JP7526139B2 - Earth leakage detection circuits, earth leakage breakers and distribution boards - Google Patents

Description

This disclosure relates to a leakage current detection circuit, a leakage current interrupter, and a distribution board, and more specifically to a leakage current detection circuit, a leakage current interrupter, and a distribution board that have an overcurrent protection function.

Patent Document 1 discloses a circuit breaker that includes a first contact that cuts off the main circuit, a second contact that cuts off the power supply circuit to a leakage detection unit that detects leakage current, and a surge absorbing element through which an overcurrent caused by a lightning surge or the like flows.

JP 2020-167089 A

In a circuit breaker such as that described in Patent Document 1, there is a possibility that an overcurrent caused by a lightning surge or the like may flow through the second contact portion.

The present disclosure has been made in consideration of the above-mentioned reasons, and aims to provide a leakage current detection circuit, a leakage current breaker, and a distribution board that can protect the contact part that cuts off the power supply path to the leakage current detection part from an overcurrent (surge current).

A leakage current detection circuit according to one aspect of the present disclosure includes a first terminal, a second terminal, a third terminal, a fourth terminal, a first electric circuit, a second electric circuit, a first contact portion and a second contact portion, a leakage current detection portion, a third contact portion, and a surge absorber. The first terminal and the second terminal are connected to a first connection object which is one of a power source and a load. The third terminal and the fourth terminal are connected to a second connection object which is the other of the power source and the load. The first electric circuit connects the first terminal and the third terminal. The second electric circuit connects the second terminal and the fourth terminal. The first contact portion and the second contact portion are provided on the first electric circuit and the second electric circuit, respectively. The leakage current detection portion is connected between a first input portion provided between the first contact portion and the first terminal, and a second input portion provided between the second contact portion and the fourth terminal. The leakage current detection unit switches the first contact unit and the second contact unit from on to off when it detects the occurrence of leakage current. The third contact unit includes a first end and a second end that is the other end of the first end, the first end being connected to the first input unit or the second input unit, and the second end being connected to the leakage current detection unit. The third contact unit switches on/off in conjunction with the on/off switching of the first contact unit and the second contact unit. The surge absorber is connected between the first electric circuit and the second electric circuit without passing through the third contact unit.

The earth leakage circuit breaker according to one aspect of the present disclosure includes the earth leakage detection circuit.

The distribution board according to one embodiment of the present disclosure is equipped with the earth leakage circuit breaker.

The present disclosure has the advantage that the contact portion (i.e., the third contact portion) that cuts off the power supply path to the earth leakage detection portion can be protected from surge currents.

FIG. 1 is a schematic circuit diagram of a leakage current detection circuit according to an embodiment of the present invention. FIG. 2 is a schematic circuit diagram of the earth leakage detection circuit. FIG. 3 is a schematic circuit diagram of the earth leakage detection circuit of the above embodiment. FIG. 4 is a schematic front view showing the inside of the distribution board according to the embodiment. FIG. 5 is a schematic front view of the earth leakage circuit breaker according to the embodiment. FIG. 6 is a schematic circuit diagram of a leakage current detection circuit according to the first modification. FIG. 7 is a schematic circuit diagram of a leakage current detection circuit according to the second modification. FIG. 8 is a schematic circuit diagram of a leakage current detection circuit according to the third modification.

A leakage current detection circuit 1, a leakage current breaker 11, and a distribution board 12 according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the embodiment and modified examples described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiment and modified examples. Even if the embodiment and modified examples are different from the embodiment and modified examples, various modifications can be made according to the design, etc., as long as they do not deviate from the technical concept of the present disclosure. In addition, the following embodiments (including modified examples) may be realized in appropriate combinations.

(1) Overview First, an overview of a leakage current detection circuit 1 according to the present embodiment will be described with reference to FIG.

The leakage current detection circuit 1 includes a first terminal 41 and a second terminal 42 that are connected to a first connection object, which is one of the power source 2 and the load 3. In this embodiment, the first connection object is, for example, the power source 2. The leakage current detection circuit 1 also includes a third terminal 43 and a fourth terminal 44 that are connected to a second connection object, which is the other of the power source 2 and the load 3. In this embodiment, the second connection object is, for example, the load 3. Note that the first terminal 41 and the second terminal 42 may be connected to the load 3, and the third terminal 43 and the fourth terminal 44 may be connected to the power source 2.

The first terminal 41 and the third terminal 43 are connected by a first electric circuit C1, and the second terminal 42 and the fourth terminal 44 are connected by a second electric circuit C2. In other words, the first electric circuit C1 and the second electric circuit C2 are power supply paths from the power source 2 to the load 3. In addition, the first electric circuit C1 and the second electric circuit C2 are provided with a first contact portion S1 and a second contact portion S2, respectively.

The leakage current detection circuit 1 also includes a leakage current detection unit 5, a third contact unit S3, and a surge absorber (first surge absorber 61).

The leakage current detection unit 5 is connected between a first input unit 71 provided between the first contact unit S1 and the first terminal 41, and a second input unit 72 provided between the second contact unit S2 and the fourth terminal 44. The leakage current detection unit 5 operates by receiving power from the power source 2. The leakage current detection unit 5 monitors the current flowing between the power source 2 and the load 3 via the first electric circuit C1 and the second electric circuit C2, and when it detects the occurrence of a leakage current, it switches the first contact unit S1 and the second contact unit S2 from on to off. This makes it possible to stop the power supply from the power source 2 to the load 3 when a leakage current occurs.

The third contact portion S3 includes a first end portion (end portion P1) and a second end portion (end portion P2) which is the other end of the first end portion (end portion P1). In this embodiment, the end portion P1 is connected to the first input portion 71. The end portion P2 is connected to the leakage current detection portion 5. That is, the third contact portion S3 is connected between the first input portion 71 and the leakage current detection portion 5. The end portion P1 may be connected to the second input portion 72, or the third contact portion S3 may be connected between the second input portion 72 and the leakage current detection portion 5. The third contact portion S3 switches on/off in conjunction with the switching on/off of the first contact portion S1 and the second contact portion S2. For example, in this embodiment, when the first contact portion S1 and the second contact portion S2 are on, the third contact portion S3 is also on, and when the first contact portion S1 and the second contact portion S2 are off, the third contact portion S3 is also off. When the third contact S3 is on, power is supplied from the power source 2 to the leakage current detection unit 5. When the third contact S3 is switched off, power supply from the power source 2 to the leakage current detection unit 5 is stopped.

The first surge absorber 61 is connected between the first electric circuit C1 and the second electric circuit C2 without passing through the third contact portion S3. As a result, when a surge voltage is applied between the first electric circuit C1 and the second electric circuit C2, for example due to a lightning strike, the surge current flows through the first surge absorber 61 without passing through the third contact portion S3, so that the third contact portion S3 can be protected from the surge current.

(2) Details Hereinafter, details of the earth leakage detection circuit 1 and the earth leakage breaker 11 according to the embodiment will be described with reference to FIGS.

(2.1) Configuration of the Earth Leakage Detection Circuit The configuration of the earth leakage detection circuit 1 will now be described with reference to FIG.

The earth leakage detection circuit 1 according to this embodiment includes a first terminal 41 to a fourth terminal 44. The first terminal 41 and the second terminal 42 are connected to the power source 2. In this embodiment, the power source 2 is, for example, a commercial AC power source. The third terminal 43 and the fourth terminal 44 are connected to the load 3. The AC power output by the power source 2 is supplied to the load 3 via a first electric circuit C1 that connects the first terminal 41 and the third terminal 43, and a second electric circuit that connects the second terminal 42 and the fourth terminal 44. The earth leakage detection circuit 1 can also operate in a state in which the first terminal 41 and the second terminal 42 are connected to the load 3 and the third terminal 43 and the fourth terminal 44 are connected to the power source 2, and this connection state is sometimes called a "reverse connection state."

The first electrical circuit C1 and the second electrical circuit C2 are provided with a first contact portion S1 and a second contact portion S2, respectively. The on/off switching operation of the first contact portion S1 and the second contact portion S2 will be described later.

The earth leakage detection circuit 1 includes an earth leakage detection unit 5, a third contact unit S3, and a first surge absorber 61. The earth leakage detection circuit 1 further includes a trip mechanism unit 8, a test unit 9, and a zero-phase current transformer 10 (ZCT).

The leakage current detection unit 5 has, for example, a rectifier circuit that rectifies the AC voltage input from the power source 2 to a DC voltage, a smoothing circuit that smoothes the output voltage of the rectifier circuit, and a computer system having a processor and memory provided after the smoothing circuit. The computer system functions as the leakage current detection unit 5 when the processor executes a program stored in the memory. The program executed by the processor is pre-recorded in the memory of the computer system here, but may be recorded on a recording medium such as a memory card and provided, or may be provided via a telecommunications line such as the Internet. Furthermore, the leakage current detection unit 5 is not limited to being configured with a digital IC such as a processor, and may be configured with an analog IC.

The leakage current detection unit 5 is connected between a first input unit 71 provided between the first contact unit S1 and the first terminal 41, and a second input unit 72 provided between the second contact unit S2 and the fourth terminal 44. In detail, the leakage current detection unit 5 has terminals T1 to T4, with terminal T1 connected to the first input unit 71 and terminal T2 connected to the second input unit 72. The leakage current detection unit 5 monitors the current flowing between the power source 2 and the load 3 via the first electrical circuit C1 and the second electrical circuit C2, and detects leakage current.

The third contact portion S3 is connected between the terminal T1 of the leakage current detection portion 5 and the first input portion 71. In detail, the third contact portion S3 includes an end P1 and an end P2, with the end P1 being connected to the first input portion 71 and the end P2 being connected to the terminal T1. The third contact portion S3 is switched on/off by the trip mechanism portion 8 described later in conjunction with the on/off switching of the first contact portion S1 and the second contact portion S2.

The first surge absorber 61 is a varistor that protects the earth leakage detection unit 5 from a surge voltage caused by lightning or the like, and is, for example, a Zinc Oxide Nonlinear Resistor (ZNR). Note that the first surge absorber 61 is not limited to a varistor, and may be a gas discharge tube (GDT) or an avalanche diode, etc.

The first surge absorber 61 is connected between the first electric circuit C1 and the second electric circuit C2 without passing through the third contact portion S3. In detail, the first surge absorber 61 includes an end P3 and an end P4, and the end P3 is connected between the second input portion 72 and the end P5 of the trip coil 81 described later, and the end P4 is connected to the first input portion 71. The end P4 is also connected to the end P1 of the third contact portion S3. That is, the end P3 is connected to the second input portion 72, and the end P4 is connected between the first input portion 71 and the end P1 of the third contact portion S3. As a result, the surge current generated between the first electric circuit C1 and the second electric circuit C2 flows to the first surge absorber 61 without passing through the third contact portion S3, so that the leakage current detection portion 5 and the third contact portion S3 can be protected from the surge current.

The trip mechanism 8 is connected between the terminal T2 of the leakage current detection unit 5 and the second input unit 72. The trip mechanism 8 has a function of switching the first contact S1, the second contact S2, and the third contact S3 from on to off (tripping) when the leakage current detection unit 5 detects the occurrence of leakage current.

The trip mechanism unit 8 includes, for example, a trip coil 81, a switching unit 82, and a link unit 83.

The trip coil 81 is a coil connected between the terminal T2 of the earth leakage detection unit 5 and the second input unit 72. In detail, the trip coil 81 includes an end P5 and an end P6, where the end P5 is connected to the second input unit 72 and the end P6 is connected to the terminal T2 of the earth leakage detection unit 5.

The switching unit 82 switches the first contact S1 and the second contact S2 from on to off when the leakage current detection unit 5 detects the occurrence of leakage current. The switching unit 82 includes, for example, a movable core made of a magnetic material, a pushing pin connected to the movable core, and a switching mechanism that cooperates with the pushing pin to switch the first contact S1 and the second contact S2 from on to off. When the leakage current detection unit 5 detects the occurrence of leakage current based on the output of the zero-phase current transformer 10, it passes a driving current through the trip coil 81. This changes the magnetic flux that penetrates the movable core housed in the coil bobbin of the trip coil 81, and the movable core moves in a direction that cancels the change in magnetic flux. The pushing pin moves together with the movable core. The switching mechanism of the switching unit 82 cooperates with the movement of the pushing pin to switch the first contact S1 and the second contact S2 from on to off.

The link unit 83 switches the third contact unit S3 from on to off in conjunction with the switching of the first contact unit S1 and the second contact unit S2 from on to off by the switching unit 82. Note that the trip coil 81, the switching unit 82, and the link unit 83 are not essential components of the trip mechanism unit 8, and the function of the trip mechanism unit 8 may be realized by a different configuration.

The test unit 9 is connected between the first input unit 71 and the second input unit 72. The test unit 9 includes a test switch 91 and a resistor 92. In detail, the test switch 91 includes an end P7 and an end P8, the end P7 is connected to an end P10 of the resistor 92 described later, and the end P8 is connected between the first input unit 71 and the end P1 of the third contact unit S3. The test switch 91 is a normally-off switch, and is turned on by a user when testing the leakage detection function of the leakage detection unit 5 and the trip function of the trip mechanism unit 8. The resistor 92 includes an end P9 and an end P10, the end P9 is connected between the second input unit 72 and the end P5 of the trip coil 81, and the end P10 is connected to the end P7 of the test switch 91. The test of the leakage detection function of the leakage detection unit 5 by the test switch 91 will be described in detail in "(2.2.2) Test operation".

The zero-phase current transformer 10 has an annular core 101 and a coil 102, and has a structure in which the coil 102 is wound around a part of the annular core 101. The coil 102 is connected between terminals T3 and T4 of the earth leakage detection unit 5. A first electric circuit C1, a second electric circuit C2, and a third electric circuit C3 are passed through the holes of the annular core 101. Here, the third electric circuit C3 is an electric circuit that connects the end P10 of the resistor 92 and the end P7 of the test switch 91. Here, the first electric circuit C1 and the second electric circuit C2 are passed so that the directions of current flow are opposite to each other. The operation of the zero-phase current transformer 10 will be explained in detail in "(2.2.1) Earth leakage detection operation".

In this embodiment, the leakage current detection circuit 1 further includes a second surge absorber 62 in addition to the first surge absorber 61. The second surge absorber 62 includes an end P11 and an end P12, with the end P11 being connected between the end P6 of the trip coil 81 and the terminal T2 of the leakage current detection unit 5, and the end P12 being connected between the end P2 of the third contact portion S3 and the terminal T1 of the leakage current detection unit 5.

(2.2) Operation of the Earth Leakage Detection Circuit Hereinafter, each operation of the earth leakage detection circuit according to the embodiment will be described with reference to FIGS.

(2.2.1) Leakage Detection Operation Hereinafter, the leakage detection operation in the leakage detection circuit 1 will be described with reference to FIG.

When the first contact S1, the second contact S2, and the third contact S3 are on, no leakage current occurs, and power is normally supplied from the power source 2 to the load 3, the current I1 flowing through the first circuit C1 and the current I2 flowing through the second circuit C2 are equal. Here, as described above, the first circuit C1 and the second circuit C2 pass through the inside of the annular core 101 of the zero-phase current transformer 10 so that the currents I1 and I2 flow in opposite directions. Therefore, the magnetic fluxes created by the currents I1 and I2 are offset, and no current flows through the coil 102. On the other hand, when a leakage current occurs, the currents I1 and I2 become unbalanced, and a current corresponding to the difference between the currents I1 and I2 flows through the coil 102. The leakage current detection unit 5 can detect the occurrence of a leakage current by detecting the current flowing through this coil 102.

When the leakage current detection unit 5 detects the occurrence of leakage current, it passes a drive current through the trip coil 81, causing the trip mechanism unit 8 to switch the first contact unit S1, the second contact unit S2, and the third contact unit S3 from on to off. When the first contact unit S1, the second contact unit S2, and the third contact unit S3 switch from on to off, the power supply from the power source 2 to the load 3 is cut off, thereby protecting the load 3.

(2.2.2) Test Operation Next, the test operation of the earth leakage detection function and the trip function by the test unit 9 will be described with reference to FIG.

The test unit 9 is configured to pass a pseudo leakage current I3 through the third circuit C3 passing through the inside of the annular core 101, and to cause the trip mechanism unit 8 to switch the first contact unit S1, the second contact unit S2, and the third contact unit S3 from on to off.

When the first contact S1, the second contact S2, and the third contact S3 are on, no leakage current is occurring, and power is being normally supplied from the power source 2 to the load 3, the user of the leakage current detection circuit 1 can test whether the leakage current detection function and the trip function of the leakage current detection circuit 1 are operating normally.

As shown in FIG. 2, a user performing a test switches the test switch 91 from off to on. When the test switch 91 is switched from off to on, a current flows from the power source 2 through the test switch 91 and resistor 92, and a pseudo leakage current I3 flows in the third electric circuit C3 passing through the inside of the annular core 101. At this time, the currents I1 and I2 passing through the first electric circuit C1 and the second electric circuit C2, respectively, are balanced, but the pseudo leakage current I3 flows through the third electric circuit C3, causing the currents I1, I2, and pseudo leakage current I3 to become unbalanced, and a current corresponding to the pseudo leakage current I3 flows in the coil 102. The leakage current detection unit 5 can detect the pseudo leakage current by detecting the current flowing in this coil 102.

If the leakage current detection unit 5 and the trip mechanism unit 8 are normal, when the leakage current detection unit 5 detects a pseudo leakage current, it passes a drive current through the trip coil 81, and the trip mechanism unit 8 switches the first contact unit S1, the second contact unit S2, and the third contact unit S3 from on to off. Therefore, the user can check whether the leakage current detection function and the trip function are operating normally.

(2.2.3) Surge Voltage Absorption Operation Hereinafter, the surge voltage absorption operation in the leakage current detection circuit 1 will be described with reference to FIG.

Here, it is assumed that the first contact S1, the second contact S2, and the third contact S3 are on, power is being supplied from the power source 2 to the load 3, and a surge voltage is applied between the first electric circuit C1 and the second electric circuit C2, for example, due to a lightning strike.

The surge voltage applied between the first electric circuit C1 and the second electric circuit C2 is also applied to the first surge absorber 61. At this time, if the surge voltage is greater than the varistor voltage of the first surge absorber 61, which is a varistor, the electrical resistance of the first surge absorber 61 drops suddenly, and a surge current Is flows through the first surge absorber 61. The surge current that flows through the first surge absorber 61 flows to the power source 2 via the first electric circuit C1 or the second electric circuit C2. This makes it possible to prevent the surge current from flowing into the leakage current detection unit 5. In addition, at this time, the surge current can flow without passing through the third contact portion S3, so that the third contact portion S3 can be protected from the surge current.

The leakage current detection unit 5 may be configured to detect the occurrence of a surge current. In this case, when the leakage current detection unit 5 detects the occurrence of a surge current, it passes a drive current through the trip coil 81, causing the trip mechanism unit 8 to switch the first contact unit S1, the second contact unit S2, and the third contact unit S3 from on to off.

(2.3) Regarding the reverse connection state Since the leakage current detection circuit 1 according to this embodiment has the third contact portion S3, it can also operate in a reverse connection state in which the first terminal 41 and the second terminal 42 are connected to the load 3 and the third terminal 43 and the fourth terminal 44 are connected to the power source 2.

Now, let us consider a case where the leakage current detection circuit 1 does not have the third contact portion S3. If a ground fault or the like occurs on the load 3 side connected to the first terminal 41 and the second terminal 42 in the reverse connection state, a ground fault current may flow through the leakage current detection portion 5 even if the first contact portion S1 and the second contact portion S2 are off.

In contrast, in this embodiment, the leakage current detection circuit 1 is equipped with a third contact portion S3. When the first contact portion S1 and the second contact portion S2 are off, the third contact portion S3 is also off. Therefore, even if a ground fault or the like occurs on the load 3 side, it is possible to prevent a ground fault current from flowing through the third contact portion S3, improving reliability.

(2.4) Earth Leakage Circuit Breaker Hereinafter, an earth leakage circuit breaker 11 including an earth leakage detection circuit 1 will be described with reference to FIGS. 1, 4 and 5. FIG.

The earth leakage circuit breaker 11 is provided with an earth leakage detection circuit 1, and has the function of detecting a leakage current and interrupting the flow of electricity through the first circuit C1 and the second circuit C2, which are the power supply paths from the power source 2 to the load 3. As shown in FIG. 4, the earth leakage circuit breaker 11 is used in a distribution board 12 installed in a house, for example. The location where the distribution board 12 is installed is not limited to a house, and may be a non-residential location, such as an office, a store, a factory, or a hospital. The earth leakage circuit breaker 11 is attached to a mounting surface 131 of a DIN rail 13 provided in the distribution board 12. The mounting surface 131 is, for example, the surface of the DIN rail 13 that faces the earth leakage circuit breaker 11.

The earth leakage circuit breaker 11 can be used as either a branch breaker or a main breaker. As shown in FIG. 4, among the multiple earth leakage circuit breakers 11 attached to the DIN rail 13 of the distribution board 12, for example, the earth leakage circuit breaker 11 (11M) attached to the far right side functions as the main breaker, and the other earth leakage circuit breakers 11 (11B) function as branch breakers. Note that the wiring inside the distribution board 12 is not shown in FIG. 4.

As shown in FIG. 5, the earth leakage circuit breaker 11 has a first terminal 111 and a second terminal 112 at its upper end, and a third terminal 113 and a fourth terminal 114 at its lower end. The earth leakage circuit breaker 11 also has an operating handle 115 and a test button 116 on the operating surface 110.

The first terminal 111 to the fourth terminal 114 correspond to the first terminal 41 to the fourth terminal 44, respectively, of the earth leakage detection circuit 1 shown in FIG. 1. In other words, the first terminal 111 and the second terminal 112 are connected to the power source 2, and the third terminal 113 and the fourth terminal 114 are connected to the load 3. The earth leakage breaker 11 can also operate when the first terminal 111 and the second terminal 112 are connected to the load 3, and the third terminal 113 and the fourth terminal 114 are connected to the power source 2.

The operating handle 115 is a part of the link unit 83 of the trip mechanism unit 8, and operates in conjunction with the on/off of the first contact unit S1 and the second contact unit S2. For example, when the first contact unit S1 and the second contact unit S2 are on, the operating handle 115 is in an upwardly tilted state (on state), and when the first contact unit S1 and the second contact unit S2 are switched off, the operating handle 115 is in a downwardly tilted state (off state) as shown in FIG. 5. The third contact unit S3 is configured to operate in conjunction with the operating handle 115. When the operating handle 115 is in the on state, the third contact unit S3 is on, and when the operating handle 115 is switched to the off state, the third contact unit S3 is off. As a result, when the leakage current detection circuit 1 detects, for example, a leakage current, the first contact unit S1, the second contact unit S2, and the third contact unit S3 are switched from on to off, and the operating handle 115 is switched from on to off. In addition, when the first contact S1, the second contact S2, and the third contact S3 are on, the first contact S1, the second contact S2, and the third contact S3 can be switched off by switching the operating handle 115 from the on state to the off state. This makes it possible to prevent the generation of a surge current by switching the operating handle 115 to the off state before, for example, a lightning strike occurs. In addition, when the first contact S1, the second contact S2, and the third contact S3 are off, the first contact S1, the second contact S2, and the third contact S3 can be switched on by switching the operating handle 115 from the off state to the on state. This makes it possible for the user to operate the operating handle 115 to resume the supply of power from the power source 2 to the load 3, for example, when the cause of the leakage current is identified and safety is confirmed after the leakage detection circuit 1 switches the first contact S1, the second contact S2, and the third contact S3 from on to off.

The test button 116 switches the test switch 91 of the earth leakage detection circuit 1 on and off. By pressing the test button 116, the user of the earth leakage circuit breaker 11 can turn on the test switch 91 and test whether the earth leakage detection function and the trip function of the earth leakage detection circuit 1 are operating normally.

(3) Modifications The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, a function similar to that of the earth leakage detection circuit 1 according to the above embodiment may be embodied in a control method for the earth leakage detection circuit 1, a computer program, or a non-transitory recording medium having a computer program recorded thereon, etc.

Below, we will list some variations of the above embodiment. The variations described below can be applied in appropriate combinations.

(3.1) Modification 1
6, this modified example 1 differs from the above embodiment in that an end P4 of the first surge absorber 61 is connected between the first contact portion S1 and the third terminal 43. Hereinafter, the same components as those in the embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate.

In this modified example 1, as shown in FIG. 6, the third input 73 is provided between the first contact S1 and the third terminal 43, and the end P4 of the first surge absorber 61 is connected to the third input 73. The end P3 of the first surge absorber 61 is connected to the second input 72, and the first surge absorber 61 is connected between the second input 72 and the third input 73. By adopting the above-mentioned configuration, the earth leakage detection circuit 1 according to this modified example 1 has the advantage that a withstand voltage test of the first contact S1 and the second contact S2 can be performed, for example, by the following method.

When conducting a voltage resistance test on the first contact S1 and the second contact S2 in the leakage current detection circuit 1, for example, a pulse voltage of several kV is applied between the shorted first terminal 41 and the shorted second terminal 42 and the shorted third terminal 43 and the shorted fourth terminal 44. At this time, the first contact S1 and the second contact S2 are switched from on to off. This allows confirmation of whether or not insulation breakdown occurs when the first contact S1 and the second contact S2 are off.

At this time, in this modified example 1, end P3 of the first surge absorber 61 is connected to the second input portion 72, and end P4 is connected to the third input portion 73, thereby preventing a pulse voltage from being applied to the first surge absorber 61 during the voltage resistance test.

(3.2) Modification 2
As shown in FIG. 7, the present modified example 2 differs from the above embodiment and modified example 1 in that an end P3 of a first surge absorber 61 is connected between the second contact portion S2 and the second terminal 42.

In this modification 2, as shown in FIG. 7, the fourth input 74 is provided between the second contact S2 and the second terminal 42, and the end P3 of the first surge absorber 61 is connected to the fourth input 74. The end P4 of the first surge absorber 61 is connected to the first input 71, and the first surge absorber 61 is connected between the first input 71 and the fourth input 74. By adopting the above-mentioned configuration, the earth leakage detection circuit 1 according to this modification 2 has the advantage that a withstand voltage test of the first contact S1 and the second contact S2 can be performed in the same manner as described in the modification 1.

(3.3) Modification 3
The present modification 3 differs from the above-described embodiment, modification 1, and modification 2 in that the end P1 is connected to the second input portion 72 as shown in FIG. 8, and the third contact portion S3 is connected between the second input portion 72 and the earth leakage detection portion 5. In this case, the terminal T1 of the earth leakage detection portion 5 is connected to the second input portion 72, and the third contact portion S3 is connected between the terminal T1 and the second input portion 72. Also in this case, the terminal T2 of the earth leakage detection portion 5 is connected to the first input portion 71. That is, the trip mechanism portion 8 is connected between the terminal T2 and the first input portion 71. Note that even when the end P1 of the third contact portion S3 is connected to the second input portion 72 as in the present modification 3, the earth leakage detection portion 5 operates normally by the AC power supplied from the power source 2.

(3.4) Other Modifications Other modifications of the embodiment are listed below. The following modifications may be implemented in appropriate combination.

The leakage current detection unit 5 of the leakage current detection circuit 1 in the present disclosure includes a computer system. The computer system is mainly composed of a processor and a memory as hardware. The processor executes a program recorded in the memory of the computer system to realize the function of the leakage current detection unit 5 of the leakage current detection circuit 1 in the present disclosure. The program may be pre-recorded in the memory of the computer system, provided through an electric communication line, or provided by recording it in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits such as IC or LSI referred to here are called by different names depending on the degree of integration, and include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, a field programmable gate array (FPGA) that is programmed after the LSI is manufactured, or a logic device that allows reconfiguration of the connection relationship within the LSI or reconfiguration of the circuit partition within the LSI, can also be used as a processor. The multiple electronic circuits may be integrated into one chip, or may be distributed among multiple chips. The multiple chips may be integrated into one device, or may be distributed among multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

In addition, it is not essential for the earth leakage detection circuit 1 that multiple functions are concentrated in one housing, and the components of the earth leakage detection circuit 1 may be distributed across multiple housings. Furthermore, at least some of the functions of the earth leakage detection circuit 1, for example, some of the functions of the earth leakage detection unit 5, may be realized by the cloud (cloud computing), etc. Conversely, multiple functions of the earth leakage detection circuit 1 may be concentrated in one housing, as in the earth leakage circuit breaker 11 of the above embodiment.

(4) Summary As described above, the leakage current detection circuit (1) according to the first aspect includes the first terminal (41), the second terminal (42), the third terminal (43), the fourth terminal (44), the first electric circuit (C1), the second electric circuit (C2), the first contact portion (S1) and the second contact portion (S2), the leakage current detection portion (5), the third contact portion (S3), and the surge absorber (61). The first terminal (41) and the second terminal (42) are connected to a first connection object, which is one of the power source (2) and the load (3). The third terminal (43) and the fourth terminal (44) are connected to a second connection object, which is the other of the power source (2) and the load (3). The first electric circuit (C1) connects the first terminal (41) and the third terminal (43). The second electric circuit (C2) connects the second terminal (42) and the fourth terminal (44). The first contact portion (S1) and the second contact portion (S2) are provided on the first electric circuit (C1) and the second electric circuit (C2), respectively. The leakage current detection portion (5) is connected between a first input portion (71) provided between the first contact portion (S1) and the first terminal (41) and a second input portion (72) provided between the second contact portion (S2) and the fourth terminal (44). When the leakage current detection portion (5) detects the occurrence of a leakage current, it switches the first contact portion (S1) and the second contact portion (S2) from on to off, respectively. The third contact portion (S3) includes a first end portion (P1) and a second end portion (P2) which is the other end of the first end portion (P1), the first end portion (P1) is connected to the first input portion (71) or the second input portion (72), and the second end portion (P2) is connected to the earth leakage detection portion (5). The third contact portion (S3) is switched on/off in conjunction with the switching on/off of the first contact portion (S1) and the second contact portion (S2). The surge absorber (61) is connected between the first electric circuit (C1) and the second electric circuit (C2) without passing through the third contact portion (S3).

According to this embodiment, the third contact portion (S3) can be protected from surge currents.

The leakage current detection circuit (1) according to the second aspect is the first aspect in which one end of the surge absorber (61) is connected to the first end (P1) of the third contact portion (S3).

According to this embodiment, the third contact portion (S3) can be protected from surge currents.

The leakage current detection circuit (1) according to the third aspect is the first aspect in which one end of the surge absorber (61) is connected between the first contact portion (S1) and the third terminal (43), and the other end of the surge absorber (61) is connected to the second input portion (72).

According to this embodiment, a voltage resistance test of the first contact portion (S1) and the second contact portion (S2) can be performed by applying a voltage between the shorted first terminal (41) and second terminal (42) and the shorted third terminal (43) and fourth terminal (44).

In the fourth aspect of the earth leakage detection circuit (1), in the first or second aspect, one end of the surge absorber (61) is connected between the second contact portion (S2) and the second terminal (42), and the other end of the surge absorber (61) is connected to the first input portion (71).

According to this embodiment, a voltage resistance test of the first contact portion (S1) and the second contact portion (S2) can be performed by applying a voltage between the shorted first terminal (41) and second terminal (42) and the shorted third terminal (43) and fourth terminal (44).

The earth leakage circuit breaker (11) according to the fifth aspect includes an earth leakage detection circuit (1) according to any one of the first to fourth aspects.

According to this embodiment, the third contact portion (S3) can be protected from surge currents.

The earth leakage circuit breaker (11) according to the sixth aspect is the fifth aspect and is provided with a switching mechanism that switches the first contact portion (S1), the second contact portion (S2), and the third contact portion (S3) on/off in response to a switching operation of the operating handle (115).

According to this aspect, the user of the earth leakage circuit breaker (11) can arbitrarily switch the first contact portion (S1), the second contact portion (S2), and the third contact portion (S3) on/off.

The distribution board (12) according to the seventh aspect is equipped with the earth leakage circuit breaker (11) according to the sixth aspect.

According to this embodiment, the third contact portion (S3) can be protected from surge currents.

Note that the second to fourth aspects are not essential components of the earth leakage detection circuit (1) and can be omitted as appropriate.

The sixth aspect is not an essential component of the earth leakage circuit breaker (11) and can be omitted as appropriate.

REFERENCE SIGNS LIST 1 earth leakage detection circuit 2 power source 3 load 5 earth leakage detection section 61 surge absorber 11 earth leakage breaker 12 distribution board 41 first terminal 42 second terminal 43 third terminal 44 fourth terminal 71 first input section 72 second input section 115 operation handle C1 first electric circuit C2 second electric circuit P1 first end P2 second end S1 first contact section S2 second contact section S3 third contact section

Claims (7)

a first terminal and a second terminal connected to a first connection object, which is one of a power source and a load;
a third terminal and a fourth terminal connected to a second connection object, which is the other of the power source and the load;
a first electric path connecting the first terminal and the third terminal;
a second electric path connecting the second terminal and the fourth terminal;
a first contact portion and a second contact portion provided on the first electric circuit and the second electric circuit, respectively;
a leakage current detection unit that is connected between a first input unit provided between the first contact unit and the first terminal and a second input unit provided between the second contact unit and the fourth terminal, and that switches the first contact unit and the second contact unit from on to off when it detects an occurrence of a leakage current;
a third contact portion including a first end portion and a second end portion which is the other end of the first end portion, the first end portion being connected to the first input portion or the second input portion, the second end portion being connected to the earth leakage detection portion, and switching on/off in conjunction with switching on/off of the first contact portion and the second contact portion;
a surge absorber connected between the first electric circuit and the second electric circuit without passing through the third contact portion. The earth leakage detection circuit according to claim 1 , wherein one end of the surge absorber is connected to the first end of the third contact portion. one end of the surge absorber is connected between the first contact portion and the third terminal,
The earth leakage detection circuit according to claim 1 , wherein the other end of the surge absorber is connected to the second input section. one end of the surge absorber is connected between the second contact portion and the second terminal,
The earth leakage detection circuit according to claim 1 or 2, wherein the other end of the surge absorber is connected to the first input section. A ground fault circuit interrupter comprising the ground fault detection circuit according to any one of claims 1 to 4. The earth leakage circuit breaker according to claim 5 , further comprising a switching mechanism that switches the first contact portion, the second contact portion, and the third contact portion on and off in response to a switching operation of an operating handle. A distribution board comprising the earth leakage circuit breaker according to claim 6.

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