JP2010213450A - Apparatus for detection of line-to-ground fault - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line-to-ground fault detecting apparatus generating a DC power required for the line-to-ground fault detecting apparatus inside and transmitting a line-to-ground fault detecting signal to a controller without using a high breakdown voltage transformer. <P>SOLUTION: Feeding means 3 and 4 are connected to connection points of a first resistance element group GR1 and a second resistance element group GR2, which are connected in series between a positive side and a negative side of a DC power supply 1, so as to secure power. A third resistance element group GR3 where a line-to-ground fault current flows is connected between a mutual connection point M of the first resistance element group GR1 and the second resistance element group GR2 and a ground point G. The apparatus includes intermittent signal generating means 6 and 7 comparing an inter-terminal voltage VC between the connection point C of the resistance elements constituting the third resistance element group GR3 and the mutual connection point M with a reference voltage VSET, and generating an intermittent signal when the inter-terminal voltage exceeds the reference voltage and an electric light converting means 8 converting the intermittent signal generated by the intermittent signal generating means into an optical signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground fault detection device that detects a ground fault such as a power converter.

In a device using a high-voltage DC power source such as an inverter constituting a power converter, a DC ground fault detector is generally used to detect a ground fault.
FIG. 5 is a circuit diagram of an apparatus using a conventional DC ground fault detection apparatus. In FIG. 5, reference numeral 101 denotes a DC power source, which uses a rectifier that rectifies a commercial power source to generate a DC voltage, or uses a DC power generator such as a solar cell or a fuel cell. The direct current output of the direct current power supply 101 is supplied to a power converter 102 such as an inverter. The power converter 102 is a load device connected to the P pole and the N pole of the DC power supply 101. Further, voltage dividing resistors R1 and R2 having equal resistance values are connected in series between the P pole and the N pole, and the voltage between the P pole and the N pole is divided by the voltage dividing resistors R1 and R2. The DC ground fault detection device is constituted by the grounding resistor R3 and the ground fault detection relay 103 connected in series between the characteristic point M and the ground point G.

In such a DC ground fault detection device, when no ground fault occurs, the neutral point M is an intermediate voltage between the P pole and the N pole, so it has the same zero potential as the ground point, and the ground resistance R3 and ground fault detection No current flows through the relay 103, and therefore the ground fault detection relay 103 does not operate and no ground fault is detected.
However, when the positive pole of the DC circuit is grounded, the potential at the neutral point M changes from zero potential to a negative potential, and the detection current I1 flows through the grounding resistor R3 and the ground fault detection relay 103, thereby causing the ground fault detection relay 103. The result is transmitted to a control device (not shown) and recognized as a ground fault.

Further, when the negative electrode of the DC circuit is grounded, the potential at the neutral point M changes from zero potential to a positive potential, and the detection current I2 flows through the grounding resistor R3 and the ground fault detection relay 103, thereby causing the ground fault detection relay 103. This is transmitted to a control device (not shown) to recognize a ground fault.
However, since the ground fault detection relay is expensive and has a problem in availability in terms of delivery time, a DC ground fault detection device that does not use the ground fault detection relay as shown in the circuit diagram of FIG. 6 is another method. It has been proposed (see, for example, Patent Document 1).

  6 shows a circuit diagram of only the DC ground fault detector. In an actual device, for example, it is connected between the P pole and the N pole of FIG. 4, and the voltage dividing resistors R1 and R2, the grounding resistor R3, and the ground fault are connected. It is used in the form of replacing the DC ground fault detector composed of the detection relay 103. In FIG. 6, voltage dividing resistors R1P and R1N and R2P and R2N are voltage dividing resistors connected in series between the positive electrode P and the negative electrode N of the DC circuit. In these voltage dividing resistors, the connection point M between R1P and R1N is directly connected to the ground point G, and the connection point A between the voltage dividing resistors R2P and R1P and the connection point B between the voltage dividing resistors R1N and R2N are respectively voltage detection points. A and B are used. An absolute value voltage difference detection circuit 104 is connected to the voltage detection points A and B. In the absolute value voltage difference detection circuit 104, the voltage VA of the voltage detection point A with respect to the ground point G and the voltage detection point with respect to the ground point G are detected. A difference ΔVG with respect to the voltage VB of B is detected and output.

The output of the absolute value voltage difference detection circuit 104 and the reference voltage VR set by the voltage level setting unit 107 are input to the ground fault determination circuit 105.
In general, the ground fault phenomenon that occurs in a DC circuit is caused by the deterioration of the insulation between the P or N pole and the ground. In this case, between the P pole or N pole and the ground point G, an insulation resistance according to the degree of insulation deterioration is apparently connected. The circuit state when the P pole is grounded is equivalent to FIG. As shown in FIG. 7, when the ground fault resistance is RG, the combined resistance RP of the positive electrode P and the neutral point M is expressed by the following formula (1), and the combined resistance RN of the negative electrode N and the neutral point M is the following ( 2) It is expressed by the formula.

  The voltage VP of the positive electrode P with respect to the neutral point is expressed by the following equation (3), where the DC voltage is E, and the voltage VN of the negative electrode N is similarly expressed by the following equation (4).

  Next, the voltage VA at the voltage detection point A and the voltage VB at the voltage detection point B with respect to the neutral point M are obtained from the above formulas (1) to (4) as in the following formulas (5) and (6). .

From the above equations (5) and (6), the absolute value ΔVo of the voltage difference between the voltage detection points A and B with respect to the neutral point M is
ΔVo = | VB−VA | (7)
It becomes.

In determining the resistance, the neutral points M are set to zero potential, which is an intermediate potential between the P and N poles of the DC power supply, by equalizing the values of the voltage dividing resistors R2P, R2N and R1P, R1N. Here, paying attention to the same resistance value of the voltage dividing resistors R2P, R2N and R1P, R1N,
R1P = R1N = R1 (8)
R2P = R1N = R2 (9)
Then, when the above-mentioned formulas (5), (6), (8) and (9) are substituted into the above-mentioned formula (7) and rearranged, the following formula (10) is obtained.

  The voltage dividing ratio of the voltage dividing resistors R1P, R2P and R1N, R2N may be determined in consideration of the voltage that can be used in the absolute value voltage difference detection circuit 104 connected to these connection points A and B.

  With the above configuration, when either the P pole or the N pole is grounded, the voltage difference ΔVG is output from the absolute value voltage difference detection circuit 104, and this value and the voltage VR set by the voltage level setting unit 106 are output. Are compared by the ground fault determination circuit 105, and when ΔVG> VR, a ground fault detection signal is output from the ground fault determination circuit 105, and this ground fault detection signal is input to a control device (not shown) by means not shown. Recognized as a ground fault.

  By applying the configuration of FIG. 6, it is possible to configure a DC ground fault detector using an operational amplifier, a resistance element, or the like, which is a general electronic component, without using a ground fault relay.

JP-A-2-237421

  However, in the conventional example described in Patent Document 1, it is possible to configure a ground fault detection device using a general electronic component such as an operational amplifier or a resistance element, but the circuit operates. No consideration is given to the power supply that is indispensable for the purpose. Therefore, a separate power supply is prepared. In this case, if the voltage of the DC circuit becomes high, the withstand voltage of the power supply must be increased correspondingly, resulting in the size and cost of that portion. Since it increases, there exists an unsolved subject that it becomes the obstacle of size reduction and cost reduction as a whole.

Further, in the above-described conventional example, no consideration is given to the means for transmitting the ground fault detection signal to the control device. Therefore, when the voltage of the DC circuit is high, the high withstand voltage transformer for insulating the ground fault detection signal. However, there is an unresolved problem that this is an obstacle to downsizing and cost reduction as a whole.
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and generates a DC power source required for the ground fault detection device inside, and outputs the ground fault detection signal to the high voltage transformer. It is an object of the present invention to provide a ground fault detection device that can be transmitted to a control device without using an alarm.

  To achieve the above object, a ground fault detection device according to claim 1 includes a first resistance element group and a second resistance element group connected in series between a positive side and a negative side of a DC power source, A third resistor element group in which a ground fault current is connected between an interconnection point of the first resistor element group and the second resistor element group and a ground point, and the first resistor element group is configured. A power supply means connected to a connection point between the resistance elements to be connected to each other and a connection point between the resistance elements constituting the second resistance element group, and outputs at least a positive power supply and a negative power supply, and an output side of the power supply means Comparing the reference voltage and the inter-terminal voltage between the connected first and second power storage means and the connection point between the resistance elements constituting the third resistance element group and the interconnection point Intermittent signal generating means for generating an intermittent signal when the voltage between the terminals exceeds the reference voltage; Electro-optic conversion means for converting the intermittent signal generated by the signal generation means into an optical signal, and supplying at least positive power of the power supply means to the intermittent signal generation means and the electro-optic conversion means, To do.

  According to this configuration, the DC power necessary for the power supply means can be covered, and the inter-terminal voltage and the reference voltage between the connection points of the resistance elements constituting the third resistance element group and the interconnection points are obtained. In comparison, an intermittent signal is generated when the inter-terminal voltage exceeds the reference voltage, and this intermittent signal is converted into light and output, so that it is possible to transmit a ground fault detection signal to the control device with low power. It becomes.

In the ground fault detection apparatus according to claim 2, the first resistor element group, the second resistor element group, and the third resistor element group constitute a voltage dividing resistor circuit.
According to this configuration, by providing three sets of voltage dividing resistor circuits, it is possible to perform necessary DC power supply and ground fault detection.
Further, in the ground fault detection device according to claim 3, the power supply means includes a first power supply means connected to a connection point between the resistance elements constituting the first resistance element group, and the second resistance. It is characterized by being comprised with the 2nd electric power feeding means connected to the connection point of the resistive elements which comprise an element group.

According to this configuration, the first power supply means can form a positive power supply, the second power supply means can form a negative power supply, and the intermittent signal generating means and the electro-optic conversion means can provide necessary power. it can.
The ground fault detection apparatus according to claim 4 is characterized in that the power supply means is constituted by a DC / DC converter.

According to this configuration, the power supply means can be configured by a single circuit of the DC / DC converter, so that the overall configuration can be simplified.
Further, in the ground fault detection device according to claim 5, the intermittent signal generating means is configured such that the width of the ON section of the intermittent signal is set to a sufficiently short width compared to the period.
According to this configuration, the average current consumption of the ground fault detection device as a whole can be reduced to a level that does not affect ground fault detection.

  Further, in the ground fault detection device according to claim 6, the intermittent signal generating means compares the inter-terminal voltage and the reference voltage, and outputs a comparison output when the inter-terminal voltage exceeds the reference voltage. The voltage comparator circuit, and an intermittent signal oscillator that generates an intermittent signal when the comparison output of the voltage comparator circuit is input, the positive power source and the negative power source are supplied to the voltage comparator, The positive power supply is supplied to the intermittent signal oscillator.

  According to this configuration, in the voltage comparison circuit, one or both of the input and the output move in both the positive side and the negative side. Therefore, the positive power source and the negative power source of the power supply means are supplied, and the intermittent signal is supplied. In the oscillator, the input and output move only in the range of the positive side, so only the positive side power supply of the power supply means is supplied.

  According to the present invention, since the ground fault detected by the ground fault detector is converted into an optical signal that is intermittently lit and transmitted to the control device, the power consumed by the lighting of the optical signal in the ground fault detection device is minimized. The intermittent signal generating means can be operated with a minute current fed from the DC power source through the first resistor group and the second resistor group constituted by voltage dividing resistors, and no external power supply is required. In addition, by outputting the ground fault detection signal to the outside via the optical signal, there is no need for a high voltage device such as an insulation transformer, so that the entire device can be reduced in size and cost can be obtained. .

It is a block diagram which shows one Embodiment of the ground fault detection apparatus by this invention. It is a signal waveform diagram with which it uses for description of operation | movement of the ground fault detection apparatus of this invention. It is a signal waveform diagram with which it uses for description of an intermittent signal. It is a block diagram which shows other embodiment of this invention. It is a circuit diagram which shows the conventional ground fault detection apparatus. It is a circuit diagram which shows the ground fault detection apparatus which does not use the conventional ground fault relay. It is a circuit diagram equivalently showing a circuit state when a P pole is grounded.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a high-voltage DC power supply, which uses a rectifier that rectifies a commercial AC power supply to generate a DC voltage, or a DC power generator such as a solar cell or a fuel cell, as in the conventional example described above. Can be used.
A power converter 2 such as an inverter serving as a load device is connected in series between the P pole and the N pole of the DC power supply 1.

The first resistor element group GR1 in which the voltage dividing resistors R1P and R2P are connected in series between the P pole and the N pole of the DC power supply 1 and the second resistor element group in which the voltage dividing resistors R1N and R2N are connected in series. GR2 is connected in series with each other.
A connection point A of the voltage dividing resistors R1P and R2P of the first resistance element group GR1 is connected to a positive power supply circuit 3 as a first power supply means, and a positive power supply Vcc is output from the positive power supply circuit 3. . As the positive-side power supply circuit 3, power supply circuits having various configurations can be applied. As the simplest one, a rectifying diode may be used, and the output voltage is made constant as in a three-terminal regulator. An element having the ability to adjust may be used. In addition, since a voltage range that can be set as an input is narrow in a diode or a three-terminal regulator, a circuit such as a DC / DC converter may be used to ensure a sufficient operation even when the fluctuation of the DC voltage is large.

  Further, the connection point B of the voltage dividing resistors R1N and R2N of the second resistor element group GR2 is connected to the negative power supply circuit 4 as the second power supply means, and the negative power supply Vee outputs the negative power supply Vee. Is done. The negative side power supply circuit 4 is basically the same as the positive side power supply circuit 3 in consideration of the fact that the direction of the current as a power source differs from that of the positive side power supply circuit 3 described above. Configuration can be applied.

A capacitor C1 as a first power storage means is connected between the interconnection point M of the first resistance element group GR1 and the second resistance element group GR2 and the output side of the positive power supply circuit 3, and the interconnection A capacitor C2 as a second power storage unit is connected between the point M and the output side of the negative power supply circuit 4.
Further, a third resistance element group GR3 is connected between the interconnection point M of the first resistance element group GR1 and the second resistance element group GR2 and the ground G. The third resistance element group GR3 also has a configuration in which ground resistors R1G and R2G serving as voltage dividing resistors are connected in series, and a voltage VC between terminals of the voltage dividing resistor R1G from a connection point C of the ground resistors R1G and R2G. Is detected.

  The inter-terminal voltage VC detected at the connection point C is input to the other input side of the voltage comparison circuit 6 in which the reference voltage VSET is input from the reference voltage setting circuit 5 to one input side. In this voltage comparison circuit 6, for example, when the inter-terminal voltage VC is equal to or lower than the reference voltage VSET, the comparison output Vdet becomes, for example, a logical value “0”, and when the inter-terminal voltage VC exceeds the reference voltage VSET, Is output.

  The comparison output Vdet output from the voltage comparison circuit 6 is input to the intermittent signal oscillation circuit 7. The intermittent signal oscillation circuit 7 outputs a pulse-like intermittent signal Sint that repeats an ON state and an OFF state at a predetermined cycle while the comparison output Vdet is a logical value “1”. Here, as shown in FIG. 3, the intermittent signal Sint has an off-state interval T2 having a logical value “0” compared to an on-state interval T1 having a logical value “1” during a period T. It is set to be long enough. As this intermittent signal oscillation circuit, a CR timing generation circuit composed of an integration circuit, a comparator, a flip-flop circuit, etc., an oscillation circuit combining an integration circuit and a Schmitt trigger circuit, etc. can be applied. An intermittent signal is generated by comparing with a reference voltage.

  The intermittent signal Sint output from the intermittent signal oscillation circuit 7 is supplied to an E / O conversion circuit 8 as an electro-optical conversion circuit that converts an electrical signal into an optical signal, and the E / O conversion circuit 8 performs intermittent light. Converted to a signal. The intermittent optical signal output from the E / O conversion circuit 8 is optically transmitted via the optical cable 9 to a control device 11 including an O / E conversion circuit 10 that performs photoelectric conversion.

  The reference voltage setting circuit 5 is supplied with the positive power supply Vcc output from the positive power supply circuit 3, and the other end is an interconnection point between the first resistance element group GR1 and the second resistance element group GR2. Connected to a certain neutral point M. In addition, since at least one of the input and the output works in both the positive side and the negative side in the voltage comparison circuit 6, the positive power supply Vcc and the negative power supply Vee of the positive power supply circuit 3 and the negative power supply circuit 4 are used. Is supplied to the remaining intermittent signal oscillation circuit 7 and the E / O conversion circuit 8 because only the positive side power supply Vcc of the positive side power supply circuit 3 is supplied to the input and output. Connect the end to the neutral point M.

Next, the operation of the above embodiment will be described.
In FIG. 1, the voltage dividing resistors R1P, R2P and R1N, R2N of the first and second resistance element groups GR1 and GR2 connected in series divide the voltage between the P electrode and the N electrode, thereby The potential of the neutral point M, which is an interconnection point between the two resistance element groups GR1 and GR2, is determined. Between these, the neutral point M does not generate a ground fault by setting equal values of the voltage dividing resistors R2P, R1P, R1N, and R2N of the first and second resistance element groups GR1 and GR2 connected in series. In operation, the potential is zero, and the ground point G is also zero.

  In this state, the input of the positive power supply circuit 3 is connected to the connection point A of the voltage dividing resistors R2P and R1P connected in series of the first resistance element group GR1, and the output passing through the positive power supply circuit 3 is positive. The side power supply Vcc is supplied as an operating voltage to the reference voltage setting circuit 5, the voltage comparison circuit 6, the intermittent signal oscillation circuit 7, and the E / O conversion circuit 8, and the capacitor C1 is charged. At this time, the common potential (ground) of the circuit is the neutral point M. Further, the output passing through the negative power supply circuit 4 is supplied as an operating voltage to the voltage comparison circuit 6 as a negative power supply Vee.

As described above, when the operation voltage is supplied to the reference voltage setting circuit 5, the voltage comparison circuit 6, the intermittent signal oscillation circuit 7, and the E / O conversion circuit 8, each of these circuits enters an operation state.
Here, in the state where no ground fault has occurred, as described above, the neutral point M is at zero potential and the ground point G is also at zero potential. The ground fault current Ig flowing through the voltage dividing resistors R1G and R2G of the third resistive element group GR3 connected to the point G becomes zero, and as a result, the terminal voltage VC generated at both ends of the voltage dividing resistor R1G is It becomes zero.

  Therefore, when this inter-terminal voltage VC and the reference voltage VSET set by the reference voltage setting circuit 5 are compared by the voltage comparison circuit 6, VC <VSET, and the comparison output Vdet of the voltage comparison circuit 6 has the logical value “0”. It becomes. For this reason, the intermittent signal Sint is not output from the intermittent signal oscillation circuit 7 that receives the comparison output Vdet, and the optical signal is not output from the E / O conversion circuit 8, so that the ground fault is recognized also on the control device 11 side. There is no.

  When a ground fault occurs in FIG. 1 from this normal state, a ground fault current Ig that gradually increases from time t0 flows through the third resistance element group GR3 as shown in FIG. 2A. When the ground fault current Ig flows through the third resistance element group GR3 in this way, the terminal voltage VC shown in FIG. 2B is generated at both ends of the ground resistance R1G according to the magnitude of the ground fault current Ig. .

  Then, when the ground fault current Ig increases and the inter-terminal voltage VC increased in response thereto exceeds the reference voltage VSET set by the reference voltage setting circuit 5 at time t1, the comparison output from the voltage comparator 6 is performed. The output Vdet is inverted from the logical value “0” to the logical value “1” as shown in FIG.

  As described above, when the comparison output Vdet is inverted to the logical value “1”, the intermittent signal oscillation circuit 7 outputs the intermittent signal Sint temporarily having the logical value “1” in the period T, and the intermittent signal Sint is output from the E / O. Input to the conversion circuit 8. In this E / O conversion circuit 8, the internal light emitting element is turned on when the intermittent signal Sint is a logical value “1”, for example, and outputs an intermittent optical signal. The intermittent optical signal is transmitted via the optical cable 9. Optically transmitted to the O / E conversion circuit 10 of the control device 11. Then, the control device 11 recognizes the occurrence of the ground fault by converting the intermittent optical signal into the intermittent electric signal by the O / E conversion circuit 10 and stops the output of the DC power source 1 by any means (not shown). Then, a preset process such as stopping the operation of the power converter 2 is executed.

  Here, in the present embodiment, in the case of the positive side, a current is taken out from the connection point A serving as a feeding point via the voltage dividing resistor R2P from the P pole of the DC power source 1, and in the case of the negative side, A current is taken out from the connection point B serving as a feeding point from the N pole via the voltage dividing resistor R2N. However, in order to determine the potential of the neutral point M in the voltage dividing resistors R2P and R2N, a current flowing from the P pole to the N pole of the DC power supply 1 and a ground fault current also flow. It is conceivable that the voltage at the neutral point M varies as the current increases. When the voltage at the neutral point M fluctuates, the magnitude of the ground fault current also changes, and when a ground fault is detected in a normal state where no ground fault has occurred, or when a ground fault occurs, a ground fault occurs. May not be detected. Therefore, in this embodiment, even if the E / O conversion circuit 8 that requires large power consumption is used, the intermittent detection as shown in FIG. In the cycle t of the signal Sint, an average signal of the entire ground fault detection device is obtained by using an intermittent signal in which the ON state interval T1 of the logical value “1” is shorter than the OFF state interval T2 of the logical value “0”. The power consumption can be reduced to a level that does not affect the detection of the ground fault, and the erroneous detection of the ground fault can be surely prevented.

In addition, since the E / O conversion circuit 8 converts the signal into an intermittent optical signal and outputs it, a high-voltage device such as an insulation transformer is not required, and thus the entire apparatus can be reduced in size and cost.
In the above embodiment, the case where a CR timing oscillation circuit, an integration / Schmitt trigger oscillation circuit, or the like is applied as the intermittent signal oscillation circuit has been described. However, the present invention is not limited to this, as shown in FIG. If an intermittent signal with a small on-duty can be formed, any intermittent signal oscillation circuit can be applied.

  In the above-described embodiment, the case where the voltage comparison circuit 6 outputs the comparison output Vdet that is inverted from the logical value “0” to the logical value “1” when VC> VSET is described. However, the present invention is not limited to this. Instead, the comparison output Vdet that is inverted from the logical value “1” to the logical value “0” may be output when VC> VSET. In this case, the intermittent signal oscillation circuit 7 outputs the logical value “0”. The intermittent signal Sint may be output when the comparison output Vdet is input.

  In the above embodiment, the case where the E / O conversion circuit 8 and the O / E conversion circuit 10 of the control device 11 are connected by the optical cable 9 has been described. However, the present invention is not limited to this. The conversion circuit 8 and the O / E conversion circuit 10 may be connected by an optical wireless communication system.

  In the above-described embodiment, the description has been given of the configuration using two power feeding circuits, that is, the positive power feeding circuit 3 and the negative power feeding circuit 4. However, depending on the circuit system such as a DC / DC converter, as shown in FIG. In addition, a configuration in which the positive side power source and the negative side power source can be fed as a single component can be applied. By adopting such a configuration, the circuit configuration can be further simplified.

  That is, in FIG. 4, the input side of the DC / DC converter 21 has two inputs of the positive side and the negative side, and the output side has three outputs of ground M (zero potential) in addition to the positive side and the negative side. The positive input side of the DC / DC converter 21 is connected to the connection point A of the voltage dividing resistors R2P and R1P connected in series of the first resistor element group GR1, and the negative input side is connected in series to the second resistor element group GR2. Is connected to a connection point B of the divided voltage dividing resistors R1N and R2N, and a capacitor C1 as a first power storage means is connected between the positive output on the output side and the ground M, and the ground M and the negative output are connected to each other. A capacitor C2 as a second power storage means is connected between them. Further, the connection is made to connect the ground M of the DC / DC converter 21 (power supply) to a neutral point M which is an interconnection point of the main circuit.

  DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... Power converter, 3 ... Positive side feeding circuit, 4 ... Negative side feeding circuit, 5 ... Reference voltage setting circuit, 6 ... Voltage comparison circuit, 7 ... Intermittent signal oscillation circuit, 8 ... E / O Conversion circuit, 9 ... optical cable, 10 ... O / E conversion circuit, 11 ... control circuit, 21 ... DC / DC converter, GR1 ... first resistor element group, GR2 ... second resistor element group, GR3 ... third Resistive element group, R1P, R2P, R1N, R2N ... voltage dividing resistor, G1G, R2G ... ground resistance

Claims (6)

A first resistor element group and a second resistor element group connected in series between the positive side and the negative side of the DC power supply;
A third resistor element group through which a ground fault current connected between an interconnection point and a ground point of the first resistor element group and the second resistor element group flows;
Power supply means connected to a connection point between the resistance elements constituting the first resistance element group and a connection point between the resistance elements constituting the second resistance element group, and outputting at least a positive power source and a negative power source When,
First and second power storage means connected to the output side of the power supply means;
The inter-terminal voltage between the connection points of the resistance elements constituting the third resistance element group and the interconnection point is compared with the reference voltage, and intermittent when the inter-terminal voltage exceeds the reference voltage Intermittent signal generating means for generating a signal;
Electro-optic conversion means for converting the intermittent signal generated by the intermittent signal generation means into an optical signal;
With
A ground fault detection apparatus characterized in that at least a positive power source of the power supply means is supplied to the intermittent signal generation means and the electro-optic conversion means.   2. The ground fault detection device according to claim 1, wherein the first resistance element group, the second resistance element group, and the third resistance element group constitute a voltage dividing resistor circuit.   The power supply means is connected to a connection point between the first power supply means connected to the resistance elements constituting the first resistance element group and a connection point between the resistance elements constituting the second resistance element group. The ground fault detection device according to claim 1, wherein the ground fault detection device comprises:   The ground fault detection apparatus according to claim 1, wherein the power feeding unit is configured by a DC / DC converter.   The ground fault according to any one of claims 1 to 4, wherein the intermittent signal generating means is set such that the width of the ON section of the intermittent signal is sufficiently shorter than the period. Detection device.   The intermittent signal generating means compares the inter-terminal voltage with the reference voltage, and outputs a comparison output when the inter-terminal voltage exceeds the reference voltage, and a comparison output of the voltage comparison circuit And an intermittent signal oscillator that generates an intermittent signal when the signal is input, the positive power supply and the negative power supply are supplied to the voltage comparator, and the positive power supply is supplied to the intermittent signal oscillator. The ground fault detection apparatus according to any one of claims 1 to 5, wherein

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