Earth leakage circuit breaker

Abstract

To obtain a residual current circuit breaker that can improve the minimum operating voltage of the residual current circuit breaker. [Solution] The earth leakage circuit breaker 100 includes a tripping device 8 that trips the switching contacts 5 that open and close the AC circuit 3, a test current circuit 13 that sends a simulated leakage current to a zero-phase current transformer 6, an earth leakage detection circuit 7 that receives the output signal from the zero-phase current transformer 6 and outputs a trip command when it determines that there is an earth leakage or ground fault, a test switch 17 that supplies operating power to the test current circuit 13 and outputs a simulated leakage current, and a tripping device drive circuit 50 that supplies drive current to the tripping device 8 in response to the trip command. After the test switch 17 is pressed, the tripping device drive circuit 50 stops the output of the simulated leakage current to the test current circuit 13 with the trip command output of the earth leakage detection circuit 7, and then trips the switching contacts 5 after a first time has elapsed.

Description

Technical Field

[0001] The present disclosure relates to a leakage circuit breaker for detecting a leakage current flowing through an AC circuit such as a power distribution system, interrupting the AC circuit, and preventing a leakage accident in advance.

Background Art

[0002] As a conventional leakage circuit breaker, for example, in Patent Document 1 below, there is a zero-phase current transformer inserted into an AC circuit and having a secondary winding and a test winding, a leakage detection circuit that outputs a signal based on the output current of the secondary winding of the zero-phase current transformer, a tripping device that opens the switching unit inserted into the AC circuit by the signal of the leakage detection circuit, a test circuit configured to flow a test current through the test winding of the zero-phase current transformer, and a control power supply circuit that supplies a DC voltage obtained by stepping down the AC voltage of the AC circuit to a predetermined voltage to the leakage detection circuit, the tripping device, and the test circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure has been made in view of the above, and an object thereof is to obtain a leakage circuit breaker capable of improving the minimum operating voltage of the leakage circuit breaker.​ [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objectives, the earth leakage circuit breaker according to this disclosure includes switching contacts for opening and closing an AC circuit, and a leakage current sensor for detecting leakage current in the AC circuit, as well as a test circuit, an earth leakage detection circuit, a tripping device, a tripping device drive circuit, a power supply circuit, and an earth leakage test button. The test circuit sends a simulated leakage current to the leakage current sensor, and the earth leakage detection circuit, upon receiving the output signal from the leakage current sensor and determining that it is an earth leakage or ground fault, outputs a trip command. The tripping device trips the switching contacts, and the tripping device drive circuit supplies drive current to the tripping device in response to the trip command. The power supply circuit is powered by the AC circuit and supplies operating power to the tripping device, tripping device drive circuit, test circuit, and earth leakage detection circuit. The earth leakage test button supplies operating power to the test circuit and outputs a simulated leakage current. After the leakage test button is pressed, the tripping device drive circuit stops the output of a simulated leakage current to the test circuit with the trip command output of the leakage detection circuit, and then trips the open / closed contacts after a first time has elapsed. [Effects of the Invention]

[0007] The residual current circuit breaker described herein has the effect of improving the minimum operating voltage of the residual current circuit breaker. [Brief explanation of the drawing]

[0008] [Figure 1] Circuit diagram showing a ground fault circuit breaker according to Embodiment 1 [Figure 2] Figure 1 shows a detailed circuit diagram of the step-down circuit and constant voltage circuit. [Figure 3] Block diagram showing the test current circuit shown in Figure 1. [Figure 4] A circuit diagram showing the details of the DC pulse generation circuit shown in Figure 3. [Figure 5] Figure 3 shows a detailed circuit diagram of the H-shaped bridge circuit. [Figure 6] Figure 1 shows a detailed circuit diagram of the drive circuit and delay circuit. [Figure 7] Block diagram illustrating the operation of the test current circuit according to Embodiment 1 [Figure 8] A first circuit diagram illustrating the operation of the oscillator circuit included in the test current circuit according to Embodiment 1. [Figure 9] A second circuit diagram illustrating the operation of the oscillator circuit included in the test current circuit according to Embodiment 1. [Figure 10] A first time chart illustrating the operation of the test current circuit according to Embodiment 1. [Figure 11] A second time chart illustrating the operation of the test current circuit according to Embodiment 1. [Figure 12] Time chart illustrating the operation of a test current circuit in prior art. [Figure 13] Circuit diagram showing a ground fault circuit breaker according to Embodiment 2 [Figure 14] Circuit diagram showing details of the drive circuit and delay circuit of the earth leakage circuit breaker according to Embodiment 2. [Figure 15] Circuit diagram showing a residual current circuit breaker according to Embodiment 3 [Figure 16] Circuit diagram showing details of the drive circuit, delay circuit, and EAL of the earth leakage circuit breaker according to Embodiment 3. [Figure 17] Circuit diagram showing a ground fault circuit breaker according to Embodiment 4 [Figure 18] Circuit diagram showing details of the drive circuit and delay circuit of the earth leakage circuit breaker according to Embodiment 4. [Modes for carrying out the invention]

[0009] The earth leakage circuit breaker according to the embodiment of this disclosure will be described in detail below with reference to the attached drawings.

[0010] Embodiment 1. FIG. 1 is a circuit diagram showing a leakage circuit breaker 100 according to Embodiment 1, FIG. 2 is a circuit diagram showing details of the step-down circuit 11 and the constant voltage circuit 12 shown in FIG. 1, FIG. 3 is a block diagram showing the test current circuit 13 shown in FIG. 1, FIG. 4 is a circuit diagram showing details of the DC pulse generation circuit 13b shown in FIG. 3, FIG. 5 is a circuit diagram showing details of the H-bridge circuit 13c shown in FIG. 3, and FIG. 6 is a circuit diagram showing details of the drive circuit section 15 and the delay circuit section 16 shown in FIG. 1.

[0011] As shown in FIG. 1, the leakage circuit breaker 100 mainly includes an AC circuit 3, an opening / closing mechanism section 4, an opening / closing contact 5, a zero-phase current transformer 6, a leakage detection circuit 7, a tripping device 8, a single-phase full-wave rectifier circuit 10, a step-down circuit 11, a constant voltage circuit 12, a test current circuit 13, a tripping device drive circuit 50, a test switch 17, and capacitors 18 and 19. The tripping device drive circuit 50 includes a drive circuit section 15 and a delay circuit section 16. The zero-phase current transformer 6 is a leakage current sensor, and the test switch 17 is a leakage test button. The test current circuit 13 is a test circuit that passes a test current, which is a pseudo-leakage current, through the zero-phase current transformer 6. The single-phase full-wave rectifier circuit 10, the step-down circuit 11, and the constant voltage circuit 12 are power supply circuits that supply an operating power source to at least one of the tripping device 8, the test current circuit 13, the drive circuit section 15, and the delay circuit section 16.

[0012] The leakage circuit breaker 100 has a power supply side connection terminal 1 and a load side connection terminal 2. The AC circuit 3, which is the main circuit, has circuits for each of the R phase, S phase, and T phase, and is connected between the power supply side connection terminal 1 and the load side connection terminal 2. The conductors of each phase that make up each circuit in the AC circuit 3 all pass through the zero-phase current transformer 6. The zero-phase current transformer 6 has a secondary winding 6a and a tertiary winding 6b. The secondary winding 6a is a winding for detecting the leakage current or ground fault current (hereinafter simply referred to as "leakage current") flowing through the AC circuit 3. The tertiary winding 6b is a winding for performing a test of leakage detection. The opening and closing contact 5 is driven by the opening and closing mechanism section 4 to open and close each circuit of the AC circuit 3. The leakage detection circuit 7 monitors the current signal of the secondary winding 6a of the zero-phase current transformer 6 to determine the presence or absence of leakage or ground fault (hereinafter simply referred to as "leakage"). The tripping device 8 drives the opening and closing mechanism section 4 by the output signal of the leakage detection circuit 7 when leakage occurs, trips the opening and closing contact 5, and interrupts the AC circuit 3. In this document, the output signal of the leakage detection circuit 7 output when leakage occurs may be referred to as a "trip command".

[0013] The single-phase full-wave rectifier circuit 10 is supplied with AC power from the AC circuit 3 via the impedance element 9 and converts the AC power into DC power. The step-down circuit 11 is connected to both ends of the DC side of the single-phase full-wave rectifier circuit 10, converts the voltage of the DC power supplied from the single-phase full-wave rectifier circuit 10 into a first DC voltage VD (for example, DC40V), and supplies an operating power source to the tripping device 8. The capacitor 19 is connected between the cathode of the diode 14 and the ground GND to smooth the first DC voltage VD. The constant voltage circuit 12 converts the DC power from the step-down circuit 11 smoothed by the capacitor 19 into a second DC voltage VC (for example, DC5V) lower than the first DC voltage VD. The second DC voltage VC is also applied to the leakage detection circuit 7 as an operating power source for the leakage detection circuit 7.

[0014] The test current circuit 13 is driven via the capacitor 18 when the test switch 17 is pressed. When the test current circuit 13 is driven, a test current flows through the tertiary winding 6b. The drive circuit 15 supplies drive current to the tripping device 8 based on the output signal of the leakage current detection circuit 7. The delay circuit 16 operates based on the trip command output of the leakage current detection circuit 7. The delay circuit 16 has the function of stopping the output of test current to the test current circuit 13 and then delaying the drive of the tripping device 8 by the drive circuit 15 for a predetermined first time.

[0015] The earth leakage circuit breaker 100 is connected to a three-phase AC circuit (not shown) to detect earth leakage current via a power supply side connection terminal 1 and a load side connection terminal 2. The single-phase full-wave rectifier circuit 10 is constructed by connecting four rectifier diodes D1, D2, D3, and D4 in a well-known bridge configuration, and rectifies the three-phase AC voltage of the AC circuit 3 to supply DC power to the step-down circuit 11. The AC side of the single-phase full-wave rectifier circuit 10 is connected to the R-phase and T-phase circuits of the AC circuit 3, respectively, via an impedance element 9. The impedance element 9 is, for example, a resistor or an inductor.

[0016] As shown in Figure 2, a DC voltage that has been full-wave rectified by a single-phase full-wave rectifier circuit 10 is applied to the step-down circuit 11. The step-down circuit 11 steps down the applied DC voltage to a first DC voltage VD. The step-down circuit 11 comprises a field-effect transistor (hereinafter referred to as "FET") 11a, a first Zener diode 11b, and a first resistor 11c with a resistance of several hundred kΩ to several MΩ. The drain of the FET 11a is connected to the positive output side of the single-phase full-wave rectifier circuit 10. The cathode of the first Zener diode 11b is connected to the gate of the FET 11a, and the anode is connected to the negative output side of the single-phase full-wave rectifier circuit 10, i.e., to ground GND. The first resistor 11c is connected between the drain and gate of the FET 11a and supplies Zener current to the first Zener diode 11b.

[0017] In the step-down circuit 11, the Zener voltage, which is the voltage across the first Zener diode 11b, is applied to the gate of FET 11a. Therefore, if the gate voltage of FET 11a is Vc1, then Vc1 ≈ (Zener voltage of the first Zener diode 11b). Also, the first DC voltage VD, which is the output voltage of the step-down circuit 11, is VD = Vc1 - (on-voltage of FET 11a). As mentioned above, Vc1 ≈ (Zener voltage of the first Zener diode 11b), and the first DC voltage VD is VD ≈ (Zener voltage of the first Zener diode 11b) - (on-voltage of FET 11a). Here, if the on-voltage of FET 11a is about 3V and the Zener voltage of the first Zener diode 11b is about 43V, then the first DC voltage VD will be VD ≈ 43V - 3V = about 40V.

[0018] The output voltage of the step-down circuit 11 is applied to the anode of the diode 14. A smoothing capacitor 19 is provided between the cathode of the diode 14 and ground GND, and the third DC voltage VS, smoothed by the capacitor 19, is applied to the constant voltage circuit 12.

[0019] The constant voltage circuit 12 comprises a transistor 12a, a second Zener diode 12b, a second resistor 12c with a resistance of several hundred kΩ, and a capacitor 12d. The collector of transistor 12a is connected to the cathode of diode 14. The cathode of the second Zener diode 12b is connected to the base of transistor 12a, and the anode is connected to ground (GND). The second resistor 12c is connected between the collector and base of transistor 12a and supplies Zener current to the second Zener diode 12b.

[0020] In the constant voltage circuit 12, the base of transistor 12a is subjected to a Zener voltage, which is the voltage across the second Zener diode 12b. Therefore, if the base voltage of transistor 12a is Vc2, then Vc2 ≈ (Zener voltage of the second Zener diode 12b). Also, the output voltage of the constant voltage circuit 12, the second DC voltage VC, is given by VC = Vc2 - (on-voltage of transistor 12a). The second DC voltage VC is maintained by capacitor 12d. As mentioned above, Vc2 ≈ (Zener voltage of the second Zener diode 12b), and the second DC voltage VC is given by VC ≈ (Zener voltage of the second Zener diode 12b) - (on-voltage of transistor 12a). Here, if we set the ON voltage of transistor 12a to approximately 3V and the Zener voltage of the second Zener diode 12b to approximately 8V, then the second DC voltage VC will be approximately VC ≈ 8V - 3V = 5V.

[0021] Next, the details of the test current circuit 13, which performs the leakage current test operation, will be explained. The leakage current test operation is performed by flowing a simulated leakage current as a test current through the tertiary winding 6b provided in the zero-phase current transformer 6, thereby simulating a leakage current, and causing the leakage current detection circuit 7 to detect the leakage current and perform leakage current tripping.

[0022] For example, suppose the sensitivity current of the earth leakage circuit breaker 100 is 500mA and the tertiary winding 6b has 100 turns. As a simulated leakage current, it is necessary to flow a current of about twice that, so 500(mA) × 2(times) / 100(turns) = 10mA. Therefore, the simulated leakage current needs to be set to a current value of about 10mA.

[0023] As shown in Figure 3, the test current circuit 13 comprises a Zener diode 13a, a DC pulse generation circuit 13b, and an H-bridge circuit 13c. The cathode of the Zener diode 13a is connected to a first DC voltage VD. The DC pulse generation circuit 13b is connected between the anode of the Zener diode 13a and ground GND, and generates a DC pulse synchronized with the voltage of the AC circuit 3. The H-bridge circuit 13c converts the DC pulse from the DC pulse generation circuit 13b into an AC pulse.

[0024] As shown in Figure 4, the DC pulse generation circuit 13b comprises a transistor 13b1 and resistors 13b2 to 13b4. The base of transistor 13b1 is connected to the anode of Zener diode 13a via resistor 13b2. Resistor 13b3 is connected between the base and emitter of transistor 13b1. One end of resistor 13b4 is connected to the test switch 17 via capacitor 18, and the other end is connected to the collector of transistor 13b1. The emitter of transistor 13b1 is connected to ground GND, and the collector of transistor 13b1 is connected to the H-bridge circuit 13c.

[0025] As shown in Figure 5, the H-shaped bridge circuit 13c comprises transistors 13c1, 13c2, 13c7, and 13c8, resistors 13c3 to 13c6, 13c13, 13c14, and 13c17 to 13c19, capacitors 13c9, 13c10, 13c15, and 13c16, and diodes 13c11 and 13c12. Figure 5 also shows the transistor 13b1 and resistor 13b4 of the DC pulse generation circuit 13b included in the test current circuit 13.

[0026] In the H-bridge circuit 13c, transistor 13c1 has its emitter connected to a first DC voltage VD and its collector connected to one end of the tertiary winding 6b via resistor 13c19. Transistor 13c2 has its emitter connected to the first DC voltage VD and its collector connected to the other end of the tertiary winding 6b. Resistor 13c3 is connected between the base and emitter of transistor 13c1, resistor 13c4 is connected between the base and emitter of transistor 13c2, resistor 13c5 is connected between the base of transistor 13c1 and the collector of transistor 13c2, and resistor 13c6 is connected between the base of transistor 13c2 and the collector of transistor 13c1. Transistor 13c7 has its collector connected to the other end of the tertiary winding 6b and its emitter connected to ground GND. The transistor 13c8 has its collector connected to one end of the tertiary winding 6b, and its emitter connected to ground (GND).

[0027] In the H-bridge circuit 13c, one end of capacitor 13c9 is connected to the base of transistor 13c7, and the other end is connected to the collector of transistor 13b1. One end of capacitor 13c10 is connected to the base of transistor 13c8, and the other end is connected to the collector of transistor 13b1. The cathode of diode 13c11 is connected to the collector of transistor 13c7. The cathode of diode 13c12 is connected to the collector of transistor 13c8. One end of resistor 13c13 is connected to the anode of diode 13c11, and the other end is connected to the test switch 17 via capacitor 18 (see Figure 3). One end of resistor 13c14 is connected to the anode of diode 13c12, and the other end is connected to the test switch 17 via capacitor 18 (see Figure 3).

[0028] Furthermore, in the H-shaped bridge circuit 13c in Figure 5, one end of capacitor 13c15 is connected to the anode of diode 13c12 and the other end is connected to the base of transistor 13c7. One end of capacitor 13c16 is connected to the anode of diode 13c11 and the other end is connected to the base of transistor 13c8. Resistor 13c17 is connected in parallel with capacitor 13c15, resistor 13c18 is connected in parallel with capacitor 13c16, and resistor 13c19 is connected in parallel with the collector of transistor 13c1 and the other end is connected to one end of the tertiary winding 6b.

[0029] As shown in Figure 6, the drive circuit 15 comprises transistors 15a, 15c, 15f, and 15i, and resistors 15b, 15d, 15e, 15g, 15h, and 15j. Transistor 15a has its base connected to the output of the leakage current detection circuit 7 and its emitter connected to ground GND. One end of resistor 15b is connected to the collector of transistor 15a. Transistor 15c has its base connected to the other end of resistor 15b and its emitter connected to the second DC voltage VC. Resistor 15d is connected between the emitter and base of transistor 15c, and one end of resistor 15e is connected to the collector of transistor 15c. Transistor 15f has its base connected to the other end of resistor 15e, its emitter connected to ground GND, and its collector connected to the connection point between capacitor 18 and test current circuit 13 (see Figure 1).

[0030] Furthermore, in the drive circuit section 15 of Figure 6, resistor 15g is connected between the emitter and base of transistor 15f, and resistor 15h has one end connected to the collector of transistor 15c. Transistor 15i has its base connected to the other end of resistor 15h, its collector connected to one end of tripping device 8, and its emitter connected to ground GND. Resistor 15j is connected between the emitter and base of transistor 15i. The other end of tripping device 8 is connected to a third DC voltage VS, and when transistor 15i is turned on, the tripping device 8 is energized and the switching mechanism section 4 is driven.

[0031] Furthermore, as shown in Figure 6, the delay circuit section 16 includes a capacitor 16a, a transistor 16b, and resistors 16c and 16d. One end of the capacitor 16a is connected to the base of the transistor 15i. The collector of the transistor 16b is connected to the other end of the capacitor 16a, and its emitter is connected to ground (GND). One end of the resistor 16c is connected to the test switch 17, and the other end is connected to the base of the transistor 16b. The resistor 16d is connected between the emitter and base of the transistor 16b.

[0032] Next, the operation of the leakage current test in the leakage circuit breaker 100 will be described. Figure 7 is a block diagram illustrating the operation of the test current circuit 13 according to Embodiment 1, Figure 8 is a first circuit diagram illustrating the operation of the oscillation circuit included in the test current circuit 13 according to Embodiment 1, Figure 9 is a second circuit diagram illustrating the operation of the oscillation circuit included in the test current circuit 13 according to Embodiment 1, Figure 10 is a first time chart illustrating the operation of the test current circuit 13 according to Embodiment 1, Figure 11 is a second time chart illustrating the operation of the test current circuit 13 according to Embodiment 1, and Figure 12 is a time chart illustrating the operation of the test current circuit in the prior art. Figure 12 is shown for comparison with the operation of Embodiment 1. The oscillation circuit is a general term for the circuit including the DC pulse generation circuit 13b and the H-shaped bridge circuit 13c. The operating waveforms shown in Figures 10 to 12 will be explained by referring to the necessary parts as appropriate.

[0033] When the test switch 17 is pressed, a second DC voltage VC is applied to the test current circuit 13 via the test switch 17 and the capacitor 18, as shown in Figure 7. Figure 11(b) shows the voltage applied via the test switch 17 between timings t11 and t12. If the test switch 17 is continuously pressed, charge will accumulate in the capacitor 18 after a second time sufficiently longer than the leakage current test time. Due to this action, the capacitor 18 has the function of preventing current from continuing to flow through the DC pulse generation circuit 13b and the H-bridge circuit 13c, regardless of the duration for which the test switch 17 is pressed.

[0034] When a second DC voltage VC is applied from the constant voltage circuit 12 to the DC pulse generation circuit 13b and the H-bridge circuit 13c, capacitors 13c9 and 13c10 are charged via resistors 13c13, 13c14, 13c17, and 13c18, and transistor 13c7 or transistor 13c8 attempts to be turned on. At this time, because there are variations in the resistance values ​​of resistors 13c13, 13c14, 13c17, and 13c18, the capacitance of capacitors 13c9 and 13c10, and the on-sensitivity of transistors 13c7 and 13c8, either transistor 13c7 or transistor 13c8 will turn on first. When one of transistors 13c7 or 13c8 turns on first, the other turns off. When transistor 13c7 turns on and transistor 13c8 turns off, current flows through resistors 13c3 and 13c5, causing transistor 13c1 to turn on. Conversely, when transistor 13c8 turns on and transistor 13c7 turns off, current flows through resistors 13c4 and 13c6, causing transistor 13c2 to turn on.

[0035] Next, as shown in Figure 8, we will explain the operation assuming that the current state is with transistors 13c7 and 13c1 ON, and transistors 13c8 and 13c2 OFF, that is, with a positive test current flowing through the tertiary winding 6b. Timing t1 in Figure 10 is the timing when the positive test current is flowing through the tertiary winding 6b as described above.

[0036] In the state described above, as shown in Figure 8, current is supplied to the base of transistor 13c7 via resistor 13c17. Capacitor 13c9 is positively charged on the side of resistor 13c17 and negatively charged on the side of transistor 13b1. Capacitor 13c15 is positively charged on the side of resistor 13c14 and negatively charged on the side of capacitor 13c9. Capacitor 13c16 is negatively charged on the side of resistor 13c13 and positively charged on the side of capacitor 13c10. Capacitor 13c10 is negatively charged on the side of capacitor 13c16 and positively charged on the side of transistor 13b1. The current supplied from the step-down circuit 11 flows in the following order: transistor 13c1, resistor 13c19, tertiary winding 6b, and transistor 13c7.

[0037] When transistors 13c7 and 13c1 are ON, and transistors 13c8 and 13c2 are OFF, at timing t2 in Figure 10, as shown in Figure 10(b), the first DC voltage VD, which is the voltage on the cathode side of the Zener diode 13a, momentarily drops, and the Zener diode 13a also momentarily becomes non-conductive. Then, when the first DC voltage VD returns to its original state, the Zener diode 13a also returns to the conducting state.

[0038] When the Zener diode 13a becomes non-conductive, transistor 13b1 turns off, and then when the Zener diode 13a becomes conductive again, transistor 13b1 turns on. When transistor 13b1 changes from off to on, capacitor 13c9 has a positive charge on the side with resistor 13c17, so no current flows through capacitor 13c9, but capacitor 13c10 has a negative charge on the side with resistor 13c18, so a current flows through capacitor 13c10 for a moment.

[0039] As a result, in Figure 9, current flows from the constant voltage circuit 12 through resistors 13c13 and 13c18, as indicated by the dashed arrows. This current causes capacitor 13c10 to become positively charged on the side of resistor 13c18 and negatively charged on the side of transistor 13b1, turning on transistor 13c8.

[0040] When transistor 13c8 is turned on, current flows in the order of resistor 13c17, diode 13c12, and transistor 13c8, and no current flows to the base of transistor 13c7, so transistor 13c7 is turned off. At this time, capacitor 13c15 has the side of resistor 13c14 negative and the side of capacitor 13c9 positive, and capacitor 13c9 has the side of resistor 13c17 negative and the side of transistor 13b1 positive.

[0041] When transistor 13c7 is turned off, no current flows through resistors 13c3 and 13c5, so transistor 13c1 is turned off. Conversely, when transistor 13c8 is turned on, current flows through resistors 13c4 and 13c6, so transistor 13c2 is turned on.

[0042] As a result, transistors 13c7 and 13c1 are turned off, and transistors 13c8 and 13c2 are turned on. The current supplied from the step-down circuit 11 flows in the order of transistor 13c2, tertiary winding 6b, resistor 13c19, and transistor 13c8, and the current flowing through tertiary winding 6b is a negative current in the opposite direction.

[0043] Next, as shown in Figure 9, we will explain the operation assuming that the current state is with transistors 13c1 and 13c7 off, and transistors 13c2 and 13c8 on, that is, with a negative test current flowing through the tertiary winding 6b. Timing t3 in Figure 10 is the timing when the negative test current is flowing through the tertiary winding 6b as described above.

[0044] In the state described above, as shown in Figure 9, current is supplied to the base of transistor 13c8 via resistor 13c18. Capacitor 13c10 is positively charged on the side of resistor 13c18 and negatively charged on the side of transistor 13b1. Capacitor 13c16 is positively charged on the side of resistor 13c13 and negatively charged on the side of capacitor 13c10. Capacitor 13c15 is negatively charged on the side of resistor 13c14 and positively charged on the side of capacitor 13c9. Capacitor 13c9 is negatively charged on the side of capacitor 13c15 and positively charged on the side of transistor 13b1. The current supplied from the step-down circuit 11 flows in the following order: transistor 13c2, tertiary winding 6b, resistor 13c19, and transistor 13c8.

[0045] When transistors 13c8 and 13c2 are ON, and transistors 13c7 and 13c1 are OFF, at timing t4 in Figure 10, as shown in Figure 10(b), the first DC voltage VD, which is the voltage on the cathode side of the Zener diode 13a, momentarily drops, and the Zener diode 13a also momentarily becomes non-conductive. Then, when the first DC voltage VD returns to its original state, the Zener diode 13a also returns to the conducting state.

[0046] When the Zener diode 13a becomes non-conductive, transistor 13b1 turns off, and then when the Zener diode 13a becomes conductive again, transistor 13b1 turns on. When transistor 13b1 changes from off to on, capacitor 13c10 has a positive charge on the side with resistor 13c18, so no current flows through capacitor 13c10, but capacitor 13c9 has a negative charge on the side with resistor 13c17, so a current flows through capacitor 13c9 for a moment.

[0047] As a result, in Figure 8, current flows from the constant voltage circuit 12 through resistors 13c14 and 13c17, as indicated by the dashed arrows. This current causes capacitor 13c9 to become positively charged on the side of resistor 13c17 and negatively charged on the side of transistor 13b1, turning on transistor 13c7.

[0048] When transistor 13c7 is turned on, current flows in the order of resistor 13c18, diode 13c11, and transistor 13c7, and no current flows to the base of transistor 13c8, so transistor 13c8 is turned off. At this time, capacitor 13c16 has the side of resistor 13c13 negative and the side of capacitor 13c10 positive, and capacitor 13c10 has the side of resistor 13c18 negative and the side of transistor 13b1 positive.

[0049] When transistor 13c8 is turned off, no current flows through resistors 13c4 and 13c6, so transistor 13c2 is turned off. Conversely, when transistor 13c7 is turned on, current flows through resistors 13c3 and 13c5, so transistor 13c1 is turned on.

[0050] As a result, transistors 13c2 and 13c8 turn off, and transistors 13c1 and 13c7 turn on. The current supplied from the step-down circuit 11 flows in the following order: transistor 13c1, resistor 13c19, tertiary winding 6b, and transistor 13c7. The current flowing through the tertiary winding 6b is a positive current, opposite in direction to the negative current that flows at timing t3 in Figure 10, as shown at timing t5 in Figure 10.

[0051] Here, when the test switch 17 is pressed, the delay circuit 16 causes current to flow to the base of transistor 16b through resistor 16c, and transistor 16b turns on (see Figure 6). However, at this point, transistor 15c is not yet turned on, so no current flows between the collector and emitter of transistor 16b.

[0052] Meanwhile, as a result of the above operation, an AC test current flows through the tertiary winding 6b. The AC test current flows between timings t11 and t12, as shown in Figure 11(c). When the test current flows, as shown in Figure 11(d), the leakage detection circuit 7 detects the current and outputs a trip command, which is a signal to drive the tripping device 8 to trip the switching contact 5, to the drive circuit unit 15.

[0053] In the drive circuit section 15, when a trip command from the leakage current detection circuit 7 is input to the base of transistor 15a, transistor 15a turns on. When transistor 15a turns on, transistor 15c also turns on, current flows to the base of transistor 15f, and transistor 15f also turns on. On the other hand, when transistor 15f turns on, the potential of capacitor 18 is connected to ground GND via transistor 15f, so the power supply to the test current circuit 13 connected to capacitor 18 stops. As a result, the operation of the test current circuit 13 stops, and the test current that was flowing through the tertiary winding 6b also stops, as shown at timing t12 in Figure 11(c). Up to this point, the operation is the same regardless of the presence or absence of the delay circuit section 16. Figures 11(e) and 12(e) show how the "test circuit OFF trigger" is output when the operation of the test current circuit 13 stops.

[0054] Next, we will compare and explain the difference in operation with and without the delay circuit 16. First, when the delay circuit 16 is not provided, as shown in Figure 12, the test current starts flowing from timing t21, and at timing t22, the leakage detection circuit 7 drives the drive circuit 15. In the drive circuit 15, as described above, transistors 15a → 15c → 15f are turned on in that order. When the delay circuit 16 is not provided, when transistor 15c is turned on, transistor 15i, which is a coil drive transistor, is also turned on along with transistor 15f, as shown in Figure 12(f). As a result, the tripping device 8 is driven, as shown in Figure 12(g).

[0055] At this time, the third DC voltage VS gradually decreases from timing t21 to t22 as the test current flows through the tertiary winding 6b, as shown in Figure 12(a). Thus, if the delay circuit 16 is not provided, the tripping device 8 is driven at timing t22 when the third DC voltage VS has decreased. Then, at timing t23, the tripping of the switching contact 5 is completed, and all signals are turned off.

[0056] In the operation described above, if the power supply voltage received from the AC circuit 3 connected to the earth leakage circuit breaker 100 decreases, the third DC voltage VS will also decrease accordingly, making it impossible to drive the tripping device 8. Therefore, if the delay circuit section 16 is not provided, the power supply voltage received from the AC circuit 3, which is capable of performing the earth leakage test, must be set to a higher voltage.

[0057] On the other hand, in Embodiment 1, even if transistor 15c is turned on, transistor 15i does not turn on at the same time. When transistor 15c is turned on, current flows through resistor 15h to capacitor 16a. As a result, charge accumulates in capacitor 16a, and as shown in timing t12~t13 of Figure 11(f), the voltage at the base of transistor 15i, which is a coil driving transistor, gradually increases.

[0058] Then, when the voltage at the base of transistor 15i reaches the ON voltage, transistor 15i turns on, and as shown in Figure 11(g), a voltage is applied to the tripping device 8, and current flows through the tripping device 8, driving the switching mechanism 4 and opening the switching contact 5. In other words, even if the leakage detection circuit 7 detects a leakage current and outputs a trip command to the drive circuit 15, transistor 15i, which directly drives the tripping device 8, turns on with a delay of (t13-t12) seconds, which corresponds to the first time mentioned above.

[0059] Next, we will explain the fluctuations of the third DC voltage VS that supplies operating power to the tripping device 8.

[0060] As shown in Figure 11(a), the third DC voltage VS gradually decreases from timing t11 to t12 as the test current is passed to the tertiary winding 6b. On the other hand, at timing t12, the leakage current detection circuit 7 outputs a trip command, stopping the test current to the tertiary winding 6b, but the tripping device 8 is not driven at that point. Because the tripping device 8 is not driven immediately, the third DC voltage VS recovers as shown in Figure 11(a), and by timing t13, it has recovered to almost its original voltage.

[0061] As described above, in Embodiment 1, the third DC voltage VS recovers for the duration of the delay time caused by the delay circuit 16. Therefore, compared to the case where the delay circuit 16 is not provided, it becomes possible to perform a leakage current test even when the power supply voltage received from the AC circuit 3 is low.

[0062] Here, the tripping time specified in the earth leakage circuit breaker 100, that is, the time from pressing the test switch 17 to the tripping of the open / closed contact 5, is referred to as the "second time." An example of the second time is 100 milliseconds. The time from pressing the test switch 17 to the earth leakage detection circuit 7 detecting an earth leakage is referred to as the "third time." The third time can be, for example, one cycle of the power supply frequency. If the power supply frequency is 50 Hz, the third time is 20 milliseconds, and if the power supply frequency is 60 Hz, the third time is 16.7 milliseconds. Therefore, if the first time mentioned above, that is, the delay time for delaying the driving of the tripping device 8 by the drive circuit unit 15 after stopping the output of the test current to the test current circuit 13, is set to approximately the third time, the sum of the first time and the third time will be approximately 40 milliseconds, which is sufficient to satisfy the tripping time of 100 milliseconds.

[0063] Furthermore, the first delay time can be set by a time constant obtained from the product of the capacitance of capacitor 16a and the resistance of resistor 15h, and a threshold base voltage at which transistor 15i turns on. Generally, in the case of a series circuit of a resistor and a capacitor, if the charging time of the capacitor is t, the voltage across the capacitor at charging time t is V2(t), the voltage applied to the capacitor is V1, the resistance of the resistor is R, and the capacitance of the capacitor is C, then the voltage V2(t) can be expressed by the following equation (1).

[0064] V2(t)=V1×(1-e^(-t / (R×C)) (1)

[0065] Here, in the circuit of the earth leakage circuit breaker 100 according to Embodiment 1, for example, let the second DC voltage VC be 5V and the threshold base voltage when the transistor 15i is turned on be 0.6V. Then, from equation (1) above, we can find the resistance value and the capacitance of the capacitor such that the time it takes to charge to 0.6V when 5V is applied to the series circuit of the resistor and capacitor is 20 msec. For example, if the resistance value is 3.3 kΩ and the capacitance is 47 μF, the first time, which is the delay time, will be 20 msec.

[0066] In Embodiment 1, as shown in Figure 11, when the transistor 15f, which is a coil drive transistor, is turned on, the operation of the test current circuit 13 stops, and the test current also stops. When the leakage current detection circuit 7 outputs a drive signal to the drive circuit section 15, the transistor 15f turns on without delay, so after the test current stops, the tripping device 8 is driven with a delay of the set delay time. As a result, although the third DC voltage VS is in a reduced state at the time the test current stops, similar to the conventional technology, the tripping device 8 is driven with a delay of the delay time, allowing the third DC voltage VS to recover during that delay time.

[0067] Furthermore, since the tripping device 8 is driven after the third DC voltage VS is restored by the delay circuit 16, it is possible to perform a leakage current test even when the power supply voltage received from the AC circuit 3 is lower.

[0068] As described above, the leakage circuit breaker according to Embodiment 1 includes switching contacts for opening and closing an AC circuit, and a leakage current sensor for detecting leakage current in the AC circuit, as well as a test circuit, a leakage detection circuit, a tripping device, a tripping device drive circuit, a power supply circuit, and a leakage test button. The test circuit sends a simulated leakage current to the leakage current sensor, and the leakage detection circuit receives the output signal from the leakage current sensor and outputs a trip command when it determines that there is a leakage current or ground fault. The tripping device trips the switching contacts, and the tripping device drive circuit supplies drive current to the tripping device in response to the trip command. The power supply circuit is powered by the AC circuit and supplies operating power to the tripping device, tripping device drive circuit, test circuit, and leakage detection circuit. The leakage test button supplies operating power to the test circuit and outputs a simulated leakage current. The tripping device drive circuit, after the leakage test button is pressed, stops the output of the simulated leakage current to the test circuit with the trip command output of the leakage detection circuit, and then trips the open / closed contacts after a first time has elapsed. With the leakage circuit breaker configured as described above, the open / closed contacts trip after a first time has elapsed after the output of the simulated leakage current to the test circuit has been stopped, so the open / closed contacts can be tripped after the third DC voltage applied to the tripping device has been restored. As a result, by using the leakage circuit breaker according to Embodiment 1, it is possible to improve the minimum operating voltage of the leakage circuit breaker.

[0069] Embodiment 2. Figure 13 is a circuit diagram showing the earth leakage circuit breaker 200 according to Embodiment 2, and Figure 14 is a circuit diagram showing the details of the drive circuit section 15 and delay circuit section 16A of the earth leakage circuit breaker 200 according to Embodiment 2. As shown in Figure 13, in the earth leakage circuit breaker 200 according to Embodiment 2, the tripping device drive circuit 50 according to Embodiment 1 is replaced by the tripping device drive circuit 50A, and inside the tripping device drive circuit 50A, the delay circuit section 16 is replaced by the delay circuit section 16A. Also, as shown in Figure 14, the delay circuit section 16A according to Embodiment 2 is provided with a switch 20 that operates in conjunction with the on, off, and tripping of the earth leakage circuit breaker 200. Note that other configurations are the same as or equivalent to those of Embodiment 1, and the same or equivalent components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0070] In a typical earth leakage circuit breaker, as described in Embodiment 1, the step-down circuit 11, which is the operating power source that drives the tripping device 8, is connected between the switching contact 5 of the earth leakage circuit breaker 100 and the load-side connection terminal 2. Therefore, if the earth leakage circuit breaker 100 is used in reverse connection, that is, with a load connected to the power supply-side connection terminal 1 and a power supply connected to the load-side connection terminal 2, the step-down circuit 11 will remain energized even if the switching contact 5 opens due to the tripping operation. As a result, the earth leakage circuit breaker 100 will continue to supply current to the tripping device 8, which could lead to burnout of the tripping device 8 or other problems.

[0071] In contrast, the earth leakage circuit breaker 200 according to Embodiment 2 is configured to quickly stop the power supply to the tripping device 8 by tripping even when the earth leakage circuit breaker 200 is used in a reverse connection state, thereby preventing unnecessary current from flowing to the tripping device 8.

[0072] Specifically, as shown in Figure 14, the delay circuit section 16A is provided with a switch 20 that includes a contact 20a, a common terminal 20b, an OFF terminal 20c, and a TRIP terminal 20d. In the switch 20, the common terminal 20b is connected to one end of the contact 20a and to earth GND. The OFF terminal 20c is connected to the other end of the contact 20a when the earth leakage circuit breaker 200 is off, and the TRIP terminal 20d is connected to the other end of the contact 20a when the earth leakage circuit breaker 200 is tripped.

[0073] In switch 20, when the earth leakage circuit breaker 200 is off, the common terminal 20b and the OFF terminal 20c are connected, and when the earth leakage circuit breaker 200 trips, the common terminal 20b and the TRIP terminal 20d are connected. Also, when the earth leakage circuit breaker 200 is on, the common terminal 20b is not connected to either the OFF terminal 20c or the TRIP terminal 20d.

[0074] Additionally, the OFF terminal 20c of switch 20 is connected to capacitor 18, and the TRIP terminal 20d of switch 20 is connected to the base of transistor 15i.

[0075] Next, the operation of the leakage current test in the leakage circuit breaker 200 according to Embodiment 2, which includes a delay circuit section 16A, will be described. The operation from when the test switch 17 is pressed until the transistor 15i turns on and the tripping device 8 is driven is the same as in Embodiment 1.

[0076] In Embodiment 2, since a switch 20 is provided, when the tripping device 8 is driven and the open / closed contact 5 trips, the switch 20 operates, and the common terminal 20b and the TRIP terminal 20d become conductive. As a result, the base of the transistor 15i becomes conductive with the ground GND, the transistor 15i turns off, and power to the tripping device 8 is stopped.

[0077] According to Embodiment 2, as described above, when the circuit breaker trips, the switch 20 is activated, turning off the transistor 15i and stopping the power supply to the tripping device 8. Therefore, even if the earth leakage circuit breaker 200 is reverse-connected, no unnecessary current will continue to flow to the tripping device 8.

[0078] As described above, in the earth leakage circuit breaker according to Embodiment 2, the tripping device drive circuit is configured such that the drive current to the tripping device is stopped by the tripping operation of the switching contacts. With an earth leakage circuit breaker configured in this way, even if the earth leakage circuit breaker is reverse-connected, it is possible to prevent the continuous flow of unnecessary current to the tripping device, thereby preventing failure of the tripping device due to reverse connection.

[0079] Embodiment 3. Figure 15 is a circuit diagram showing the earth leakage circuit breaker 300 according to Embodiment 3, and Figure 16 is a circuit diagram showing the details of the drive circuit section 15, delay circuit section 16B, and EAL 21 of the earth leakage circuit breaker 300 according to Embodiment 3. As shown in Figure 15, in the earth leakage circuit breaker 300 according to Embodiment 3, the tripping device drive circuit 50A according to Embodiment 2 is replaced with the tripping device drive circuit 50B, and inside the tripping device drive circuit 50B, the delay circuit section 16A is replaced with the delay circuit section 16B, and furthermore, an earth leakage alarm switch (hereinafter referred to as "EAL") 21, which is an accessory device of the earth leakage circuit breaker 300, is provided. Also, as shown in Figure 16, the delay circuit section 16B according to Embodiment 3 is provided with an EAL output circuit 22 for generating an input signal to the EAL 21. The EAL 21 is an accessory device that remains open when the earth leakage circuit breaker 300 trips due to an overload or short circuit fault, but closes when the earth leakage circuit breaker 300 trips due to an earth leakage. Furthermore, the other components are the same as or equivalent to those in Embodiment 2, and the same or equivalent components are denoted by the same reference numerals, with redundant explanations omitted as appropriate.

[0080] In Embodiment 2, since the switch 20 was used to stop the power supply to the tripping device 8, the EAL 21 could not be driven even if it was installed in the same configuration. Therefore, in Embodiment 3, an EAL output circuit 22 is provided.

[0081] As shown in Figure 16, in the switch 20, the OFF terminal 20c is connected to the capacitor 18, and the TRIP terminal 20d is connected to the EAL output circuit 22. Also as shown in Figure 16, the EAL output circuit 22 comprises transistors 22a, 22d, and 22g, and resistors 22b, 22c, 22e, 22f, 22h, and 22i.

[0082] In the EAL output circuit 22, the emitter of transistor 22a is connected to the second DC voltage VC. Resistor 22b is connected to the emitter of transistor 22a at one end and to the base of transistor 22a at the other end. Resistor 22c is connected to the base of transistor 22a at one end and to the TRIP terminal 20d of switch 20 at the other end. The collector of transistor 22d is connected to the base of transistor 15i and the emitter is connected to ground GND. Resistor 22e is connected to the collector of transistor 22a and to the base of transistor 22d at one end. Resistor 22f is connected to the base of transistor 22d and to ground GND at the other end. The emitter of transistor 22g is connected to ground GND and the collector is connected to EAL21. Resistor 22h is connected to the collector of transistor 22a and to the base of transistor 22g at the other end. Resistor 22i is connected to the base of transistor 22g at one end and to the emitter of transistor 22g at the other end. EAL21 is connected to the second DC voltage VC at its higher potential and to the collector of transistor 22g at its lower potential.

[0083] Next, the operation of the leakage current test in the leakage circuit breaker 300 according to Embodiment 3, which includes a delay circuit section 16B, will be described. The operation from when the test switch 17 is pressed until the transistor 15i is turned on and the tripping device 8 is driven is the same as in Embodiment 1.

[0084] In Embodiment 3, since a switch 20 and an EAL output circuit 22 are provided, when the tripping device 8 is driven and the open / closed contact 5 trips, the switch 20 operates, and the common terminal 20b and the TRIP terminal 20d become conductive. As a result, the base of transistor 15i becomes conductive with ground GND, and the base of transistor 22a is connected to ground GND via resistor 22c, so transistor 22a turns on.

[0085] When transistor 22a is turned on, the base of transistor 22d is connected to the second DC voltage VC via resistor 22e, and transistor 22d is turned on. When transistor 22d is turned on, the base of transistor 15i becomes conductive with earth GND, so transistor 15i is turned off, and power to the tripping device 8 is stopped.

[0086] Furthermore, when transistor 22a is turned on, the base of transistor 22g is connected to the second DC voltage VC via resistor 22h, and transistor 22g also turns on. When transistor 22g turns on, current flows from the second DC voltage VC to a relay (not shown) provided in EAL21, causing EAL21 to turn on.

[0087] According to Embodiment 3, as described above, when tripping occurs, the switch 20 is activated, turning on transistors 22a and 22d. When transistors 22a and 22d are turned on, transistor 15i is turned off, and power to the tripping device 8 is stopped. Therefore, even if the earth leakage circuit breaker 300 is reversed, unnecessary current will not continue to flow to the tripping device 8. Furthermore, even in the case of reversed connection, the EAL 21 can be turned on while stopping power to the tripping device 8. Accordingly, Embodiment 3 can accommodate the installation of the EAL 21.

[0088] As described above, the earth leakage circuit breaker according to Embodiment 3 is equipped with an earth leakage alarm switch that operates to close when the earth leakage circuit breaker trips due to an earth leakage current, and the tripping device drive circuit is equipped with an earth leakage alarm switch drive circuit that drives the earth leakage alarm switch when the earth leakage circuit breaker trips. With the earth leakage circuit breaker according to Embodiment 3, an earth leakage alarm switch can be applied to the configuration of the earth leakage circuit breaker according to Embodiment 2, so that the effects of Embodiment 2 can be enjoyed while it is possible to identify whether the switching contacts operated due to an earth leakage current or a ground fault and notify the user or worker.

[0089] Embodiment 4. Figure 17 is a circuit diagram showing the earth leakage circuit breaker 400 according to Embodiment 4, and Figure 18 is a circuit diagram showing the details of the drive circuit section 15C and delay circuit section 16 of the earth leakage circuit breaker 400 according to Embodiment 4. As shown in Figure 17, in the earth leakage circuit breaker 400 according to Embodiment 4, the tripping device drive circuit 50 according to Embodiment 1 is replaced by the tripping device drive circuit 50C, and inside the tripping device drive circuit 50C, the drive circuit section 15 is replaced by the drive circuit section 15C. Also, as shown in Figure 18, in the drive circuit section 15C according to Embodiment 4, a latch circuit 15C1 is provided between the earth leakage detection circuit 7 and the transistor 15c in the drive circuit section 15 according to Embodiment 1. Note that other configurations are the same as or equivalent to those of Embodiment 1, and the same or equivalent components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0090] The earth leakage circuit breaker 400 according to Embodiment 4 is configured to ensure that an earth leakage test can be reliably performed even when the output time from the earth leakage detection circuit 7 is insufficient, i.e., when the output time is short, when an earth leakage current is detected. The details of the earth leakage circuit breaker 400 according to Embodiment 4 will be described below.

[0091] As mentioned above, the drive circuit section 15C includes a latch circuit 15C1. The latch circuit 15C1 includes transistors 15k and 15m, as shown in Figure 18. The base of transistor 15k is connected to the output of the leakage current detection circuit 7, and its emitter is connected to ground GND. The base of transistor 15m is connected to the collector of transistor 15k, the collector of transistor 15m is connected to the base of transistor 15k, and its emitter is connected to resistor 15b.

[0092] Next, the operation of the leakage current test in the leakage circuit breaker 400 according to Embodiment 4, which includes a drive circuit section 15C, will be described.

[0093] When the leakage current detection circuit 7 detects a leakage current and changes its output, the trip command output, from Low to High, transistor 15k turns on. When transistor 15k turns on, transistor 15m also turns on. When transistor 15m turns on, a second DC voltage VC is applied to the base of transistor 15k via resistors 15d and 15b. Therefore, even if the trip command output of the leakage current detection circuit 7 transitions from High to Low, transistors 15m and 15k remain latched in the ON position. When transistors 15m and 15k turn on, transistor 15c turns on. After transistor 15c turns on, the operation is the same as in Embodiment 1.

[0094] Figures 17 and 18 show a configuration in which the above-described drive circuit section 15C is applied to the tripping device drive circuit 50 according to Embodiment 1. However, it is also possible to apply it to the tripping device drive circuit 50A described in Embodiment 2, and also to the tripping device drive circuit 50B described in Embodiment 3.

[0095] According to Embodiment 4, as described above, when transistor 15f is turned on, the operation of the test current circuit 13 stops, and the test current also stops. Also, as described above, when the leakage current detection circuit 7 outputs a trip command to the drive circuit 15C, transistor 15f turns on without delay, but transistor 15i, which directly drives the tripping device 8, turns on with a delay of a first time. As a result, when the test current is stopped, the third DC voltage VS is in a low state, but the third DC voltage VS can be recovered during the first delayed time. Then, after the third DC voltage VS is recovered by the delay circuit 16, the tripping device 8 is driven, so that a leakage current test can be performed even when the power supply voltage received from the AC circuit 3 is lower. In addition, since the latch circuit 15C1 latches the trip command output of the leakage current detection circuit 7, a leakage current test can be reliably performed even when the output time of the leakage current detection circuit 7 is short.

[0096] As described above, according to the leakage circuit breaker of Embodiment 4, a latch circuit is provided on the output side of the leakage detection circuit, so that a leakage test can be reliably performed even when the output time of the leakage detection circuit is short.

[0097] Furthermore, the configurations shown in the above embodiments are merely examples, and it is possible to combine them with other known technologies, combine different embodiments, and omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of Symbols]

[0098] 1 Power supply side connection terminal, 2 Load side connection terminal, 3 AC circuit, 4 Switching mechanism, 5 Switching contact, 6 Zero-phase current transformer, 6a Secondary winding, 6b Tertiary winding, 7 Leakage current detection circuit, 8 Tripping device, 9 Impedance element, 10 Single-phase full-wave rectifier circuit, 11 Step-down circuit, 11a FET, 11b First Zener diode, 11c First resistor, 12 Constant voltage circuit, 12a, 13b1, 13c1, 13c2, 13c7, 13c8, 15a, 15c, 15f, 15i, 15k, 15m, 16b, 22a, 22d, 22g Transistor, 12b Second Zener diode, 12c Second resistor, 12d, 13c9, 13c10, 13c15, 13c16, 16a, 18, 19 Capacitor, 13 Test current circuit, 13a Zener diode, 13b DC pulse generation circuit, 13b2, 13b3, 13b4, 13c3, 13c4, 13c5, 13c6, 13c13, 13c14, 13c17, 13c18, 13c19, 15b, 15d, 15e, 15g, 15h, 15j, 16c, 16d, 22b, 22c, 22e, 22f, 22h, 22i Resistor, 13c H-bridge circuit, 13c11, 13c12, 14 Diode, 15, 15C Drive circuit section, 15C1 Latch circuit, 16, 16A, 16B Delay circuit section, 17 Test switch, 20 Switch, 20a Contact, 20b Common terminal, 20c OFF terminal, 20d TRIP terminal, 21 EAL, 22 EAL output circuit, 50, 50A, 50B, 50C tripping device drive circuit, 100, 200, 300, 400 earth leakage circuit breaker, D1, D2, D3, D4 rectifier diode.

Claims

1. Switching contacts that open and close AC circuits, A leakage current sensor for detecting leakage current in the aforementioned AC circuit, A test circuit that applies a simulated leakage current to the aforementioned leakage current sensor, A leakage current detection circuit receives the output signal from the leakage current sensor and, when it determines that there is a leakage current or ground fault, outputs a trip command. A tripping device for tripping the aforementioned open / closed contact, A tripping device drive circuit that supplies drive current to the tripping device in response to the trip command, A power supply circuit, which is powered by the aforementioned AC circuit and supplies operating power to the tripping device, the tripping device drive circuit, the test circuit, and the leakage detection circuit, The system includes a leakage test button that supplies power to the test circuit and outputs the simulated leakage current, After the leakage test button is pressed, the tripping device drive circuit, using the trip command output of the leakage detection circuit, stops the output of the simulated leakage current to the test circuit, and then trips the switching contact after a first time has elapsed. A residual current circuit breaker characterized by the following features.

2. The first time is set within the second time period, which is defined as the time from pressing the leakage test button to the trip. The earth leakage circuit breaker according to feature 1.

3. The tripping device drive circuit is configured such that the drive current to the tripping device is stopped when the switching contacts trip. A leakage circuit breaker according to feature 1 or 2.

4. The system includes a ground fault alarm switch that operates to close when the ground fault circuit breaker trips due to a ground fault, The tripping device drive circuit includes a leakage alarm switch drive circuit that drives the leakage alarm switch when the leakage circuit breaker trips. The earth leakage circuit breaker according to feature 3.

5. A latch circuit is provided on the output side of the aforementioned leakage current detection circuit. A leakage circuit breaker according to feature 1 or 2.

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