JPH1014092A - Ground leakage breaker with lightning surge protection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an equipment from discharging and lessen damage to the equipment by cutting off a leakage breaker when a current transformer which detects a combined current of distribution lines detects current of a specified value or above. SOLUTION: When lightning surge occurs, a lighting arrestor 4 operates and then discharging current due to lightning surge is caused to flow in a ground line 5. Therefore, a current transformer 6 detects current in a distribution line 1 and current in the ground line 5. A leakage detection relay 7 also detects these currents and starts to operate to cut off a leakage breaker 3 before an equipment discharges. Since the discharging current in the ground line due to surge is detected before the equipment starts discharging and then the leakage breaker 3 is cut off, the equipment can be prevented from being damaged and discharging of the equipment due to surge can be lessened even if a ground resistance is specifically high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage circuit breaker with a lightning surge protection disposed on a low-voltage wiring circuit, and more particularly to an earth leakage breaker having a function of detecting the intrusion of a lightning surge and switching off and on again.

[0002]

2. Description of the Related Art FIG. 2 is a view for explaining an example of a conventional switchgear installed on a low-voltage wiring line. In the figure, reference numeral 1 denotes a wiring line connected to outdoor distribution lines and equipment. Y is a power supply side terminal, X ₀ and Y ₀ are load side terminals.
Usually, as shown, no fuse breaker (NBF)
Normally, the earth leakage breaker 2 and the earth leakage breaker 3 are arranged in series.
For equipment installed outdoors in the mountains where lightning often occurs, such as a water level detection device for a dam of a hydroelectric power plant, a lightning surge arrester (AL) 4 for lightning surge discharge is installed to protect the device. ing. Although the lightning arrester 4 is grounded through the ground line 5, the grounding resistance is reduced in order to sufficiently exhibit the performance of the lightning arrester.

[0003]

However, in the mountains, the grounding resistance cannot be sufficiently reduced due to the rocky geology, so that the performance of the lightning arrester cannot be sufficiently exhibited. It will discharge. In this case, the earth leakage breaker detects a ground fault current, and operates and shuts off the equipment in the same manner as in the case of normal earth leakage, but causes considerable damage to the equipment.

[0004] When the earth leakage breaker is cut off, the equipment goes to the installation site of the equipment and the earth leakage breaker is turned on again. However, the electric discharge of the equipment due to the lightning surge often recovers immediately. In order to turn on the earth leakage breaker again, the user has to go to the installation site of the equipment, which is a great burden for the maintenance worker.

According to the present invention, the frequency of occurrence of such lightning is high,
Applied to equipment installed in the mountains where the grounding resistance cannot be reduced sufficiently, the breaker is cut off by detecting the intrusion of lightning surge quickly, preventing discharge in the equipment, reducing damage to the equipment, and maintaining An object of the present invention is to provide an earth leakage breaker that can reduce a burden on an operator.

[0006]

According to a first aspect of the present invention, a lightning arrester has a lightning arrestor at a power supply side terminal, and flows to each line of a ground line of the lightning arrester and a wiring path connected to the earth leakage breaker. It has a current transformer for detecting a combined current, and shuts off the earth leakage breaker when the current transformer detects a current equal to or more than a predetermined value.

[0007] A second aspect of the present invention is characterized in that, in the first aspect of the present invention, the power supply is turned on a predetermined time after the earth leakage breaker is cut off.

A third aspect of the present invention is characterized in that, in the second aspect of the present invention, when the power is shut off again within a predetermined time after the re-input, the re-input is repeated a predetermined number of times.

A fourth aspect of the invention is characterized in that, in the third aspect of the present invention, after the circuit is repeatedly turned on a predetermined number of times, the circuit breaker is maintained in the cutoff state and an alarm is displayed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a current transformer for detecting an earth leakage current is provided on a wiring line of equipment and a ground line of an arrester installed on the wiring line, and a discharge current caused by a lightning surge flowing through the ground line of the arrester is provided. In addition to detecting and shutting off the earth leakage breaker, the earth leakage breaker is turned on again after a certain period of time. Is displayed.

A conventional earth leakage breaker detects a discharge current of a device due to the intrusion of a lightning surge.
The present invention detects the discharge current of a lightning arrester that discharges faster than the device so that it can be cut off before the device discharges, and can also fulfill the function of the original earth leakage breaker. It is.

FIG. 1 is a view for explaining an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a wiring path connected to an outdoor power distribution line and equipment, and 2 denotes a no-fuse breaker. (NFB), 3 is earth leakage breaker, 3a is earth leakage breaker 3.
, 3b is a contact of the earth leakage breaker 3, 4 is a lightning arrester (AL), 5 is a grounding line of the lightning arrester, 6 is a current transformer (ZCT) for detecting a current between the wiring line 1 and the grounding line 5, 7
Is a leakage detection relay (EL) that operates with the detection current of the current transformer (ZCT) 6, and 7a and 7b are leakage detection relays (E).
L), 10 is a counter (C), 10a is an operating contact of the counter 10, 12 is an over-operation detection relay (D), 12
a and 12b are contacts of an over-operation detection relay, 14 is an over-operation alarm indicator, 15 is a reset switch of an earth leakage breaker, 1
Reference numeral 6 denotes a control circuit for setting the operation of the leakage detection relay 7 and the counter 10.

In this switchgear, the power source terminals X and Y of the no-fuse breaker (NFB) 2 are connected to the distribution line 1, the load sides X0 and Y0 of the contact 3b of the earth leakage breaker are connected and wired to the equipment, and The ground end E of the ground line 5 is connected to a grounding device. The grounding resistance of the grounding device should be as low as possible, but if it is 30 ohms or less, the device can be reliably protected against normal induced lightning surges apart from direct lightning and lightning surges close to direct lightning. When a leakage occurs in the wiring path or the equipment connected to the equipment, the current transformer (ZCT) 6 detects the unbalanced current in the wiring path 1 due to the leakage current, the leakage detection relay (EL) 7 operates, and its contact 7b Is released, the excitation of the operation coil 3a of the earth leakage breaker is released, and the contact 3b of the earth leakage breaker is cut off. This is the same as the operation of the normal earth leakage breaker 3 shown in FIG.

When a lightning surge enters, the intruded surge is discharged to the ground by the lightning arrester (AL) 4, but when the discharge current is large or the ground resistance is high, the voltage of the wiring path 1 increases. However, despite the operation of the lightning arrester, the voltage may reach the voltage at which the equipment discharges. In such a case, in the conventional switchgear, the leakage current accompanying the discharge of the device is detected and cut off in the same manner as the normal leakage.

On the other hand, in the present invention, when the lightning surge arrives, the lightning arrester 4 operates and the discharge current of the lightning surge flows to the ground line 5, so that the current transformer (ZCT) 6
The current flowing through this ground line 5 is also detected along with the current of
The leakage detection relay (EL) 7 detects this and operates, and shuts off the leakage breaker 3 before the device is discharged.

In the conventional device, if the grounding resistance cannot be reduced sufficiently even when the lightning arrester operates, the surge is not sufficiently absorbed, the ground voltage of the wiring path (equipment) increases, and the equipment is discharged. According to the apparatus of the present invention, the discharge current of the surge flowing through the ground line is detected and cut off before the device reaches the discharge, so that the device can be prevented from being damaged. Even when the ground resistance is particularly high, the discharge of the device due to the penetration of the surge can be greatly reduced.

(Embodiment 2) An earth leakage detection relay (E
L) The operation value of 7 and the return time of the contacts 7a and 7b are set by the control circuit 16. When the leakage detection relay 7 operates to close the contact 7a and open the contact 7b, the leakage breaker 3 is cut off and the counter 10 counts the cutoff operation.
When the contacts 7a and 7b return after a certain set time, the operation coil 3a of the earth leakage breaker 3 is excited again, and the earth leakage breaker 3 is turned on again. If there is no discharge of the device due to the intrusion surge and the leakage detection relay 7 does not operate again within a predetermined time after re-input, the counter 10 resets the count and enters the initial state.

(Embodiments of Claims 3 and 4) Even if a surge discharge occurs in the equipment, it is usually recovered instantaneously by the breaker 3 being cut off. 7 operates and the breaker 3 shuts off. in this case,
The same operation as above is repeated, and the counter 10 counts two interruptions. If the fault does not recover, the counter 10 counts the interruption in this way, and after counting a certain number of times, the contact 10a closes, the over-operation detection relay 12 operates, the contact 12a closes, and the alarm indicator lights. 14 is turned on. The contact 12a of the relay 12 holds the operation of the relay 12, and the counter returns after a predetermined time due to the opening of the contact 12b.

After confirming the recovery by checking and repairing the failure, the reset switch 15 is pressed to return to the initial state. The count of the counter 10 and the return time are set by the control circuit 16. It is obvious that the above operation is not limited to the intrusion of the lightning surge but is also the same in the case of a normal earth leakage fault.

[0020]

As described above, according to the present invention, it is possible to cut off a lightning surge without damaging the device, as well as cut off the normal earth leakage detection. Maintenance work can also be reduced by re-input.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram for explaining an embodiment of the present invention.

FIG. 2 is an electric circuit diagram for explaining an example of a conventional switchgear.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1: Wiring line connected to outdoor power distribution line and equipment, 2: No fuse breaker (NFB), 3: Earth leakage breaker, 3
a: operation coil of earth leakage breaker, 3b: contact of earth leakage breaker, 4: lightning arrester (AL), 5: grounding line of lightning arrester, 6
… Current transformer (ZC) that detects current in wiring line and ground line
T), 7 ... Leakage detection relay (EL) that operates with the detection current of the current transformer, 7a, 7b ... Contacts of leakage detection relay 7, 10
... Counter (C), 10a ... Counter operating contacts, 12
… Over-operation detection relays (D), 12a, 12b… Over-operation detection relay contacts, 14… Over-operation alarm indicators, 15… Electric leakage breaker reset switch, 16… Electric leakage detection relay and counter operation setting control circuit.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mikio Yoshida 5024 Iyanoshita, Toyohoku Electric Power Co., Ltd.Aginogawa Dam, Toyohoku Electric Power Co., Inc. Yoshibori 1-1 Shinobu Electric Co., Ltd.

Claims (4)

[Claims] 1. An earth leakage arrester is provided at a power supply side terminal of an earth leakage breaker, and a current transformer is provided for detecting a combined current flowing in each line of a wiring line connected to the earth line of the earth arrester and the earth leakage breaker. An earth leakage breaker with lightning surge protection, wherein the earth leakage breaker is cut off when the current transformer detects a current equal to or more than a predetermined value. 2. The earth leakage circuit breaker with lightning surge protection according to claim 1, wherein the earth leakage circuit breaker is turned on a predetermined time after the earth leakage circuit breaker is shut off. 3. The earth leakage circuit breaker with lightning surge protection according to claim 2, wherein when the power is cut off again within a predetermined time after the power is turned on again, the power is turned on again a predetermined number of times. 4. The earth leakage circuit breaker with lightning surge protection according to claim 3, wherein the circuit breaker is maintained in a cut-off state after repeating re-injection a predetermined number of times and an alarm is displayed.