JPH04284385A - Failure surveillance device for arrester - Google Patents

Abstract

PURPOSE:To automatically survey damage of non-linear resistance element of arrester by detecting arc discharge light generated in an insulating container in which an arrester element is stored, and by extracting the light airtight to the outside, so as to supply a signal to a remote surveillance point. CONSTITUTION:A light receiving element 11 which will be in continuity state by detecting arc discharge light generated by excessive discharge current running in an insulating container 3 in which a laminated body 2 of a non-linear resistance device as arrester element 1, is provided. The continuity state is connected to a surveillance circuit 15 of a surveillance point 20 which is away from the continuity state, through an airtight terminal of the lead-out part 12. By forming the surveillance circuit 15 out of a signal power source 17, a failure display 18 and a signal circuit 16, the continuity state of the light receiving element 11 is automatically remote-surveyed from the point 20 by a very simple failure surveillance device. Failure of arrester is detected early, and the failure breaker is separated from the power system while a repairing/exchange work is expedited.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to a type of zinc oxide type, for example, which is placed in a substation or transmission tower to absorb surge currents such as lightning currents that have entered the power system, and which does not have a series gap to block the following current. This invention relates to a lightning arrester, and in particular to a lightning arrester equipped with a failure monitoring device for its lightning protection elements.

0002

2. Description of the Related Art In recent years, zinc oxide type lightning arresters, which do not have a series gap, have become mainstream as lightning arresters for protecting electrical equipment in power systems from abnormal voltages such as lightning voltages and switching surges. FIG. 3 is a schematic cross-sectional view showing the general structure of a lightning arrester using a nonlinear resistance element. The lightning arrester element 1 is composed of a laminate of disc-shaped nonlinear resistance elements 2 whose main component is, for example, zinc oxide. Tightening plate 6b and insulation stud 6a
It is integrated by a tightening member 6 such as. The insulating container 3 has a structure in which both ends of an insulating tube such as an insulator are sealed with metal end plates 5a and 5b, and the lightning protection element 1 is biased in one direction via a compression spring 4 between the pair of end plates. sandwiched between. In the lightning arrester configured in this way, one end plate, for example 5a, is grounded, and the other end plate 5b is conductively connected to the power system, so that the ground AC voltage of the power system is constantly applied to the lightning arrester element 1. At the same time, abnormal currents such as lightning surge voltage caused by lightning strikes on the grid and switching surges caused by switching on and off of the grid are discharged to the ground side, and the abnormal voltage is suppressed to below a predetermined voltage limit.

[0003] In the lightning arrester constructed as described above, the nonlinear resistance element 2, which has zinc oxide as its main component, has an extremely large voltage-current characteristic in which the discharge current reaches the 40th power of the voltage in the limit voltage region of abnormal voltage. Since it exhibits nonlinearity, it discharges surge current to the ground side, suppresses the voltage at the line end below the limit voltage, and functions to protect the insulation of electrical equipment in the power system from abnormal voltage. In addition, when the abnormal voltage at the line end decreases due to discharge, the discharge current rapidly decreases, and it functions to stabilize the grid voltage by interrupting the follow-on current at the ground voltage of the power grid, for example, in 1/2 cycle or less. . However, in an excessive discharge current range exceeding the limited voltage range, the nonlinearity of the voltage-current characteristics decreases and energy loss of the nonlinear resistance element increases, increasing the risk of thermal destruction of the nonlinear resistance element. Therefore, the lightning arrester has a limit discharge current (for example, several tens to several hundreds of KA) of the lightning strike current that can maintain a predetermined limited voltage.

However, a lightning strike is a natural phenomenon, and although the probability is low, a lightning strike current exceeding a specified limit discharge current occurs, and the nonlinear resistance element 2 is thermally destroyed by the excessive discharge current, causing an arc within the insulating container 3. As the discharge occurs,
The breaking performance of the follow-on current deteriorates, and a ground fault current of tens to hundreds of amperes continues to flow, and the system circuit breaker that detects this ground fault current operates, causing an inconvenience that develops into a power outage accident. In addition, the internal pressure of the insulating container 3 increases due to arc discharge,
The risk of the insulating container being destroyed also increases. Therefore, when such a situation occurs, there is a need for a failure detection device that can quickly discover a failed lightning arrester and speed up its repair or replacement work. That is, in FIG. 3, a current transformer 9 having the grounding wire as the primary conductor is provided on the grounding wire side of the lightning arrester, and the duration and magnitude of the follow-on current are monitored. Alternatively, the pressure relief plate 8b is airtightly attached to the end plate 5b of the lightning arrester, and the internal pressure of the insulating container is applied to the pressure relief plate 8b through the opening 8a formed in the end plate 5b. Methods of suppressing and detecting increases are known.

[0005]

[Problems to be Solved by the Invention] Among the conventional techniques, in the method using a current transformer, it is possible to identify a faulty lightning arrester at a distant monitoring location by detecting the output current of the current transformer 9 at the monitoring location. However, if the current transformer core is magnetically saturated due to the discharge current of the lightning arrester, which is several tens to several hundred KA, it becomes difficult to detect a follow-on current of several tens to several hundred A. Moreover, if the iron core is made larger to avoid magnetic saturation with the discharge current, the current transformer itself becomes larger, resulting in an economic disadvantage. On the other hand, the pressure release plate is provided for the purpose of preventing the insulating container 3 from bursting, and is
It is set to operate when the follow-on current of the order of magnitude continues to flow for several tens of cycles, so if the system breaker that detects the follow-on current shuts off the system after only a few cycles, a failure will be displayed. Not only is this not possible, but even if the pressure relief plate is activated, it is necessary to go around to visually inspect the pressure relief plate for damage, and there is a drawback that failure of the lightning arrester cannot be automatically monitored from a remote monitoring location.

An object of the present invention is to detect damage to a nonlinear resistance element caused by discharging an excessive lightning current at an early stage when an arc discharge occurs in an insulating container, and to automatically monitor it at a remote monitoring location. The objective is to obtain a fault monitoring device for lightning arresters that can be used.

[0007]

[Means for Solving the Problems] In order to solve the above problems, according to the present invention, there is provided a lightning arrester element made of a laminate of disc-shaped nonlinear resistance elements, and a pair of lightning arrester elements connected via a compression spring. and an insulating container that is held and stored between end plates,
In a lightning arrester that discharges a surge current and interrupts a follow-on current, a light receiving element disposed within the insulating container detects light emission due to a failure of the nonlinear resistance element and becomes conductive;
A lead-out part that airtightly draws out the terminal of the light-receiving element to the outside of the insulating container, and a monitoring circuit that is connected to the light-receiving element through the lead-out part and monitors continuity of the light-receiving element from the monitoring location side. do.

[0008] Furthermore, the monitoring circuit includes a signal power source and a fault indicator disposed on the monitoring location side, and a signal circuit connecting these to a derivation section, and the fault indicator It shall be formed so as to be activated by a signal current to indicate a failure.

Furthermore, the monitoring circuit is provided with a signal conversion circuit that insulates the derivation section and the signal circuit from each other.

0010

[Operation] The structure of the present invention is based on the fact that in a lightning arrester in which the lightning arrester element does not have a series gap, the inside of the insulating container is maintained in a dark state unless an internal abnormality such as destruction of the nonlinear resistance element occurs. A light-receiving element that detects arc discharge light generated when an excessive discharge current flows through the non-linear resistance element and becomes conductive within an insulating container containing a laminate of non-linear resistance elements as a lightning protection element. By providing a monitoring circuit that monitors continuity from a remote monitoring location and connecting it to the light-receiving element via the lead-out section, the monitoring circuit can be driven by a signal power supply located at the monitoring location and a signal current. By constructing a failure indicator with a fault indicator connected to the light receiving element through a lead-out section and a signal circuit that connects these to the light receiving element through a lead-out section, the continuity of the light receiving element can be automatically monitored remotely from the monitoring location using a fault monitoring device with an extremely simple configuration. can. In addition, since a failure of a lightning arrester can be detected early at the point when an arc discharge occurs, a failure of a lightning arrester can be detected before the circuit breaker in the power system operates, and the faulty circuit breaker can be reliably identified.
This provides functionality that speeds up the disconnection from the power system and the repair and replacement of lightning arresters.

[0011] Furthermore, if the monitoring circuit has a signal conversion circuit that insulates the derivation section and the signal circuit from each other, it is possible to avoid the influence of ground potential fluctuations caused by the arrester discharging excessive lightning current. Highly reliable failure monitoring can be performed.

0012

EXAMPLES The present invention will be explained below based on examples. FIG. 1 is a block diagram schematically showing a failure monitoring device for a lightning arrester using a nonlinear resistance element according to an embodiment of the present invention, and the same parts as those in the conventional device are given the same reference numerals to avoid redundant explanation. Omitted. In the figure, reference numeral 11 denotes a light-receiving element fixed in the insulating container 3 using, for example, an insulating stud 6, and both terminals of the light receiving element are externally connected by a lead-out portion 12 consisting of an airtight terminal passing through the end plate of the insulating container 3 in an airtight manner. A signal power source 17 and a failure indicator 18 are drawn out to the monitoring site 20 and placed on the monitoring site 20 side via the signal circuit 16 of the monitoring circuit 15.
connected to a series circuit. As the light-receiving element 11, a photoconductive semiconductor element such as a photodiode, a phototransistor, or a photothyristor is used, and the failure indicator 18 receives a signal current supplied from the signal power source 17 by the conduction of the light-receiving element 11. An instantaneous electromagnetic or electronic fault indicator is used, which is driven by a fault indicator and has a self-hold function to indicate a fault.

In the device of the above embodiment, an excessive discharge current exceeding the limit discharge current flows through the lightning protection element 1 of the lightning arrester due to a lightning strike on the power system, and even one nonlinear resistance element that cannot withstand this is thermally destroyed. When an arc discharge occurs in the insulating container 3, the light receiving element 11 captures this arc light as direct light or anti-shading light, and the two terminals become conductive, and a signal is transmitted from the signal power source 17 arranged on the monitoring place 20 side. The current i is supplied to the fault indicator 18 through the light receiving element 11, and as a result, the fault of the lightning arrester can be known at a monitoring location remote from the arrester. In addition, the failure monitoring device is electrically insulated from the grounding system of the lightning arrester by the airtight terminal as the lead-out part, so it is less susceptible to ground potential fluctuations due to excessive discharge current.
In addition, the fault indicator operates instantaneously and indicates a fault before the grid circuit breaker detects the follow-on current and interrupts the grid.
Failure of the lightning arrester can be detected reliably. In particular,
By configuring the monitoring circuits of the fault monitoring devices installed for each of many lightning arresters to be collected and monitored at one monitoring location, a faulty lightning arrester can be immediately identified, making it possible, for example, to disconnect a faulty arrester from the power system and start power transmission. operations to restart,
This provides the advantage of speeding up the work to repair or replace a failed lightning arrester. Furthermore, the configuration of the failure monitoring device is extremely simple, and there is no need to increase the size of the current transformer in response to excessive discharge current, unlike the conventional method of providing a current transformer in the grounding system.

FIG. 2 is a connection diagram of a failure monitoring device showing a different embodiment of the present invention, in which a relay 21 is provided to electrically insulate between the deriving section 12 and the signal circuit 16, and the coil 21a and the driving power source are connected to each other. 22 to the light receiving element 1 via the deriving section 12.
1, the normally open relay contact 21b is connected to the signal circuit 16 side, and the conduction of the light receiving element 11 is detected when the contact of the relay 21 closes and a signal current flows. This is different from the embodiment described above, and it is possible to obtain a function to further ensure failure indication by eliminating malfunction of the device due to the influence of disturbances such as fluctuations in ground potential due to discharge of an excessive discharge current. Note that the relay 21 may be replaced with an E-O converter. In this case, if the signal circuit 16 is an optical fiber and the O-E converter is provided on the monitoring location side, the influence of disturbances will be reduced. A highly reliable lightning arrester failure monitoring device can be obtained.

[0015]

[Effects of the Invention] As described above, the present invention detects arc discharge light generated when an excessive discharge current flows through a nonlinear resistance element in an insulating container housing a laminate of nonlinear resistance elements as a lightning protection element. A light receiving element that becomes conductive is provided, and a monitoring circuit for monitoring the conduction from a remote monitoring location is connected to the light receiving element via a lead-out portion. As a result, a signal power supply with a monitoring circuit arranged at a monitoring location, for example,
By configuring a fault indicator driven by a signal current and a signal circuit that connects these to the light receiving element via a lead-out section, a fault monitoring device with an extremely simple configuration can automatically check the continuity of the light receiving element from the monitoring location. It becomes possible to monitor from a distance. Therefore, we have developed a fault monitoring device that eliminates the drawbacks of conventional fault detection devices using pressure relief plates, allows fault monitoring from a distance, and has a simpler and cheaper configuration than conventional devices that use current transformers. Lightning arresters can be provided. Also,
Since failure of a lightning arrester can be detected early at the point when an arc discharge occurs, even if a power system circuit breaker trips, the faulty arrester can be reliably identified, and the faulty arrester can be disconnected from the system and repaired or replaced. In addition to speeding up
Since there is no need to go around checking the operation of the pressure relief plate, there is an advantage that monitoring work and maintenance work can be greatly reduced.

[0016] Furthermore, if the monitoring circuit has a signal conversion circuit that insulates the derivation section and the signal circuit from each other, the ground potential will fluctuate due to the lightning arrester discharging an excessive lightning current, which may cause a failure. Problems such as malfunction of the monitoring device are eliminated, and a lightning arrester failure monitoring device having highly reliable failure monitoring performance can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing a failure monitoring device for a lightning arrester using a nonlinear resistance element according to an embodiment of the present invention.

[Figure 2
] Connection diagram of a failure monitoring device showing different embodiments of the present invention

[Figure 3] Schematic cross-sectional diagram showing the general structure of a lightning arrester using a nonlinear resistance element

[Explanation of symbols]

1 Lightning protection element 2 Nonlinear resistance element 3 Insulating container 4 Compression spring 5a End plate 5b End plate 6 Tightening member 8b Pressure relief plate 9 Current transformer 11 Photo receiving element 12 Derivation part (airtight terminal) 15 Monitoring circuit 16 Signal circuit 17 Signal power supply 18 Malfunction indicator 20 Monitoring location 21 Relay 21a Relay coil 21b Relay contact 22 Drive power supply i Signal current

Claims (3)

[Claims] Claim 1: A lightning arrester comprising a laminate of disk-shaped nonlinear resistance elements, and an insulating container in which the lightning arrester is sandwiched and housed between a pair of end plates via a compression spring. In a lightning arrester that interrupts discharge and follow-on current, a light receiving element is arranged in the insulating container and becomes conductive by sensing light emission caused by a failure of the nonlinear resistance element, and a terminal of the light receiving element is connected to the insulating container. A failure monitoring device for a lightning arrester, comprising: a lead-out part that is airtightly drawn out to the outside; and a monitoring circuit that is connected to the light-receiving element through the lead-out part and monitors continuity of the light-receiving element from a monitoring location side. . 2. The monitoring circuit includes a signal power source and a fault indicator disposed on the side of the monitoring location, and a signal circuit connecting these to a derivation section, and the fault indicator is connected to a signal source and a fault indicator disposed on the side of the monitoring location, and a signal circuit that connects these to a derivation section, wherein the fault indicator is connected to a light receiving element. 2. The lightning arrester failure monitoring device according to claim 1, wherein the device is configured to operate based on a signal current to indicate a failure. 3. The lightning arrester failure monitoring device according to claim 2, wherein the monitoring circuit includes a signal conversion circuit that insulates the lead-out section and the signal circuit from each other.