WO2013186951A1 - Spark gap arrester - Google Patents

Abstract

[Problem] To provide a spark gap arrester having an enclosed structure in which: arc extinguishing performance is enhanced by generating sufficient arc extinguishing gas during the generation of electrical discharge and causing an arc resulting from lightning surge current to move in a reliable manner within an arc extinguishing plate; and in which melting and evaporation of the arc extinguishing plate that are caused by lightning surge current are reduced so as to increase the use life of the spark gap arrester. [Solution] An insulating discharge cap comprising a composite body of an insulating resin that generates arc extinguishing gas when heated and a conductive resin that generates arc extinguishing gas in a similar manner when heated are arranged between a pair of discharge electrodes. The discharge electrodes are arranged so as to face one another with an interval therebetween inside a cylindrical metal case, and form a circular truncated cone or round pillar shape. A plurality of arc-extinguishing metal plates are arranged with a predetermined interval therebetween on the outer surface of the insulating discharge cap, said arc-extinguishing metal plates being formed from a conductive sintered alloy configured by mixing and sintering one or more metals having a high melting point with one or more metals having a low melting point.

Description

Spark gap arrestor

The present invention relates to a spark gap arrester that is installed in a low-voltage power supply circuit and that bypasses lightning current to the ground and discharges it in order to protect electronic devices that are sensitive to overvoltage during lightning strikes.

As a spark gap arrester that can safely discharge lightning current by bypassing it to the ground, the one shown in Patent Document 1 is known.

FIG. 9 shows the configuration of the spark gap arrester disclosed in Patent Document 1.

In FIG. 9, 10 is a spark gap arrester, and all parts are arranged in a rotationally symmetric structure with respect to the central axis.

The pair of discharge electrodes 11 a and 11 b of the arrester 10 are opposed to each other while maintaining a certain discharge gap G by the cylindrical insulator 12. The size of the discharge gap G determines the discharge voltage. Lead conductors 17a and 17b are drawn out from the discharge electrodes 11a and 11b, and the arrester 10 is connected to an electric circuit to be protected through these lead conductors. When a high-voltage lightning impulse voltage induced in the electric circuit is applied to the arrester 10, the arrester 10 generates a discharge that starts from a spark discharge at the discharge gap G between the discharge electrodes 11a and 11b and shifts to an arc discharge. Absorbs lightning impulse voltage. The large-current arc discharge causes rapid ionization and expansion in the air in the internal space S of the arrester 10, but the cylindrical insulator 13, the insulating plates 14a and 14b, and the insulating caps 15a and 15b surrounding the discharge electrodes 11a and 11b. The outer side of the insulating case is covered with a metal pipe 16 and its upper and lower ends are firmly closed by curling, so that it does not explode or break even if the internal pressure exceeds several tens of atmospheres.

The lightning impulse current has a short duration of 1 ms or less, and the heat capacity of the metal parts is sufficiently large. Therefore, the discharge of this current does not cause an excessive temperature rise.

However, in such a conventional spark gap arrester 10, since the air passage in the internal space S is ionized after the extinction of the lightning impulse current, a current continuity is generated from the power supply circuit through the air passage. If this continuity is interrupted by an external circuit breaker, the power supply to the load circuit is interrupted, or the spark gap arrester 10 is interrupted from the power supply line, resulting in a disadvantage that the overvoltage protection function is lost. .

As a spark gap arrester for solving this problem, a spark gap arrester having a configuration shown in Patent Document 2 is already known.

FIG. 10 is a longitudinal sectional view showing the configuration of the spark gap arrester 20 disclosed in Patent Document 2. As shown in FIG. All the components are constructed and arranged in rotational symmetry.

The conventional spark gap arrester 20 in FIG. 10 has a pair of discharge electrodes 21a and 21b arranged in a cylindrical metal case 28 so as to face each other while maintaining a predetermined discharge gap G. Each discharge electrode is configured by joining tip portions 23a and 23b made of a copper tungsten alloy having excellent heat resistance and arc resistance to the tips of base portions 22a and 22b made of a copper material. The pair of discharge electrodes is fixedly supported in the metal case 28 via the insulator 24, the insulating plates 26a and 26b, and the insulating caps 27a and 27b. The size of the discharge gap G can be easily set by adjusting the thickness of the insulator 24 sandwiched between the discharge electrodes 21a and 21b. An insulating ring 25 made of an organic insulating material that generates an arc extinguishing gas by heating is fitted on the outer periphery of the insulator 24. Around the discharge electrodes 21a and 21b, a plurality of arc-extinguishing plates 29 (ai) made of magnetic metal rings are arranged so as to be insulated from each other at a predetermined interval.

In the internal space S of the spark gap arrester 20, the discharge generated between the discharge electrodes 21a and 21b is initially generated in the arc discharge path A extending between the tip portions 23a and 23b of both electrodes. When an arc discharge occurs in the arc discharge path A, arc-extinguishing gas is released from the insulating ring 25 made of an organic arc-extinguishing insulating material disposed between both electrodes due to the heat of the arc. Due to the pressure of this gas and the electromagnetic force between the magnetic arc extinguishing plate 29 and the arc current, the arc of the arc discharge path A is moved in the direction of the arc extinguishing plate 29 and the arc discharge path B spreads over the entire arc extinguishing plate 29. Move. Arc discharge and anode voltage drop occur on both sides of each arc extinguishing plate 29 in the arc discharge path B.

Since an anode voltage drop also occurs in the discharge electrodes at both ends of the arc discharge, when n arc extinguishing plates are used, the anode and cathode voltage drop in the arc discharge path B is (n + 1) × (U _A + U _K ) Thus, it acts as a counter electromotive force on the voltage applied between the discharge electrodes 21a and 21b. The continuity of the current flowing from the AC power supply circuit immediately before the lightning impulse current disappears forms an arc through the same path as the discharge path of the lightning impulse current, but the instantaneous value of the voltage of the AC power supply circuit is When the voltage is lower than the counter electromotive voltage, the continuity is interrupted and the arc discharge disappears.

Therefore, according to the conventional spark gap arrester 20, it is possible to cut off the continuity from the power supply circuit after the extinction of the lightning impulse current.

However, this conventional spark gap arrester 20 also has the following two drawbacks.
(1) Since the insulating ring 25 that generates the arc-extinguishing gas when the arc is generated is disposed inside the discharge electrode, the amount of arc-extinguishing gas generated is small. Accordingly, the force for moving the arc to the arc extinguishing plate becomes insufficient, and the arc extinguishing performance is deteriorated due to insufficient arc moving distance.
(2) When a magnetic material such as pure iron is used for the arc extinguishing plates 29a to 29i, the lightning impulse current is an extremely large current of 20 kA or more and a rising speed of 2 kA / μs or more, When the arc extinguishing plate is melted and evaporated by the arc current, the function of the arc extinguishing plate is lowered and the life of the arrester is shortened.

European Patent Application No. 0789434 International Publication No. 2005-074084

Accordingly, an object of the present invention is to improve arc extinguishing performance in a spark gap arrester having an encapsulated structure by sufficiently generating an arc extinguishing gas at the time of occurrence of a discharge and reliably moving an arc caused by a lightning impulse current into the arc extinguishing plate. Another object of the present invention is to provide a spark gap arrester that can prevent the continuity and reliably extend the life of the arc extinguishing plate due to lightning impulse current.

In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a resin insulator formed of an insulating resin that generates an arc-extinguishing gas by heating between the pair of discharge electrodes is similarly extinguished by heating. Arranging a resin interval body composed of a composite with a resin conductor formed of a conductive resin that generates arc gas, between one of the discharge electrodes and the resin conductor portion of the resin interval body, A layer of the resin insulator part of the resin interval forming the insulating discharge gap is interposed, and one or more high melting point metals and one or more low melting point metals are disposed outside the resin interval. A plurality of metal arc-extinguishing plates formed of a conductive sintered alloy formed by sintering are arranged separated by a predetermined distance.

The invention of claim 2 is characterized in that, in the invention of claim 1, the sintered alloy forming the metal arc extinguishing plate is characterized in that the low melting point metal is copper and the high melting point metal is tungsten.

According to a third aspect of the present invention, in the first or second aspect of the present invention, one end of the resin interval body made of a resin insulator and the other end made of a resin conductor are respectively connected to the pair of discharge electrodes. The depth of the recessed portion of the discharge electrode on the fitted side of one end, which is configured by the resin insulator of the resin interval body, and the resin of the resin interval body inserted into the recess The size of the discharge gap is defined by the difference with the thickness of the insulator on one end side made of an insulator.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, a plurality of spaces are formed by partitioning a space around the pair of discharge electrodes with a partition wall made of an insulating material. And the other one as an expansion chamber, and these chambers communicate with each other by a gas passage.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the resin conductive material constituting the resin spacing member is provided in the arc chamber provided in the space between the pair of discharge electrodes. A body part is accommodated, and the metal arc extinguishing plate is arranged opposite to the conductor part.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, an insulating cylinder configured by connecting and joining a plurality of divided insulating rings is inserted inside the cylindrical metal case, The plurality of metal arc extinguishing plates are fixed by being electrically insulated from the metal case while being spaced apart from each other by an insulating ring constituting the insulating cylinder.

The invention of claim 7 is the invention of any one of claims 1 to 6, wherein the tip is bent into a hook shape on the inner periphery of a part of the insulating ring inserted inside the metal case. An annular projection having an annular groove is provided.

The invention of claim 8 is characterized in that, in the invention of claim 6 or 7, at least one of the insulating rings constituting the insulating cylinder is provided with at least one air passage leading to the inner and outer periphery of the ring.

The invention according to claim 9 is the invention according to claim 8, wherein the air passage is provided at a joint portion of an insulating ring constituting the insulating cylinder.

The invention of claim 10 is characterized in that, in any one of the inventions of claims 1 to 9, the insulating resin that generates arc-extinguishing gas by heating is a composite resin containing an inorganic reinforcing material.

The invention of claim 11 is the invention according to any one of claims 1 to 10, wherein the insulating resin that generates an arc extinguishing gas by heating is a polyoxymethylene (POM) resin, and the arc extinguishing by the heating. The conductive resin that generates the reactive gas is a resin in which carbon powder is mixed with the polyoxymethylene (POM) resin.

According to the present invention, the following excellent effects can be obtained.
(1) Resin insulator formed with an insulating resin that generates arc-extinguishing gas by heating a resin spacer disposed between truncated cones or cylindrical discharge electrodes and conductive resin that generates arc-extinguishing gas by heating Since the discharge gap is formed on the surface of the insulator portion, the arc generated in the discharge gap can be propagated along the entire surface of the resin interval body. A large amount of arc extinguishing gas can be generated from the surface of the resin spacer by arc discharge. As a result, the arc traveling on the surface of the resin interval body can be reliably moved to the arc extinguishing plate side, and the arc can be divided to increase the arc voltage. Can be prevented.
(2) In a spark gap arrester enclosed in a cylindrical metal case, a metal arc extinguishing plate arranged in a space between a pair of conical frustums or a columnar discharge electrode is used as a low melting metal powder and a high melting metal. Composed of a sintered alloy formed by mixing and sintering powder, the arc extinguishing plate is reduced in wear even if the metal arc extinguishing plate is exposed to arc discharge by lightning impal current, and the life of the arrester is extended. be able to.

It is a figure which shows the fundamental structure of the spark gap arrester of this invention, (a) is a cross-sectional view which follows the aa line in (b), (b) is along the bb line in (a). FIG. Sectional drawing which shows typically the structure of the sintered alloy board which comprises the metal arc-extinguishing board used for this invention. The diagram which shows the voltage-current characteristic of the arc discharge used for operation | movement description of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the 1st Example of this invention, (a) is a longitudinal cross-sectional view, (b) is the elements on larger scale which expand and show the A section in (a). The cross-sectional view which follows the VV line of Fig.4 (a). It is a block diagram which shows the 2nd Example of this invention, (a) is a longitudinal cross-sectional view, (b) is the elements on larger scale which expand and show the A section in (a). The longitudinal cross-sectional view which shows the structure of the spark gap arrester of the 3rd Example of this invention. It is a block diagram of one insulating ring used for the spark gap arrester of 3rd Example of this invention, (a) is a top view, (b) Left side view, (c) is cc in (a). The longitudinal cross-sectional view which follows a line. The longitudinal cross-sectional view which shows the structure of the prior art example of a spark gap arrester. The longitudinal cross-sectional view which shows the structure of the other conventional example of a spark gap arrester.

First, the basic configuration of the spark gap arrester according to the present invention shown in FIG. 1 will be described.

In FIG. 1, reference numeral 30 denotes a spark gap arrester, which includes a pair of discharge electrodes 31a and 31b accommodated in a cylindrical insulating case 33 at a predetermined interval. The spacing between the electrodes 31a and 31b is maintained by a circular resin spacing member 32 inserted therebetween. The resin spacer 32 includes, for example, an arc extinguishing resin insulator 32a formed of a resin that generates an arc extinguishing gas at a high temperature, such as a polyoxymethylene resin called POM, and the polyoxymethylene. It is composed of a composite resin formed by integrally joining an arc extinguishing resin conductor 32b formed of a resin imparted with conductivity by adding conductive carbon powder to the resin. For this reason, as for the resin space | interval body 32, the half part 32a divided into 2 by the axial direction shows insulation, and the remaining half part 32b shows electroconductivity.

Since the polyoxymethylene resin does not lose the characteristic of generating a large amount of arc-extinguishing gas at a high temperature even when a conductive agent such as carbon is added and mixed, the arc-extinguishing resin conductor 32b is an arc-extinguishing resin. It has an arc extinguishing gas generation function exactly the same as that of the insulator 32a.

The resin spacing member 32 is formed in a columnar shape by joining the arc extinguishing resin insulator 32a and the arc extinguishing resin conductor 32b formed in a substantially semi-cylindrical shape to each other in a plane portion (FIG. 1). (See (a)). A thin semi-disc-shaped protrusion 32c protruding in the radial direction of the resin spacer 32 is formed in the middle of the arc-extinguishing resin insulator 32a, and the outer peripheral surface of the protrusion 32c is the arc-extinguishing resin conductor. It extends to the outer peripheral surface of 32b and is exposed in the arc chamber 36a (see FIG. 1B). The upper and lower surfaces of the projecting portion 32c are electrically coupled to the discharge electrodes 31a and 31b via the divided bodies 32b-1 and 32b-2 divided above and below the arc-extinguishing resin conductor 32b disposed on each surface, respectively. Is done. The thickness of the protrusion 32c forms a discharge gap G between the discharge electrodes 31a and 31b. For example, if the size of the discharge gap G is selected to be 0.3 mm, a lightning impulse of about 2 kV between the discharge electrodes 31a and 31b. When a voltage is applied, the insulation of the discharge gap G is broken and a flash (spark discharge) is generated.

The internal space of the cylindrical insulating case 33 enclosing the discharge electrodes 31a and 31b and the resin spacer 32 is a boundary portion between the insulator 32a and the conductor 32b of the resin spacer 32 and is similar to the resin spacer 32. Two spaces are formed which are partitioned by insulating partition walls 35a and 35b in the radial direction made of arc-extinguishing insulating resin. One of the two spaces is an arc chamber 36a and the other is an expansion chamber 36b. The insulating partition walls 35a and 35b are provided with air passages 35h and 35h, respectively, so that both chambers communicate with each other. Therefore, the expansion chamber 36b absorbs an excessive increase in internal pressure due to the arc in the arc chamber 36b, and the arc chamber 36a It works to suppress the pressure rise.

In the arc chamber 36a, the arc-extinguishing resin conductor 32b of the resin interval body 32 is accommodated, and the arc-extinguishing resin insulator 32a is accommodated in the expansion chamber 36b. In the arc chamber 36a, arc extinguishing plates 37 are arranged at predetermined intervals so as to face the outer peripheral surfaces of the arc extinguishing resin conductor 32b and the projecting portion 32c of the arc extinguishing resin insulator 32a. . The arc-extinguishing plate 37 is formed by laminating a plurality of conductive metal arc-extinguishing plates 37a to 37e having a shape obtained by partially cutting an annular flat plate at predetermined intervals in the axial direction. The metal arc extinguishing plates 37a to 37e are composed of conductive sintered alloy plates formed by sintering one or more types of low melting point metal powders and one or more types of high melting point metal powders, and are spaced apart from each other by a certain distance. And is held by the insulating case 33.

As the sintered alloy forming the arc extinguishing plate 37, for example, a sintered alloy containing 20% by weight of copper as a low melting point metal and 80% by weight of tungsten as a high melting point metal can be used.

Next, the operation of the spark gap arrester of the present invention configured as described above will be described.

The normal working voltage of the electrical circuit of the protected facility to which the arrester is connected is a low voltage of about 100 to 400V. The withstand voltage between the pair of discharge electrodes 31a and 31b is several kV due to the discharge gap G between the edge portions of the arc extinguishing resin conductor 32b facing each other across the protruding portion 32c of the insulator 32a of the resin spacer 32. Therefore, even if a normal operating voltage is applied between the pair of discharge electrodes 31a and 31b, the insulation of the discharge gap G is maintained and no discharge occurs.

A high-voltage lightning impulse voltage is induced in the electric circuit of the electric circuit by a lightning strike or the like, and the divided conductors 32b-1 facing each other with the protrusion 32c of the insulator 32a of the resin interval body 32 between the discharge electrodes 31a and 31b interposed therebetween. When a lightning impulse voltage higher than the withstand voltage of the discharge gap G is applied between the upper and lower edges of 32b-2, the insulation of the discharge gap G is broken and a flash (spark discharge) is generated. By this flashing, the gap between flashing points a and b at the opposing edges of the upper and lower divided conductors 32b-1 and 32b-2 via the outer peripheral surface of the protrusion 32c of the insulator 32a of the resin interval 32 is achieved. Since a large current is supplied to the discharge path A indicated by the dotted line, the arc discharge is developed. Furthermore, the arc inside the arc chamber 36b is ionized by this arc discharge, so that the arc expands to a discharge path B indicated by a dotted line extending between points c and d of the pair of discharge electrodes 31a and 31b. When the arc extinguishing resin conductor 32b is heated to a high temperature by the arc of the discharge path B, a large amount of arc extinguishing gas is generated from the surface, and a gas flow from the arc chamber toward the expansion chamber is formed. The arc of the discharge path B between the pair of discharge electrodes moves to the center of the metal arc extinguishing plates 37a to 37e by the gas pressure at that time, and the discharge path C indicated by the dotted line is formed.

Thus, the arc is divided by the plurality of metal arc extinguishing plates 37a to 37e, and the arc voltage rises due to a negative and anode voltage drop of about 30V generated between the arc extinguishing plates.

The arc voltage U _A, as shown in FIG. 1 (b), when the arc extinguishing plate 37 is provided five, to which the discharge electrodes 31a, since the cathode and anode voltage drop 31b is applied,
U _A = 30 (V) × (5 + 1) = 180 (V) (1)
It becomes. In this way, the arc voltage between the pair of discharge electrodes 31a and 31b rises, and after the lightning impulse current disappears, the internal air in the arc chamber 36b is ionized, so that the continuity flows from the power supply circuit. However, since the negative and anode voltage drop generated by the arc extinguishing plate 37 is maintained, when the instantaneous value of the power supply circuit voltage applied between the pair of discharge electrodes 31a and 31b is reduced to 180 V or less, the negative and anode voltage is reduced. Since the descent cannot be maintained, this can be reliably blocked.

In the metal arc-extinguishing plate 37, contact with the arc of the lightning impulse current causes an anode voltage drop of about 30 V in a thin region of micron order at the contact portion, and this voltage and an impulse current reaching 20 kA Loss heat is determined by the product of The surface of the arc extinguishing plate 37 is melted by this heat loss. In the case of a conventional magnetic metal arc extinguishing plate made of pure iron or the like, the molten metal is instantaneously scattered by a high arc pressure, and the consumed amount of the arc extinguishing plate increases, so that the molten part further reaches the deep part. Therefore, a through-hole may be formed in the arc extinguishing plate and the continuity blocking function may be lost.

In the present invention, the metal arc extinguishing plate 37 is formed by sintering a low melting point metal that melts at a relatively low temperature, such as copper powder, and a high melting point metal that does not melt up to a high temperature, such as tungsten powder. Since it is made of a sintered alloy, the amount of melting and evaporation due to lightning impulse current is extremely small, and wear of the arc extinguishing plate can be reduced.

This reason will be described with reference to FIG.

FIG. 2 is a metal structure diagram schematically showing a longitudinal section of an arc extinguishing plate made of a sintered alloy of a low melting point metal and a high melting point metal. As shown in this figure, the metal structure of the arc extinguishing plate has a structure in which a large number of tungsten particles W of high melting point metal are bonded to each other by high-temperature firing, and the void portion is filled with copper particles Cu of low melting point metal. It has become.

When an arc of lightning impulse current comes into contact with such an arc extinguishing plate, a few low melting point metal copper particles Cu exposed on the surface immediately melt and scatter, but a framework structure composed of high melting point metal tungsten particles W. The copper inside the metal stays inside the arc extinguishing plate without scattering even if it melts, absorbs the heat lost by the arc by the heat of fusion and acts to transmit it to the surroundings, so the arc extinguishing plate is cooled, The temperature rise of the arc extinguishing plate can be suppressed. For this reason, the disappearance due to melting and evaporation of the copper particles Cu of the low melting point metal is reduced, and the melting point of the tungsten particles W is much higher than the melting point of the copper powder, so that the framework structure is firmly maintained without melting. The

Therefore, the arc extinguishing plate of the present invention composed of a sintered alloy composed of a metal having a relatively high melting point and a metal having a relatively low melting point has a very small wear even when it comes into contact with the arc, thus extending the life of the arrester. Can keep.

Specific examples of the spark gap arrester according to the present invention are shown in FIGS. This will be described below.

Next, specific embodiments of the present invention will be described with reference to examples shown in the drawings.

FIG. 4 and FIG. 5 show a first embodiment of the present invention. 4 is a longitudinal sectional view showing the configuration of the spark gap arrester 40 of the first embodiment, and FIG. 5 is a transverse sectional view taken along the line VV of FIG.

Also in the first embodiment, most of the constituent elements are configured and arranged in rotational symmetry with respect to the axis. However, only the arc extinguishing plate 47 has a shape obtained by cutting a part of an annular flat plate at a predetermined arc angle as shown in a plan view in FIG. 5, and does not have a rotationally symmetric configuration.

As shown in FIG. 4, the pair of discharge electrodes 41a and 41b includes base portions 41a-2 and 41b-2 made of a copper material which is a normal conductor, and heat resistance bonded to the tips of the base portions. The tip portions 41a-1 and 41b-1 are made of a chip made of a copper tungsten alloy having excellent arc resistance. The base portions 41a-2 and 41b-2 and the tip portions 41a-1 and 41b-1 are integrated without performing troublesome processing such as brazing by inserting the base portion into a recess provided in the tip portion. ing.

The tip portions 41a-1 and 41b-1 of the discharge electrodes 41a and 41b are formed in a truncated cone shape in the first embodiment, but may be formed in a columnar shape instead. The pair of discharge electrodes 41a and 41b have a constant facing distance by a resin interval body 42 formed by integrally joining an arc extinguishing resin insulator 42a and an arc extinguishing resin conductor 42b sandwiched therebetween. Retained. The discharge electrodes 41a and 41b are formed of insulating caps 43a and 43b and an insulating plate having elasticity in an insulating case formed by connecting and connecting insulating rings 44a to 44f divided into a plurality of parts. 44j and 44k. The insulating case constituted by the insulating cylinder 44 and the like is fitted by a metal case 45 made of a metal pipe from the outside. The metal case 45 is strong by bending the upper and lower ends inward by curling and applying clamping pressure in the axial direction to the flange portions 41a-3 and 41b-3 of the discharge electrode base portions 41a-2 and 41b-2. A pressure-resistant structure is configured.

Between the tip portions 41a-1 and 41b-1 of the pair of discharge electrodes, a plurality of, here, three arc extinguishing plates 47a to 47c are stacked and arranged with a space between each other. These arc-extinguishing plates 47a to 47c are fixedly supported by being fitted into annular grooves 44g to 44i formed at portions where the insulating rings 44b to 44d constituting the insulating cylinder 44 are connected to each other. These arc extinguishing plates 47 (a to c) are formed of a sintered alloy containing at least one kind of low melting point metal such as copper and one or more high melting point metals such as tungsten, as described above.

The resin interval body 42 is formed by an arc extinguishing resin insulator 42a and exposed at the upper end portion and almost half of the outer periphery. And the lower end part and the remaining half part of the outer periphery are formed of the arc extinguishing resin conductor 42b and exposed. The upper end portion of the resin spacer 42 is fitted and coupled to the tip portion 41a-1 of the upper discharge electrode 41a, and the lower end portion is fitted and coupled to the tip portion 41b-1 of the lower discharge electrode 41b. The upper end portion of the resin insulator 42a of the resin interval member 42 joined to the tip end portion 41a-1 of the upper discharge electrode 41a is exposed at the entire periphery, and is exposed to the outer peripheral surface side where the resin conductor 42b of the resin interval member 42 is exposed. The thickness g of the portion to be determined determines the insulating discharge gap G between the tip portion 41a-1 of the upper discharge electrode 41a and the resin conductor 42b of the resin spacer 42.

FIG. 4B shows an enlarged view of the portion A in FIG. 4A including the discharge gap G.

As shown in FIG. 4B, the arc-extinguishing resin insulator 42a of the resin interval body 42 in the portion fitted in the recess 41a-6 provided on the end face of the tip end portion 41a-1 of the discharge electrode 41a. The thickness g of the portion exposed to the resin conductor is determined by the difference between the thickness t and the depth d of the recess 41a-6. Since the thickness g automatically determines the dimension of the insulating discharge gap G between the electrodes, it is only necessary to determine the dimensions of the resin spacer 42 and the discharge electrode tip 41a-1 for assembly. No position adjustment is required. When drawing out the lead conductor from the discharge electrode bases 41a-2 and 41b-2 to the outside, screw the lead conductor (not shown) into the screw holes 41a-4 and 41b-4 for connecting the lead conductor provided in the external lead portion. Can be pulled out by.

As shown in FIG. 5, the space around the resin interval body 42 in the insulating cylinder 44 is a pair of radii that protrudes inwardly facing the inner periphery of the divided insulating rings 44a to 44f constituting the insulating cylinder 44. Divided into two spaces by direction partition walls 44p, 44q. The space that accommodates the arc extinguishing resin conductor 42b and the arc extinguishing plates 47 (47a to 47c) of the resin interval member 42 is an arc chamber 46a, and the space that accommodates the other resin insulator 42a is the expansion chamber 46b. And Grooves 44r and 44s extending in the upper and lower axial directions are formed in the partition walls 44p and 44q, and the projecting ridges 42c projecting outwardly facing the outer periphery of the resin insulator 42a of the resin spacer 42 in the grooves. By fitting 42d, the internal space in the insulating cylinder 44 is completely partitioned into two spaces.

As shown in FIG. 4, the arc chamber 46a and the expansion chamber 46b are formed by voids 46c and 46d formed between the discharge electrode tip portions 41a-1 and 41b-1 and the base portions 41a-2 and 41b-2. It is communicated. When the internal pressure of the arc chamber 46a suddenly increases due to the arc generated in the arc chamber 46a, the pressure in the arc chamber 46a is increased by letting the pressure escape to the expansion chamber 46b through these cavities 46c and 46d. To prevent destruction due to increased pressure in the arrester. The arc moves to the central part of the arc extinguishing plates 47a, 47b, 47c by the arc extinguishing gas flow generated at this time.

Next, the operation of the spark gap arrester 40 thus configured will be described.

A pair of discharge electrodes 41a and 41b of the arrester 40 are electrically connected between the electric circuit of the electric circuit to be protected from lightning voltage and the ground.

It is formed between the end edge of one discharge electrode tip 41a-1 of this arrester 40 and the end edge of the conductor 42b of the resin spacing member 42 opposite to the insulator 42a of the resin spacing member 42. Further, the withstand voltage of the insulation discharge gap G (see FIG. 4B) is set to a voltage sufficiently higher than a normal use voltage of, for example, about 100 to 400 V, for example, 1.5 kV. When used with voltage, the insulation of the discharge gap G is maintained and no discharge occurs.

However, when a lightning impulse voltage is induced in the electric circuit of the electric circuit and a lightning impulse voltage of several kV or more, which is higher than the withstand voltage of the discharge gap G, is applied through the discharge electrodes 41a and 41b, the insulation of the discharge gap G is broken. As a result, a flashover (spark discharge) occurs, and the edge of the upper discharge electrode tip 41a-1 and the resin conductor 42b of the resin spacer 42 pass through the surface of the upper end 42c of the insulator 42a of the resin spacer 42. Since a large current is supplied between the flash points a and b at the upper edge of the flash, the flash (spark discharge) develops into an arc discharge. Further, the internal air of the arc chamber 46a is ionized by this arc discharge, so that the arc extends between points a and c of the pair of discharge electrodes 41a and 41b, and the arc extinguishing resin conductor of the resin interval 42 is obtained. Run on the exposed surface of 42b. As a result, the surface of the arc extinguishing resin conductor 42b of the resin interval 42 is heated to a high temperature, and a large amount of arc extinguishing gas is generated from the surface of the resin conductor 42b. The arc that is pushed by the pressure of the arc extinguishing gas and runs on the surface of the resin conductor 42b moves to the center of the arc extinguishing plates 47a to 47c.

Thus, when arc discharge is generated in the arrester 40 by the lightning impulse voltage, the lightning voltage is released to the ground via the arrester 40, and the electric circuit can be protected from the lightning voltage.

When the arc in the arrester 40 moves to the three conductive metal arc-extinguishing plates 47a to 47e, this is divided by the arc-extinguishing plates. An anode voltage drop occurs.

A pair of discharge electrodes 41a, overall shade occurring between 41b, the anode voltage drop U _A is three shade of extinguishing plate, the shadow of the discharge electrode of one pair of the anode voltage drop, since the anode voltage drop is applied,
U _A = 30 (V) × (3 + 1) = 120 (V) (2)
It becomes.

The arc voltage of the arc path without the arc extinguishing plate changes depending on the arc current as shown by the characteristic line B in FIG. 3 due to the large arc resistance of the long discharge path. As shown by the characteristic line A in FIG. 3, the arc voltage becomes substantially constant 120 V, as shown by the characteristic line A, due to the shadow generated in the arc extinguishing plate, the anode voltage drop, and the small arc resistance of the short arc discharge path. For this reason, even if the lightning impulse current exceeds the peak value and enters the decay process, the arc voltage is kept substantially constant, so the lightning impulse current becomes substantially zero, and the instantaneous value of the power supply voltage becomes smaller than the arc voltage. When this occurs, the continuity from the power circuit is interrupted, the arc disappears, and the arrester insulation is restored.

When an arc discharge is generated in the arrester 40, the metal of the discharge electrode and the arc extinguishing plate is evaporated and scattered by the heat of the arc, and the metal oxide adheres to the inner surface of the insulating cylinder 44, whereby a pair of discharge electrodes An electrical bypass circuit is formed between them, and the insulation resistance between the discharge electrodes decreases.

In the first embodiment, in order to prevent such a decrease in the insulation resistance, an annular shape in which tip portions are bent inwardly on the inner periphery of the insulating rings 44a and 44f at both ends forming the insulating cylinder 44. By providing the protrusions, the annular grooves 44m and 44n are formed in which the metal oxide evaporated and scattered from the electrode or the like does not enter. In the annular grooves 44m and 44n, the metal oxide melted and evaporated from the discharge electrode and the metal arc extinguishing plate by the arc is reduced, so that the metal oxide layer adhering to the inner surface of the insulating cylinder 44 is here. As a result, the decrease in insulation resistance between the pair of discharge electrodes can be prevented for a long period of time.

Further, since the insulating rings 44a to 44f constituting the outer walls of the arc chamber 46a and the expansion chamber 46b are formed of an insulating resin, there is a possibility that they are damaged by a large internal pressure applied when the arc is generated. In order to prevent this, it is preferable to increase the mechanical strength by adding an inorganic reinforcing material such as glass fiber to the insulating resin.

Further, the metal arc extinguishing plate 47 of Example 1 is also obtained by sintering a low melting point metal that melts at a relatively low temperature, for example, copper powder and a high melting point metal that does not melt to a high temperature, for example, tungsten powder. Since it is composed of the formed sintered alloy, the synergistic function of the low melting point metal and the high melting point metal, as in the embodiment of FIG. Since the wear of the plate can be reduced, the life of the arrester can be extended.

Furthermore, since a second specific embodiment of the present invention is shown in FIG. 6, this will be described.

In the second embodiment, the structure of the upper end portion of the resin insulator 42a and the upper electrode tip portion 41a-1 of the resin spacing member 42 that maintains the distance between the pair of discharge electrodes 41a and 41b in the first embodiment is improved. Is.

In the first embodiment, the thickness g of the exposed portion of the resin insulator in the gap forming the discharge gap G is set to the depth d of the fitting recess 41a-6 provided in the upper electrode tip 41a-1. The resin insulator 42a to be fitted in is determined based on the difference from the thickness t of the fitting portion at the upper end portion. On the other hand, in the second embodiment, the thickness of the exposed portion of the resin insulator 42a between the upper electrode tip portion 41a-1 and the upper end of the exposed portion of the resin conductor 42b of the resin interval body 42. The size of the insulating discharge gap G is uniquely determined by g.

Therefore, in the second embodiment, as shown in FIG. 6A, the protrusion 42a-1 of the resin insulator 42a of the resin spacer 42 is formed in the fitting hole 41a-7 of the upper electrode tip portion 41a-1. The resin spacer 42 is coupled to the upper electrode tip 41a-1 by fitting, but in the first embodiment, the recess 41a-6 of the upper electrode tip 41a-1 for determining the size of the insulation gap G is used. In addition, no fitting convex portion of the resin insulator 42a is provided in the concave portion.

Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

According to the second embodiment, the thickness of the exposed portion of the outer peripheral surface between the upper electrode tip portion 41a-1 of the resin insulator 42a of the resin spacer 42 and the upper end of the resin conductor 42b of the resin spacer 42. Since the insulated discharge gap G can be defined simply by forming g in a dimension corresponding to the desired withstand voltage, the insulation gap G can be easily defined.

7 and 8 show a third embodiment of the present invention.

In the spark gap arrester of the first embodiment, the mechanical strength of the insulating rings 44a to 44f formed of an insulating resin constituting the outer walls of the arc chamber 46a and the expansion chamber 46b is increased, and a large internal pressure rise when an arc is generated. In contrast to this, in this third embodiment, the vent ring is provided in the outer wall of the insulating ring to balance the pressure inside and outside the insulating ring. Is preventing.

As shown in FIG. 7, the spark gap arrester according to the third embodiment includes two insulating rings 44a to 44f made of insulating resin divided into a plurality of parts constituting an insulating cylinder 44 housed in a cylindrical metal case 45. The only difference is the configuration of the first embodiment except that one air passage 44b-1 and 44e-1 are provided in the rings 44b and 44e, respectively. To do.

Only one insulating ring 44b of the insulating cylinder 44 provided with the air passage is taken out and shown in FIG.

Inside the insulating ring 44b, a pair of partition walls 44p and 44q are formed to protrude so as to face each other. A resin interval body 42 virtually indicated by a one-dot chain line is accommodated in the insulating cylinder 44 and is fitted and coupled to the partition walls 44p and 44q so that the internal space of the insulating cylinder 44 is partitioned into an arc chamber 46a and an expansion chamber 46b. . In the arc chamber 46a, an arc extinguishing plate 47 that is virtually indicated by a one-dot chain line is installed. The ventilation path 44b-1 is provided in the outer insulating ring 44b of the expansion chamber. One or two or more ventilation paths may be provided as communication holes that communicate with the inside and outside of the peripheral wall of the insulating ring.

Similarly, the air passage 44e-1 provided in the insulating ring 44e is also provided on the surface to be joined to the other insulating ring 44d of the insulating ring 44e.

FIG. 7 shows an example in which two insulating rings provided with an air passage are provided, but only one insulating ring provided with an air passage may be provided, or two or more may be provided.

When an arc discharge is generated between the discharge electrodes 41a and 41b in the spark gap arrester to absorb the lightning impulse voltage, first, the internal pressure of the arc chamber 46a in the insulating cylinder 44 rises. Since the internal pressure of the expansion chamber 46b communicating therewith also increases, a large stress is applied from the inside to the insulating rings 44a to 44f constituting the inside of the insulating cylinder 44, and the insulating ring may be damaged by this stress.

In the first embodiment, the mechanical strength of the insulating ring constituting the insulating cylinder is increased to prevent the insulating ring from being damaged due to an increase in internal pressure accompanying the occurrence of arc discharge. However, since the insulation ring is made of resin, there is a limit to increasing the mechanical strength of the insulation ring. This method completely prevents damage to the insulation ring due to internal pressure rise due to arc discharge. Difficult to do.

On the other hand, in the spark gap arrester of Example 3, as described above, a part of the insulating cylinder 44 accommodated in the metal case 45 is provided with a ventilation path leading to the inner and outer periphery of the insulating cylinder 44. When an arc discharge occurs in the spark gap arrester and the internal pressure of the arc chamber 46a and the expansion chamber 46b in the insulating cylinder 44 rises, a part of the high-pressure gas is passed through the ventilation paths 44b-1, 44b-2, 44e-. 1 and 44e-2 are led to a gap between the insulating cylinder 44 outside the insulating cylinder 44 and the metal case 45, and escaped here.

As a result, the pressure inside and outside the insulating cylinder 44 becomes equal. Therefore, even if the internal pressure inside the insulating cylinder 44 rises due to arc discharge generated inside the spark gap arrester, the tensile force applied to each insulating ring constituting the insulating cylinder 44 There is no increase in force, only compression force is applied. Therefore, even if the mechanical strength of the insulating ring is not increased, it is possible to completely prevent the insulating ring from being damaged due to an increase in internal pressure accompanying the occurrence of arc discharge.

In addition, since a part of the internal pressure of the insulating cylinder is released in the gap between the insulating cylinder 44 and the metal case 45, the internal pressure of the metal case 45 is greatly increased. Stress is applied. However, since the tensile strength of the metal material is extremely higher than that of the resin material, the metal material is not damaged by the internal pressure increase accompanying the occurrence of arc discharge.

Therefore, according to the spark gap arrester of Example 3, since the insulating ring can be formed of an insulating resin having low mechanical strength, the spark gap arrester can be manufactured at low cost and can be used safely for a long time. it can.

40: Spark gap arrester, 41a, 41b: Discharge electrode, 42: Resin spacer, 42a: Resin insulator, 42b: Resin conductor, 43a, 43b: Insulation cap, 44 (44a to 44f): Insulating cylinder (split insulation) Ring), 44b-1, 44e-1, 45: metal case, 46a: arc chamber, 46b: expansion chamber, 47 (47a to 47c): metal arc extinguishing plate.

Claims (11)

1. In a spark gap arrester provided with a pair of discharge electrodes in the shape of a truncated cone or a column arranged opposite to each other inside a cylindrical metal case,
   Between the pair of discharge electrodes, a resin insulator formed of an insulating resin that generates an arc-extinguishing gas when heated, and a resin conductor formed of a conductive resin that similarly generates an arc-extinguishing gas when heated The resin insulator portion of the resin interval body is arranged such that an insulating discharge gap is formed between one of the discharge electrodes and the resin conductor portion of the resin interval body. And a plurality of conductive sintered alloys formed by sintering one or more high melting point metals and one or more low melting point metals on the outside of the resin interval. A spark gap arrester characterized in that the metal arc extinguishing plates are separated from each other by a predetermined distance.
2. The spark gap arrester according to claim 1, wherein the sintered alloy forming the metal arc extinguishing plate has a low melting point metal of copper and a high melting point metal of tungsten.
3. One end made of a resin insulator of the resin interval body and the other end made of a resin conductor are fitted into the recesses of the opposite end surfaces of the pair of discharge electrodes, respectively, and the resin insulation of the resin interval body Due to the difference between the depth of the recessed portion of the discharge electrode on the fitting side of the one end constituted by the body and the thickness of the insulating member on the one end side constituted by the resin insulator of the resin spacer inserted in the recessed portion The spark gap arrester according to claim 1 or 2, characterized in that a dimension of the discharge gap is defined.
4. A space around the pair of discharge electrodes is partitioned by a partition wall made of an insulating material to form a plurality of spaces, one of which is an arc chamber and the other is an expansion chamber. The spark gap arrester according to claim 1, wherein the spark gap arrester is in communication with each other.
5. A resin conductor portion constituting the resin interval member is accommodated in the arc chamber provided in a space between the pair of discharge electrodes, and the metal arc extinguishing plate is disposed to face the conductor portion. The spark gap arrester according to claim 4.
6. An insulating cylinder constituted by connecting and joining a plurality of divided insulating rings is inserted inside the cylindrical metal case, and the plurality of metal arc-extinguishing plates are mutually connected by an insulating ring constituting the insulating cylinder. 6. The spark gap arrester according to claim 1, wherein the spark gap arrester is fixed and electrically insulated from the metal case.
7. 7. An annular protrusion having an annular groove formed by bending the tip into a hook shape on the inner periphery of a part of the insulating ring inserted inside the metal case. The spark gap arrester according to one.
8. The spark gap arrester according to claim 6 or 7, wherein at least one air passage leading to the inner and outer peripheries of the ring is provided in at least one of the insulating rings constituting the insulating cylinder.
9. The spark gap arrester according to claim 8, wherein the air passage is provided at a joint portion of an insulating ring constituting the insulating cylinder.
10. 10. The spark gap arrester according to claim 1, wherein the insulating resin that generates an arc extinguishing gas by heating is a composite resin containing an inorganic reinforcing material.
11. The insulating resin that generates arc-extinguishing gas by heating is polyoxymethylene (POM) resin, and the conductive resin that generates arc-extinguishing gas by heating is carbon powder in the polyoxymethylene (POM) resin. 10. The spark gap arrester according to claim 1, wherein the spark gap arrester is a mixed resin.

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