JP2005184945A - Load connection type distribution line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a load connection type distribution line capable of quickly estimating a ground fault section without the movement of a maintenance serviceman when the ground fault occurs to a target load connection type distribution line. <P>SOLUTION: The load connection type distribution line has the following constitution. A ground fault detector, which is composed of a zero-phase current transformer and a ground fault relay having an operating contact closed by a detected current of the zero-phase current transformer, is installed in the power supply side of each branch connection point of the load connection type distribution line branched and connected to a plurality of loads arranged at intervals from a power supply part, in which a contactor provided with a breaker and a leakage protection function is connected to a three-phase four-wire type power supply. A resistor is connected between each branch connection point and the ground via the operating contact of the ground fault relay. A ground fault section estimating device, which is provided with a selection switch for selecting each line and impressing an inspection voltage, is installed in the output side of the power supply part. The breaker is made into a closed state by maintaining a closed state of the contactor during the occurrence of the ground fault. The inspection voltage is impressed to each line. The ground fault section is estimated by a current detection value flowing in each line. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a load-connected distribution line that supplies power to a load in which a plurality of loads are arranged at intervals, such as lighting equipment on highways and lighting equipment on oil bases.

For example, in an electrical installation such as a highway lamp or a city park lamp, it is a load-connected distribution line in which the load is branched and connected to the distribution line, and the power supply part has a ground fault. A protection device is provided, and when a ground fault occurs, the ground fault is detected by the ground fault protection device and the power supply is cut off.
In general, when a ground fault failure is detected, a maintenance staff assesses the ground fault interval by a so-called two-division method. The evaluation of the ground fault section by this two-division method is to disconnect the distribution line near the center of a series of distribution lines, measure the insulation resistance on the upstream and downstream sides of the distribution line, and select the ground fault point for the smaller insulation resistance value. The ground fault point side is further divided into two, the upstream and downstream insulation resistances are measured to identify the ground fault point, and the ground fault section is narrowed down repeatedly until reaching the minimum unit section. Is the way to go. The evaluation method of the ground fault section by this two-division method is the work of repeatedly measuring the insulation resistance for all the distribution lines, requiring a large number of maintenance personnel, and it takes a long time to reach the rating. There is a problem.

For example, Patent Document 1 discloses a method for solving the problems of the ground fault section evaluation method for the load-connected distribution line by the above two-division method.
As shown in FIG. 2 of Patent Document 1, a leakage current measurement CT is provided on the power supply side or downstream side of each branch connection point of a distribution line in which a plurality of loads are branch-connected at intervals. Provided with a terminal slave station that wirelessly transmits the leakage current value detected by this leakage current measurement CT as leakage current information, and the leakage current information transmitted from the terminal slave station moves along the distribution line It is received by the mobile master station mounted on the car, and the ground fault section is evaluated based on the received leakage current information.
The ground fault section evaluation method is that when a ground fault occurs in the distribution line, the leakage current detection means on the power source side detects the leakage current value from the ground fault point, and the leakage current is not detected downstream from the ground fault point. The ground fault section is evaluated.

JP 11-41796 A

In the conventional evaluation method of the ground fault section by the two-division method, when a ground fault occurs, it is necessary for the maintenance staff to cut the target distribution line and measure the insulation resistance. It is necessary, takes time to reach the rating, and there is a problem that it takes time to repair.
In addition, in the method for evaluating a ground fault point according to Patent Document 1, the evaluation can be made without disconnecting the target distribution line, but the maintenance inspection vehicle moves along the target distribution line and receives and evaluates the leakage current information. There was a problem that it took time to evaluate the section of the cable and it took time to recover.

  The present invention has been made to solve the above problems, and when a ground fault occurs in the target load-connected distribution line, the ground fault section is promptly evaluated without the maintenance staff moving. It aims at providing the load connection type distribution line which can be performed.

  In the load connection type distribution line according to the present invention, a plurality of loads arranged at intervals from the power source portion in which a contactor having a circuit breaker and a leakage protection function is connected to a three-phase four-wire power source A zero-phase current transformer provided on the power supply side of each branch connection point to which a plurality of loads are connected, and the zero-phase current transformer, which is configured to be branched between any phase and a neutral wire Equipped with a ground fault detector consisting of a ground fault relay that has an operating contact that is closed by the detected current of the earth, and via the operating contact of the ground fault relay between each branch connection point where multiple loads are connected and the ground A ground fault section rating device equipped with a selection switch that selects each line of the load-connected distribution line and applies the inspection voltage to the output side of the power supply unit is installed. Maintaining the open circuit state and setting the circuit breaker to the open circuit state, the ground fault section rating device Applying each line to test the voltage of phase four-wire distribution line, it is intended to assess the inter-land 絡区 by the detected current value of each line.

  According to this invention, when a ground fault occurs in the load-connected distribution line, the ground fault section can be quickly evaluated without the maintenance staff moving.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration in the case of, for example, a highway lighting facility that is a load-connected distribution line according to the first embodiment. In the configuration of FIG. 1, the power supply is loaded on the output side of the power supply section in which the circuit breaker 2 and the contactor 3 are connected to the power transformer secondary circuit 1 in which the secondary circuit of the substation is output in a three-phase four-wire system An articulated distribution line 5 is connected. The contactor 3 includes a main contact and an auxiliary contact 3a, a zero-phase current transformer 3b, and a ground fault disconnector 3c. When a ground fault occurs in the load connection type distribution line 5, the circuit is interrupted by the ground fault disconnector 3c. is there. The load connection type distribution line 5 includes five lines of 5R, 5S, and 5T high voltage lines, a dimming light 5X via the auxiliary contact 3a of the contactor 3, and a neutral line 5N via the neutral line switch 4. Is output. On the output side of the power supply unit, a ground fault section evaluation device 8 configured to select each line excluding the neutral line 5N of the load connection type distribution line 5 and to allow an inspection current to flow therethrough is provided. The ground fault section evaluation device 8 selects each line of the DC power supply 8a, the current detector 8b, the current measuring instrument 8c, and the load connection type distribution line 5 for supplying a DC inspection current to the load connection type distribution line 5 and energizes it. The changeover switch 8d is provided.

The load-connecting distribution line 5 is wired with the above-described five wires while reaching a plurality of loads arranged at intervals, and each load is branched and connected. In the first load among the plurality of loads in FIG. 1, for example, the lamp L1 is branched and connected between the high voltage line 5R and the neutral line 5N via the ballast M1, and the ballast M1 has an illuminance control of the lamp L1. A branch connection is made from the dimming line 5X of the line. The second lamp L2, the third lamp L3,..., The nth lamp Ln is dispersed in the 5R, 5S, and 5T phases so that the three-phase equilibrium is achieved in the same way as the first lamp L1. Branch connected.
Then, zero-phase current transformers Z1, Z2,... Zn are mounted on the power supply side at each position where the lamps L1, L2,... Ln are branched and connected, and ground fault relays Y1, Y2,. Yn is connected. The ground fault relays Y1, Y2,... Yn have contacts X1, X2,.
From the branch connection point of each lamp L1, L2... Ln to the ground, resistors R1, R2,... Via the respective contacts X1, X2. ..Rn is connected.

  In the load connection type distribution line 5 configured in this way, for example, if a ground fault occurs on the downstream side of the fourth lamp L4, a ground fault current flows to the ground from the ground fault point, and the load connection is connected from the power supply unit. Zero-phase current transformers Z1, Z2, Z3, and Z4 between the ground fault points of the distribution line 5 detect the zero-phase current, the ground fault relays Y1, Y2, Y3, and Y4 operate, and the contactor 3 is grounded. Each phase of the high-voltage lines 5R, 5S, and 5T and the dimming light 5X are blocked by operating with current.

With the contactor 3 opened, the neutral wire switch 4 of the neutral wire 5N is opened, the circuit breaker 2 is opened, and each line 5R excluding the neutral wire 5N is detected by the ground fault section evaluation device 8. Each line of 5S, 5T and dimming light 5X is selected by the changeover switch 8d, a predetermined inspection voltage is applied to each line, and a current value to be energized is detected. When there is a ground fault in the fourth lamp L4, the resistance value between the two resistors R1 and R4 and the ground in the ground fault position is in a parallel state in the high voltage line 5R. It flows up to the current limiter value of the ground fault section rating device. In the high voltage line 5S, the current flowing in one resistor of the resistor R3 is detected in the resistors R2 and 5T. In the dimming light 5X, since no resistor is connected, no current is detected if it is normal.
In addition, if resistance value of resistor R1, R2 ... Rn is made sufficiently large with respect to the resistance value of a distribution line, the resistance value of a distribution line can be disregarded. If the inspection voltage value is V, and the resistance values of the resistors R1, R2,... Rn are R, the detected current value I is I = V / R × N (N is the number of connected resistors). Can be sought.

  Since the load in FIG. 1 is sequentially distributed and connected to the high-voltage lines 5R, 5S, and 5T so as to be three-phase balanced, the current value at 5R is detected as the current of two resistors, and the energization current at 5S and 5T is detected. Is the current value for one resistor, the ground fault interval is evaluated to be between the fourth lamp L4 and the fifth lamp L5.

  In the above description, the power source for applying the inspection voltage of the ground fault section evaluation device 8 is the power source for applying the DC voltage, but may be the power source for applying the AC voltage. In the case of alternating current, the charging current flows through the ground capacitance of the load-connected distribution line 5, and therefore it is necessary to make a determination in consideration of this capacitance. However, the current detector 8b and the current measuring device 8c are simple. There is merit to become composition.

Embodiment 2. FIG.
The configuration of the second embodiment is shown in FIG. In the second embodiment, the power supply unit of the first embodiment is provided with a zero-phase current transformer 6 and a leakage current measuring means 7 for detecting a minute leakage current. The configuration of FIG. 2 is the same as that of FIG. 1 of the first embodiment except for the zero-phase current transformer 6 and the leakage current measuring means 7, and a description thereof will be omitted.
By configuring in this way and measuring the leakage current of the always load-connected distribution line, the state of the change can be monitored, so that it can be utilized as preventive maintenance information to predict the occurrence of a ground fault.

Embodiment 3 FIG.
For example, in highway lighting equipment, there are environments where the load is located near the environment where there is a lot of moisture, such as in tunnels, where ground faults are likely to occur, and where the environment is relatively good, such as outdoors. . In addition, it may be easy to cause ground faults over time after installation, so it is not necessary to install them in all circuits from the beginning of the installation of lighting equipment, and initially limited to parts where ground faults are likely to occur. In addition, it may be added to the portion with good environment when the leakage current changes or needs arise.

  In the third embodiment, in consideration of the installation environment, the ground fault rating device is installed only in the existing part when the section is extended in the illumination lamp of the highway and the like is not provided in the new part. is there. An example is shown in FIG. The existing part in the figure is the ground fault section rating device 8, the zero phase current transformers Z1, Z2... Zn, and the ground fault relay Y1 having the contacts X1, X2. Y2... To Yn and the branch connection point of each lamp L1, L2... Ln to the ground via the respective contacts X1, X2... Xn of the ground fault relays Y1, Y2. Resistors R1, R2... Rn connected to each other, and a zero-phase current transformer 6 and a current measuring device 7 for detecting a minute leakage current are provided so that the leakage current can be constantly monitored. The newly installed part does not have a part corresponding to the ground fault, and the initial investment is suppressed. On the neutral point side of the transformer secondary circuit 1 in the power supply part, the zero-phase current transformer 9 and the minute leakage current measurement The device 10 is provided so that the leakage current of the entire circuit of the load connection type distribution line 5 in the existing part and the load connection type distribution lines 15 and 25 in the extension part can be monitored. At the beginning of installation, it is configured in this way, the leakage current of the entire circuit is constantly monitored, and when the leakage current becomes large and the possibility of a ground fault has occurred, a ground fault section evaluation device is installed at the necessary part. If it is provided, initial investment can be suppressed.

FIG. 3 is a circuit diagram illustrating a configuration of a load-connected distribution line according to the first embodiment. FIG. 6 is a circuit diagram illustrating a configuration of a load-connected distribution line according to a second embodiment. FIG. 6 is a circuit diagram illustrating a configuration of a load-connected distribution line according to a third embodiment.

Explanation of symbols

1 Power transformer secondary circuit 2 Circuit breaker 3 Contactor 4 Neutral wire switch
5 Load-connected distribution line, 6 Zero phase current transformer, 7 Micro leak current measuring device,
8 Ground fault section rating device, 9 Zero phase current transformer, 10 Micro leak current measuring device,
L1, L2 ... Ln load, M1, M2 ... Mn ballast,
Y1, Y2 ... Yn ground fault relay, X1, X2 ... Xn contact,
R1, R2... Rn resistors.

Claims (4)

A multi-phase four-wire power source is connected to a contactor with a circuit breaker and a leakage protection function, and multiple loads arranged at intervals are branched between any phase and neutral wire A zero-phase current transformer disposed on the power supply side of each branch connection point to which the plurality of loads are connected, and a detected current of the zero-phase current transformer Equipped with a ground fault detector composed of a ground fault relay having an operating contact that is closed by a circuit, between each branch connection point to which the plurality of loads are connected and the ground, via the operating contact of the ground fault relay A ground fault interval rating that connects a resistor and includes a selection switch for selecting each line of the load-connected distribution line on the output side of the power supply unit, and applies a predetermined voltage to the selected line to pass an inspection current. Equipped with a device to keep the contactor open and shut off when a ground fault occurs. A load connection characterized in that a grounding section is evaluated by applying a predetermined inspection voltage to each line of the three-phase four-wire distribution line by the ground fault section evaluation device with the device in an open circuit state, and detecting the current value. Type distribution line. The load-connected distribution line according to claim 1, wherein the ground fault section evaluation device is configured to be able to apply a predetermined direct current voltage. The load-connected distribution line according to claim 1, wherein the ground fault section rating device is configured to be able to apply a predetermined alternating voltage. The load connection type distribution line according to any one of claims 1 to 3, wherein a minute leakage current measuring device is provided on an output side of the power supply unit.

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