JPH08162252A - Lighting arrester for power transmission - Google Patents

Abstract

PURPOSE: To provide an economical lightning arrester with a small size, lightweight and high performance and which enables lightning surge current to flow without generating discharge between insulator horns and quickly restores insulation to shut continuous flow after that. CONSTITUTION: A capacitor corn 12 is composed by installing electrode layer 13 surrounding a reinforcing cylinder 3 made of FRP in a main body part 4 of an insulating cover tube 2 in which an arrester element 7 is received and installing a thin film insulating layer 14 arranged between the electrode layers 13 overlapped in the longitudinal direction of the cover tube, and a capacitance of the apparatus in thus improved. The arrester 1 can be manufactured at low cost without becoming complicated in the structure. Further, the arrester 1 is light in weight and moreover has a high capacitance, so that short circuit is gaps Cg in series can surely occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission lightning arrester for protecting overhead power lines from lightning surges.

[0002]

2. Description of the Related Art The lightning arrester described above uses a characteristic of a zinc oxide arrester element that has a low resistance in a high voltage region and a high resistance in a low voltage region, when a surge is applied to an overhead power transmission line. It is used for the purpose of passing an electric current and then promptly recovering the insulation to interrupt the follow current.

FIG. 4 shows a usage state of the apparatus. This lightning protection device 20 is hung on a steel tower 23 in parallel with a support insulator 22 of a power transmission line 21 and electrically connected to an upper electrode 5 at a ground potential via an arrester element (which is housed in an insulating sleeve 4). The lower electrode 6 is made to face the horn metal fitting 24 provided on the support insulator 22 on the voltage applying side via a predetermined series gap Cg.

With this device, when there is a lightning strike on the tower, the series gap Cg flashes over, and the lightning current flows from the tower 23 through the series gap Cg of the apparatus 20 to the electric wire 2.
Flows to 1. In addition, after a momentary lightning surge, the voltage is in the low voltage region, which is the voltage applied to the wire, so the arc in the series gap portion is extinguished due to the high resistance of the arrester element, and the insulation is quickly restored. With this device, the voltage difference between the upper electrode 5 and the lower electrode 6 when the series gap Cg flashes over is suppressed by the characteristics of the arrester element, and no discharge occurs between the insulator horns 25. This insulator horn 2
Once a discharge occurs between the five, the atmosphere between the horns is ionized, so that the discharge is connected even in the low voltage region, and this follow-up current activates the relay and leads to a power failure. The lightning arrester is for preventing the power failure.

By the way, in such a lightning arrester, the larger the electrostatic capacity is, the more the insulation coordination characteristic is improved, and the series gap portion is more surely flashed. Therefore, as a measure for increasing the electrostatic capacity, there has been proposed a method in which an aluminum pressure-resistant container is embedded in an insulating sleeve made of EP (ethylene propylene) rubber or the like (see Japanese Patent Laid-Open No. 4-137382). In the disclosed technology of the publication, in a conventional lightning arrester in which an arrester element is housed in an insulating sleeve reinforced by a FRP cylinder, a capacitor is externally mounted in parallel between an upper electrode and a lower electrode. Suggestions are also included.

[0006]

A lightning arrester using an aluminum pressure resistant container is difficult to reduce in cost and weight. Further, since the thickness of the pressure resistant container is added to the outer diameter, the device diameter also becomes large. Further, although not mentioned in the above publication,
The explosion-proof mechanism provided as a protection measure when an arc occurs inside due to deterioration of the arrester element becomes complicated. In this explosion-proof mechanism, a rubber cutting blade slidably supported by a lower electrode moves by internal pressure to push off a part of rubber of an insulating sleeve and contact with an aluminum pressure resistant container. As a result, a current flows between the upper and lower electrodes via the aluminum pressure vessel, and the internal arc disappears,
Although the structure is such that the rise of the internal pressure is stopped, if such an explosion-proof mechanism including a movable mechanism is provided, the device becomes complicated and the cost is greatly affected.

[0007] The external lightning arrester of the external capacitor type is not practical because it has problems in terms of overall size, installation space, and securing a surface distance on the outer circumference of the capacitor.

Therefore, an object of the present invention is to increase the electrostatic capacity of a conventional lightning arrester adopting a simple explosion-proof mechanism without using an external capacitor.

[0009]

In order to solve the above problems, according to the present invention, an arrester element is housed in an insulating sleeve having an FRP reinforcing tube inside, and an upper electrode and a lower portion are interposed through the arrester element. In the insulation sleeve of the lightning arrester having a structure in which the electrodes are electrically connected, a capacitor including an electrode layer surrounding a reinforcing tube and overlappingly arranged in the longitudinal direction of the sleeve and a thin film insulating layer sandwiched between the electrode layers is formed. is there.

As a constituent material of the electrodes of the capacitor, a conductor plate, a conductor foil, a mesh sheet in which conductive wires are knitted, a conductive rubber, a conductive tape, a conductive paint, etc. can be considered.

The material of the insulating layer between the electrodes is E
P rubber, silicone rubber, cross-linked polyethylene, etc. are considered.

It should be noted that it is desirable to eliminate the edge at the end because the electrode layer may cause a partial discharge between adjacent electrodes if there is an edge at the end.

[0013]

In the present invention, since the capacitor is provided in the wall material of the insulating sleeve, there is no problem when an external capacitor is used.

Further, as the explosion-proof mechanism, a simple arc-blowing system can be used, so that the apparatus can be simplified and the cost can be reduced. The arc blow-out explosion-proof mechanism has pressure relief ports with safety valves on the upper and lower electrodes.When the internal pressure of the insulation sleeve rises above a certain level due to the internal arc, the safety valve opens and the pressure relief port is opened. It has a structure that allows pressure to escape from it, and does not include a complicated moving mechanism. Further, in this type of explosion-proof mechanism, since the internal pressure relief passage is secured between the FRP reinforcing cylinder and the arrester element accommodated therein, the arrester element can be easily inserted.

Further, the apparatus of the present invention does not include an aluminum pressure resistant container, so that the weight can be reduced.

In addition, the explosion-proof mechanism having a complicated structure and the need for burying an aluminum pressure-resistant container, which is time-consuming to manufacture, are not required, so that mass production is easy and further miniaturization can be achieved.

Further, since the upper electrode and the lower electrode are fixed to the FRP reinforcing cylinder to increase the strength, it is possible to add a plurality of the same devices in series to cope with a change in the voltage class.

[0018]

FIG. 1 shows an example of the present invention. This lightning arrester 1
Is an insulating sleeve 2 made by compounding a main body 4 having pleats for increasing the surface extension distance on the outer periphery of a FRP reinforcing tube 3.
An upper electrode 5 and a lower electrode 6 fixed to the reinforcing tube 3 and provided on both ends of the sleeve 2, a solid-state arrester element 7 of zinc oxide inserted in series into the inner cavity of the insulating sleeve 2. It comprises a spring 8 for pressing the divided body 5a of the upper electrode against the arrester element 7 for the purpose of increasing the contact pressure of the element.

A gap 9 is formed between the reinforcing cylinder 3 and the arrester element 7 to serve as a passage for releasing the internal pressure. Further, the upper and lower electrodes 5, 6 are provided with a pressure release port 10 for explosion protection. Are provided facing each other. The pressure release port 10 is normally closed by a pressure release film 11 that functions as a safety valve. When the internal pressure of the sleeve 2 rises above a set pressure due to the occurrence of an internal arc due to an abnormality, the pressure release film 11 is broken and the internal pressure rises. Is discharged from the pressure relief port. Therefore, the device does not burst or scatter. The pressure release film 11 may be replaced with a general safety valve such as a poppet valve capable of recovering its function.

Reference numeral 12 is a condenser cone formed in the main body 4 of the insulating sleeve. This condenser cone 12
Is made by embedding an annular electrode layer 13 having a larger diameter toward the lower side surrounding the reinforcing tube 3 in the main body portion 4 in such a manner that they are sequentially overlapped in the longitudinal direction of the sleeve. Each electrode layer 13
A thin film insulating layer 14 (see FIG. 2) is sandwiched between them, and the lowermost electrode layer 13 is electrically connected to the lower electrode 6 on the high voltage side. Therefore, the overlapping part of each electrode layer functions as a capacitor, and the capacitance of the device increases.

As shown in FIG. 3, when the end portions of the electrode layer 13 are rounded, partial discharge is unlikely to occur between the electrode layers. When the electrode layer 13 is formed of a copper plate, a copper foil, a mesh sheet or the like, such end treatment is easy, but the electrode layer 13 is formed of conductive rubber, conductive tape, conductive paint, etc. in total. Is rather advantageous.

The insulating layer 14 and the sleeve body 4 are preferably made of EP rubber, silicon rubber, cross-linked polyethylene or the like. It is not impossible to make it from ceramics, but this is not so preferable considering the time and effort for manufacturing and the increase in weight of the device.

The EP rubber may be wound on a tape and crosslinked. Also, silicone rubber can be extruded, and crosslinked polyethylene can be made into a heat-shrinkable tube to form an insulating layer by heat-shrinking. The uppermost electrode layer 13 is formed on the insulating layer 14 provided on the reinforcing cylinder 3, and the insulating layer 14 and the electrode layer 13 of the next stage are sequentially formed on the uppermost electrode layer 13 to repeat the operation, and the capacitor cone 12 is manufactured. By forming the remaining pleated portion of the main body portion 4 on the outer periphery thereof, the insulating sleeve 2 as shown in FIG. 1 is completed.

Next, in the illustrated structure, the AC8 is now taken as an example.
77kV class transmission line lightning arrester with a withstand voltage characteristic of 0.5kV and lightning impulse 305kV (inner diameter of cylinder 2 is 60mm,
Consider a design with an outer diameter of 90 mm and an arrester diameter of 50 mm). In this case, assuming that the gap between the electrode layers 13 (thickness of the insulating layer 14) is 1 mm with respect to the insulating sleeve 2 made of cross-linked polyethylene having a relative dielectric constant ε = 2.5, the design electric field between the electrode foils of polyethylene is set. Since the strength is 50 kV / mm, the number of foils required to withstand an impulse of 300 kV is 7 (the number of capacitors in series is n = 6).

On the other hand, in order to surely discharge in the series gap, it is necessary to increase the shared voltage of the arrester device and the series gap in the series gap.
It is necessary to have a capacitance of about 0 pF. In this case, if the inner diameter of the inner electrode is 90 mm,
In order to provide the capacitance of 0 pF, the capacitance of each of the six capacitors connected in series is required to be 600 pF, and in order to secure this, the required overlap amount of the pair of electrode layers 13 (see FIG. 2). L) is about 90 mm. Therefore,
In order to secure a total electrostatic capacity of 100 pF, it is sufficient to make a capacitor cone (capacitor number 6) in which seven layers of electrodes each have a length of 90 mm, and the total length of the insulation sleeve 2 is 700 mm. As long as it is strong, it is possible to provide a practical lightning protection device.

When the insulating sleeve 2 is replaced with a rubber one having ε = 2.75 or more, if the gap between electrodes and the inner diameter of the electrode are 1 mm and 90 mm, which are the same as above, the required number of foils is 11 sheets. (10 capacitors). Therefore, in this case, if the total capacitance is 100 pF, each capacitor cone becomes 1000 pF, and the electrode layer 13
The required overlap amount is 130 mm. Therefore,
In this case, if the length of the insulating sleeve 2 is a little over 1300 mm, it can be built in the sleeve, so that it can be sufficiently put into practical use.

Reference numeral 15 in FIG. 1 denotes a joint fitting that can be connected to the mounting base of the upper electrode 5. When such a joint fitting is used, the upper electrode 5 can be connected to the lower electrode of the upper lightning arrester and a plurality of lightning arresters can be added in series. Therefore, it is possible to cope with changes in the voltage class without changing the design. In this way, if the same device is used for the transmission lines of a plurality of voltage classes, the models can be integrated, which is more advantageous in terms of cost.

The apparatus of the present invention is used in the same state as in FIG.

[0029]

As described above, according to the present invention, since the capacitor is formed in the wall material of the insulating sleeve to increase the capacitance, the weight increase when the aluminum pressure resistant container is embedded, Also, it is possible to solve the problem of cost increase due to complication of the apparatus and increase in material cost.

Further, problems such as an increase in size of the device when using an external capacitor and restrictions on use in space can be solved, which is essential for more reliable and economical protection of overhead power transmission lines. It is possible to provide a lightning protection device that is small, lightweight, high-performance, and inexpensive that cannot be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a lightning arrester of the present invention.

2 is a partially enlarged cross-sectional view of the device of FIG.

FIG. 3 is a cross-sectional view showing an example of an end treatment of a capacitor electrode.

FIG. 4 is a diagram showing a usage state of the lightning protection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lightning arrester 2 Insulation sleeve 3 FRP reinforcement cylinder 4 Main body 5 Upper electrode 5a Split body 6 Lower electrode 7 Arrestor element 8 Spring 9 Air gap 10 Pressure release port 11 Pressure release film 12 Capacitor cone 13 Electrode layer 14 Thin film insulation layer 15 Joint fitting 20 Lightning arrester 21 Transmission line 22 Support insulator 23 Steel tower 24 Horn fitting 25 Insulator horn Cg Series gap L Electrode layer overlap amount

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kohei Furukawa 1-3-3 Shimaya, Konohana-ku, Osaka No. 3 Sumitomo Electric Industries, Ltd. Osaka Works

Claims (3)

[Claims] 1. An arrester element is housed in an insulating sleeve having an FRP reinforcing tube inside, and an upper electrode and a lower electrode electrically connected through the element are provided at both ends of the reinforcing tube. In the lightning protection device, the upper electrode is connected to the element on the steel tower side and is hung in parallel with the support insulator of the transmission line on the steel tower, and the tip of the lower electrode is opposed to the horn metal fitting on the power supply side through a predetermined series gap. A lightning arrester for power transmission, characterized in that a capacitor comprising an electrode layer surrounding a reinforcing tube and overlappingly arranged in the longitudinal direction of the tube and a thin film insulating layer sandwiched between the electrode layers is formed in the insulating tube. 2. The lightning arrester for power transmission according to claim 1, wherein the edge portion of the electrode layer is rounded to eliminate the edge of the layer edge. 3. The power transmission lightning arrester according to claim 1, wherein the insulating layer and the main body of the insulating sleeve are made of ethylene propylene rubber, silicon rubber or crosslinked polyethylene.