JP2014187741A - Ground fault current suppression device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground fault current suppression device that is able to detect a ground fault accident that has occurred at a low-voltage circuit of a transformer secondary side of a high-voltage power reception facility without malfunction, and to suppress ground fault current.SOLUTION: A voltage limiting element 18 connected in parallel with a current limiting element 17 for suppressing ground fault current flowing between one terminal of the secondary side of a transformer and the earth suppresses voltage at the secondary side of the transformer to below a prescribed voltage when the primary side and the secondary side of the transformer comes into contact. A grounding contact 16 of an earth leakage circuit breaker 16 for detecting a ground fault accident on the basis of zero phase current of a low-voltage circuit of the secondary side of a transformer of a high-voltage power reception facility is connected in parallel with the current limiting element 17, and closed at normal times, but it opens when a ground fault detection unit 20 of the earth leakage circuit breaker detects a ground fault accident. A monitoring transmission device 19 transmits an alarm for the ground fault accident to a mobile communication system 14 when a grounding contact 21 opens.

Description

  The present invention relates to a ground fault current suppressing device that suppresses a ground fault current of a low voltage circuit on a transformer secondary side of a high voltage power receiving facility.

  An earth leakage breaker and an insulation monitoring device are applied to protect the ground fault of the low-voltage circuit on the secondary side of the transformer of the high-voltage power receiving equipment to prevent electric shock and fire. When a ground fault is detected, the earth leakage circuit breaker interrupts the low-voltage circuit where the ground fault occurred. The earth leakage breaker is hardly grounded in the electric circuit except where it must be legally installed, and it does not protect all the low-voltage circuits.

  On the other hand, when the insulation monitoring device detects a ground fault in the low voltage circuit, it issues a warning to the maintenance staff (chief engineer). Take action. As an insulation monitoring device, there is a device in which a low-frequency exploration current is superimposed on a low-voltage circuit on a secondary side of a transformer of a high-voltage power receiving facility so that a ground fault is detected by the exploration current (see, for example, Patent Document 1). .

JP-A-6-258363

  However, if the insulation monitoring device detects a ground fault during the daytime and notifies the maintenance personnel of an alarm, the maintenance staff can deal with the ground fault accident, but maintenance such as at night or on holidays. It may not be possible to deal with the time when staff is absent.

  In addition, the conventional insulation monitoring apparatus requires a power supply facility for superimposing the exploration current. When an inverter is connected to the load of the low-voltage circuit, the inverter has a frequency in the same band as the exploration current (for example, 10 Hz). When an electric current of 20 Hz is generated, the insulation monitoring device may erroneously detect a ground fault.

  Therefore, even if a ground fault occurs on the secondary side of the transformer of the high-voltage power receiving equipment, and maintenance personnel cannot respond immediately to the ground fault, it is requested that the effects of the ground fault do not increase. Is done.

  An object of the present invention is to provide a ground fault current suppressing device capable of detecting a ground fault occurring in a low voltage circuit on a transformer secondary side of a high voltage power receiving facility without malfunction and suppressing a ground fault current.

  A ground fault current suppressing device according to the invention of claim 1 is provided between the one end of the transformer secondary side of the high voltage power receiving equipment and the ground, and suppresses the ground fault current of the low voltage circuit on the transformer secondary side. In the fault current suppressor, the earth leakage breaker that detects a ground fault based on the zero-phase current of the low-voltage circuit on the secondary side of the transformer of the high-voltage power receiving equipment, and the one end between the secondary side of the transformer and the ground A current limiting element that suppresses a flowing ground fault current and a voltage on the secondary side of the transformer that is connected in parallel to the current limiting element and the primary side and secondary side of the transformer are reduced to less than a predetermined voltage. A voltage limiting element and a grounding contact that is connected in parallel to the current limiting element and is normally closed and opens when the earth leakage breaker detects a ground fault; and when the ground contact opens, the ground fault And a monitoring transmission device for transmitting the alarm of the mobile communication system to the mobile communication system And features.

  According to a second aspect of the present invention, there is provided a ground fault current suppressing device that is provided between one end of the transformer secondary side of the high voltage power receiving equipment and the ground, and suppresses the ground fault current of the low voltage circuit on the transformer secondary side. In the fault current suppressor, a leakage monitoring relay that detects a ground fault based on a resistance current in a zero-phase current of a low-voltage circuit on the secondary side of the transformer of the high-voltage power receiving facility, and one end on the secondary side of the transformer, A current limiting element that suppresses a ground fault current flowing between the transformer and a voltage connected to the current limiting element that is connected in parallel with the primary side and the secondary side of the transformer is set to a predetermined voltage on the secondary side of the transformer. A voltage limiting element that suppresses to less than a voltage, a grounding contact that is connected in parallel to the current limiting element and is normally closed, and opens when the ground fault monitoring relay detects a ground fault, and when the grounding contact opens Is monitoring to send the ground fault alarm to mobile communication system Characterized in that a signal device.

  According to the present invention, since a ground fault is detected based on a zero-phase current of a low-voltage circuit or a resistive current in the zero-phase current instead of a search current, a ground fault is detected. There is no false detection of ground faults due to current. In addition, the ground contact is normally closed, and when a ground fault is detected, the ground contact is opened and the ground fault current flows through the current limiting element, so that the ground fault current can be suppressed.

Explanatory drawing of the ground-fault current suppression apparatus of Embodiment 1 of this invention. The block diagram of the ground-fault current suppression apparatus of Embodiment 2 of this invention. The system diagram of the low voltage circuit of the transformer secondary side of the high voltage power receiving equipment of another example to which the ground fault current suppressing device of Embodiments 1 and 2 of the present invention is applied.

  Embodiments of the present invention will be described below. FIG. 1 is an explanatory diagram of a ground fault current suppressing device according to Embodiment 1 of the present invention, and FIG. 1 (a) is a diagram illustrating a transformer 2 of a high-voltage power receiving facility to which the ground fault current suppressing device according to Embodiment 1 of the present invention is applied. FIG. 1B is a configuration diagram of the ground fault current suppressing device according to the first embodiment of the present invention. FIG. 1A shows a case where there are two transformers 11 of the high-voltage power receiving facility, and a ground fault current suppressing device 12 is provided for each transformer 11.

  As shown in FIG. 1A, the transformers 11a and 11b of the high-voltage power receiving equipment step down the high voltage of the primary winding to generate a low voltage in the secondary winding, and the low voltage from the secondary winding to the secondary side. Power is supplied to the circuits 13a and 13b. Ground fault current suppression devices 12a and 12b are respectively provided between one end of the transformers 11a and 11b on the secondary winding side and the ground.

  The ground fault current suppression devices 12a and 12b detect a ground fault in the low voltage circuits 13a and 13b on the transformer secondary side and suppress the ground fault current. When a ground fault is detected, the ground fault current is detected. While suppressing, a ground fault alarm is transmitted to the mobile communication system 14. The mobile communication system 14 notifies a ground fault alarm to the mobile device 15 carried by the maintenance staff.

  As shown in FIG. 1 (b), the ground fault current suppression device 12 includes an earth leakage breaker (ELCB) 16 that detects a ground fault, a current limiting element 17 that suppresses the ground fault current, and a voltage that suppresses the voltage. A limiting element 18 and a monitoring transmitter 19 for transmitting a ground fault alarm to the mobile communication system are provided.

  The earth leakage breaker 16 includes a ground fault detection unit 20 having a zero-phase current transformer for detecting earth leakage, and a ground contact 21 for grounding one end of the secondary winding of the transformer. The wire detector 20 and the ground contact 21 are connected in series. The ground fault detector 20 of the earth leakage breaker 16 detects a ground fault based on the zero-phase current of the low voltage circuit on the secondary side of the transformer of the high voltage power receiving equipment, and the ground contact 21 is normally closed. It opens when the ground fault detector 20 detects a ground fault.

  The current limiting element 17 is connected in parallel to the ground fault detection unit 20 and the ground contact 21 connected in series. When a ground fault occurs and the ground contact 21 is opened, one end of the transformer secondary side is connected. For example, a current-suppressing resistor is used to suppress a ground fault current flowing between the ground and the ground. The voltage limiting element 18 is connected in parallel to the current limiting element 17 and suppresses the voltage on the secondary side of the transformer below a predetermined voltage when the primary side and the secondary side of the transformer come into contact with each other. Arresta. Further, the monitoring transmitter 19 monitors whether the ground fault detection unit 20 has detected a ground fault and has opened the ground contact 21, and when the ground contact 21 is opened, a ground fault alarm is transmitted by mobile communication. This is sent to the system 14.

  In this way, the ground contact 21 of the earth leakage breaker 16 is closed when normal, and when the ground fault detection unit 20 connected in series to the ground contact 21 detects a ground fault, the ground contact 21 is open. Therefore, since the ground fault current flows through the current limiting element 17, even if a ground fault occurs, the ground fault current is limited to a small value and the dangerous state is greatly reduced. In addition, since the ground fault is detected based on the zero phase current of the low voltage circuit by the ground fault detection unit 20 having the zero phase transformer, the same frequency as the search current is used as in the case of using the search current. There is no false detection of ground faults due to current.

  Next, the ground fault current suppression device according to the second embodiment of the present invention will be described. FIG. 2 is a configuration diagram of the ground fault current suppressing device according to the second embodiment of the present invention. The second embodiment is different from the first embodiment shown in FIG. 1B in that a ground fault monitoring relay 22 for detecting a ground fault is provided instead of the ground fault circuit breaker 16, and the ground contact 21 of the ground fault monitoring relay 22 is provided. It is provided. The same elements as those in FIG. 1B are denoted by the same reference numerals, and redundant description is omitted.

  As illustrated in FIG. 2, the ground fault current suppression device 12 of the second embodiment includes a ground contact 21 of the leakage monitoring relay 22, a current limiting element 17 that suppresses the ground fault current, and a voltage limiting element 18 that suppresses the voltage. Are connected in parallel, and when the ground fault monitoring relay 22 detects a ground fault, it transmits an alarm for the ground fault to the mobile communication system via the monitoring transmitter 19.

  The leakage monitoring relay 22 inputs the current of the low-voltage circuit on the secondary side of the transformer of the high-voltage power receiving equipment, extracts the resistance current in the zero-phase current of the low-voltage circuit, and extracts the resistance current in the zero-phase current of the low-voltage circuit. Detecting ground faults based on Thereby, since the electrostatic current is removed, it is possible to prevent malfunction and unnecessary operation due to the capacitance to the ground, and it is possible to detect the ground fault current with high accuracy.

  As in the case of the first embodiment, the ground contact 21 of the leakage monitoring relay 22 is closed when normal, and the ground contact 21 is opened when the ground monitoring relay 22 detects a ground fault. Therefore, since the ground fault current flows through the current limiting element 17, even if a ground fault occurs, the ground fault current is limited to a small value and the dangerous state is greatly reduced. In addition, since the ground fault is detected based on the resistance current in the zero-phase current of the low-voltage circuit, the fault of the ground fault caused by the current having the same frequency as the current for exploration is used, as in the case of using the current for exploration. There is no detection, and the ground fault current can be detected with high accuracy.

  In the above description, the case where the ground fault current suppression devices 12a and 12b are provided for the two transformers 11a and 11b is shown. However, as shown in FIG. 3, the two transformers 11a and 11b are provided. On the other hand, a common ground fault current suppression device 12 may be provided.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 ... Transformer, 12 ... Ground fault current suppression apparatus, 13 ... Low voltage circuit, 14 ... Mobile communication system, 15 ... Mobile equipment, 16 ... Leakage breaker, 17 ... Current limiting element, 18 ... Voltage limiting element, 19 ... Monitoring Transmitting device, 20 ... ground fault detection unit, 21 ... contact for grounding, 22 ... leakage monitoring relay

Claims (2)

In the ground fault current suppression device that is provided between one end of the transformer secondary side of the high voltage power receiving equipment and the ground and suppresses the ground fault current of the low voltage circuit on the transformer secondary side,
An earth leakage breaker that detects a ground fault based on the zero-phase current of the low-voltage circuit on the secondary side of the transformer of the high-voltage power receiving facility,
A current limiting element for suppressing a ground fault current flowing between one end of the transformer secondary side and the ground; and
A voltage limiting element that is connected in parallel to the current limiting element and suppresses the voltage on the secondary side of the transformer below a predetermined voltage when the primary side and the secondary side of the transformer are in contact with each other;
A grounding contact that is connected in parallel to the current limiting element and is normally closed and opens when the ground fault interrupter detects a ground fault,
A ground fault current suppressing device, comprising: a monitoring transmission device that transmits an alarm of the ground fault accident to a mobile communication system when the ground contact is opened. In the ground fault current suppression device that is provided between one end of the transformer secondary side of the high voltage power receiving equipment and the ground and suppresses the ground fault current of the low voltage circuit on the transformer secondary side,
A leakage monitoring relay for detecting a ground fault based on a resistance current in a zero-phase current of a low-voltage circuit on a secondary side of a transformer of a high-voltage power receiving facility;
A current limiting element for suppressing a ground fault current flowing between one end of the transformer secondary side and the ground; and
A voltage limiting element that is connected in parallel to the current limiting element and suppresses the voltage on the secondary side of the transformer below a predetermined voltage when the primary side and the secondary side of the transformer are in contact with each other;
A ground contact that is connected in parallel to the current limiting element and is normally closed and opens when the ground fault monitoring relay detects a ground fault,
A ground fault current suppressing device, comprising: a monitoring transmission device that transmits an alarm of the ground fault accident to a mobile communication system when the ground contact is opened.

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