JP2008236967A - Discharge device for prevention of ground fault - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge device for prevention of a ground fault, reduced in size by eliminating a coil for opening/closing a side passage and a side passage opening/closing device, also reduced in maintenance work, and performing maintenance of the discharge device at the optimum timing. <P>SOLUTION: This discharge device includes: a discharger 3 connected between a protective line and a ground mat, or between a negative feeder and the ground mat; and a surge absorption part 2 which is connected to the discharger 3 in parallel to prevent unnecessary discharge of the discharger 3 by absorbing surge voltage at a rail. This discharge device is constituted without providing the side passage opening/closing device with the discharger 3 in parallel, and the discharger 3 has discharge withstand current rating with 20,000 A or more of current and 200 msec or more of discharge time. A measuring device 7 which detects the current discharged by the discharger 3 and counts the number of operation times of the discharger is provided, thus performing maintenance of the discharger 3, based on the counter value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ground fault protection discharge device for causing a ground fault current to flow into a rail or a negative wire when a ground fault occurs in an AC feeder.

  In an AC feeder substation and an AC feeder section, a grounding mat is generally installed, and each facility in the feeder substation or feeder section is grounded by connecting a ground wire to the grounding mat. When a ground fault occurs in a trolley wire or feeder at a substation or feeder section, the grounding mat potential increases due to grounding resistance, and weak electrical circuits such as control circuits and communication circuits connected to the grounding mat break down. There is a possibility. In order to prevent such an insulation breakdown accident, a ground fault protection discharge device has been conventionally provided (see Patent Document 1).

In the AT feeding system in which an autotransformer (AT) is installed, a ground fault protection discharge device 10 is provided between a protective wire 31 and a grounding mat 32 as shown in FIG. Generally, as shown in FIG. 3, the ground fault protection discharge device 10 includes a capacitor 11 and a resistor 12 and is connected to a surge absorber 13 that absorbs a surge voltage, and a bypass switch coil 14. The bypass switch 15 and the discharger 20 are connected in parallel to each other. When a ground fault occurs in the trolley wire 33 or the AT feeder 34 at an AC feeder substation or the like, the potential of the grounding mat 32 rises and a voltage higher than the discharge start voltage acts on the gap of the discharger 20. Discharges. As a result, the grounding mat 32 and the protection line 31 are short-circuited, and the grounding mat 32 has substantially the same potential (substantially grounding potential) as the protection line 31, so that a control circuit, a communication circuit, etc. Such a breakdown of the weak electric circuit 35 can be prevented. Further, due to the discharge, a current flows through the coil 14 for the side switch, whereby the side switch 15 is closed, the current flowing to the discharger 20 is bypassed, and the discharger 20 is protected. The bypass current flows to the feeder circuit via the rail 36 and the AT feeder line 34, whereby the protective relay 37 operates to open the breaker 38 and interrupt the accident current. When the fault current no longer flows through the side switch coil 15, the side switch 15 opens and returns to the normal state.
Japanese Patent Laid-Open No. 10-166909

  By the way, in the conventional ground fault protection discharge device as described above, it is necessary to provide the side switch coil 14 and the side switch 15 in order to protect the discharger 20, which increases the size of the device and bypasses it. The maintenance work of the switch 15 was complicated and required labor. In addition, the idea was to improve the discharge tolerance of the discharger 20 and omit the installation of the coil 14 for the side switch and the side switch 15, but what is the time tolerance for the discharge? In this case, since it is unclear whether the bypass switch coil 14 and the bypass switch 15 can be omitted, it cannot be easily realized. It was also an important issue to maintain the function of the device by maintaining the discharger at an optimal time.

  The present invention has been made to solve the above-described conventional problems, and its object is to reduce the size of the apparatus by omitting the installation of the coil for the side switch and the side switch, and to perform maintenance. An object of the present invention is to provide a ground fault protection discharge device capable of reducing work and maintaining a discharger at an optimal time.

  Therefore, the ground fault protection discharge device according to claim 1 includes a discharger 3 connected between the protection line and the grounding mat or between the negative wire and the grounding mat, and the discharger 3 connected in parallel to the rail. A surge absorber 2 that absorbs surge voltage and prevents unnecessary discharge of the discharger 3, is configured without providing a side switch in parallel with the discharger 3, and the discharger 3 has a current 20, It has a discharge tolerance of 000 A or more and a discharge time of 200 msec or more.

  The ground fault protecting discharge device according to claim 2 is characterized in that a measuring means 7 for detecting a current due to discharge of the discharger 3 and measuring the number of operations of the discharger is provided.

  As in the case of the ground fault protection discharge device according to the first aspect of the present invention, in the case of having a discharge tolerance of a current of 20,000 A or more and a discharge time of 200 msec or more, a conventional side switch coil and a side switch are installed. It was not necessary, and it became clear that these could be omitted. As a result, the apparatus can be miniaturized and maintenance work can be greatly reduced.

  According to the ground fault protection discharge device of the second aspect, maintenance of the discharge device 3 can be performed at an optimal time based on the exact number of operations of the discharge device 3, thereby always providing the ground fault protection discharge device. Can be maintained in an optimal state and the equipment can be protected from a ground fault.

  Next, specific embodiments of the ground fault protecting discharge device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a ground fault protecting discharge device according to the present invention. In this ground fault protection discharge device 1, the surge absorber 2 and the discharger 3 are connected in parallel. The surge absorber 2 is configured by connecting a capacitor 4 and a resistor 5 in series, and absorbs a rail surge voltage. And in order to employ | adopt such a structure, ie, the structure which abbreviate | omitted installation of the coil for a side switch, and a side switch, to what extent the time tolerance of discharge is required as the discharger 3 We examined whether there was. As a result, the discharge tolerance required for the discharger 3 is preferably 20,000 A or more, a discharge time of 200 msec or more, and preferably manufactured at a current of 20,000 A or more and a discharge time of 200 to 300 msec. It became clear that this was sufficient.

  In FIG. 1 and FIG. 2, when a ground fault occurs in the trolley wire 33 or the AT feeder 34, the potential of the ground mat 32 rises and a voltage higher than the discharge start voltage is applied to the gap of the discharger 3. Discharges. As a result, the grounding mat 32 and the protection line 31 are short-circuited, and the grounding mat 32 has substantially the same potential (substantially grounding potential) as the protection line 31, and the ground side of the control circuit, communication circuit, etc. connected to the grounding mat 32 Therefore, the dielectric breakdown of the weak electric circuit 35 can be prevented. At this time, the ground fault current flows through the rail (rail) 36 to the feeder circuit, so that the protective relay 37 operates to open the circuit breaker 38 and interrupt the accident current.

  In the above configuration, since the time tolerance of the discharge of the discharger 3 is high, it is not necessary to install a side switch and a side switch as in the prior art, and therefore, these can be omitted. As a result, the apparatus can be miniaturized and maintenance work can be greatly reduced.

  Further, as shown in FIG. 1, a current detector (CT) 6 is provided on the grounding mat 32 side of the discharger 3 and its output side is connected to a counter 7 to measure the number of operations of the discharger 3. Thereby, based on the exact frequency | count of operation of the discharger 3, the maintenance of the discharger 3 can be performed at the optimal time, and thereby, the function of the discharge device 1 for ground fault protection is always maintained in an optimal state, Equipment can be protected from ground faults.

  Although the embodiment of the ground fault protection discharge device of the present invention has been described above, the present invention is not limited to the above embodiment, and can be implemented with various modifications. For example, in the above description, the AT feeding system in which an autotransformer (AT) is installed has been described, but the present invention can also be applied to a BT feeding system in which a booster transformer (BT) is installed. In the case of the BT feeding system, the ground fault protection discharge device 1 is connected between the negative wire and the ground.

It is a circuit diagram which shows embodiment of the discharge device for ground fault protection of this invention. It is explanatory drawing of the whole structure which shows arrangement | positioning of the discharge device for earth fault protection. It is a circuit diagram of the conventional discharge device for earth fault protection.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Ground fault protection discharge device, 2 ... Surge absorption part, 3 ... Discharger, 6 ... Current detector, 7 ... Counter

Claims (2)

  The discharger (3) connected between the protective wire and the grounding mat or between the negative wire and the grounding mat, and connected to the discharger (3) in parallel to absorb the rail surge voltage and Comprising a surge absorber (2) for preventing unnecessary discharge, configured without providing a bypass switch in parallel with the discharger (3), and the discharger (3) having a current of 20,000 A or more, A discharge device for earth fault protection having a discharge tolerance of 200 msec or more for discharge time.   The ground fault protection discharge device according to claim 1, further comprising a measuring means (7) for detecting a current due to discharge of the discharger (3) and measuring the number of operations of the discharger.