current when the effective value of the leakage current is equal to or greater than the threshold value and the number of half waves of the leakage current (the period during which the leakage current is equal to or greater than a specified value) is equal to or greater than a specified value (e.g., three half waves: equivalent to the first hour). On the other hand, if the effective value of the leakage current is less than the threshold value or the number of half waves of the leakage current is less than the specified value, it judges that there is no leakage current. This allows the judgment circuit 31 to avoid judging that there is a leakage current based on leakage current other than normal leakage current (leakage current due to lightning surge and switching leakage current).

On the other hand, the test device 5 in the first modification causes the current generating circuit 50 to generate a test current Is within a second time period that is shorter than the first time period, and causes the test determination circuit 51 to determine whether a detection voltage value equal to or greater than the threshold value is input within the second time period. However, the frequency of the test current Is generated by the current generating circuit 50 is, for example, the same as or close to the power supply frequency (for example, 40 Hz to 70 Hz). In addition, the second time period is determined by the number of half-waves of the test current Is (for example, one half-wave).

The test device 5 in the first modification thus passes the test current Is within a second time period that is shorter than the first time period during which the leakage current determination device 3 determines whether or not there is a leakage current, and therefore the test can be performed while avoiding erroneous determination of leakage current by the leakage current determination device 3. Furthermore, when a normal leakage current flows through the electric circuits 13A, 13B, and 13C, the detection voltage value that is equal to or greater than the threshold continues for at least the first time period, and therefore the leakage current determination device 3 can determine whether or not there is a leakage current even during testing by the test device 5.

(3-2) Modification 2
The earth leakage circuit breaker A1 of the second modification is characterized by the configuration of the test device 5.

In the test device 5 in the second modification, the current value of the test current Is generated by the current generating circuit 50 is set to a value smaller than a specified value (a value corresponding to a threshold value compared with the detected voltage value by the judgment circuit 31). For example, if the default value is 22 mA, the current value of the test current Is is preferably about 1 mA. However, the frequency of the test current Is generated by the current generating circuit 50 is the same as or close to the power supply frequency (e.g., 40 Hz to 70 Hz), as in the first modification.

The test device 5 in the second modification sets the current value of the test current Is generated by the current generating circuit 50 to a value smaller than the specified value, so that the test can be performed while avoiding erroneous determination of leakage in the leakage determination device 3. Furthermore, when a normal leakage current flows through the electric circuits 13A, 13B, and 13C, a detection voltage value equal to or greater than the threshold value is detected, so that the leakage determination device 3 can determine the presence or absence of leakage even during testing by the test device 5.

In the earth leakage circuit breaker A1 of the above-mentioned embodiment and modified examples 1 and 2, the current generating circuit 50 may generate the test current Is multiple times, and the test determination circuit 51 may determine that the test current Is has been detected when the effective value of the multiple test currents Is is equal to or greater than a threshold value.

In other words, if the current generating circuit 50 generates the test current Is only once in one test, the test current Is may be affected by noise, etc., and the judgment accuracy of the test judgment circuit 51 may decrease. In response to this, by generating the test current Is multiple times in one test and comparing the effective values of the detected voltage values of the test current Is multiple times with a threshold value, it is possible to suppress a decrease in the judgment accuracy of the test judgment circuit 51.

The notification circuit 53 may also have a communication function with an external device, and may use this communication function to notify the external device of the test results of the test device 5. It is preferable that the external device is equipped with a monitor device such as a liquid crystal display, and that the test results received from the notification circuit 53 are displayed on the monitor device.

(4) Summary The earth leakage circuit breaker (A1) according to the first aspect of the present disclosure includes contacts (14A, 14B, 14C) inserted into an electric circuit (13A, 13B, 13C), a zero-phase current transformer (2), an earth leakage determination device (3), a trip device (4), and a test device (5). The zero-phase current transformer (2) detects an earth leakage current flowing through the electric circuit (13A, 13B, 13C). The earth leakage determination device (3) determines the presence or absence of an earth leakage based on whether or not the earth leakage current detected by the zero-phase current transformer (2) has reached a specified value. The trip device (4) opens the contacts (14A, 14B, 14C) when the earth leakage determination device (3) determines the presence of an earth leakage. The test device (5) tests the earth leakage determination device (3). The test device (5) has a current generating circuit (50) that generates a test current (Is) that is detected by the zero-phase current transformer (2), and a test determination circuit (51) that determines whether or not the test current (Is) detected by the zero-phase current transformer (2) can be detected via the leakage current determination device (3).

The earth leakage circuit breaker (A1) according to the first aspect can be tested by a test device (5) to determine whether the earth leakage determination device (3) can normally perform an earth leakage determination, and the trip device (4) is not operated during the test by the test device (5). As a result, the earth leakage circuit breaker (A1) according to the first aspect can perform an earth leakage detection test without interrupting the electric circuit (13A, 13B, 13C).

The earth leakage circuit breaker (A1) according to the second aspect of the present disclosure can be realized by combining it with the first aspect. In the earth leakage circuit breaker (A1) according to the second aspect, it is preferable that the current generating circuit (50) generates an alternating current as the test current (Is). It is preferable that the test determination circuit (51) determines that the test current (Is) has been detected when the effective value of the test current (Is) is equal to or greater than a threshold value.

The earth leakage circuit breaker (A1) according to the second aspect compares the effective value of the test current (Is) detected by the zero-phase current transformer (2) with a threshold value, thereby reducing the influence of noise contained in the output of the zero-phase current transformer (2) and improving the reliability of the judgment.

The earth leakage circuit breaker (A1) according to the third aspect of the present disclosure can be realized by combining it with the first or second aspect. In the earth leakage circuit breaker (A1) according to the third aspect, it is preferable that the earth leakage determination device (3) and the test determination circuit (51) are configured as a single integrated circuit (IC1).

The earth leakage circuit breaker (A1) according to the third aspect can improve the reliability of the test results of the test device (5) by configuring the earth leakage determination device (3) and the test determination circuit (51) as a single integrated circuit (IC1).

The earth leakage circuit breaker (A1) according to the fourth aspect of the present disclosure can be realized by combining it with any one of the first and second aspects. In the earth leakage circuit breaker (A1) according to the fourth aspect, it is preferable that the test device (5) further includes a control circuit (52) that controls the current generation circuit (50) and the test judgment circuit (51). It is preferable that the control circuit (52) controls the current generation circuit (50) and the test judgment circuit (51) so as to periodically operate the current generation circuit (50) and the test judgment circuit (51).

The earth leakage circuit breaker (A1) according to the fourth aspect can improve the reliability of earth leakage determination by periodically testing the earth leakage determination device (3) while eliminating the need for a person to perform a test using the test device (5).

The earth leakage circuit breaker (A1) according to the fifth aspect of the present disclosure can be realized by combining it with any of the second to fourth aspects. In the earth leakage circuit breaker (A1) according to the fifth aspect, it is preferable that the current generating circuit (50) generates, as the test current (Is), an alternating current having a frequency higher than the power supply frequency supplied to the electric circuit (13A, 13B, 13C).

The earth leakage circuit breaker (A1) according to the fifth aspect reduces the possibility that the earth leakage determination device (3) will determine the presence of an earth leakage based on the test current (Is), and can determine the presence or absence of an earth leakage even during testing by the test device (5).

The earth leakage circuit breaker (A1) according to the sixth aspect of the present disclosure can be realized by combining it with any of the first to fifth aspects. In the earth leakage circuit breaker (A1) according to the sixth aspect, it is preferable that the test device (5) further includes a control circuit (52) that controls the current generating circuit (50) and the test determination circuit (51). It is preferable that the control circuit (52) operates the test determination circuit (51) within a predetermined time after operating the current generating circuit (50).

The earth leakage circuit breaker (A1) according to the sixth aspect can improve the reliability of the test results by reducing the possibility that the test determination circuit (51) will erroneously determine that harmonic noise is the test current (Is).

The earth leakage circuit breaker (A1) according to the seventh aspect of the present disclosure can be realized by combining it with any of the first to sixth aspects. In the earth leakage circuit breaker (A1) according to the seventh aspect, it is preferable that the earth leakage determination device (3) determines that there is an earth leakage when the period during which the earth leakage current is equal to or greater than a specified value is equal to or greater than a first time. It is preferable that the current generating circuit (50) generates the test current (Is) within a second time that is shorter than the first time.

The earth leakage circuit breaker (A1) according to the seventh aspect can be tested by the test device (5) while avoiding erroneous earth leakage determination by the earth leakage determination device (3).

The earth leakage circuit breaker (A1) according to the eighth aspect of the present disclosure can be realized by combining it with any of the first to sixth aspects. In the earth leakage circuit breaker (A1) according to the eighth aspect, it is preferable that the current generating circuit (50) sets the current value of the test current (Is) to a value smaller than a specified value.

The earth leakage circuit breaker (A1) according to the eighth aspect can be tested by the test device (5) while avoiding erroneous earth leakage determination by the earth leakage determination device (3).

The earth leakage circuit breaker (A1) according to the ninth aspect of the present disclosure can be realized by combining it with any of the first to eighth aspects. In the earth leakage circuit breaker (A1) according to the ninth aspect, it is preferable that the current generating circuit (50) generates the test current (Is) multiple times. It is preferable that the test determination circuit (51) determines that the test current (Is) has been detected when the effective value of the multiple test currents (Is) is equal to or greater than a threshold value.

The earth leakage circuit breaker (A1) according to the ninth aspect can suppress a decrease in the judgment accuracy of the test judgment circuit (51).

The earth leakage circuit breaker (A1) according to the tenth aspect of the present disclosure can be realized by combining it with any of the first to ninth aspects. In the earth leakage circuit breaker (A1) according to the tenth aspect, it is preferable that the test device (5) further includes a notification circuit (53) that notifies the result of the determination by the test determination circuit (51).

The earth leakage circuit breaker (A1) according to the tenth aspect can prompt the implementation of measures, particularly for defective test results, by having the alarm circuit (53) notify the test results of the test device (5).

The distribution board (B1) according to the eleventh aspect of the present disclosure includes a ground fault circuit interrupter (A1) according to any one of the first to tenth aspects, and a cabinet (70) that houses internal equipment including the ground fault circuit interrupter (A1).

The distribution board (B1) according to the eleventh aspect is equipped with a leakage current breaker (A1) according to any one of the first to tenth aspects, so that a leakage current detection test can be performed without interrupting the electric circuit (13A, 13B, 13C).

A1 Earth leakage circuit breaker (internal device)
B1 Distribution board C1 Branch switchgear (internal equipment)
D1 Primary feed branch switch (internal device)
Is Test current IC1 Integrated circuit 2 Zero-phase current transformer 3 Leakage current determination device 4 Trip device 5 Test device 13A, 13B, 13C Electric circuit 14A, 14B, 14C Contacts 50 Current generating circuit 51 Test determination circuit 52 Control circuit 53 Notification circuit 70 Cabinet

Claims (11)

A contact to be inserted into an electrical circuit;
a zero-phase current transformer for detecting a leakage current flowing in the electric circuit;
a leakage current determination device that determines the presence or absence of leakage current based on whether the leakage current detected by the zero-phase current transformer has reached a specified value;
a tripping device that opens the contacts when the leakage current determining device determines that there is a leakage current;
A test device for testing the leakage current determination device;
Equipped with
The test device comprises:
a current generating circuit for generating a test current to be detected by the zero-phase current transformer;
a test determination circuit that determines whether the test current detected by the zero-phase current transformer can be detected via the leakage current determination device;
having
Earth leakage circuit breaker. the current generating circuit generates an AC current as the test current;
the test determination circuit determines that the test current has been detected when the effective value of the test current is equal to or greater than a threshold value.
The earth leakage circuit breaker according to claim 1. The leakage current determination device and the test determination circuit are configured as a single integrated circuit.
3. The earth leakage circuit breaker according to claim 1 or 2. the test apparatus further comprises a control circuit for controlling the current generating circuit and the test determination circuit;
the control circuit controls the current generating circuit and the test determination circuit so as to periodically operate the current generating circuit and the test determination circuit.
3. The earth leakage circuit breaker according to claim 1 or 2. the current generating circuit generates, as the test current, an AC current having a frequency higher than a power supply frequency supplied to the electric circuit;
The earth leakage circuit breaker according to claim 2. the test apparatus further comprises a control circuit for controlling the current generating circuit and the test determination circuit;
the control circuit operates the test determination circuit within a predetermined time after operating the current generating circuit;
3. The earth leakage circuit breaker according to claim 1 or 2. The leakage current determination device determines that there is a leakage current when a period during which the leakage current is equal to or greater than a specified value is equal to or greater than a first time,
the current generating circuit generates the test current within a second time period that is shorter than the first time period;
3. The earth leakage circuit breaker according to claim 1 or 2. the current generating circuit sets the current value of the test current to a value smaller than the specified value.
3. The earth leakage circuit breaker according to claim 1 or 2. the current generating circuit generates the test current a plurality of times;
the test determination circuit determines that the test current has been detected when an effective value of the test current detected multiple times is equal to or greater than a threshold value.
3. The earth leakage circuit breaker according to claim 1 or 2. the test device further comprises a notification circuit for notifying a result of the determination by the test determination circuit.
3. The earth leakage circuit breaker according to claim 1 or 2. The earth leakage circuit breaker according to claim 1 or 2,
A cabinet that houses internal equipment including the earth leakage circuit breaker;
Equipped with
Distribution board.

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