JP5636698B2 - DC accident point inspection device - Google Patents

Description

  The present invention relates to a DC fault point inspection apparatus for inspecting in which part of a DC circuit an accident has occurred.

  For example, direct current is supplied as control power from a direct current power source to a control circuit that controls equipment in a substation. The direct current circuit is configured to supply direct current power from a direct current power source to an equipment panel connected in parallel via a DC distribution board, and the equipment board constitutes a branch circuit.

  If a ground fault occurs on any plus side of the branch circuit of this DC circuit, the DC ground fault overvoltage protection relay in the charger operates and a fault indication is issued to the control station. At the stage where a ground fault occurs only on the positive side, there is no particular problem in operation of the device. However, if a DC ground fault occurs on the negative side in this situation, the process shifts to a short circuit of the DC circuit. Then, the DC circuit of the branch circuit where the accident occurred is interrupted by a switch (for example, NFB) of the distribution board, leading to the loss of the control power of the equipment panel that is the branch circuit, which prevents the operation of the equipment and protection of the power system accident. It becomes impossible. This can cause a wide-area power outage in the distribution system.

  Therefore, when the DC ground fault overvoltage protection relay operates, the fault point is investigated using the DC fault point inspection device. FIG. 11 is an explanatory diagram of an example of investigating an accident point of a DC circuit using a conventional DC fault point inspection device.

  As shown in FIG. 11, the DC circuit includes a battery 11 that stores DC power, a charger board 12 that charges the battery 11 with DC power, and a DC power from the battery 11 that branches to a plurality of equipment boards 13 a to 13 n. And a DC distribution board 14 to be supplied. DC loads 15a to 15n are connected to the device boards 13a to 13n, and DC power is supplied from the DC distribution board 14 to the loads 15a to 15n via the switches 16a to 16n. The loads 15a to 15n are equivalently connected in parallel with the capacitances Ca to Cn of the control cable in parallel.

  The AC / DC converter 17 of the charger panel 12 converts AC power from an AC system (not shown) into DC power and stores it in the battery 11. The charger panel 12 is provided with a DC ground fault overvoltage protection relay 18, and when a ground fault occurs on any plus side of the DC circuit, the DC ground fault overvoltage protection relay 18 in the charger panel 12 operates. Then, a failure display is issued to a control station (not shown). FIG. 11 shows a case where a ground fault F has occurred in the branch circuit of the equipment panel 13a. When the DC ground fault overvoltage protection relay 18 operates and a fault indication is issued to the control station, the worker searches for the fault point using the DC fault point inspection device.

  The accident point inspection apparatus includes a voltage power supply device 19 for applying an AC voltage for inspection of an accident point to a DC circuit, a clamp CT20 for measuring a current waveform of a current flowing in a branch circuit to be inspected, and the clamp CT20. And an ammeter 21 for displaying the measured current value.

  In investigating the accident point, first, one end of the voltage power supply device 19 of the DC accident point inspection apparatus is connected to the positive power line of the DC circuit and the other end is grounded. In addition, the clamp CT20 is held on a connection line to the DC distribution board 14 of the branch circuit 13 to be inspected. Thereby, the electric current which flows into the apparatus board 13 to be examined is detected.

  For example, when the inspection target is a branch circuit of the equipment panel 13a, the clamp CT20 is installed on the load 15a side of the switch 16a of the DC distribution board 14, and an AC voltage for inspection is applied from the voltage power supply device 19 in this state. . In this case, since the ground fault F is generated in the branch circuit of the device board 13a to be inspected, the current flowing through the branch circuit of the device board 13a to be inspected by the AC voltage for inspection is the ground fault resistance of the ground fault F. This is the sum of currents flowing through the parallel circuit of Rf and capacitance Ca. This current is detected by the clamp CT20 and displayed on the ammeter 21.

On the other hand, when the inspection target is a branch circuit of the equipment panel 13b, the clamp CT20 is installed on the load 15b side of the switch 16b of the DC distribution board 14, and in this state, an AC voltage for inspection is applied from the voltage power supply device 19. . In this case, since the ground fault F does not occur in the branch circuit of the device board 13b to be inspected, the current flowing through the branch circuit of the device board 13b to be inspected by the AC voltage for inspection is the current flowing through the capacitance Cb. It becomes. This current is detected by the clamp CT20 and displayed on the ammeter 21.

  Thus, the current flowing through the branch circuit of the equipment panel 13a where the ground fault F is generated and the current flowing through the branch circuit of the equipment panel 13b where the ground fault F is not generated are the current flowing through the ground fault resistance Rf. Therefore, the operator monitors the current value displayed and output on the ammeter 21 to determine whether or not a ground fault F has occurred in the branch circuit of the device panel 13a to be inspected. Judging.

  Here, the voltage V and the leakage current measured by measuring the supply voltage V from the AC power supply device to the cable with an AC ground fault current converter are used to specify the region where the insulation deterioration of the electric wire or cable that conducts electricity has occurred. There is one in which the resistance difference R is detected by detecting the phase difference θ with I, and the insulation resistance R is detected by dividing the supply voltage V by the resistance leakage current Ir (see, for example, Patent Document 1).

JP 2005-62124 A

  However, the thing of patent document 1 detects the insulation failure location of an alternating current distribution system, and applies it to what detects the insulation failure location of the DC circuit which supplies DC power to the apparatus panel connected in parallel. I can't.

  Further, in the conventional DC fault point inspection apparatus shown in FIG. 11, since the current value detected by the ammeter 21 is determined based on the absolute value display, it may not be possible to determine the failure current and the healthy current. That is, when the ground fault resistance Rf of the ground fault F is small, it can be easily determined that the ground fault F has occurred in the branch circuit of the device panel 13a to be inspected. Is large, the current flowing through the ground fault resistance Rf is small. Therefore, the absolute value of the sum of the current flowing through the ground fault resistance Rf and the current flowing through the capacitance Ca is the electrostatic capacitance of the branch circuit of the sound equipment panel 13b. The absolute value of the current flowing through the capacitor Cb may not be distinguished.

  As a cause, when the load 15 of the device panel 13 in recent years is, for example, a digital relay, a capacitor is attached as a filter to the power supply circuit, so the current flowing through the capacitance of the capacitor cannot be ignored. . In addition, the capacitance of DC circuits is increasing due to the standardization of CVV-S cables. From this, since the charging current due to the application of the AC voltage of the voltage power supply device 19 is increased, the current display of the ammeter 21 becomes a large value even in a healthy branch circuit of the equipment panel 13b, and the ground fault F is The generated current cannot be distinguished from the current flowing through the branch circuit of the equipment panel 13a, and the accident point may not be determined.

  Therefore, when the DC ground fault overvoltage protection relay 18 is operated, all the main devices supplying the control power from the DC circuit are stopped, and the switches 16a to 16n are sequentially turned on the DC distribution board 14. It may be determined that a ground fault F has occurred in the branch circuit of the equipment panel 13 when the DC ground fault overvoltage protection relay 18 is recovered from failure after being opened. However, in such a case, since all the main devices that supply the control power from the DC circuit have to be stopped, a power outage section occurs in the distribution system.

  An object of the present invention is to provide a DC fault point inspection device capable of accurately detecting an accident point even when the DC circuit supplying DC power to a load of a branch circuit connected in parallel from a DC power source has a large capacitance. It is to be.

A DC fault point inspection device according to the invention of claim 1 is a voltage power supply device that applies an AC voltage for fault point inspection to a DC circuit that supplies DC power to a load of a branch circuit connected in parallel from a DC power source; A reference resistor connected in series to the voltage power supply device and generating a reference voltage for inspection and a branch circuit of the DC circuit that is gripped by the branch circuit to be inspected at the fault point and flows to the branch circuit of the DC circuit Based on the phase of the clamp CT for measuring the current waveform of the current and the current waveform measured by the clamp CT and the voltage waveform of the reference voltage generated by the reference resistor, the current waveform is the voltage waveform of the reference voltage. When the phase of the current waveform is delayed from the phase of the voltage waveform of the reference voltage, it is determined that a complete ground fault has occurred in the branch circuit to be inspected. Wherein the ground fault in the branch circuits elephant and a are the determining fault point determination device occurred.

According to a second aspect of the present invention, there is provided a DC fault point inspection apparatus according to the first aspect of the present invention, further comprising a vector multimeter that displays a current waveform measured by the clamp CT and a voltage waveform of a reference voltage generated by the reference resistance. characterized in that was.

According to the first aspect of the present invention, a reference resistor is connected in series to the voltage power supply device, a reference voltage for inspection is generated by the reference resistor, and a branch circuit to be inspected for an accident point among the branch circuits of the DC circuit. When the current waveform is in phase with the voltage waveform of the reference voltage by the accident point determination device, it is determined that a complete ground fault has occurred in the branch circuit to be inspected. When the phase of the current waveform is delayed from the phase of the voltage waveform of the reference voltage, it is determined that a ground fault has occurred in the branch circuit to be inspected. It can be easily detected.

According to the invention of claim 2, since the current waveform measured by the clamp CT and the voltage waveform of the reference voltage generated by the reference resistance are displayed on the vector multimeter, in addition to the effect of the invention of claim 1, the reference resistance The phase between the voltage waveform of the generated reference voltage and the current waveform measured by the lamp CT can be displayed. Therefore, from the phase relationship, for example, when the phase of the current waveform is delayed from the phase of the reference voltage waveform, it can be determined that an accident has occurred in the branch circuit to be inspected .

The block diagram applied to the investigation of the fault point of a DC circuit using the DC fault point inspection apparatus of Example 1 which concerns on embodiment of this invention. Explanatory drawing of the electric current which flows into a DC circuit when the reference resistance and power supply voltage apparatus of the DC fault point inspection apparatus which concern on embodiment of this invention are connected to a DC circuit. The AC voltage E of the power supply voltage device, the reference voltage V of the reference resistance, the overall current I, and the shunt current I1 when the AC voltage of the power supply voltage device of the DC fault point inspection device according to the embodiment of the present invention is applied to the DC circuit. ~ In vector diagram. The vector diagram of the reference voltage V of the reference resistance and the total current I when the ground fault resistance is zero (in the case of a complete ground fault). The waveform figure of the electric current which flows through the reference voltage when a ground fault has not occurred, and the healthy equipment panel. The waveform diagram of the reference voltage and the current flowing through the equipment panel when a ground fault with a ground fault resistance of zero occurs. The waveform diagram of the reference voltage and the current flowing through the equipment panel when a ground fault with a medium resistance value where the ground fault resistance is not zero occurs. The waveform diagram of the reference voltage and the current flowing through the equipment panel when a ground fault having a high resistance value with non-zero ground fault occurs. The block diagram applied to the investigation of the fault point of a DC circuit using the DC fault point inspection apparatus of Example 2 which concerns on embodiment of this invention. The block diagram applied to the investigation of the fault point of a DC circuit using the DC fault point inspection apparatus of Example 3 which concerns on embodiment of this invention. Explanatory drawing of an example which investigates the fault point of a DC circuit using the conventional DC fault point inspection apparatus.

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram applied to the investigation of an accident point of a DC circuit using the DC accident point inspection apparatus of Example 1 according to the embodiment of the present invention. In contrast to the conventional example shown in FIG. 11, a reference resistor 22 for generating a test reference voltage V is connected in series to a voltage power supply device 19, and a vector multimeter 23 is provided in place of the ammeter 21. The current waveform measured by the clamp CT20 and the voltage waveform of the reference voltage V generated by the reference resistor 22 are displayed on the multimeter 23. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  The voltage power supply device 19 applies an AC voltage for inspecting an accident point to a DC circuit. That is, when the DC ground fault overvoltage protection relay 18 in the charger panel 12 is operated, the voltage power supply device 19 is connected at one end to the positive power line of the DC circuit and grounded at the other end. The test AC voltage generated in the voltage power supply device 19 is an AC voltage having a frequency of 32 Hz and a voltage level of 42 V or less, for example, a frequency of commercial power frequency (60 Hz, 50 Hz) or less.

  The reference resistor 22 is connected in series between the DC positive electrode power line and the voltage power supply device 19, and an AC voltage for inspection is applied from the voltage power supply device 19 to the equipment panels 13 a to 13 n which are branch circuits of the DC circuit. When applied, it generates a reference voltage V for inspection. The reference resistor 22 is composed of a variable resistor whose resistance value can be varied. For example, a resistor whose resistance value can be adjusted within a range of 100Ω or less is used. Thereby, the voltage level of the reference voltage V generated by the reference resistor 22 can be adjusted.

  When an AC voltage for inspection is applied to the DC circuit, when no ground fault has occurred, a closed circuit is formed through the reference resistor 22 and the capacitances Ca to Cn of the equipment panels 13a to 13n. Further, when a ground fault occurs, a closed circuit is formed through the ground fault resistance in addition to the capacitances Ca to Cn of the equipment panels 13a to 13n. The reference voltage V is generated in the reference resistor 22 by the current flowing in the closed circuit. As described above, since the reference resistor 22 is a variable resistor whose resistance value can be varied, the current flowing through the closed circuit is changed by changing the resistance value of the reference resistor 22, and the reference voltage generated by the reference resistor 22 is changed. Adjust the voltage level.

  The clamp CT is for measuring the waveform of the current flowing through each of the equipment boards 13a to 13n, and is a closed circuit formed on each of the equipment boards 13a to 13n when an AC voltage for inspection is applied to the DC circuit. Measure the current. In this case, the clamp CT holds the positive and negative power lines of the branch circuit for each of the equipment boards 13a to 13n branched from the DC distribution board 14, and sequentially holds the gripped portions. The current flowing through each of the equipment boards 13a to 13n is measured after changing. The reason why both the positive and negative power supply lines of the branch circuits of the device boards 13a to 13n are held is to cancel the measurement of the AC component included in the DC circuit.

  The vector multimeter 23 displays the current waveform measured by the clamp CT20 and the voltage waveform of the reference voltage V generated by the reference resistor 22, and the current waveform and the reference voltage V flowing through the branch circuits of the equipment panels 13a to 13n. Since these voltage waveforms are displayed, these phase relationships can be easily grasped. In this case, the resistance value of the reference resistor 22 is made variable, the voltage level of the reference voltage V generated by the reference resistor 22 is adjusted, and the phase relationship between the current waveform measured by the clamp CT20 and the voltage waveform of the reference voltage V is obtained. Make it easy to distinguish.

  FIG. 2 is an explanatory diagram of a current flowing through the DC circuit when the reference resistor and the power supply voltage device of the DC fault point inspection apparatus according to the embodiment of the present invention are connected to the DC circuit. In FIG. 2, the ground fault F has generate | occur | produced in the equipment board 13b, and the other equipment boards 13a and 13c-13n have shown the case where it is healthy. When the AC voltage of the power supply voltage device 19 is applied to the DC circuit, the entire current I flows through the reference resistor 22, and the current I is shunted to the branch circuit to each of the equipment panels 13a to 13n. In (I = I1 + I2 +... In) flows.

  FIG. 3 is a vector diagram of the AC voltage E of the power supply voltage device 19 when the AC voltage of the power supply voltage device 19 is applied to the DC circuit, the reference voltage V of the reference resistor 22, the total current I, and the shunt currents I1 to In. . As shown in FIG. 3A, the shunt currents I1, I3,... In flowing through the sound equipment boards 13a, 13c to 13n are currents flowing through the capacitances Ca, Cc to Cn. This is a current whose phase is advanced by π / 2 from the AC voltage E. On the other hand, the shunt current I2 flowing through the equipment panel 13b in which the ground fault F has occurred is a vector sum of the current Ic flowing through the capacitance Cb and the ground fault current Ig flowing through the ground fault resistance Rg.

  The total current I is a vector sum of the shunt currents I1 to In, and the reference voltage V of the reference resistor 22 is in phase with the total current I. As shown in FIG. 3 (b), the shunt current Ii flowing in the sound equipment panel 13i (i is the one excluding 13b in which the ground fault occurs, i = a, c... N, the same applies hereinafter) Since the current flows through Ci, it is a current whose phase is advanced by π / 2 from the AC voltage E of the power supply voltage device 19, and is a current that is further advanced than the phase of the reference voltage V. On the other hand, the current I2 flowing through the equipment panel 13b in which the ground fault F has occurred is a vector sum of the current Ic flowing through the capacitance Cb and the ground fault current Ig flowing through the ground fault resistance Rg, and therefore, as shown in FIG. As shown, the current is delayed from the phase of the reference voltage V.

  When the ground fault resistance Rg of the ground fault F is zero (in the case of a complete ground fault), the entire current I is in phase with the reference voltage V as shown in FIG. In the case of a complete ground fault, since the entire current I flows through the ground fault point of the equipment panel 14b where the ground fault F has occurred, the shunt current Ii hardly flows through the healthy equipment panel 14i.

  For this reason, when the ground fault F is not generated, the phase of the current Ii flowing through the sound equipment panel 13i always advances from the reference voltage V. On the other hand, when a ground fault occurs in which the ground fault resistance Rg is not zero, the phase of the current Ii flowing through the healthy equipment panel 13i always advances from the reference voltage V, and the equipment in which the ground fault F has occurred. The current I2 of the panel 13b is always delayed from the reference voltage V. When a ground fault with a ground fault resistance Rg of zero occurs, the current Ii flowing through the sound equipment board 13i is almost zero, and the current I2 of the equipment board 13b where the ground fault F is generated is the reference voltage V. Become in phase. From these relationships, it is possible to determine the equipment panel 13b in which the ground fault F has occurred.

  Therefore, in the embodiment of the present invention, the currents I1 to In flowing through the branch circuits of the respective instrument panels 13a to 13n are sequentially measured by the clamp CT20, and the currents I1 to In and the reference are supplied to the vector multimeter 23. The reference voltage V of the resistor 22 is displayed, and the equipment panel 13b where the ground fault F has occurred is determined from the phase relationship between the currents I1 to In and the reference voltage V.

  Next, the reference voltage V of the reference resistor 22 displayed on the vector multimeter 23 and the current Ii flowing through the branch circuit of the equipment panel 13i will be described.

  FIG. 5 is a waveform diagram of the reference voltage V and the current Ii flowing through the healthy equipment panel 13i when the ground fault F is not generated. When the ground fault F has not occurred, the current Ii flowing through the sound equipment panel 13i has a waveform whose phase is advanced by π / 2 from the reference voltage V. Thus, when the current Ii flowing through the equipment panel 13i has a waveform whose phase is advanced by π / 2 from the reference voltage V, it is assumed that no ground fault has occurred in each of the equipment boards 13a to 13n of the DC circuit. I can judge.

  FIG. 6 is a waveform diagram of the reference voltage V and the current Ij flowing through the equipment panel 13j (j = a to n) when a ground fault having a ground fault resistance Rg of zero occurs. FIG. FIG. 6B is a waveform diagram of the current I2 flowing through the device panel 13b where the reference voltage V and the ground fault F are generated. In the case of a ground fault (complete ground fault) in which the ground fault resistance Rg is zero, the entire current I flows through the ground fault point. Therefore, the current Ii flowing through the sound equipment panel 13i becomes zero as shown in FIG. On the other hand, the current I2 flowing through the equipment panel 13b in which the ground fault has occurred is equal to the total current I, and therefore has a current in phase with the reference voltage V as shown in FIG. Thus, when the current Ij flowing through the device board 13j is zero, it can be determined that a failure has occurred in any of the device boards 13j of the DC circuit. When the current Ij flowing through the equipment panel 13j is in phase with the reference voltage V, it can be determined that a complete ground fault has occurred in the equipment board 13j.

  FIG. 7 is a waveform diagram of the reference voltage V and the current Ij flowing through the equipment panel 13j when a ground fault having a medium resistance value where the ground fault resistance Rg is not zero occurs. FIG. FIG. 7B is a waveform diagram of the current I2 flowing through the equipment panel 13b in which the reference voltage V and the ground fault F are generated. When a ground fault having a medium resistance value with a non-zero ground fault resistance Rg occurs, as shown in FIG. 2, the current Ii flows through the electrostatic capacity Ci in the sound equipment panel 13i, and a ground fault occurs. A current I2 which is a vector sum of the current Ic flowing through the capacitance Cb and the current Ig flowing through the ground fault resistance Rg flows through the device board 13b.

  In the healthy equipment panel 13i, the current Ii flowing through the capacitance Ci is a current whose phase is advanced from the reference voltage V as shown in FIG. On the other hand, the current I2 flowing through the equipment panel 13b where the ground fault has occurred is a current whose phase is delayed from the reference voltage V as shown in FIG. As a result, when the current Ij flowing through the equipment panel 13j is a current whose phase is less than π / 2 from the reference voltage V, a fault has occurred in any equipment panel 13j of the DC circuit. It can be determined that the board 13j is a healthy equipment board 13i. When the current Ij flowing through the device panel 13j is delayed from the reference voltage V, it can be determined that the device panel 13j is the device panel 13b in which a ground fault has occurred.

  FIG. 8 is a waveform diagram of the reference voltage V and the current Ij flowing through the equipment panel 13j when a ground fault having a high resistance value where the ground fault resistance Rg is not zero occurs. FIG. FIG. 8B is a waveform diagram of the current I2 flowing through the equipment panel 13b in which the reference voltage V and the ground fault F are generated. When a ground fault having a high resistance value with non-zero ground fault resistance Rg occurs, the current Ii flowing through the electrostatic capacity Ci in the sound equipment panel 13i is equal to the reference voltage V as in the case shown in FIG. The current is more advanced in phase, and the current I2 flowing through the equipment panel 13b in which the ground fault has occurred becomes a current delayed in phase from the reference voltage V.

  In this case, since the ground fault resistance Rg has a high resistance value, the phase difference between the reference voltage V and the current Ii flowing through the healthy equipment panel 13i is as shown in FIG. It is smaller than the case of medium resistance value. Similarly, as shown in FIG. 8B, the phase difference between the reference voltage and the current I2 flowing through the equipment panel 13b in which the ground fault has occurred is compared with the case of the middle resistance value in FIG. 7B. It is getting smaller. Thereby, the magnitude of the ground fault resistance Rg can be determined to some extent from the phase difference between the reference voltage V and the current Ij flowing through the equipment panel 13j.

  According to the first embodiment, a reference resistor 22 is connected in series to a voltage power supply device, and a reference voltage V for inspection is generated by the reference resistor 22, and an accident is detected among the branch circuits of the DC circuit boards 13a to 13n. The current flowing through the branch circuit of the device board 13j to be inspected is sequentially measured by the clamp CT20, and the current waveform measured by the clamp CT20 and the voltage waveform of the reference voltage V generated by the reference resistor 22 are measured by the vector multimeter 23. Therefore, the phase between the voltage waveform of the reference voltage V displayed on the vector multimeter 23 and the current waveform measured by the lamp CT20 can be determined. Thereby, it can be determined from the phase relationship whether or not an accident has occurred in the branch circuit to be inspected.

  For example, when the current value of the current waveform is zero, it can be determined that the sound circuit is a complete ground fault, and when the current waveform is in phase with the reference voltage V, the ground fault is a complete ground fault. When the phase of the current waveform is behind the phase of the reference voltage waveform, it can be determined that an accident has occurred in the branch circuit to be inspected. Furthermore, the magnitude of the ground fault resistance Rg can be determined to some extent by determining the phase difference.

  Next, a DC fault point inspection apparatus of Example 2 according to the embodiment of the present invention will be described. FIG. 9 is a configuration diagram applied to the investigation of the fault point of the DC circuit using the DC fault point inspection apparatus of Example 2 according to the embodiment of the present invention. In the second embodiment, an accident point determination device 24 is provided in addition to the vector multimeter with respect to the first embodiment shown in FIG. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  The accident point determination device 24 inputs the current waveform measured by the clamp CT 20 and the voltage waveform of the reference voltage V, and determines the phase difference. When the phase of the current waveform and the phase of the voltage waveform of the reference voltage V are in phase, it is determined that a complete ground fault has occurred in the branch circuit to be inspected. When the phase of the current waveform is delayed from the phase of the voltage waveform of the reference voltage V, it is determined that a ground fault has occurred in the branch circuit to be inspected. When these complete ground faults or ground faults are detected, the fact is reported to the outside. Thereby, the worker can easily recognize whether or not a ground fault has occurred in the equipment panel 13j to be inspected.

  Although the case where the accident point determination device 24 is provided in addition to the vector multimeter has been described above, the accident point determination device 24 may be provided instead of the vector multimeter.

  FIG. 10 is a configuration diagram applied to the investigation of the fault point of the DC circuit using the DC fault point inspection apparatus of Example 3 according to the embodiment of the present invention. In the third embodiment, in contrast to the first embodiment shown in FIG. 1, the clamps CT20a to 20n for measuring the currents I1 to In flowing in the branch circuits of the respective device boards 13a to 13n are installed in advance, and the vector multimeter In place of 23, a recording device 25 for recording the currents I1 to In detected by the clamps CT20a to 20n and the reference voltage V of the reference resistor 22 is provided. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 10, clamps CT 20 a to 20 n are respectively provided on the respective equipment boards 13 a to 13 n, and currents I 1 to In flowing through the respective equipment boards 13 a to 13 n are measured and input to the recording device 25. . On the other hand, the reference voltage V from the reference resistor 22 is also input to the recording device 25. The recording device 25 then displays the current waveforms of the currents I1 to In and the voltage waveform of the reference voltage V detected by the clamps CT20a to 20n for a predetermined period when the DC ground fault overvoltage protection relay 18 operates. Record. The predetermined period is a period in which a ground fault can be determined from the recorded current waveforms of the currents I1 to In and the voltage waveform of the reference voltage V. Thereby, after the DC ground fault overvoltage protection relay 18 is operated, a ground fault occurs in any of the equipment panels 13j from the current waveforms of the currents I1 to In and the voltage waveform of the reference voltage V recorded in the recording device 25. You can determine if you are.

  As described above, according to the embodiment of the present invention, the reference resistor 22 is provided in series with the voltage power supply device 19, and the phase measurement with the current waveforms of the currents I1 to In flowing in the branch circuits of the equipment panels 13a to 13n is performed. The voltage waveform of the reference voltage V is taken in, and the phase difference between the voltage waveform of the reference voltage V and the current waveforms of the currents I1 to In can be obtained. Therefore, the ground fault can be easily determined based on this phase difference.

DESCRIPTION OF SYMBOLS 11 ... Battery, 12 ... Charger panel, 13 ... Equipment panel, 14 ... DC distribution board, 15 ... Load, 16 ... Switch, 17 ... AC / DC converter, 18 ... DC ground fault overvoltage protection relay, 19 ... Voltage Power supply device, 20 ... Clamp CT, 21 ... Ammeter, 22 ... Reference resistance, 23 ... Vector multimeter, 24 ... Accident point determination device, 25 ... Recording device

Claims (2)

A voltage power supply device for applying an AC voltage for inspection of an accident point to a DC circuit that supplies DC power to a load of a branch circuit connected in parallel from a DC power supply;
A reference resistor connected in series to the voltage power supply device for generating a reference voltage for inspection;
Clamp CT for measuring the current waveform of the current that is gripped by the branch circuit to be inspected at the fault point among the branch circuits of the DC circuit and flows through the branch circuit of the DC circuit;
Based on the phase of the current waveform measured by the clamp CT and the voltage waveform of the reference voltage generated by the reference resistor, when the current waveform is in phase with the voltage waveform of the reference voltage, the branch circuit to be inspected When the phase of the current waveform is delayed from the phase of the voltage waveform of the reference voltage, it is determined that a ground fault has occurred in the branch circuit to be inspected. DC fault point testing apparatus is characterized in that a fault point determination apparatus. The DC fault point inspection apparatus according to claim 1, further comprising a vector multimeter for displaying a current waveform measured by the clamp CT and a voltage waveform of a reference voltage generated by the reference resistor .

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