JP2011227019A - Dc circuit ground fault search device and dc circuit ground fault accident spot search method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC circuit ground fault search device and a DC circuit ground fault accident part search method, which allow a firm search for a ground fault accident spot on an uninterruptive power basis.SOLUTION: The DC circuit ground fault search device 10 includes: an insulated DC power source 11 for supplying an output voltage a few bolts lower than a circuit voltage supplied from a DC power supply device 110 to one of first through third loads instead of the circuit voltage to the load when a ground fault accident spot is searched for and when circuits 3through 3connecting voltage supply lines 1 and 2 to the one load are disconnected; a voltage-to-ground measurement part 12 for measuring a positive voltage-to-ground and a negative voltage-to-ground of the voltage supply lines 1 and 2; and a control part 13 for determining whether the circuit is a ground fault accident spot on the basis of the positive earth voltage and the negative earth voltage measured by the voltage-to-ground measurement part 12 when the ground fault accident spot is searched for.

Description

  The present invention relates to a ground fault accident location when a grounding fault occurs in a DC circuit in which a plurality of loads are connected in parallel to the DC power supply apparatus and a circuit voltage is supplied from the DC power supply apparatus to the plurality of loads via a voltage supply line. The present invention relates to a DC circuit ground fault searching apparatus and a DC circuit ground fault accident searching method suitable for specifying the above.

A DC positive voltage of +55 V is supplied to a positive bus (positive voltage supply line) 1 from a DC power supply device 110 having a DC 110 V storage battery 111 and a ground fault detection device (64D) 112 as shown in FIG. Voltage supply line) 2 is supplied with a negative DC voltage of −55 V and is branched from the positive bus 1 and the negative bus 2 through the _first to _third terminal blocks 4 ₁ to 4 3. In a DC circuit that supplies a DC voltage to the _first to _third loads through the wirings (circuits) 3 _{1 to} 3 ₃ , for example, when a ground fault (grounding accident) occurs on the positive electrode side of the second wiring 3 ₂ , the DC since the fact that the positive electrode side in ground fault circuit has occurred is displayed on the grounding detector 112, the second wiring 3 ₂ specific a ground fault point (search) was necessary to eliminate the ground fault accident There is.

  As a method of identifying such a ground fault accident location, the ground fault accident location is identified based on whether or not the ground fault is resolved by sequentially powering off the first to third loads that supply DC voltage. A method and a method for identifying a ground fault location without a power failure using a dedicated DC circuit ground fault search device are mainly used.

  For example, in the ground fault detection circuit of the DC power supply circuit disclosed in Patent Document 1 below, a DC ground fault location can be detected through a branch circuit so that the DC ground fault location can be detected without stopping the power supply to the DC load. A DC ground fault detector is provided between the outputs of the DC power supply to detect a ground fault in the branch circuit of the DC power supply circuit that supplies DC power to the DC load and whose detection sensitivity changes due to a change in the resistance value of the measurement circuit. In the middle of at least the positive line of each branch circuit, a parallel circuit formed by connecting in parallel a small resistance circuit composed of a diode and a short-circuit switch circuit that short-circuits the small resistance circuit during ground fault measurement is connected in series. .

  In the DC power shutoff device disclosed in Patent Document 2 below, an electric shock accident at the time of the occurrence of a ground fault occurs while minimizing the influence on the behavior of these facilities without changing the permanent facilities of the substation. A DC power shutoff device is added between the control DC power supply device and the load device in the substation to prevent the occurrence of a short circuit accident and prevent the occurrence of a short circuit accident on the currently active control circuit. Connect the DC power breaker when the ground fault occurs, before the operation of the DC ground fault overvoltage relay of the control DC power supply, the circuit breaker on / off circuit based on the ground fault detection signal of the ground fault detection circuit When the load circuit breaker is switched to the cut-off state and a short-circuit accident, overload or overcurrent occurs, before the overcurrent relay operation of the control DC power supply, based on the detection signal such as a short circuit of the overcurrent detection circuit By circuit breaker on / off circuit And to switch the load breaker to cut-off state.

  In the ground fault detection device disclosed in the following Patent Document 3, when a ground fault occurs in a plurality of circuits, the ground fault detection device is in the control panel so that the control circuit can be performed without power failure when specifying the location of the ground fault occurrence. In order to supply direct current control power to a plurality of control circuits, the first power supply dividing means that divides and splits the original power supply and the secondary side after the first power supply dividing means are subdivided. The second power source splitting means that branches, a ground fault relay that operates when a ground fault occurs, and a ground fault detector that detects a ground fault current that flows when a ground fault occurs with a load feeder on the secondary side of the second power split means In the power supply circuit configuration comprising: a third power supply dividing means for supplying the original power supply to the plurality of control circuits through another path, and a secondary side after the third power supply dividing means Subdivided by a separate circuit So that a power supply switching means for.

  In the DC ground fault detection device disclosed in Patent Document 4 below, each series ground fault detection device is caused by the wraparound of the ground fault current when a DC ground fault occurs in the multiplexed DC power supply circuit that constantly supplies power to the load in parallel. 2 sets of resistors are connected in series between the positive and negative electrodes of the DC power supply circuit, and the middle point of the two sets of resistors is set to the third In a DC ground fault detection circuit that has a ground circuit that grounds through a resistor, and detects a DC ground fault by means of a current flowing through the ground circuit, the reverse flow prevention with the direction flowing from the positive electrode toward the middle point of the resistance as the forward direction And a backflow prevention element having a forward direction from the middle point of the resistance toward the negative electrode.

JP-A-6-113442 JP 2007-110844 A JP 2003-61239 A JP 2009-38929 A

However, in the method of identifying the ground fault location by whether or not the ground fault is resolved by sequentially powering down the first to third loads that supply DC voltage, the load must Therefore, measures should be taken so that no problem will occur even if the load is stopped in advance, or the risk caused by stopping the load (for example, loss of the protective function during the load stop) may be allowed. Therefore, there was a problem of conducting a ground fault search.
In addition, in general, a method is used to expand the search range from the terminal part, which has little effect even when the DC circuit is stopped, to the power supply part. There was a problem that there was a case where there was a power outage and the range of power outages could be wide.

  A method for identifying the location of a ground fault without a power failure using a dedicated DC circuit ground fault search device (for example, using a commercially available general-purpose measurement device) does not involve a load power failure, but a DC circuit There was a problem that the ground fault location could not be searched depending on the overall insulation conditions (capacity to ground and the magnitude of the insulation resistance of the entire DC circuit).

  An object of the present invention is to provide a DC circuit ground fault searching apparatus and a DC circuit ground fault accident searching method that can reliably search for a ground fault accident location without a power failure.

In the DC circuit ground fault search device of the present invention, a plurality of loads are connected in parallel to the DC power supply device (110), and a circuit voltage is supplied from the DC power supply device to the plurality of loads via the voltage supply lines (1, 2). A DC circuit ground fault search device (10) for specifying a ground fault fault location when a ground fault has occurred in a DC circuit to be supplied, wherein the voltage supply line and the plurality of the plurality of voltage supply lines are searched when searching for a ground fault fault location. In order to supply an output voltage several volts lower than the circuit voltage to the one load instead of the circuit voltage when the circuit (3 _{1 to} 3 ₃ ) connecting to one of the loads is disconnected A DC insulated power source (11), a ground voltage measuring unit (12) for measuring a positive ground voltage and a negative ground voltage of the voltage supply line, and the ground voltage measuring unit when searching for a ground fault The positive ground voltage and the negative ground voltage Based on the pressure, the circuit is characterized by comprising a control unit (13) for determining whether a ground fault point.
Here, the control unit obtains a difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage measured by the ground voltage measuring unit after disconnecting the circuit, and an absolute value of the obtained difference is obtained. If it is less than a predetermined threshold value, it may be determined that the balance between the positive ground voltage and the negative ground voltage is good, and the circuit may be identified as a ground fault location. Further, the circuit may be identified as a ground fault location by reversing the polarity when the absolute value of the obtained difference is equal to or greater than a predetermined threshold value.
The balance between the positive ground voltage and the negative ground voltage measured by the ground voltage measuring unit, the balance between the positive ground voltage and the negative ground voltage determined by the control unit, and the control unit You may further comprise the display part (15) for displaying the polarity reversal of the difference of the said positive ground voltage and the said negative ground voltage, and the ground fault accident location specified by the said control part.
Even if the DC insulated power supply has a variable output voltage and is connected to a circuit that does not cause a ground fault, it has a built-in current backflow prevention commutator for preventing current from flowing back. Good.
According to the DC circuit ground fault location searching method of the present invention, when a ground fault occurs in the DC circuit, the ground fault location is specified by using the DC circuit ground fault searching device (10) of the present invention. Features.

The DC circuit ground fault searching device and the DC circuit ground fault accident searching method of the present invention have the following effects.
(1) Since the output voltage (DC voltage) of the DC insulated power supply is supplied to the load that is disconnected from the DC power supply device at the time of searching for the ground fault accident location, it is possible to search for the ground fault location without any power failure.
(2) The search range can be reduced because the search for the positive and negative sides of the circuit on the terminal block can be performed in addition to the search in units where the circuit can be separated by a switch, etc., and a ground fault can occur. The location can be easily identified.
(3) Since the grounding capacitance of the DC circuit and the insulation resistance value of the entire DC circuit do not affect the search for the ground fault location, it is possible to search for the ground fault location in any DC circuit with any insulation condition. it can.
(4) In the conventional dedicated DC circuit ground fault search device, it was necessary to disable the DC ground fault detection relay when searching for the location of the ground fault, whereas the ground fault detection device (ground fault detection relay) It becomes possible to search for the ground fault accident location in the normal state with using.
(5) In the conventional dedicated DC circuit ground fault search device, the target circuit voltage is limited. However, if the output voltage of the DC insulated power supply is variable, it is within the range of the variable voltage. Search for ground faults regardless of circuit voltage. For example, if a variable direct-current insulated power supply up to DC 150V is used, it can be applied to 24V, 48V and 100V as a general DC circuit.

It is a figure which shows the structure of the DC circuit ground fault search apparatus 10 by one Example of this invention. Ground fault location search operation using the DC circuit ground fault search device 10 when a ground fault occurs between the second terminal block 4 ₂ on the positive electrode side of the second wiring 3 ₂ and the second load It is a figure for demonstrating the procedure of. It is a figure for demonstrating the procedure of the ground fault accident location search operation | work using the DC circuit ground fault search apparatus 10 shown in FIG. It is a flowchart for demonstrating the procedure of the ground fault accident location search operation | work using the DC circuit ground fault search apparatus 10 shown in FIG. Ground fault accident search operation using the DC circuit ground fault search device 10 when a ground fault occurs between the second terminal block 4 ₂ on the negative electrode side of the second wiring 3 ₂ and the second load It is a figure for demonstrating the procedure of. It is a figure which shows the example of 1 structure of the DC circuit for demonstrating the conventional ground fault accident search method.

  For the above purpose, when searching for the location of the ground fault, when the circuit connecting the voltage supply line and one of the plurality of loads is disconnected, an output voltage that is several volts lower than the circuit voltage is used instead of the circuit voltage. This was realized by supplying this load from a DC insulated power supply and determining whether or not this circuit was a ground fault location based on the positive ground voltage and negative ground voltage measured by the ground voltage measuring unit.

Embodiments of a ground fault search device and a DC circuit ground fault search method according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a DC circuit ground fault search apparatus 10 according to an embodiment of the present invention includes a variable DC insulated power supply 11 that can set an output voltage, a ground voltage measurement unit 12, a control unit 13, An input unit 14, a display unit 15, a positive output voltage terminal 21, a negative output voltage terminal 22, a positive voltage measurement terminal 23, a negative voltage measurement terminal 24, and a device power supply terminal 25 are provided.

Here, the DC insulated power supply 11 is for supplying a DC voltage (output voltage) to a load connected to a wiring (circuit) disconnected from the DC power supply device 110 when searching for a ground fault accident location.
The output voltage of the DC insulated power supply 11 is a voltage (for example, DC108V) lower by several volts (for example, about 1 to 2V) than the circuit voltage (for example, DC110V) output from the DC power supply device 110 by the control unit 13. Set to
The DC insulated power supply 11 is connected to a device power supply (AC power supply or DC power supply) (not shown) via a device power supply terminal 25, and generates an output voltage by converting a voltage supplied from the device power supply. .
Further, the DC insulated power supply 11 is provided with a positive output voltage terminal 21 and a negative output voltage terminal 22 in a circuit in which no ground fault has occurred (see the _first to _third wirings 31 to 33 shown in FIG. 5). It has a built-in current backflow prevention commutator for preventing current from flowing backward even if connected through the circuit.

The ground voltage measuring unit 12 measures the ground voltage (hereinafter referred to as “positive ground voltage”) of the positive bus 1 inputted via the positive voltage measuring terminal 23 and also inputted via the negative voltage measuring terminal 24. For measuring the ground voltage of the negative electrode bus 2 (hereinafter referred to as “negative ground voltage”).
The ground voltage measuring unit 12 outputs a ground voltage signal indicating the measured positive ground voltage and negative ground voltage to the control unit 13.

  The input unit 14 instructs to start a ground fault accident location search operation, disconnects wiring, a measurement start signal indicating either positive electrode disconnection or negative electrode disconnection, a measurement stop signal to instruct to stop ground fault accident location search operation, and a ground fault This is for inputting a measurement end signal or the like for instructing the end of the location search operation to the control unit 13.

  In accordance with the display control signal input from the control unit 13, the display unit 15 displays the positive voltage to ground voltage, the negative voltage to ground voltage, the balance between the positive voltage to ground voltage and the negative voltage to ground voltage, and the difference voltage between the positive voltage to ground voltage and the negative voltage to ground voltage. This is for displaying the judgment result of polarity reversal and the location of the ground fault.

The control unit 13 obtains a constant circuit voltage (= positive ground voltage−negative ground voltage) based on the ground voltage signal input from the ground voltage measuring unit 12 and outputs an output voltage that is several volts lower than the obtained regular circuit voltage. The DC insulated power supply 11 is controlled so as to generate.
Further, the control unit 13 causes the display unit 15 to display normal positive ground voltage and negative ground voltage.
Further, the control unit 13 determines the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage based on the ground voltage signal input from the ground voltage measurement unit 12 (from the positive ground voltage to the negative ground) when searching for the ground fault accident location. If the absolute value of the obtained difference is less than a predetermined threshold value (for example, 10 V), it is determined that “the balance between the positive ground voltage and the negative ground voltage is good”. On the other hand, if the absolute value of the obtained difference is equal to or greater than the threshold value, it is determined that the balance between the positive ground voltage and the negative ground voltage is poor, and the ground fault location is specified based on the determination result. At the same time, the determination result and the ground fault location are displayed on the display unit 15.
Furthermore, when searching for a ground fault location, the control unit 13 determines that the absolute value of the obtained difference is a predetermined threshold value (for example, 10 V) or more and the polarity of the obtained difference is inverted. It is determined that “a ground fault has occurred”, the ground fault location is specified, and the determination result and the ground fault location are displayed on the display unit 15.

Then, in a DC circuit shown in FIG. 5, ground fault between the second wiring 3 of the _second positive electrode side second terminal block 4 ₂ and the second load, as indicated by a thick arrow in FIG. 2 A procedure for ground fault accident location search using the DC circuit ground fault search device 10 when a fault occurs will be described with reference to the flowchart shown in FIG.

As shown in FIG. 2, the positive voltage measuring terminal 23 and the negative voltage measuring terminal 24 of the DC circuit ground fault search device 10 are connected to the positive bus 1 and the negative bus 2 through connection lines, respectively.
The ground voltage measuring unit 12 of the DC circuit ground fault search device 10 always measures the positive ground voltage and the negative ground voltage, and the measured positive ground voltage (= + 55 V) and negative ground voltage (= −55 V) at all times. Is output to the control unit 13.
The control unit 13 obtains the circuit voltage (= + 55 V − (− 55 V) = 110 V) by subtracting the normal negative ground voltage from the normal positive ground voltage based on the ground voltage signal input from the ground voltage measuring unit 12. The DC insulated power supply 11 is controlled so as to generate an output voltage that is 2 volts lower (= 108 V) than the obtained circuit voltage. Thereby, the output voltage of the DC insulated power supply 11 is set to 108V (positive output voltage = + 54V and negative output voltage = −54V) (step S11).
Further, the control unit 13 outputs a display control signal indicating a normal positive ground voltage and a negative ground voltage to the display unit 15. Thus, the normal positive ground voltage and negative ground voltage are displayed on the display unit 15.

When a ground fault occurs in the second wiring 3 ₂ on the positive electrode side, since the fact that a ground fault has occurred is displayed on the grounding detector 112 at the positive electrode side of the direct current circuit, the operator, the DC circuit ground Using the input unit 14 of the search device 10, a measurement start signal indicating the start of ground fault location search operation and positive electrode disconnection is input to the control unit 13.
In response to this measurement start signal, the control unit 15 starts a ground fault accident location search operation and outputs a display control signal indicating positive electrode disconnection to the display unit 15 to display “positive electrode disconnection” on the display unit 15. (Steps S12 and S13).

In addition, the worker connects the positive output voltage terminal 21 and the positive electrode side of the first wiring 3 ₁ via a connection line, and connects the negative output voltage terminal 22 and the negative electrode side of the first wiring 3 ₁ to the connection line. After connected via a disconnect the first terminal block 4 _first positive bus 1 side for connecting the wiring 3 ₁ and positive electrode bus line 1 first, as shown by the solid line × mark in FIG. Thereby, since the output voltage is supplied from the DC insulated power supply 11 of the DC circuit ground fault search device 10 to the first load, it is possible to search for the ground fault location without causing the first load to fail. .

The control unit 13 obtains a difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage based on the ground voltage signal input from the ground voltage measuring unit 12, and the positive ground voltage and the negative ground voltage are balanced. Or whether the polarity of the difference is reversed (step S15).
If the ground fault occurs in the second wiring 3 ₂ on the positive electrode side, since the voltage balance does not change even detach first positive electrode side of the interconnect 3 _1, for example a positive voltage to ground is 45V becomes negative voltage to ground Since −65V, the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is −20V (= 45V−65V). As a result, since the absolute value (= 20V) of the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is equal to or greater than the threshold (= 10V), the control unit 13 determines that the positive ground voltage and the negative ground voltage are Is determined to be poor, and the determination result “balance between positive ground voltage and negative ground voltage = bad” is displayed on the display unit 15 (step S17).

  The control unit 13 continues the ground fault accident location search operation unless a measurement stop signal is input from the input unit 14 (step S18).

The operator, when the display unit 15 "Balance = failure between positive ground voltage and a negative ground voltage" is displayed, ground fault location is determined not to be the first wiring 3 _1, the first terminal table 4 ₁ After connecting the positive pole bus 1 side, the DC circuit ground fault seeker positive output voltage terminal 21 of the 10 with the first wiring 3 ₁ of the connecting line which connects the positive electrode side first wiring 3 Remove from the positive side of ₁ .
Thereafter, the worker, after connecting the positive output voltage terminal 21 and the second positive electrode side of the wiring 3 ₂ via the connection line, positive bus 1 and the second as indicated by the dashed × mark in FIG. 2 The positive electrode bus 1 side of the second terminal block 4 ₂ connecting the wiring 3 ₂ is cut off. Thereby, since the output voltage is supplied from the DC insulated power supply 11 of the DC circuit ground fault search device 10 to the second load, it is possible to search for the ground fault location without causing the second load to fail. .

  The control unit 13 obtains a difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage based on the ground voltage signal input from the ground voltage measuring unit 12, and is the positive ground voltage and the negative ground voltage balanced? Alternatively, it is determined whether or not the polarity of this difference is reversed (step S15).

When a ground fault occurs on the positive side of the second wiring 3 _{2, if} the positive side of the second wiring 3 ₂ is disconnected, the ground fault point moves to the negative side through the second load. For example, the positive ground voltage changes from 45V to 65V and the negative ground voltage changes from -65V to -45V. Therefore, the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is 20V (= 65V-45V) and the polarity is Invert. As a result, the absolute value (= 20V) of the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is equal to or greater than the threshold value (= 10V), and the polarity of the difference is inverted. It is determined that the accident location is the second wiring 3 ₂ , and “polarity inversion of difference” and “ground fault accident location = second wiring 3 ₂ ” are displayed on the display unit 15 (step S 16). When the second load is not present, since the second wiring 3 ₂ of earth fault when disconnecting the positive electrode side is eliminated, for example, a negative voltage to ground a positive voltage to ground is returned to 55V from 45V is -55V from -65V Therefore, the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is 0V (= 55V−55V). As a result, since the absolute value (= 0V) of the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is less than the threshold value (= 10V), the control unit 13 determines that the positive ground voltage and the negative ground voltage are the ground fault location with the balance of is determined to be good is determined that the ₂ second wiring 3, "balance between the positive voltage to ground and a negative ground voltage = good" and "ground fault point = second It is displayed on the wiring 3 ₂ "display section 15 (step S16).

Thus, the operator, since the ground fault point is found to be the second wiring 3 ₂ on the positive electrode side, controls the measurement end signal instructing the ground fault location search operation ends using the input unit 14 Input to the unit 13. The control unit 13 ends the ground fault accident location search operation in response to the measurement end signal.

The worker connects the positive bus 1 side of the second terminal block 4 ₂ , and then connects the positive output voltage terminal 21 of the DC circuit ground fault search device 10 and the positive side of the second wiring 3 _2. with remove and has a connecting line from the second positive electrode side of the interconnect 3 _2, a connecting line which connects the negative electrode side negative output voltage terminal 22 and the first wiring 3 ₁ DC circuit ground seeker 10 removed from the first negative electrode side of the interconnect 3 _1.

Then, in a DC circuit shown in FIG. 5, ground fault between the second wiring 3 of the _second negative electrode side second terminal block 4 ₂ and the second load, as indicated by a thick arrow in FIG. 4 A procedure for ground fault accident location search using the DC circuit ground fault search device 10 when a fault occurs will be described with reference to the flowchart shown in FIG.

When a ground fault occurs in the second wiring 3 ₂ on the negative electrode side, since the fact that a ground fault has occurred is displayed on the grounding detector 112 at the negative electrode side of the direct current circuit, the operator, the DC circuit ground Using the input unit 14 of the search device 10, a measurement start signal indicating the start of ground fault accident location search operation and negative electrode disconnection is input to the control unit 13.
In response to the measurement start signal, the control unit 15 starts a ground fault accident location search operation and outputs a display control signal indicating negative electrode disconnection to the display unit 15 to display “negative electrode disconnection” on the display unit 15. (Steps S12 and S14).

Moreover, workers, connected to the negative output voltage terminal 22 with the first negative electrode side of the wire 3 ₁ connected via a connecting line, a positive output voltage terminal 21 and a first positive electrode side of the wire 3 ₁ After connected via a line to disconnect the first negative electrode bus 2 side of the terminal block 4 ₁ connecting the wire 3 ₁ and negative bus 2 first, as shown by the solid line × mark in FIG. Thereby, since the output voltage is supplied from the DC insulated power supply 11 of the DC circuit ground fault search device 10 to the first load, it is possible to search for the ground fault location without causing the first load to fail. .

The control unit 13 obtains a difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage based on the ground voltage signal input from the ground voltage measuring unit 12, and the positive ground voltage and the negative ground voltage are balanced. Or whether the polarity of the difference is reversed (step S15).
If the ground fault occurs in the second wiring 3 ₂ on the negative electrode side, since the voltage balance does not change even detach first negative electrode side of the interconnect 3 _1, for example a positive voltage to ground is 65V becomes negative voltage to ground Since −45V, the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is 20V (= 65V−45V). As a result, since the absolute value (= 20V) of the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is equal to or greater than the threshold (= 10V), the control unit 13 determines that the positive ground voltage and the negative ground voltage are Is determined to be poor, and the determination result “balance between positive ground voltage and negative ground voltage = bad” is displayed on the display unit 15 (step S17).

  The control unit 13 continues the ground fault accident location search operation unless a measurement stop signal is input from the input unit 14 (step S18).

The operator, when the display unit 15 "Balance = failure between positive ground voltage and a negative ground voltage" is displayed, ground fault location is determined not to be the first wiring 3 _1, the first terminal table 4 ₁ After connecting the negative electrode bus 2 side, the DC circuit ground fault seeker negative output voltage terminal 22 and the first wiring 3 ₁ of the connecting line which connects the negative electrode side first wiring 3 of 10 Remove from the negative side of ₁ .
Thereafter, the worker, after connecting to the negative output voltage terminal 22 and a second negative electrode side of the interconnect 3 ₂ via the connection line, a negative bus 2 and the second as indicated by the dashed × mark in FIG. 4 The negative electrode bus 2 side of the second terminal block 4 ₂ connecting the wiring 3 ₂ is cut off. Thereby, since the output voltage is supplied from the DC insulated power supply 11 of the DC circuit ground fault search device 10 to the second load, it is possible to search for the ground fault location without causing the second load to fail. .

  The control unit 13 obtains a difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage based on the ground voltage signal input from the ground voltage measuring unit 12, and is the positive ground voltage and the negative ground voltage balanced? Alternatively, it is determined whether or not the polarity of this difference is reversed (step S15).

When a ground fault occurs on the negative electrode side of the second wiring 3 _{2, if} the negative electrode side of the second wiring 3 ₂ is disconnected, the ground fault point moves to the positive side through the second load. Since the positive ground voltage changes from 65V to 45V and the negative ground voltage changes from -45V to -65V, the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is -20V (= 45V-65V). Invert. As a result, the absolute value (= 20V) of the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is equal to or greater than the threshold value (= 10V), and the polarity of the differential voltage is reversed. It is determined that the fault location is the second wiring 3 ₂ , and “polarity inversion of difference” and “ground fault location = second wiring 3 ₂ ” are displayed on the display unit 15 (step S 16). When the second load is not present, because Separating the second negative electrode side of the wiring 3 ₂ grounding fault eliminate, for example, a negative voltage to ground a positive voltage to ground is returned to 55V from 65V is -55V from -45V Therefore, the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is 0V (= 55V−55V). As a result, since the absolute value (= 0V) of the difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage is less than the threshold value (= 10V), the control unit 13 determines that the positive ground voltage and the negative ground voltage are the ground fault location with the balance of is determined to be good is determined that the ₂ second wiring 3, "balance between the positive voltage to ground and a negative ground voltage = good" and "ground fault point = second It is displayed on the wiring 3 ₂ "display section 15 (step S16).

Thus, the operator, since the ground fault point is found to be the second negative electrode side of the interconnect 3 _2, controls the measurement end signal instructing the ground fault location search operation ends using the input unit 14 Input to the unit 13. The control unit 13 ends the ground fault accident location search operation in response to the measurement end signal.

The worker connects the negative bus 2 side of the second terminal block 4 ₂ , and then connects the negative output voltage terminal 22 of the DC circuit ground fault search device 10 and the negative side of the second wiring 3 _2. with disconnect and has connection lines from the second anode side of the interconnect 3 _2, a connecting line which connects the positive pole side of the positive output voltage terminal 21 and the first wiring 3 ₁ DC circuit ground seeker 10 removed from the first wiring 3 ₁ of the positive electrode side.

In the above description, the positive electrode bus 1 side or the negative electrode bus 2 side of the first and second terminal blocks 4 ₁ and 4 ₂ is separated, but the positive electrode bus 1 and the negative electrode bus 2 and the first to third wirings 3 _1. to 3 ₃ and are connected by a switch, can be separated for example a negative electrode bus 2 with disconnecting the positive electrode bus 1 and the first positive electrode side of the wire 3 ₁ and the first anode side of the interconnect 3 ₁ In this case, when the operator checks whether or not a ground fault has occurred in the first wiring 3 ₁ , the positive output voltage terminal 21 of the DC circuit ground fault search device 10 and the first wiring 3 _1. After connecting the negative side negative output voltage terminal 22 and the first wiring 3 ₁ DC circuit ground seeker 10 in connecting line with the positive electrode side are connected by connection lines, and operates a switch cathode of with disconnecting the bus 1 and the first positive electrode side of the wire 3 ₁ and the negative electrode bus 2 first And the negative electrode side of the interconnect 3 ₁ may disconnect.
In this case, since the output voltage is supplied from the DC insulated power supply 11 of the DC circuit ground fault search device 10 to the first load, the ground fault location is searched without causing the first load to fail. Can do.

1 positive bus 2 negative bus 3 ₁ to 3 ₃ first to third wiring 41 _{to 3} first to third terminal block 10 the DC circuit ground fault search device 11 galvanically isolated power supply 12 to ground voltage measuring unit 13 control unit 14 Input unit 15 Display unit 21 Positive output voltage terminal 22 Negative output voltage terminal 23 Positive voltage measurement terminal 24 Negative voltage measurement terminal 25 Device power supply terminal 110 DC power supply device 111 Storage battery 112 Ground fault detection devices S11 to S18 Steps

Claims (5)

A ground fault has occurred in a DC circuit in which a plurality of loads are connected in parallel to the DC power supply device (110) and a circuit voltage is supplied from the DC power supply device to the plurality of loads via the voltage supply lines (1, 2). A DC circuit ground fault search device (10) for identifying a ground fault accident location at the time,
When a circuit (3 _{1 to} 3 ₃ ) connecting the voltage supply line and one of the plurality of loads is disconnected at the time of searching for a ground fault accident location, the circuit voltage is replaced with the circuit voltage instead of the circuit voltage. A DC insulated power supply (11) for supplying an output voltage of several volts lower to the one load;
A ground voltage measuring unit (12) for measuring a positive ground voltage and a negative ground voltage of the voltage supply line;
A control unit (13) for determining whether or not the circuit is a ground fault location based on the positive ground voltage and the negative ground voltage measured by the ground voltage measuring unit when searching for a ground fault site. When,
A DC circuit ground fault search device comprising:   The control unit obtains a difference between the magnitude of the positive ground voltage and the magnitude of the negative ground voltage measured by the ground voltage measuring unit after disconnecting the circuit, and the absolute value of the obtained difference is a predetermined value. If it is less than the threshold value, it is determined that the balance between the positive ground voltage and the negative ground voltage is good, or the polarity is inverted when the absolute value of the obtained difference is equal to or greater than a predetermined threshold value. 2. The DC circuit ground fault search apparatus according to claim 1, wherein the circuit is identified as a ground fault accident location.   The balance between the positive ground voltage and the negative ground voltage measured by the ground voltage measuring unit, the balance between the positive ground voltage and the negative ground voltage determined by the control unit, and the control unit The display device further comprises a display unit (15) for displaying a polarity reversal of a difference between the positive ground voltage and the negative ground voltage and a ground fault location specified by the control unit. Item 3. The DC circuit ground fault search device according to Item 2.   The DC insulated power supply has a built-in current backflow prevention commutator for preventing current from flowing backward even when connected to a circuit where the output voltage is variable and a ground fault has not occurred. The DC circuit ground fault search device according to any one of claims 1 to 3, wherein the DC circuit ground fault search device is characterized.   When a ground fault occurs in the DC circuit, the DC fault is identified by using the DC circuit ground fault search device (10) according to any one of claims 1 to 4. Ground fault accident location search method.

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