JP2007271610A - Method and apparatus for identifying ground-fault bank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for identifying, from a plurality of banks provided on a multiple-grounded low-pressure alternating-current distribution line, ground-fault banks with the banks remaining multiple-grounded. <P>SOLUTION: When a ground fault occurs in a bank of a multiple-grounded low-pressure alternating-current distribution line 1 including a plurality of banks B1 to B5, a current transformer 10 detects a ground-fault current that flows through a common grounding wire 5 extending between banks, and a voltage detector 20 detects any one reference voltage of the low-pressure alternating-current distribution line 1. The location of the ground-fault bank is identified comprehensively by sensing the direction of a ground-fault current between banks in accordance with the phase difference between the detected current and the detected voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ground fault bank identification method and identification apparatus in a multi-grounding type low-voltage AC distribution line in which B-type ground wires of a plurality of banks (pole transformers) for supplying power to a low-voltage consumer are connected in parallel by a common ground wire. About.

When a transformer B class ground wire is grounded alone, if a ground fault occurs in a low voltage consumer such as a house, factory, or office that is supplied with power from the low voltage AC distribution line of the bank, The ground fault current flows only in the B-type ground line of the bank that supplies power to the low-voltage consumer. In a specific bank, where a ground fault has occurred in a low-voltage customer in multiple banks, the ground fault current does not flow in another bank without a ground fault. The low-voltage consumer with a device is confirmed by checking its operation, and the low-voltage customer without the earth leakage breaker is measured with a lead-in wire to identify a low-voltage customer with a ground fault. Furthermore, ground fault current is measured by using a load line of a low-voltage customer who has been able to specify the occurrence of a ground fault, and the location where the ground fault occurs is specified (for example, see Patent Document 1).
JP 2004-101352 A

  Class B grounding works on the neutral line or one terminal of the transformer secondary side of the bank, in addition to single grounding for each bank, the B type grounding lines of each bank are connected in parallel and multiplexed. There is multiple grounding. Depending on the conditions of the land where Class B grounding work is performed, it may be economically difficult to maintain the grounding resistance at a specified value with single grounding. In such a case, the B type grounding wires of a plurality of banks are connected in parallel with a common grounding wire to lower the combined grounding resistance value and keep it at a specified value.

  In a multiple grounding (overhead joint ground type) low-voltage AC distribution line with multiple banks grounded, a ground fault occurs in a low-voltage customer supplied with power from any one bank, and a ground fault current flows. In this case, a ground fault current corresponding to the ground resistance value flows not only in the B type ground line of the bank but also in the B type ground lines of all other banks connected through the common ground line. For this reason, it is not possible to specify a bank that supplies power to low-voltage consumers in which a ground fault has occurred, and it is not possible to use the service lines or load lines of all low-voltage consumers that are supplied with power from all banks that are jointly grounded with Class B grounding. It was necessary to measure the ground fault current, and the exploration range was too wide, and it was difficult to identify and work on the ground fault occurrence location.

  Further, by separating the B-type grounding of each of the plurality of banks and returning to the single grounding, it is possible to accurately specify the bank where the ground fault has occurred. In this case, not only the trouble of disconnecting the B type grounding in a plurality of banks and the trouble of returning to the original multiple grounding is required, but also in the intermittent grounding in which the ground fault is generated intermittently, Until the next ground fault occurs, there is a problem that causes the state that the class B ground resistance value is less than the specified value, and the reliability is lacking.

  The object of the present invention is to accurately identify a bank in which multiple grounding occurs with multiple grounding when a grounding fault occurs in a plurality of banks in a multiple grounding type low-voltage AC distribution line in a low-voltage consumer supplied from a certain bank. An object of the present invention is to provide a method for identifying a ground fault bank and a device for identifying the same.

  The method of the present invention that achieves the above object is a method of identifying a ground fault bank in a multi-grounding type low-voltage AC distribution line in which B-type ground lines of a plurality of banks are connected in parallel by a common ground line, and any one of the plurality of banks A current transformer that detects ground fault current is installed on the common ground line of the ground, and the direction of the detected ground fault current is determined from the phase difference between the ground fault current detected by this current transformer and one of the voltages on the low-voltage AC distribution line. And a bank in which a ground fault occurs is specified based on the detected ground fault current direction.

  Here, the low-voltage AC distribution line can be a single-phase AC type or a three-phase AC type low-voltage distribution line that is linked to the high-voltage distribution line by a bank that is a pole transformer. A plurality of banks in this low-voltage AC distribution line are pole transformer systems that supply power to low-voltage consumers such as houses and factories, and transformer B class ground wires of each bank are connected by a common common ground wire and multiplexed. Grounded. When a ground fault occurs due to leakage in one bank, ground fault currents of different magnitudes flow in the B-type ground lines and common ground lines of all banks including the bank where the ground fault occurs. The ground fault current in each bank is an alternating current, and the current direction is a repetition of the direction flowing into the bank where the ground fault occurs and the direction flowing out from the bank where the ground fault occurs. The direction of the ground fault current in each bank is obtained from the phase difference between the ground fault current and a preset line voltage of the low-voltage AC distribution line or a reference line voltage such as a ground voltage. The bank where the ground fault occurred is identified through comprehensive interpretation. Although it is desirable to detect the direction of the ground fault current in all of the plurality of banks, depending on the position of the ground fault occurrence bank, if the direction of the ground fault current is detected by a small number of banks, the bank in which the ground fault occurs can be specified. The direction of ground fault current in each bank can be detected accurately and easily even if the ground fault current value is small due to the phase difference between the ground fault current and the line voltage used as the reference for the low-voltage AC distribution line. The identification of the bank for generating a ground fault can be carried out with accurate, simple and inexpensive equipment.

  In the method of the present invention, the ground fault current direction in the plurality of banks can be detected based on the phase difference between the ground fault current in each bank and the ground voltage between the common ground line and the ground. In this case, the ground voltage of the common ground line can be detected easily and quickly by using a contact-type voltage detector or a small, lightweight, and inexpensive non-contact-type voltage detector. It can be done with efficiency and the specified equipment cost can be reduced.

  Further, the direction of the ground fault current in the plurality of banks can be detected based on the phase difference between the ground fault current in each bank and the terminal voltage at both ends of the resistor connected in series to the B-type ground line. A ground fault current flows through the resistor connected in series with the B-type ground wire, and a terminal voltage is generated at both ends. This terminal voltage is in phase with the ground voltage, so that the ground fault current direction can be detected in the same manner as the ground voltage. Applicable. The reference voltage for detecting a ground fault current direction using a resistor is excellent in accuracy and increases the precision of ground fault current direction detection.

  Further, the resistor can be connected in series instead by removing the short-circuit bar detachably connected in series in the middle of the class B grounding wire. In an ordinary bank, an earth terminal that houses a short-circuit bar is installed at the top of a utility pole for periodic ground resistance measurement. The short-circuit bar constitutes a part of the B-type ground line, and is removed from the B-type ground line during periodic ground resistance measurement. Therefore, if a resistor is inserted in the middle of the B-type ground line instead of the short-circuit bar, inconvenient work such as cutting the B-type ground line for inserting the resistor can be omitted. Compared to the method of measuring the ground voltage by driving a grounding auxiliary electrode near the ground of the B type grounding wire, it is easier to insert a resistor into the B type grounding wire, and it is difficult to drive the grounding auxiliary electrode. It can be applied even to banks and has excellent versatility.

  In addition, if the joint ground line connection between banks where load current does not flow is selected, the ground fault current detection location does not overlap with the load current, so there is no need to separate both, and detection of the ground fault current direction is possible. It becomes easy.

  In addition, a current transformer that uniquely detects the ground fault current can be installed in each of the common ground lines of the plurality of banks, and the direction of the ground fault current can be detected simultaneously in the plurality of banks. Furthermore, a current transformer is permanently installed in each of the common ground lines of the plurality of banks, and the ground fault bank specifying operation in the plurality of banks can be performed constantly and at the same time. Thus, by always performing the ground fault bank specifying operation in a plurality of banks, it is possible to accurately cope with the specification of the bank that generates the intermittent ground fault.

  A device of the present invention that achieves the above object is a ground fault bank identification device in a multi-grounding type low-voltage AC distribution line in which transformer B type ground wires of a plurality of banks are connected in parallel by a common ground wire, A current transformer for detecting a ground fault current flowing in the line, a voltage detector for detecting a voltage of a line as a reference of any one of the low-voltage AC distribution lines, and a ground fault current and a voltage detector detected by the current transformer. And a current direction detection circuit for detecting the direction of the ground fault current in the common ground line from the phase difference of the voltage detected in (1).

  In addition, the device of the present invention includes a plurality of current transformers that are installed in each of the common ground lines of a plurality of banks and independently detect a ground fault current flowing in each common ground line, and any one of the low-voltage AC distribution lines. A voltage detector that detects the voltage of the line to be connected, and the ground difference between the ground fault current detected by the plurality of current transformers and the voltage detected by the voltage detector. It is possible to have a structure including a current direction detection recording circuit for detecting and recording each of the current directions.

  Here, the voltage detector is a contact type or non-contact type that detects a ground voltage between the common ground line and the ground, or a voltage that detects a terminal voltage at both ends of a resistor connected in series to the B-type ground line of the bank. The total is applicable. In addition, the current direction detection circuit can be applied to a circuit having a function of displaying the data of the detected ground fault current direction so as to be visible or transmitting the data to a remote place. Similarly, as the current direction detection recording circuit, a circuit having a function of displaying the recorded ground fault current direction data so as to be visible or transmitting it to a remote place can be applied. In addition, the current direction detection recording circuit detects and records the direction of the ground fault current in the common ground line of the plurality of banks, and the phase of the detected ground fault currents at the same time is the same phase or reversed phase. Can be detected and compared. In this case, if the same time phase of the ground fault current detected from the common ground line on both sides is the same phase in any single bank with the common ground line extending on both sides, the ground fault current on both sides The direction can be determined to be the same direction, and if the ground fault currents detected from the joint ground lines on both sides are the phases reversed at the same time, the ground fault current directions on both sides can be determined to be opposite directions. A single bank can also be identified as a bank with a ground fault.

  According to the present invention, even if a ground fault occurs in any of a plurality of banks of a multiple ground type low-voltage AC distribution line and a ground fault current flows through the plurality of banks, This makes it possible to easily and accurately specify the bank ground fault countermeasure for the multi-grounding type low-voltage AC distribution line with good workability and an excellent effect that it can always be accurately performed.

  In addition, by installing a current transformer in each of the common ground lines of multiple banks, it is possible to accurately detect intermittent ground faults and identify the bank that generates the intermittent ground fault. Bank ground fault countermeasures can be performed more reliably.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 shows a single-phase three-wire multiple grounded low-voltage AC distribution line 1 having a plurality of, for example, five banks B1 to B5. The B ground wires 4 of the banks B1 to B5 connected to the high-voltage AC distribution line are connected to the low-voltage line neutral line when the low-voltage line 3 is on the transformer secondary side of the low-voltage column 2, and the low-voltage line is If not, it is connected directly to the pole transformer neutral wire. Further, the neutral lines of the banks B1 to B5 are connected by the common ground line 5 and are performed by multiple grounding in which the B-type grounds of the five banks are connected in parallel. Thereby, the low-voltage line neutral line also becomes the common ground line 5 at the same time. The ground resistance value in each of the banks B1 to B5 is a combined ground resistance value when the ground resistances of the five banks B1 to B5 are connected in parallel. In addition, no load current flows through the common ground line at the location connecting the low-voltage line neutral line or the transformer neutral line of each bank B1 to B5, and a ground fault occurs in the low-voltage customer 7 of any bank. When it occurs, a ground fault current I as described later flows.

  FIG. 2 shows a case where a ground fault occurs due to a leakage in the low voltage consumer 7 supplied from the second bank B2 from the left in FIG. 1 among the five banks B1 to B5, and a ground fault current Ig is generated. . This ground fault current Ig is an alternating current, and flows out from the ground fault location to the ground. The ground fault current Ig2 returns from the ground to the ground fault generation bank B2 through the B-type ground line 4 of the ground fault generation bank B2. If the low-pressure column 2 provided with the B-type grounding supplied from the bank B2 is located other than the column, the ground fault current passing through the ground also returns from the B-type grounding wire 4. In addition, the ground fault current I passes through the B-type ground line 4 of the low-voltage column 2 (including the low-voltage column in which the bank is installed) of the banks B1, B3 to B5 other than the bank B2 in which the ground fault is generated. Ig1, Ig3 to Ig5 return from the ground. The currents Ig1, Ig3 to Ig5 return to the bank B2 where the ground fault has occurred through the common ground line 5. Assuming that the four ground fault currents I flowing through the common ground line 5 connecting the five banks B1 to B5 are Ia to Id, the local fault currents Ia to Id flow in the direction of the ground fault occurrence bank and the ground fault. The size of each bank is determined by the positional relationship of each bank and the B-type ground resistance value of each bank. The current Ig flowing out from the ground fault occurrence point to the ground returns from the ground through all the B-type ground lines 4 of the five banks B1 to B5 connected by the common ground line 5, and the currents Ig1 to Ig5 Since the directions are the same, even if the ground fault currents Ig1 to Ig5 flowing through the B-type ground line 4 are detected, the ground fault occurrence bank is not known.

  Here, as shown in FIG. 2, the ground fault current Ia flowing through the common ground line 5 connecting the leftmost bank B1 and the ground fault occurrence bank B2 flows from the left to the right in FIG. (Referred to as a minus direction). Further, the current Ib flowing through the common ground line 5 connecting the bank B2 in which the ground fault occurs and the bank B3 adjacent to the right flows in a direction flowing from right to left (hereinafter, referred to as a plus direction if necessary). Further, the current Ic flowing through the common ground line 5 connecting another bank B3 and the bank B4 and the current Id flowing through the common ground line 5 connecting the bank B4 and the bank B5 both flow in the plus direction from right to left.

  In other words, in the bank B2 in which the ground fault occurs in FIG. 2, the direction of the current flowing through the common ground line of the banks B1 and B3 adjacent on the left and right is positive and the other is negative. From this, it can be determined that the bank into which the ground fault current just flows from the adjacent bank is the ground fault occurrence bank. Furthermore, in a bank where no ground fault has occurred, the direction of the ground fault current flowing through the joint ground line with the adjacent bank is both positive, or both are negative, and the bank where the ground fault current flows in but flows out is It can be determined that the bank is not a ground fault occurrence bank.

  Although the direction of the current is set here for convenience, since the ground fault current is an alternating current, in the actual determination, the phase of the current flowing through the common ground line adjacent to the bank where the determination of the occurrence of the ground fault is made. However, as shown in the waveform diagram of FIG. 3 with respect to the voltage, whether both sides are in phase or whether the phase is reversed is determined. ZCT1 to ZCT5 shown in FIG. 3 are zero-phase current transformers that detect currents flowing through the common ground line 5, and correspond to current transformers 10 described later.

  For example, as shown in FIG. 4, when a ground fault occurs in the leftmost bank B1, there is only one common ground line with an adjacent bank in this bank B1, but banks B2 to B5 where no ground fault occurs. Currents Ia to Id are collected and flow, so that it can be determined from the magnitude thereof or from the direction of the ground fault current flowing through the common ground line 5 between the other banks.

  The position of the bank B2 in which the ground fault occurs can be specified by using the ground fault bank specifying apparatus shown in FIG. 1 or FIG.

  FIG. 1 shows a current transformer 10 that detects a ground fault current flowing in a common ground line 5 of an arbitrary bank B, a voltage detector 20 that detects the voltage of any line of the AC distribution line 1, and a current transformer. A current direction detection circuit 30 that detects the direction of the ground fault current in the common ground line 5 from the phase difference between the ground fault current detected at 10 and the line voltage detected at the voltage detector 20 is provided. The current direction detection circuit 30 can be provided with a display means 40 for displaying the detected current direction and a means (not shown) for storing the detected current direction and transmitting it to a remote place. As the voltage detector 20, for example, a contact type that detects the ground voltage of the common ground line 5 or a non-contact type that is small, light, and inexpensive can be used. The voltage detector 20 can be a voltmeter that detects the terminal voltage of the resistor R, which will be described later with reference to FIG.

  The identification work of the ground fault occurrence bank can be performed, for example, by the following procedure. A current transformer 10 is installed in the common ground line 5 between any two banks B1 and B2, and a ground fault current (corresponding to Ia in FIG. 2) is detected. For example, the phase difference from the ground voltage is obtained, and it is detected that the current direction of the ground fault current Ia in FIG. Next, a current transformer 10 is installed in the common ground line 5 between the other two banks B2 and B3 to detect a ground fault current (corresponding to Ib in FIG. 2). The phase difference from the reference ground voltage detected at 20 is obtained, and it is detected that the current direction of the ground fault current Ib in FIG. 2 is the plus direction. In the case where the ground fault occurrence bank is the bank B2, it can be seen from the result of the current direction detection twice that the ground fault current flows into the bank B2, and the bank B2 can be specified as the ground fault occurrence bank.

  Further, in the low-voltage AC distribution line 1 of FIG. 1, the direction of the ground fault current can also be detected in order from the bank B5 side at the right end. In this case, a current transformer 10 is installed in the common ground line 5 between the rightmost bank B5 and the left bank B4 to detect a ground fault current (corresponding to Id in FIG. 2). And the reference voltage detected by the voltage detector 20, for example, a phase difference with the ground voltage is obtained to detect that the current direction of the ground fault current Id in FIG. Similarly, the ground fault current direction of the common ground line 5 between the bank B4 and the bank B3 is detected, and further the ground fault current direction of the common ground line 5 between the bank B3 and the bank B2 is detected. Is detected. In this case, the ground fault occurrence bank is not identified yet, and when the ground fault current direction of the common ground line 6 between the bank B2 and the bank B1 is detected to be negative, the ground fault occurrence bank is the bank B2. Identifies it.

  In the AC distribution line 1 shown in FIG. 4, the ground fault occurrence bank is the leftmost bank B <b> 1. In this case, for example, a current transformer 10 is installed in the common ground line 5 between the bank B1 and the bank B2 to detect a ground fault current, and the ground fault current and the reference ground voltage detected by the voltage detector 20 are detected. The phase difference is obtained, and it is detected that the current direction of the ground fault current Ia in FIG. 3 is the plus direction. By detecting the current direction once, it can be seen that the ground fault current flows into the bank B1 at the extreme end of the common grounding line 5, and the bank B1 can be specified as the ground fault occurrence bank. Actually, it is also necessary to detect the direction and magnitude of current between other banks (when bank B1 is a ground fault bank, the current is the highest compared to other banks) and to identify the ground fault generating bank comprehensively. Is desirable.

  In the ground fault bank identification device of FIG. 5, current transformers 10,... Are installed on a common ground line 5 between a plurality of banks. In this case, the voltage detector 20 that detects the line voltage as a reference of the AC distribution line 1 and the ground fault currents detected by the plurality of current transformers 10. A current direction detection recording circuit 50 is provided for detecting and recording the direction of the ground fault current in the common ground line 5 between a plurality of banks based on the phase difference from the detected voltage. The current direction detection recording circuit 50 can simultaneously or sequentially detect the direction of the ground fault current flowing through the common ground line 5 between a plurality of banks.

  If the current direction detection recording circuit 50 simultaneously detects and records the direction of the ground fault current between the plurality of banks and compares the phases, the ground fault current phase flowing through the common ground line 5 is reversed on both sides of the ground fault bank. From this, the ground fault bank can be specified. In this case, the voltage detector 20 may be omitted.

  Further, by installing a current transformer 10,... On each of the common ground lines 5 between a plurality of banks and operating the current direction detection recording circuit 50 at all times, an intermittent ground fault in the intermittent ground fault generating bank is obtained. Can be detected, and an intermittent ground fault occurrence bank can be identified. That is, the ground fault generated in each of the banks B1 to B5 often occurs intermittently by recovering due to a change in the ground fault condition, and the direction of the ground fault current between the banks is detected when there is no ground fault. Even if it does, it becomes impossible to detect, and it may not be possible to specify the intermittent ground fault occurrence bank. An intermittent ground fault generation bank can be specified by permanently installing the current transformers 10,... Between the plurality of banks and performing the ground fault current direction detection between the plurality of banks at all times and at the same time. Further, if the current direction detection recording circuit 50 detects the intermittent ground fault occurrence bank, it is possible to transmit the data signal of the occurrence of the intermittent ground fault and the position data signal of the ground fault occurrence bank to the remote place by wireless or wired. desirable.

  The line voltage used as a reference of the AC distribution line 1 for detecting the direction of the ground fault current is obtained by adding a resistor R connected in series to the B-type ground line 4 in each bank B as shown in FIG. Terminal voltage is also effective. Since the ground fault current flowing through the B-type ground line 4 flows through the resistor R and the terminal voltage generated at both ends thereof is in phase with the ground voltage, it can be applied as a reference voltage for detecting the direction of the ground fault current.

  In addition, as shown in FIG. 6, a ground terminal 60 is permanently installed in the B-type ground line 4 of each bank B in preparation for periodic ground resistance measurement. A shorting bar 61 is accommodated in the earth terminal 60, and the shorting bar 61 is connected in series via terminals 62 and 63 in the middle of the class B grounding wire 4. The short-circuit bar 61 is removed from the terminals 62 and 63 during periodic ground resistance measurement, and ground resistance measurement is performed. When the ground resistance measurement is completed, the shorting bar 61 is returned to the terminals 62 and 63 and becomes a part of the class B ground wire. Therefore, when detecting the direction of the short-circuit current, the short-circuit bar 61 is removed from the B-type ground wire 4, and instead, both ends of the resistor R are connected to the terminals 62 and 63. A voltage between the terminals 62 and 63 is detected by the voltage detector 20.

  The resistance value of the resistor R to be inserted into the B-type ground line 4 is selected according to the legally prescribed ground resistance of the B-type ground line 4 and an appropriate value at which the reference voltage can be easily measured. A plurality of types of resistors R having different resistance values are prepared, and one optimal type known in advance according to the type of the B-type grounding wire 4 is used in a switching manner. Since the earth terminal 60 in which the resistor R is installed is at a high place where ordinary people cannot easily approach, the safety can be ensured even if it is permanently installed in the bank in order to specify the intermittent ground fault occurrence bank.

  Note that the ground fault bank identification device of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

It is a wiring diagram which shows the outline | summary of the low voltage | pressure AC distribution line for demonstrating the ground fault bank identification method and identification apparatus of this invention. FIG. 2 is an equivalent circuit diagram of the low-voltage AC wiring path of FIG. 1. It is the figure which added the wave form diagram which shows the phase difference of a ground voltage and a ground fault current to FIG. It is the equivalent circuit figure at the time of another ground fault condition of FIG. 2 of the low voltage | pressure AC distribution line of FIG. It is a wiring diagram which shows the outline | summary of the low voltage | pressure AC distribution line for demonstrating the ground fault bank identification method and identification apparatus different from FIG. It is a wiring diagram for demonstrating an example of the voltage measurement used as the reference | standard of a low voltage | pressure AC distribution line.

Explanation of symbols

1 Low-voltage AC distribution line 2 Low-voltage column 3 Low-voltage line 4 Class B ground wire 5 Joint ground wire (including low-voltage wire neutral wire)
7 Low voltage customer 10 Current transformer 20 Voltage detector (contact or non-contact)
30 Current direction detection circuit 40 Display means 50 Current direction detection recording circuit B1 to B5 Bank (pillar transformer)
Ia to Id Ground fault current R Resistance 60 Ground terminal 61 Short-circuit bar

Claims (10)

A ground fault bank identification method in a multiple grounding type low-voltage AC distribution line in which B-type ground wires of a plurality of banks are connected in parallel by a common ground wire,
A current transformer for detecting a ground fault current is provided in the common ground line of any of the plurality of banks, and a phase difference between the ground fault current detected by the current transformer and the voltage of any of the low-voltage AC distribution lines A ground fault bank identification method comprising: detecting a direction of the detected ground fault current, and identifying a bank in which a ground fault occurs based on the detected ground fault current direction.   The ground fault current direction in the plurality of banks is detected based on a phase difference between a ground fault current in each bank and a ground voltage between the common ground line and the ground. Ground fault bank identification method.   The ground fault current direction in the plurality of banks is detected based on a phase difference between a ground fault current in each bank and a terminal voltage at both ends of a resistor connected in series to the type B ground line. Item 2. The method for identifying a ground fault bank according to Item 1.   The resistor is connected to the B-type ground wire, and the short-circuit bar detachably connected in series in the middle of the B-type ground wire is removed from the B-type ground wire and connected in series instead of the removed short-circuit bar. The ground fault bank identification method according to claim 3, wherein:   5. A current transformer that uniquely detects a ground fault current is installed in each of the common ground lines of the plurality of banks to simultaneously detect the direction of the ground fault current in each of the plurality of banks. The ground fault bank identification method according to any of the above.   The said current transformer is permanently installed in each common ground line of said several bank, and the earth fault bank specific operation | movement in several banks is always performed at the same time, The any one of Claims 1-5 characterized by the above-mentioned. How to identify the ground fault bank. A ground fault bank identification device in a multiple grounding type low-voltage AC distribution line in which B type grounding wires of a plurality of banks are connected in parallel by a common grounding wire,
A current transformer for detecting a ground fault current flowing in the common ground line of the bank, a voltage detector for detecting a voltage of a line as a reference of the low-voltage AC distribution line, and detected by the current transformer A ground fault bank identification device comprising a current direction detection circuit for detecting a ground fault current direction in the common ground line from a phase difference between a ground fault current and a voltage detected by the voltage detector. A ground fault bank identification device in a multiple grounding type low-voltage AC distribution line in which B type grounding wires of a plurality of banks are connected in parallel by a common grounding wire,
A plurality of current transformers that are installed in each of the common ground lines of the plurality of banks and independently detect a ground fault current flowing in each common ground line, and a voltage of a line as a reference of any one of the low-voltage AC distribution lines Voltage detectors to detect, and ground fault current directions in the common ground lines of the plurality of banks from the phase difference between the respective ground fault currents detected by the plurality of current transformers and the voltages detected by the voltage detectors A ground fault bank specifying device comprising: a current direction detection recording circuit for detecting and recording each of them.   The ground fault bank identification device according to claim 7 or 8, wherein the voltage detector is a non-contact voltage detector that detects a ground voltage between the common ground line and the ground.   9. The ground fault bank identification device according to claim 7, wherein the voltage detector detects a terminal voltage at both ends of a resistor connected in series to the B-type ground line.

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