JP2022019097A - Ground fault detection circuit and ground fault detection device - Google Patents

Abstract

To notify the ground fault of a positive supply line and the ground fault of a negative supply line distinctively without erroneous operation, even when a plurality of DC voltage devices differing in generated voltage coexist.SOLUTION: Provided is a ground fault detection circuit 110 for individually detecting the ground fault of a positive supply line 231 and the ground fault of a negative supply line 232 connecting a DC voltage device 210 and a load 220. The ground fault detection circuit 110 comprises: a first current mirror circuit 130 whose reference potential is the positive supply line 231; a second current mirror circuit 140 whose reference potential is the negative supply line 232; a reference current line 150 shared by both current mirror circuits; a copy current line 160 shared by both current mirror circuits; a ground part 161 provided to the copy current line 160 between the two current mirror circuits; a reference current circuit for determining a reference current and interposedly connected to the reference current line 150 between the two current mirror circuits; and a ground potential circuit for determining the ground potential of the ground part 161 relative to the negative supply line 232 on the basis of the reference current.SELECTED DRAWING: Figure 1

Description

The present invention relates to a ground fault detection circuit and a ground fault detection device, and more particularly to a technique for detecting a ground fault in a power supply line that supplies DC power to a load by distinguishing between the positive side and the negative side.

Conventionally, Patent Document 1 has proposed a ground fault detection circuit for individually detecting ground faults in two power supply lines connected between a DC power source and a load. The ground fault detection circuit described in Patent Document 1 can also detect whether or not power is supplied to the load.

Japanese Unexamined Patent Publication No. 2009-270999

However, it was invented that when there are multiple power supply sources having different voltages and a load connected to each of them, and the potential of one of the power supply lines is common, the ground fault detection circuit provided for each malfunctions. Found.

The present invention has been made based on the knowledge of the inventor, and comprises a plurality of power supply sources having a common potential, a ground fault detection circuit capable of suppressing a malfunction even when a load is present, and a ground fault detection device. The purpose is to provide.

In order to achieve the above object, the ground fault detection circuit, which is one of the present inventions, individually separates the ground fault of either the positive side supply line or the negative side supply line connecting the DC voltage device and the load. A ground fault detection circuit for detection, which is a first current mirror circuit connected to the positive supply line and having the positive supply line as a reference potential, and connected to the negative supply line to the negative side. The second current mirror circuit using the supply line as a reference potential, the reference current line through which the reference current shared by the first current mirror circuit and the second current mirror circuit flows, and the first current mirror circuit and the second current mirror circuit. The copy current line through which the copy current shared by the current mirror circuit flows, the grounding portion provided on the copy current line, and the reference current line are intervenedly connected to each other, and based on the reference current, with respect to the negative supply line. A ground potential circuit for determining the ground potential of the ground portion is provided.

Further, in order to achieve the above object, the ground fault detecting device, which is another one of the present invention, has one of the positive side supply line and the negative side supply line connecting the DC voltage device and the load. A ground fault detection circuit for individually detecting a fault, which is connected to the positive supply line, a first current mirror circuit having the positive supply line as a reference potential, and a negative supply line. , A second current mirror circuit having the negative supply line as a reference potential, a reference current line through which a reference current shared by the first current mirror circuit and the second current mirror circuit flows, and the first current mirror circuit. The copy current line through which the copy current shared by the second current mirror circuit and the second current mirror circuit flows, the ground portion provided on the copy current line, and the reference current line are intervenedly connected to each other, and the negative is based on the reference current. The ground potential circuit that determines the ground potential of the ground portion with respect to the side supply line, the first detection element that detects the current between the first current mirror circuit and the ground portion, the second current mirror circuit, and the above. A second detection element that detects a current between the grounding portion, a first notification means that notifies a change in the current detected by the first detection element, and the second detection element, and a second notification means. To prepare for.

According to the ground fault detection circuit, the potential for detecting the ground fault can be arbitrarily set, so that it is possible to prevent the potential from other power supply sources from being similar to the potential for detecting the ground fault, and the ground fault can be prevented. It is possible to suppress the malfunction of the detection circuit.

FIG. 1 is a diagram showing a ground fault detection device including a ground fault detection circuit according to an embodiment. FIG. 2 is a diagram showing a ground fault detection device when a ground fault occurs on the positive supply line according to the embodiment. FIG. 3 is a diagram showing a ground fault detection device when a ground fault occurs in the negative supply line according to the embodiment. FIG. 4 is a diagram showing variation 1 of the mounting position of the ground potential circuit. FIG. 5 is a diagram showing variation 2 of the mounting position of the ground potential circuit.

Hereinafter, embodiments of the ground fault detection circuit and the ground fault detection device according to the present invention will be described with reference to the drawings. The numerical values, shapes, materials, components, positional relationships of the components, connection states, steps, the order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Further, in the following, a plurality of inventions may be described as one embodiment, but the components not described in the claims will be described as arbitrary components with respect to the claimed invention. ing. Further, the drawings are schematic views in which emphasis, omission, and ratio adjustment are appropriately performed in order to explain the present invention, and may differ from the actual shape, positional relationship, and ratio.

FIG. 1 is a diagram showing a ground fault detection device including a ground fault detection circuit according to an embodiment. In addition to the ground fault detection device 100, the DC voltage device 210 and the load 220 are also shown in this figure.

The DC voltage device 210 is a power source that generates a DC voltage between the positive terminal 211 and the negative terminal 212. The DC voltage V generated by the DC voltage device 210 is not particularly limited, and examples thereof include DC12V, DC24V, DC48V, and DC280V boosted by a DC / DC converter.

The load 220 is a load connected via a positive supply line 231 connected to the positive terminal 211 of the DC voltage device 210 and a negative supply line 232 connected to the negative terminal 212, for example, a motor. And electrical equipment. The negative supply line 232 is connected to ground (GND). What is connected to the ground is a potential that serves as a reference for the operation of the DC voltage device 210 and the load 220, and is a potential different from the ground potential and the frame ground. In the case of this embodiment, the connection destination of the ground wire 162 is the frame ground of the device, and the device is not connected to the ground (ground).

The ground fault detection device 100 is a device that distinguishes and detects a ground fault in either the positive side supply line 231 or the negative side supply line 232 and notifies the user or the like, and has a ground fault detection circuit 110 and a first detection. It includes an element 101, a second detection element 102, a first notification means 103, and a second notification means 104.

The ground fault detection circuit 110 is a circuit for individually detecting a ground fault according to a ground fault of the positive side supply line 231 and a ground fault of the negative side supply line 232 by different points where the current changes. It includes a first current mirror circuit 130, a second current mirror circuit 140, a reference current line 150, a copy current line 160, a grounding portion 161 and a grounding potential circuit.

The current mirror circuit (hereinafter, the first current mirror circuit 130 and the second current mirror circuit 140 may be collectively referred to as a “current mirror circuit”) operates such as amplification and rectification with the supplied power. This is a circuit capable of copying the reference current flowing through the reference current line 150 and passing a copy current having the same value as the reference current through the copy current line 160 by using an active element that performs the above.

The current mirror circuit included in the ground fault detection circuit 110 is not particularly limited, and examples thereof include a current-voltage converter, a voltage-current converter connected in cascade, and an operational amplifier. In the case of this embodiment, the current mirror circuit is configured by using a transistor. The type of transistor is not particularly limited, such as FET (Field Effect Transistor), but in the present embodiment, a bipolar transistor will be described.

The first current mirror circuit 130 is a current mirror circuit connected to the positive side supply line 231 and having the positive side supply line 231 as a reference potential. In the case of the present embodiment, the first current mirror circuit 130 includes a first transistor 131, which is a PNP type bipolar transistor and has the same specifications as each other, and a second transistor 132. The base of the first transistor 131 and the second transistor 132 are connected to each other. The same specification means, for example, elements having the same model number, and includes tolerances and errors between the elements.

The emitter of the first transistor 131 is connected to the positive supply line 231 and the collector is connected to the negative supply line 232 (second current mirror circuit 140). The collector and the base of the first transistor 131 are connected to each other. A current on the reference side flows between the emitter and collector of the first transistor 131.

The emitter of the second transistor 132 is connected to the positive supply line 231 and the collector is connected to the negative supply line 232 (second current mirror circuit 140). The base of the second transistor 132 is connected to the collector of the first transistor 131. The second transistor 132 is not connected to the collector and the base. A current on the copy side flows between the emitter and collector of the second transistor 132.

The "connection" described in the specification and the claims means an electrical connection, and "A is connected to B", "A and B are connected", and the like are A. It means connecting so that a current flows from B to B or from B to A. When a single element C or the like is interposed between A and B, or when a current flows between A and B even if there is a point where the current branches or merges between A and B. Is included in "connection". Further, the "connection" includes a connection in which A and B have the same potential when no current flows. Further, "C is interveningly connected between A and B" means that A and C are connected and C and B are connected, that is, A and B are connected via C. Means the state of being connected. "C is connected in a branched manner between A and B" means that A and B are connected without passing through C, and C branches from the current flowing between A and B, or It means a state in which a current that joins the current flowing between A and B is connected so as to flow. "C is connected to the D line in a branched manner" means that the D line is not divided by the C, but the current that branches from the current flowing through the D line or joins the current flowing through the D line flows. It means a state in which C is connected.

The second current mirror circuit 140 is a current mirror circuit connected to the negative side supply line 232 and having the negative side supply line 232 as a reference potential. In the case of the present embodiment, the second current mirror circuit 140 includes a third transistor 141, which is an NPN type bipolar transistor and has the same performance, and a fourth transistor 142. The bases of the third transistor 141 and the fourth transistor 142 are connected to each other.

The emitter of the third transistor 141 is connected to the negative side supply line 232, and the collector is connected to the positive side supply line 231 (first current mirror circuit 130). The third transistor 141 is connected to a collector and a base. A current on the reference side flows between the emitter and collector of the third transistor 141.

The emitter of the fourth transistor 142 is connected to the negative side supply line 232, and the collector is connected to the positive side supply line 231 (first current mirror circuit 130). The base of the fourth transistor 142 is connected to the collector of the third transistor 141. The fourth transistor 142 is not connected to the collector and the base. A current on the copy side flows between the emitter and collector of the fourth transistor 142.

The current mirror circuit may be provided with an element such as a resistor that absorbs the performance variation of each transistor. When an FET is used as a transistor, the base may be read as a gate, the emitter as a source, and the collector as a drain.

The reference current line 150 is an electric wire, a wiring pattern, or the like through which a reference current shared by the first current mirror circuit 130 and the second current mirror circuit 140 flows. In the case of the present embodiment, the reference current line 150 connects the collector of the first transistor 131 of the first current mirror circuit 130 and the collector of the third transistor 141 of the second current mirror circuit 140.

The current value of the reference current flowing through the reference current line 150 is the DC voltage generated by the DC voltage device 210 and the combined resistance value of the first transistor 131, the third transistor 141, and other elements connected to the reference current line 150. It is decided based on. A constant current element or a circuit may be connected to the reference current line 150 in an intervening manner to determine the reference current. A constant current element is a circuit (including an element) that maintains a reference current at a constant value (for example, 5 mA) when a voltage equal to or higher than a constant voltage is applied. As the constant current element, a constant current diode or the like can be exemplified.

The copy current line 160 is an electric wire, a wiring pattern, or the like through which a copy current shared by the first current mirror circuit 130 and the second current mirror circuit 140 flows. In the case of this embodiment, the copy current line 160 connects the collector of the second transistor 132 of the first current mirror circuit 130 and the collector of the fourth transistor 142 of the second current mirror circuit 140.

The current value of the copy current flowing through the copy current line 160 is the same as that of the reference current line 150 due to the action of the first current mirror circuit 130 and the second current mirror circuit 140 under normal conditions where no ground fault has occurred. Is.

The grounding portion 161 is a terminal or the like provided on the copy current line 160 between the first current mirror circuit 130 and the second current mirror circuit 140. The grounding portion 161 is connected to the so-called ground wire 162 so that the potential of the grounding portion 161 becomes the grounding potential.

The ground potential circuit is a circuit that determines the ground potential of the ground portion 161 with respect to the negative side supply line 232 connected to the ground based on the reference current flowing through the reference current line 150. In the case of the present embodiment, the ground potential circuit is branchedly connected to the reference current line 150 between the first current mirror circuit 130 and the second current mirror circuit 140, and the first current mirror circuit 130 and the second current are connected. A potential determination transistor 171 is interposedly connected to the copy current line 160 between the mirror circuit 140 and the mirror circuit 140.

In the case of the present embodiment, the potential determination transistor 171 is an NPN type bipolar transistor, the base is connected to the reference current line 150, the emitter is connected to the ground portion 161 side of the copy current line 160, and the collector is used. Is connected to the first current mirror circuit 130 side or the second current mirror circuit 140 side of the copy current line 160.

When an FET is used as the potential determination transistor, the base may be read as a gate, the emitter as a source, and the collector as a drain.

Further, the ground potential circuit includes a constant voltage circuit 172 connected to the reference current line 150 between the base of the potential determination transistor 171 and the second current mirror circuit 140. The constant voltage circuit 172 is not particularly limited as long as it is a circuit that supplies a constant voltage even if the temperature or the voltage supplied by the DC voltage device 210 changes, and is a circuit including a Zener diode, a three-terminal regulator, and the like. Can be exemplified. In the case of this embodiment, the constant voltage circuit 172 includes a Zener diode.

According to the constant voltage circuit 172, the ground potential, which is the potential of the ground portion 161 can be arbitrarily set. Therefore, for example, by setting the potential of the grounding portion 161 in the local fault detecting device 100 to a potential lower than the potential generated by another DC voltage device having a common potential of the negative side supply line 232, the ground fault detecting device 100 It is possible to suppress the malfunction of. Specifically, when a plurality of DC voltage devices 210 having generated voltages of DC12V, DC24V, and DC48V coexist and the negative side supply line 232 is common, the grounding portion of the local entanglement detection device 100 in each DC voltage device 210. If a constant voltage circuit 172 is provided so that the ground potential of 161 is about 4 to 8 V and the potential of the local entanglement detection device 100 is the same, the malfunction of the local entanglement detection device 100 can be suppressed.

In the case of this embodiment, the reverse voltage prevention circuit 180 is provided. In the reverse voltage prevention circuit 180, when a ground fault occurs, reverse power is applied to an element provided in the ground potential circuit such as a potential determination transistor 171 or an element provided in the current mirror circuit, thereby suppressing the occurrence of a defect such as a failure. It is provided to do. As the reverse voltage prevention circuit 180, for example, as in the present embodiment, the anode is on the potential determination transistor 171 side and the cathode is on the ground portion 161 side on the copy current line 160 between the ground portion 161 and the potential determination transistor 171. A rectifying diode interveningly connected to the ground function as a reverse voltage prevention circuit 180.

The first detection element 101 is an element that detects the current flowing through the copy current line 160 between the first current mirror circuit 130 and the grounding portion 161. The second detection element 102 is an element that detects the current flowing through the copy current line 160 between the second current mirror circuit 140 and the grounding portion 161.

The detection element (hereinafter, the first detection element 101 and the second detection element 102 may be collectively referred to as a “detection element”) is an element that detects a current flowing through the copy current line 160. The detection element is not particularly limited as long as it can detect the change in the current flowing through the copy current line 160, and may be a DC ammeter, a coil for acquiring the change in the current flowing through the copy current line 160, or the like. .. In the case of this embodiment, the detection element is a light emitting element (light emitting diode).

The first notification means 103 is a device that notifies a change in the current detected by the first detection element 101. The second notification means 104 is a device that notifies a change in the current detected by the second detection element 102.

The notifying means (hereinafter, the first notifying means 103 and the second notifying means 104 may be collectively referred to as "notifying means") transfers a change in the current detected by the detecting element to a person or another device. It is not particularly limited as long as it can be notified as information. For example, when the detection element is a light emitting element, the detection element also has a function as a notification means because the presence or absence of current can be notified to a person as information depending on the presence or absence of light emission. In the case of this embodiment, the notification means is a photodiode. Further, the first detection element 101 and the first notification means 103 are so-called photocouplers packaged. Similarly, the second detection element 102 and the second notification means 104 are packaged so-called photocouplers.

The notification means may include a notification circuit (not shown), a communication device, or the like, and output information to another device such as a computer.

Next, the operation of the ground fault detection circuit 110 and the ground fault detection device 100 in the present embodiment configured as described above will be described.

(Standing time)
The operation in a steady state where no ground fault has occurred will be described. The steady state is when the DC voltage generated by the DC voltage device 210 is applied to the load 220 and no ground fault has occurred on either the positive side supply line 231 or the negative side supply line 232. A constant reference current flows from the positive side supply line 231 toward the negative side supply line 232 in the reference current line 150 of the ground fault detection circuit 110 at regular times. The value of the reference current is not particularly limited, but for example, the resistance values of a plurality of elements connected to the reference current line 150 may be adjusted so that the value of the reference current is 5 mA, and the reference current may be adjusted. The resistance value may be adjusted by connecting a resistance for setting the value to a predetermined value by connecting it to the reference current line 150.

When a predetermined value of the reference current flows through the reference current line 150, a copy current flows through the copy current line 160 based on the first current mirror circuit 130 and the second current mirror circuit 140. The value of the copy current is the same as the reference current. The detection element detects a copy current of a predetermined value, and the notification means notifies the detection state of the detection element. Since the current value of the copy current is constant in the steady state, the detection element may not detect the change in the copy current, but in the case of the present embodiment, the detection element irradiates light based on the current. Since it is a light emitting element, the first detection element 101 and the second detection element 102 emit light based on the copy current. Further, the first notification means and the second notification means notify information indicating that a copy current is flowing at a predetermined value. From this, it is also possible to grasp that it is in a steady state.

In the steady state, the DC voltage device 210 can be regarded as a floating state because the circuit impedance of the ground fault detecting device 100 is high with respect to the ground potentially connected to the grounding portion 161. Therefore, the copy current line 160 is used. The copy current that flows does not flow to the ground.

(At the time of ground fault of the positive supply line)
Next, a case where a ground fault occurs in the positive supply line 231 will be described with reference to FIG.

When a ground fault occurs in the positive side supply line 231, the potential on the emitter side of the second transistor 132 of the first current mirror circuit 130 and the potential of the grounded portion 161 of the copy current line 160 become the same potential (grounding potential). Therefore, no current flows between the first current mirror circuit 130 of the copy current line 160 and the grounding portion 161. As a result, the first detection element 101, which is a light emitting element, stops emitting light, and the first notification means 103, which is a photodiode, provides information that no current flows, that is, the positive side supply line 231 has a ground fault. Notify.

On the other hand, the ground potential of the ground portion 161 with respect to the negative side supply line 232 is maintained at the potential set by the constant voltage circuit 172 of the ground potential circuit, and another DC voltage device having the same negative side supply line 232 is generated. Since it is also different from the voltage, a current flow is maintained in the copy current line 160 between the ground portion 161 and the negative side supply line 232. As a result, the light emission of the second detection element 102, which is a light emitting element, is maintained, and the second notifying means 104, which is a photodiode, indicates that the current does not change, that is, no ground fault has occurred on the negative side supply line 232. Notify the information to that effect.

(At the time of ground fault of negative supply line)
Next, the case where a ground fault occurs in the negative supply line 232 will be described with reference to FIG.

When a ground fault occurs in the negative side supply line 232, the potential on the emitter side of the fourth transistor 142 of the second current mirror circuit 140 and the potential of the grounded portion 161 of the copy current line 160 become the same potential (grounding potential). Therefore, no current flows between the second current mirror circuit 140 of the copy current line 160 and the grounding portion 161. As a result, the second detection element 102, which is a light emitting element, stops emitting light, and the second notification means 104, which is a photodiode, provides information that no current flows, that is, the negative side supply line 232 has a ground fault. Notify.

On the other hand, the grounding potential of the grounding portion 161 with respect to the positive side supply line 231 maintains the potential set by the constant voltage circuit 172 of the grounding potential circuit, so that the copy current line between the grounding portion 161 and the positive side supply line 231 is maintained. The current flow is maintained at 160. As a result, the light emission of the first detection element 101, which is a light emitting element, is maintained, and the first notification means 103, which is a photodiode, does not change the current, that is, no ground fault has occurred on the negative side supply line 232. Notify the information to that effect.

As described above, according to the ground fault detection device 100 provided with the ground fault detection circuit 110 of the present embodiment, the first current mirror circuit 130 and the second current mirror circuit 140 are provided with the grounding portion 161 interposed therebetween. Therefore, it is possible to distinguish between the occurrence of a ground fault on the positive side supply line 231 and the occurrence of a ground fault on the negative side supply line 232. Further, even if there is another DC voltage device sharing the negative supply line 232, the position of the ground fault can be distinguished and notified without causing a malfunction.

In addition, even if the voltage generated by the DC voltage device 210 becomes unstable due to fluctuations in the load 220 due to the ground potential circuit that can set the ground potential constant, the ground potential of the ground portion 161 is stable, so that a ground fault occurs. It is possible to suppress the malfunction of the detection device 100.

The present invention is not limited to the above embodiment. For example, another embodiment realized by arbitrarily combining the components described in the present specification and excluding some of the components may be an embodiment of the present invention. The present invention also includes modifications obtained by making various modifications that can be conceived by those skilled in the art within the scope of the gist of the present invention, that is, the meaning indicated by the wording described in the claims, with respect to the above-described embodiment. Will be.

For example, in the present embodiment, the detection of a ground fault has been described, but by acquiring information indicating that a current is flowing through the first detection element 101 and the second detection element 102 by using a notification means. It is also possible to grasp the state in which the DC voltage device 210 is operating normally without the occurrence of a ground fault.

Further, after grasping the state of normal operation, the DC voltage is obtained by acquiring the information indicating that the current has stopped flowing to the first detection element 101 and the second detection element 102 by using the notification means. It is also possible to grasp the abnormality that has occurred in the device 210.

Further, the ground potential circuit may be provided between the ground portion 161 and the second current mirror circuit 140 as shown in FIG.

Further, the ground potential circuit may be provided both between the first current mirror circuit 130 and the ground portion 161 and between the ground portion 161 and the second current mirror circuit 140 as shown in FIG.

INDUSTRIAL APPLICABILITY According to the present invention, a ground fault detection circuit for detecting a ground fault in a positive supply line connecting a DC voltage device and a load, and a ground fault in the negative supply line, a ground fault detection device, particularly a plurality of DCs sharing a negative supply line. It can also be used when the voltage device is a voltage device and the supply voltages are different from each other.

100 Ground fault detection device 101 First detection element 102 Second detection element 103 First notification means 104 Second notification means 110 Ground fault detection circuit 130 First current mirror circuit 131 First transistor 132 Second transistor 140 Second current mirror circuit 141 Third transistor 142 Fourth transistor 150 Reference current line 160 Copy current line 161 Ground wire 162 Ground wire 171 Potential determination transistor 172 Constant voltage circuit 180 Reverse voltage prevention circuit 210 DC voltage device 211 Positive terminal 212 Negative terminal 220 Load 231 Positive side supply line 232 Negative side supply line

Claims (6)

It is a ground fault detection circuit for individually detecting the ground fault of either the positive side supply line or the negative side supply line connecting the DC voltage device and the load.
A first current mirror circuit connected to the positive supply line and using the positive supply line as a reference potential,
A second current mirror circuit connected to the negative supply line and using the negative supply line as a reference potential,
A reference current line through which a reference current shared by the first current mirror circuit and the second current mirror circuit flows,
A copy current line through which a copy current shared by the first current mirror circuit and the second current mirror circuit flows,
A grounding portion provided on the copy current line and
A ground potential circuit that determines the ground potential of the ground portion with respect to the negative supply line based on the reference current.
A ground fault detection circuit equipped with. The ground potential circuit includes a potential determination transistor that is branchedly connected to the reference current line and is intermittently connected to the copy current line.
The base or gate of the potential determination transistor is connected to the reference current line, the emitter or source is connected to the ground side of the copy current line, and the collector or drain is the first of the copy current lines. The ground fault detection circuit according to claim 1, which is connected to the current mirror circuit side or the second current mirror circuit side. The ground potential circuit is
The ground fault detection circuit according to claim 2, further comprising a constant voltage circuit interveningly connected to the reference current line between the base or gate of the potential determination transistor and the second current mirror circuit. The ground fault detection circuit according to claim 3, wherein the constant voltage circuit includes a Zener diode. The ground fault detection circuit according to any one of claims 1 to 4, and the ground fault detection circuit.
The first detection element that detects the current between the first current mirror circuit and the grounding portion,
A second detection element that detects the current between the second current mirror circuit and the grounded portion, and
The first notification means and the second notification means for notifying the change of the current detected by the first detection element and the second detection element, respectively.
A ground fault detector equipped with. The first detection element and the second detection element are light emitting elements that emit light based on an electric current.
The fifth aspect of claim 5, wherein the first notifying means and the second notifying means include the first detection element, the first photodetection element for detecting the light emission of the second detection element, and the second light detection element, respectively. Ground fault detector.

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