Earth leakage breaker and distribution board

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

[Technical Field]

[0001] The present disclosure relates to an earth leakage circuit breaker and a distribution board, and more particularly to an earth leakage circuit breaker having a test function for earth leakage interruption, and a distribution board including the earth leakage circuit breaker. [Background technology]

[0002] 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-sequence current transformer whose primary winding is the AC current circuit to be detected for leakage, and an earth leakage detection unit that determines the presence or absence of leakage in the AC current circuit based on the secondary output of the zero-phase-sequence current transformer. The conventional example also includes a test device that supplies a simulated earth leakage current for an earth leakage operation test to a test winding wound around the zero-phase-sequence current transformer when a test switch is pressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-032420 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described conventional example, when the leakage current detection unit is normal, the AC electric circuit (electric circuit) is interrupted by supplying a simulated leakage current (test current) from the test device to the AC electric circuit.

[0005] An object of the present disclosure is to provide an earth leakage circuit breaker and a distribution board that can perform a test for detecting an earth leakage without interrupting an electric circuit. [Means for solving the problem]

[0006] A ground fault circuit interrupter according to one aspect of the present disclosure includes contacts inserted into an electric circuit, a zero-phase-sequence current transformer, a leakage current determination device, a tripping device, and a test device. The zero-phase-sequence current transformer detects a leakage current flowing in the electric circuit. The leakage current determination device determines the presence or absence of a leakage based on whether the leakage current detected by the zero-phase-sequence current transformer reaches a specified value. The tripping device opens the contacts when the leakage current determination device determines the presence of a leakage. The test device tests the leakage current determination device. The test device includes a current generating circuit that generates a test current detected by the zero-phase-sequence current transformer, and a test determination circuit that determines whether the test current detected by the zero-phase-sequence current transformer can be detected via the leakage current determination device. The leakage current determination device determines that a leakage current exists when the leakage current is equal to or greater than a predetermined value for a first time period or longer, and the current generating circuit generates the test current for a second time period that is shorter than the first time period.

[0007] A distribution board according to one aspect of the present disclosure includes the earth leakage circuit breaker and a cabinet that houses internal equipment including the earth leakage circuit breaker. [Effects of the Invention]

[0008] The earth leakage breaker and distribution board of the present disclosure have the advantage that a test for earth leakage detection can be performed without interrupting the electric circuit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit block diagram of an earth leakage circuit breaker according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a front view of the earth leakage breaker. [Figure 3] 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. [Figure 4] 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. DETAILED DESCRIPTION OF THE INVENTION

[0010] The earth leakage circuit breaker A1 and distribution board B1 according to the embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Note that the configurations described in the following embodiments are merely examples 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.

[0011] (1) Overview An earth leakage breaker A1 according to the embodiment includes contacts 14A, 14B, and 14C inserted into electric circuits 13A, 13B, and 13C, a zero-phase current transformer 2, an electric leakage determination device 3, a tripping device 4, and a test device 5 (see FIG. 1). The electric circuits in the embodiment are single-phase three-wire electric circuits consisting of electric circuits 13A and 13B with two voltage poles and an electric circuit 13C with one ground pole. However, the electric circuits may be single-phase two-wire, three-phase three-wire, or three-phase four-wire electric circuits.

[0012] One contact is inserted into each of the three electric circuits 13A, 13B, and 13C. That is, contact 14A is inserted into electric circuit 13A, contact 14B is inserted into electric circuit 13B, and contact 14C is inserted into electric circuit 13C.

[0013] The zero-phase-sequence current transformer 2 detects leakage currents flowing through the electric circuits 13A, 13B, and 13C. In this embodiment, the zero-phase-sequence 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.

[0014] The earth leakage determination device 3 determines whether or not there is an earth leakage based on whether or not the earth leakage current (detection voltage) detected by the zero-phase-sequence current transformer 2 has reached a specified value. In other words, the earth leakage determination device 3 determines that there is an earth leakage if the earth leakage current detected by the zero-phase-sequence current transformer 2 has reached a specified value, and determines that there is no earth leakage if the earth leakage current detected by the zero-phase-sequence current transformer 2 has not reached the specified value. When the earth leakage determination device 3 determines that there is an earth leakage, the trip device 4 opens contacts 14A, 14B, and 14C to break electric circuits 13A, 13B, and 13C.

[0015] 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 to be detected by the zero-phase-sequence current transformer 2. The test determination circuit 51 determines whether the test current detected by the zero-phase-sequence current transformer 2 can be detected via the leakage current determination device 3.

[0016] For example, if an abnormality such as a disconnection occurs in the line through which the detection voltage of the zero-phase current transformer 2 is input to the earth leakage determination device 3, the test determination circuit 51 will be unable to detect the test current detected by the zero-phase current transformer 2. Therefore, the test device 5 can test whether the earth leakage determination device 3 can normally perform earth leakage determination. Moreover, unlike conventional earth leakage tests, the test by the test device 5 does not operate the trip device 4. Therefore, the earth leakage circuit breaker A1 according to the embodiment can perform an earth leakage detection test without interrupting the electric circuits 13A, 13B, and 13C. Furthermore, in the earth leakage circuit breaker A1 according to the embodiment, the earth leakage determination device 3 and the test device 5 can operate independently of each other, so the earth leakage determination device 3 can determine the presence or absence of an earth leakage even during a test by the test device 5.

[0017] Moreover, the distribution board B1 according to the embodiment includes the earth leakage breaker A1 according to the embodiment and a cabinet 70 that houses internal devices including the earth leakage breaker A1 according to the embodiment (see FIGS. 4A and 4B).

[0018] Thus, the distribution board B1 according to the embodiment includes the earth leakage breaker A1 according to the embodiment, and therefore has the advantage that a leakage detection test can be performed without interrupting the electric circuits 13A, 13B, and 13C.

[0019] (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 the master breaker) of the distribution board B1 (hereinafter abbreviated as distribution board B1) according to the embodiment.

[0020] (2-1) Details of the distribution board The distribution board B1 is a residential distribution board (a 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.

[0021] The distribution board B1 includes, as internal equipment, an earth leakage circuit breaker A1 (main switch), a plurality of branch switches C1 (also called branch breakers), and a primary feed branch switch D1 (see FIG. 4A). Each of the plurality of branch switches C1 is configured as a molded case circuit breaker. However, at least one of the plurality of branch switches C1 may be configured as an earth leakage circuit breaker according to the embodiment.

[0022] 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 FIG. 1) of the earth leakage circuit breaker A1. However, the distribution board B1 may not be equipped with the primary feed branch switch D1.

[0023] The distribution board B1 includes a cabinet 70 that houses these internal devices (see FIGS. 4A and 4B). The cabinet 70 includes a box 71 and a cover 72.

[0024] 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 plurality of 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.

[0025] Like the box 71, the cover 72 is made of electrically insulating synthetic resin and is formed in a box shape with an open rear surface. The cover 72 is attached to the box 71 so as to cover the opening in the front surface 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 surface. The first window 721 exposes a portion of the front surface 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 surface of each of the multiple branch switches C1 housed in the box 71.

[0026] The cabinet 70 is installed by directly attaching it to the wall of the house or by embedding the rear end portion of the box 71 therein.

[0027] (2-2) Details of the earth leakage breaker As described above, the earth leakage circuit breaker A1 includes the contacts 14A, 14B, and 14C inserted into the electric circuits 13A, 13B, and 13C, the zero-phase current transformer 2, the earth leakage determination device 3, the tripping device 4, and the test device 5 (see FIG. 1). The earth leakage circuit breaker A1 also includes a case 10 that houses these components (see FIG. 2).

[0028] (2-2-1) Case Case 10 is formed into a rectangular parallelepiped shape from electrically insulating synthetic resin. 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 case 10, and the direction perpendicular to the plane of Fig. 2 is defined as the front-to-rear direction (the direction toward the front of the plane of the paper is the front direction).

[0029] A terminal block 100 is provided at the upper end of the case 10. Three primary terminals 11 are arranged in the left-right direction on the terminal block 100. These three primary terminals 11 each have 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. Insulating walls 111 are provided between each of the three terminal boards 110 that are adjacent in the left-right direction. The terminal boards 110 at both ends on the left and right are primary terminals 11 for voltage poles, and the central terminal board 110 is the primary terminal 11 for neutral poles, and the terminal boards 110 at both ends on the left and right are isolated from the central terminal board 110 by the insulating walls 111.

[0030] 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 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. Three electric wires (not shown) that form part of three electric circuits 13A, 13B, and 13C are housed within the terminal mounting portion 101.

[0031] The case 10 houses three electrical circuits 13A, 13B, and 13C that electrically connect each pair of three primary terminals 11 and 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.

[0032] The three secondary terminals 12 protrude from the upper 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 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.

[0033] Although not shown, the case 10 also houses an opening / closing mechanism that collectively opens and closes the contacts 14A, 14B, and 14C. 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).

[0034] Furthermore, the case 10 accommodates a zero-phase-sequence current transformer 2, a leakage current determination device 3, a test device 5, a power supply circuit 6, etc. The zero-phase-sequence current transformer 2 has a secondary winding (output winding) 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-sequence current transformer. Three electric circuits 13A, 13B, and 13C are inserted into the openings of the toroidal core of the zero-phase-sequence current transformer.

[0035] (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 100 V effective value 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.

[0036] (2-2-3) Earth leakage determination device The leakage determining device 3 includes 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 ASIC: application specific integrated circuit).

[0037] 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 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.

[0038] The determination circuit 31 calculates the effective value of the leakage current from the detected voltage value read from the buffer memory. Specifically, the determination circuit 31 integrates the square of the detected voltage value (absolute value) for a time period corresponding to one cycle of the power grid, 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 description, the effective value of the detected voltage calculated by the determination circuit 31 is referred to as the effective value of the leakage current.

[0039] The determination 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 determination circuit 31 determines that the leakage current is equal to or greater than a predetermined value and determines that there is a leakage, and if the effective value of the leakage current is less than the threshold value, the determination circuit 31 determines that there is no leakage.

[0040] The main causes of leakage current are thought to be the following three factors:

[0041] The first is an insulation defect in the load connected to the electric circuits 13A, 13B, and 13C via the branch switch C1. The leakage current caused by an insulation defect in the load is an alternating current (hereinafter referred to as a 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 grid). The normal leakage current will continue to flow unless the insulation defect in the load is resolved.

[0042] The second type is a lightning surge caused by induced lightning. The leakage current caused by a lightning surge is significantly larger than that of a normal leakage current, and it only flows for a short period of time.

[0043] The third is when the load is a device that uses a switching element, such as an inverter or converter. The leakage current caused by a switching element is an alternating current (hereinafter referred to as switching leakage current) with a frequency approximately equal to the switching frequency and its harmonic frequencies. Note that the switching leakage current continues to flow while the load that caused it is operating.

[0044] Thus, when earth leakage circuit breaker A1 detects a normal leakage current and determines that there is a leakage current, it desirably opens contacts 14A, 14B, and 14C to break electric circuits 13A, 13B, and 13C. On the other hand, when there is an earth leakage current due to a lightning surge or when there is a switching earth leakage current, it desirably does not break electric circuits 13A, 13B, and 13C.

[0045] Therefore, when the determination circuit 31 calculates the effective value of the leakage current from the detected voltage value read from the buffer memory, it is desirable that the determination circuit 31 uses a digital filter (low-pass filter) to remove detected voltage values ​​with frequencies 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).

[0046] 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 or a switching leakage current.

[0047] The earth leakage determining device 3 outputs an earth leakage detection signal to the tripping device 4 when it determines that an earth leakage has occurred.

[0048] (2-2-4) Tripping device When the tripping device 4 receives a leakage detection signal from the leakage determination device 3, it opens the contacts 14A, 14B, and 14C to interrupt the electric circuits 13A, 13B, and 13C. For example, the tripping device 4 is equipped with a solenoid, and energizing the excitation coil of the solenoid to move the plunger drives the opening / closing mechanism to open the contacts 14A, 14B, and 14C.

[0049] (2-2-5) Test equipment The test device 5 includes a current generating circuit 50 and a test determination circuit 51. The test device 5 further includes a control circuit 52 and a notification circuit 53.

[0050] The control circuit 52 mainly includes 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 earth leakage 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 periodically perform a test according to a time schedule, as will be described later. The specific control operation of the control circuit 52 will be described later.

[0051] The notification circuit 53 serves to notify the results of the test performed by the test device 5. For example, the notification circuit 53 includes a display element that selectively emits red light or 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.

[0052] 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, 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 case 10 through display window 103 (see FIG. 2) provided on the front surface of case 10.

[0053] The current generating circuit 50 generates a test current Is to be detected by the zero-phase current transformer 2. The current generating circuit 50 includes 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. 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 a control circuit 52.

[0054] 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 an output line 500 via a resistor R3. The other end of the output line 500 is electrically connected to one end of a 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-sequence current transformer 2.

[0055] The current generating circuit 50 is driven by a control signal Vs input from a 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 obtained by differentiating a square pulse that falls from a high level to a low level (see FIG. 3B).

[0056] When the control signal Vs changes from low to high, the first switching element Q1 is turned off and the second switching element Q2 is turned on. As a result, the charge stored in the capacitor C2 is discharged via the output line 500, the resistor R3, and the second switching element Q2, causing a discharge current (negative test current Is) to flow 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 high to low (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.

[0057] The detection voltage output from the zero-phase current transformer 2 includes a voltage with a frequency and magnitude corresponding 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 becomes a voltage with a frequency and magnitude corresponding to the frequency and magnitude of the test current Is flowing through the output line 500.

[0058] The test determination 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 determination circuit 51 determines that the test current Is has been detected (the test result is pass). On the other hand, if the detected voltage value is less than the reference value, the test determination circuit 51 determines that the test current Is has not been detected (the test result is fail). Then, the test determination circuit 51 controls the notification circuit 53 to emit light (green light or red light) corresponding to the test result (pass or fail).

[0059] In the earth leakage breaker A1, it is desirable that the test determination circuit 51 and the earth leakage determination device 3 are configured as a single integrated circuit IC1 (see FIG. 1).

[0060] (2-2-6) Explanation of the test for the earth leakage detection device Next, a description will be given of the test of the earth leakage determining device 3 by the test device 5. The earth leakage determining 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.

[0061] 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 generating circuit 50 and instructs the test judgment circuit 51 to start judgment processing. The current generating circuit 50 causes a test current Is to flow through the output line 500 in response to the control signal Vs.

[0062] Here, 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 detected voltage of the zero-phase current transformer 2 that detects the test current Is is filtered by a digital filter in the determination circuit 31 of the leakage current determination device 3, so that the effective value of the detected voltage does not exceed the threshold value. As a result, the leakage current determination device 3 determines that there is no leakage. Therefore, the earth leakage circuit breaker A1 can prevent the leakage current determination device 3 from erroneously determining that the test current Is is a normal leakage current.

[0063] Upon receiving an instruction from the control circuit 52, the test determination circuit 51 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 determination 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 determination circuit 51 determines that the test current Is cannot be detected (the test result is bad).

[0064] For example, if the line (electric wire) through which the detected voltage of the zero-phase current transformer 2 is input to the A / D conversion circuit 30 is broken or shorted, the test determination circuit 51 cannot detect the test current Is, resulting in a "Fail" test result. Alternatively, if the line (copper foil for printed wiring) through which the detected voltage value is output from the A / D conversion circuit 30 is broken or shorted, or if the A / D conversion circuit 30 malfunctions, the test determination circuit 51 cannot detect the test current Is, resulting in a "Fail" test result. Here, if the test determination circuit 51 and the earth leakage determination device 3 are configured as a single integrated circuit IC1, the test determination circuit 51 can indirectly determine whether or not the determination circuit 31 is faulty. In other words, if the test determination circuit 51 and the determination circuit 31 are configured as a single integrated circuit IC1, the possibility of a failure of only one of the test determination circuit 51 or the determination circuit 31 is considered to be significantly lower than the possibility of a failure of the entire integrated circuit IC1 including both. Therefore, the test determination circuit 51 can essentially determine whether or not the entire earth leakage determination device 3 is malfunctioning. Therefore, the earth leakage circuit breaker A1 can improve the reliability of the test results of the test device 5.

[0065] The test determination circuit 51 controls the notification circuit 53 to selectively emit green or red light, thereby notifying the test result (pass / fail) 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 breaker A1 can urge the user to take action, particularly in response to a bad test result.

[0066] Furthermore, a normal leakage current may flow through the electric circuits 13A, 13B, and 13C while the test device 5 is executing a test. In this case, the leakage current determination device 3 can determine the presence or absence of a leakage current based on the detected voltage of the zero-phase current transformer 2 without being affected by the test current Is flowing through the output line 500.

[0067] Incidentally, a load that generates harmonic noise (e.g., an electronic device equipped with a switching power supply, such as a personal computer) may be connected to a branch circuit of distribution board B1. In this case, harmonic noise in a frequency band that includes the frequency of test current Is may flow into electric circuits 13A, 13B, and 13C of earth leakage circuit interrupter A1. If harmonic noise from the load flows into electric circuits 13A, 13B, and 13C during testing by test device 5, test determination circuit 51 may erroneously determine that the harmonic noise is the test current Is.

[0068] In response to this, the control circuit 52 of the test device 5 operates the test determination circuit 51 within a predetermined time after operating the current generating circuit 50. Note that the "predetermined time" is preferably, for example, a time corresponding to the operating frequency (clock frequency) of the microcontroller, which is the main component of the control circuit 52, such as several microseconds to several tens of microseconds.

[0069] Thus, the earth leakage breaker A1 can reduce the possibility that the test determination circuit 51 will erroneously determine that harmonic noise is the test current Is, thereby improving the reliability of the test results.

[0070] 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 installed in the microcontroller to cause the test device 5 to execute a test at predetermined time intervals (for example, every 23 hours).

[0071] Thus, by having the control circuit 52 periodically operate the current generating circuit 50 and the test determination circuit 51, the earth leakage circuit breaker A1 can periodically test the earth leakage determination device 3, improving the reliability of the earth leakage determination, while eliminating the need for a person to operate the test button 16. Also, by having the control circuit 52 execute the test at 23-hour intervals (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 is less susceptible to the effects of harmonic noise and the like, improving the reliability of the test results, compared to when the test is executed every time at a specific time (hour) of the day.

[0072] (3) Modification of the earth leakage circuit breaker according to the embodiment Next, several modified examples 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 modified example described below is common to the basic configuration of the earth leakage circuit breaker A1 according to the embodiment. Therefore, the same reference numerals will be used to designate the same components as the basic configuration of the earth leakage circuit breaker A1 according to the embodiment, and illustrations and descriptions thereof will be omitted as appropriate.

[0073] (3-1) Variation 1 The earth leakage breaker A1 of the first modification is characterized by the configurations of the earth leakage determining device 3 and the test device 5.

[0074] In the first variant, the leakage current determination device 3 determines whether or not there is a leakage current by comparing the period during which the leakage current is greater than or equal to 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.

[0075] More specifically, the determination circuit 31 determines whether or not there is a leakage current based on the comparison result between the effective value of the leakage current and the threshold value, as well as the number of times the detected voltage of the zero-phase current transformer 2 reverses between positive and negative (the number of waves in the leakage current waveform). That is, the determination circuit 31 determines that there is a leakage current if 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, corresponding to a 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, the determination circuit 31 determines that there is no leakage current. This allows the determination circuit 31 to avoid determining that there is a leakage current based on leakage currents other than normal leakage currents (e.g., leakage currents due to lightning surges and switching leakage currents).

[0076] On the other hand, the test device 5 in Modification 1 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 (e.g., 40 Hz to 70 Hz). Furthermore, the second time period is defined by the number of half-waves of the test current Is (e.g., one half-wave).

[0077] Therefore, the test device 5 in the first modification causes the test current Is to flow within the 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 detected voltage value that is equal to or greater than the threshold value 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 the test by the test device 5.

[0078] (3-2) Variation 2 The earth leakage breaker A1 of the second modification is characterized by the configuration of the test device 5.

[0079] In the test device 5 of 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 determination circuit 31). For example, if the specified 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 (for example, 40 Hz to 70 Hz), as in the first modification.

[0080] Therefore, 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. Moreover, when a normal leakage current flows in 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.

[0081] Incidentally, in the earth leakage circuit breaker A1 of the above-described embodiment and variants 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 test current Is generated multiple times is equal to or greater than a threshold value.

[0082] That is, 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 or the like, which may reduce the determination accuracy of the test determination circuit 51. In contrast, 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, it is possible to prevent a reduction in the determination accuracy of the test determination circuit 51.

[0083] The notification circuit 53 may also have a function for communicating 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 desirable that the external device be equipped with a monitor device such as a liquid crystal display, and that the test results received from the notification circuit 53 be displayed on the monitor device.

[0084] (4) Summary A ground fault circuit interrupter (A1) according to a first aspect of the present disclosure includes contacts (14A, 14B, 14C) inserted into electric circuits (13A, 13B, 13C), a zero-phase current transformer (2), a leakage current determination device (3), a tripping device (4), and a test device (5). The zero-phase current transformer (2) detects a leakage current flowing through the electric circuits (13A, 13B, 13C). The leakage current determination device (3) determines whether or not a leakage current exists based on whether or not the leakage current detected by the zero-phase current transformer (2) reaches a specified value. The tripping device (4) opens the contacts (14A, 14B, 14C) when the leakage current determination device (3) determines that a leakage exists. The test device (5) tests the leakage current 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 the test current (Is) that is detected by the zero-phase current transformer (2) can be detected via the leakage current determination device (3).

[0085] The earth leakage circuit breaker (A1) according to the first aspect can test whether the earth leakage determination device (3) can normally determine an earth leakage using the test device (5), and does not operate the trip device (4) during the test using the test device (5). As a result, the earth leakage circuit breaker (A1) according to the first aspect can test earth leakage detection without interrupting the electric circuits (13A, 13B, 13C).

[0086] A ground fault circuit interrupter (A1) according to a second aspect of the present disclosure can be realized by combining it with the first aspect. In the ground fault circuit interrupter (A1) according to the second aspect, it is preferable that the current generating circuit (50) generates an AC 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.

[0087] 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.

[0088] 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, the earth leakage determination device (3) and the test determination circuit (51) are preferably configured as a single integrated circuit (IC1).

[0089] 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).

[0090] A ground fault circuit interrupter (A1) according to a fourth aspect of the present disclosure can be realized by combining it with any one of the first and second aspects. In the ground fault circuit interrupter (A1) according to the fourth 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) controls the current generating circuit (50) and the test determination circuit (51) so as to periodically operate the current generating circuit (50) and the test determination circuit (51).

[0091] 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).

[0092] The earth leakage circuit breaker (A1) according to a fifth aspect of the present disclosure can be realized by combining with any one 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 circuits (13A, 13B, 13C).

[0093] The earth leakage circuit breaker (A1) according to the fifth aspect reduces the possibility that the earth leakage determination device (3) determines that there is an earth leakage based on the test current (Is), and can determine whether there is an earth leakage even during testing by the test device (5).

[0094] A ground fault circuit interrupter (A1) according to a sixth aspect of the present disclosure can be realized by combining it with any of the first to fifth aspects. In the ground fault circuit interrupter (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).

[0095] The earth leakage breaker (A1) according to the sixth aspect can reduce the possibility that the test determination circuit (51) will erroneously determine that harmonic noise is the test current (Is), thereby improving the reliability of the test results.

[0096] A ground fault circuit interrupter (A1) according to a seventh aspect of the present disclosure can be realized by combining it with any of the first to sixth aspects. In the ground fault circuit interrupter (A1) according to the seventh aspect, the ground fault determination device (3) preferably determines that there is a ground fault when the time period during which the ground fault current is equal to or greater than a specified value is equal to or greater than a first time. The current generating circuit (50) preferably generates the test current (Is) within a second time period that is shorter than the first time period.

[0097] The earth leakage breaker (A1) according to the seventh aspect can perform a test by the test device (5) while avoiding erroneous determination of an earth leakage in the earth leakage determination device (3).

[0098] An earth leakage breaker (A1) according to an eighth aspect of the present disclosure can be realized by combining with any one of the first to sixth aspects. In the earth leakage 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.

[0099] The earth leakage breaker (A1) according to the eighth aspect can perform a test by the test device (5) while avoiding erroneous determination of an earth leakage in the earth leakage determination device (3).

[0100] A ground fault circuit interrupter (A1) according to a ninth aspect of the present disclosure can be realized by combining it with any one of the first to eighth aspects. In the ground fault circuit interrupter (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 an effective value of the test current (Is) generated multiple times is equal to or greater than a threshold value.

[0101] The earth leakage breaker (A1) according to the ninth aspect can suppress a decrease in the determination accuracy of the test determination circuit (51).

[0102] A ground fault circuit interrupter (A1) according to a tenth aspect of the present disclosure can be realized by combining it with any one of the first to ninth aspects. In the ground fault circuit interrupter (A1) according to the tenth aspect, it is preferable that the test device (5) further includes a notification circuit (53) that notifies a result of the determination by the test determination circuit (51).

[0103] The earth leakage breaker (A1) according to the tenth aspect can prompt the user to take measures, particularly for a bad test result, by having the notification circuit (53) notify the test result of the test device (5).

[0104] A distribution board (B1) according to an 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).

[0105] The distribution board (B1) according to the eleventh aspect includes the earth leakage breaker (A1) according to any one of the first to tenth aspects, and therefore can perform a leakage detection test without interrupting the electric circuits (13A, 13B, 13C). [Explanation of symbols]

[0106] A1 Earth leakage breaker (internal equipment) B1 Distribution board C1 Branch switch (internal equipment) D1 Primary feed branch switch (internal equipment) Is Test current IC1 Integrated Circuit 2 Zero phase current transformer 3 Earth leakage determination device 4 Tripping device 5 Test Equipment 13A, 13B, 13C electrical circuit 14A, 14B, 14C contacts 50 Current generation circuit 51 Test judgment circuit 52 Control circuit 53 Alarm circuit 70 Cabinet

Claims

1. 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 whether or not there is a leakage current based on whether or not 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 determining device determines that there is a leakage; 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 earth leakage determination device; and the electric leakage determination device determines that an electric leakage has occurred when a period during which the electric 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; Ground fault circuit interrupter.

2. 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.

3. The leakage current determination device and the test determination circuit are configured as a single integrated circuit.

3. The earth leakage breaker according to claim 1 or 2.

4. the test device further includes a control circuit that controls 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 breaker according to claim 1 or 2.

5. the current generating circuit generates, as the test current, an AC current having a frequency higher than a power supply frequency supplied to the electrical circuit; The earth leakage breaker according to claim 2.

6. the test device further includes a control circuit that controls 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 breaker according to claim 1 or 2.

7. The current generating circuit generates the test current multiple times, the test determination circuit determines that the test current has been detected when an effective value of the test current measured multiple times is equal to or greater than a threshold value; 3. The earth leakage breaker according to claim 1 or 2.

8. The test device further includes a notification circuit that notifies a result of the determination by the test determination circuit.

3. The earth leakage breaker according to claim 1 or 2.

9. The earth leakage circuit breaker of claim 1 or 2, a cabinet that houses internal equipment including the earth leakage breaker; Equipped with Distribution board.

Images