JPH0666167B2 - Lightning arrester - Google Patents

Description

The present invention relates to a lightning arrester, and more particularly to the structure of a cap fitting of the lightning arrester.

(Problems to be Solved by Prior Art and Invention) As a conventionally known lightning arrester, for example, as shown in FIG. 8, a porcelain bushing 2 and a lower cap fitting 3 attached to a lower end portion thereof are provided. A lower lid 4 is provided between them, and an upper lid 6 is also provided between the porcelain bushing 2 and the cap fitting 5 attached to the upper end portion thereof, and zinc oxide or the like is provided between the two lids 4 and 6. There is a structure in which a non-linear resistance element 7 as a main component and a spacer 8 are stacked.

In the lightning arrester 1 having this structure, when a lightning surge having a rated value or more enters the line and the lightning arrester 1 cannot interrupt the follow-up current, high temperature and high pressure gas are generated in the porcelain bushing 2 and the internal pressure rises. Then, the upper and lower lids 6 and 4 are broken to release the pressure in the porcelain tube 2, and a high-temperature jet plasmatized through the pressure releasing hole 3h of the lower cap fitting 3 and the pressure releasing hole 5h of the upper cap fitting 5 causes the high temperature jet Blowing outside, lower cap fitting 3
An arc path is formed between the discharge end (hereinafter, referred to as the lower discharge end) 3a of the above and the discharge end (hereinafter, referred to as the upper discharge end) 5a of the upper cap fitting 5.

However, in the lightning arrester 1 having the above-mentioned structure, since the arc discharge to the outside is not regulated, it is difficult to form a proper arc path, and there is a problem that the porcelain tube breakage easily occurs.

Structure of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention provides cap fittings attached to both ends of a porcelain tube with arc jet pressure release ports vertically facing each other. At least one of the pressure release ports,
A structure is adopted in which a conductor that is expandable and contractible and provided with a pressure receiving portion at the tip is housed in a contracted state, and the base end portion of the conductor is attached to the cap fitting.

(Operation) Since the present invention employs the above configuration, when a high-temperature jet of plasma is blown out from the pressure release port, the shock wave is received by the pressure receiving portion, and the elastic conductor expands and expands vertically. The distance between the tips of the conductors, or the flashover distance between the tips of the conductors that also have elasticity and the cap fitting to which the conductors are not fixed, is reduced, and this portion becomes a plasma atmosphere. Together, the arc firing voltage value between the upper and lower discharge ends becomes lower than the arc firing voltage value inside the lightning arrester. Therefore, when irreversible follow-up discharge occurs inside the lightning arrester and an arc is formed, the arc easily moves between the discharge ends of the upper and lower cap fittings.

(First Embodiment) Next, a first embodiment in which the present invention is embodied in a lightning arrester vertically attached to a erection device will be described with reference to FIGS.

As shown in FIG. 2, a lightning arrester 1 is supported and fixed to an arm 9 of a erection device (not shown) by a support metal fitting 10 at its insulator tube 2. The porcelain bushing 2 is formed in a cylindrical shape by a lightweight pressure-resistant insulating material such as reinforced resin, and annular projections 2b and 2a are formed on the outer peripheral sides of the upper and lower ends thereof, and the inner peripheral surface of the porcelain bushing 2 is formed. Is a barrier 1 from heat resistant insulation
1 is formed.

An inverted umbrella-shaped lower lid 4 made of an elastic material such as stainless steel is applied to the lower end of the porcelain tube 2 via an O-ring 12, and the lower cap fitting 3 is provided so as to support the lower lid 4 from below. It is fixed to the annular protrusion 2a.

As shown in FIGS. 3 and 6, on the outer peripheral side of the lower cap fitting 3, there is formed a projecting piece 3b having a substantially tongue-shaped plane at a position that divides the circumference into three equal parts.

As shown in FIGS. 1 to 5, a lower discharge end 3a is formed between a pair of adjacent projecting pieces 3b, and a base end portion of the discharge piece 5h has a concave shape to form an arc jet to the outside. It is supposed to lead to. The tip of the lower discharge end 3a has a wall thickness of 10
The arc jet, which is in the form of a mm plate and is inclined upward, is deflected upwardly from the pressure release port 3h in the direction of arrow X.

A planar hook-shaped groove U is formed on the two inner walls W of the pressure release port 3h that face each other, and a single support shaft 35 is provided horizontally between the two grooves U. The support shaft 35 has a thickness of 50 as the elastic conductor 23.
A metal foil 23a having a width of 20 mm and a length of 40 cm can be fixed at its base end.

The metal foil 23a is wound in a spiral shape by a polyethylene resin core member 36 from the tip side thereof. Therefore, in the state where the base end portion of the metal foil 23a is fixed to the support shaft 35, the front end portion side of the metal foil 23a is spirally wound to form the pressure receiving portion 34a, and inside the pressure release port 3h. It is stored in. When the pressure inside the porcelain insulator 2 is released and the arc jet is blown out from the pressure release port 3h, the pressure receiving portion 34a is blown back by receiving the blowing pressure of the arc jet, and the metal foil 23a is extended. .

Two adjacent protruding pieces 3 in the lower cap fitting 3
Recesses 3x are provided in the portion between b where the lower discharge end 3a is not provided, and by engaging engaging projections (not shown) of the porcelain bushing 2 with these recesses 3x, The lower cap fitting 3 does not rotate relative to each other.

As shown in FIG. 2, the lower cap fitting 3 is attached to the porcelain bushing 2 by holding the annular projection 2a between the projecting piece 3b and the compression plate 13 and tightening them with bolts 14 and nuts 15. ing.

A tongue-shaped lead wire mounting portion 3y is projectingly formed on one of the projecting pieces 3b of the lower cap fitting 3, and a ground side lead wire 16 is fixed to the lead wire mounting portion 3y by a bolt 17 and a nut 18. There is.

A coil spring 19 is provided on the lower lid 4, and a molecular sieve 20 for keeping the inside of the porcelain tube 2 from getting wet is placed inside the coil spring 19. A lower electrode 21 having a substantially T-shaped side surface is fixed to the upper end of the coil spring 19 at its leg portion.

A disk-shaped space plate 22 is formed on the lower electrode 21.
The rod-shaped non-linear resistance elements 7 containing zinc oxide as a main component are stacked via the spacers, and the spacers 8 and the non-linear resistance elements 7 are alternately stacked on top of them. An inverted dish-shaped upper electrode 25 is provided on the uppermost nonlinear resistance element 7 via a space plate 24.

An upper cap metal member 5 made of Al is capped and fixed to the upper end of the porcelain tube 2, and the opening of the porcelain tube 2 is sealed with an umbrella-shaped upper lid 6 made of an elastic material such as stainless steel via an O-ring 26. At the same time, the coil spring 19 is compressed to ensure the contact between the non-linear resistance element 7 and the spacer 8. The space S in the porcelain tube 2 is kept airtight while being filled with an inert gas or the like.

Like the lower cap member 3, the upper cap member 5 has an upper discharge end 5a and a recess 5x for preventing relative rotation with the porcelain tube 2.
A pressure release port 5h for guiding the arc jet to the outside is formed at the upper discharge end 5a, and an inner wall W of the pressure release port 5h is formed in the same manner as the pressure release port 3h of the lower discharge end 3a. The support shaft 35 is horizontally mounted. And
A base end portion of a metal foil 23a as a stretchable conductor 23 is attached to the support shaft 35, and is normally housed in the pressure release port 5h in a state where the tip end side thereof is wound in a spiral shape. At the time of releasing the pressure of the porcelain tube 2, the metal foil 23a is rewound and stretched in the same manner as described above.

The upper cap fitting 5 is fixed to the porcelain bushing 2 by sandwiching the annular projection 2b between the compression plate 27 and the protruding piece 5b of the upper cap fitting 5 and tightening them with bolts 28 and nuts 29. ing.

A lead wire mounting portion 5y is also formed on the upper cap metal fitting 5, and the lead wire mounting portion 5y is fixed with a lead wire 30 on the power supply side by bolts 31 and nuts 32. The power supply side lead wire 30 is electrically connected to the line of the erection device.

A cover 33 is provided on the upper cap fitting 5,
The lightning arrester 1 is protected from rainwater or bird damage.

Next, the operation and effect of this embodiment will be described. When lightning strikes a line (not shown), a lightning surge voltage is applied to the erection device. Then, in the lightning arrester 1 provided in the erection device, a lightning surge current flows through the lead wire 30 on the power-supply side-the upper cap metal fitting 5-the upper lid 6-the upper electrode 25-the space plate 24. Since the non-linear resistance element 7 has a voltage-current characteristic that the resistance value is small under the application of a current, the lightning surge current is non-linear resistance element 7-spacer 8-space plate 22-
It flows to the lower electrode 21, the coil spring 19 and the lower cap fitting 3, and is grounded from the erection device via the ground side lead wire 16.

However, when the non-linear resistance element 7 or the like is deteriorated due to an abnormal voltage exceeding the duty and gas is generated inside the porcelain insulator 2, the interior of the porcelain insulator 2 is rapidly pressurized, and the upper and lower lids 6 and 4 are set at 2 in FIG. As shown by the dotted line, the warp is released and the pressure is released. Then, the arc jet is discharged from the pressure release holes 5h and 3h as shown by an arrow X.

However, since the metal foil 23a is housed in the pressure release ports 5h and 3h in a contracted state, that is, in the state in which the pressure receiving portion 34a is formed, the pressure receiving portion 34a receives the shock wave of the arc jet. The metal foil 23a is stretched.

Since the metal foil 23a is a conductor, it exerts a function of substantially extending each of the upper discharge end 5a and the lower discharge end 3a, that is, lowering the insulation resistance to lighten the arc path formed inside the porcelain tube 2. The upper and lower discharge ends 5a and 3a are extremely short within 6 cycles after the surge current flows.
Move in between. Therefore, the porcelain insulator 2 is not heated and broken by the internal arc. The metal foil 23a is melted and evaporated by the arc jet blown from the pressure release ports 5h and 3h during pressure release.

Second Example Next, a second example in which the present invention is embodied by using a stretchable conductor as another mode will be described.

As shown in FIG. 7, the upper discharge end 5 of the upper cap fitting 5 is
In a, a support shaft 35 is attached to the pressure release port 5h, and a proximal end of a metal wire 23b spirally wound as a conductor 23 having elasticity is fixed to the support shaft 35.

A hemispherical pressure receiving portion 34 is suspended at the tip of the metal wire 23b with its flat surface facing upward. Usually, the metal wire 23b is accommodated in the pressure release port 5h without extending, and expands due to the shock wave when the pressure receiving portion 34 receives an arc jet, and the insulation resistance between the upper discharge end 5a and the lower discharge end 3a. Will be lower. Therefore, the arc path formed inside the porcelain tube 2 moves between the two discharge ends 5a and 3a. Most of the metal wire 23b that has received the arc jet at the time of pressure release melts and evaporates, and the part that has not melted releases the pressure, and then the pressure release port 5 is released by the slight elasticity of the metal wire 23b.
Even if the lightning surge voltage is applied again to the lightning arrester 1, the lightning surge current flows to the non-linear resistance element 7 side.

The metal wire 23b similar to the above is also housed in the discharge port 3h of the lower discharge end 3a, and the other structure is substantially the same as that of the first embodiment.

Also in this embodiment, the same operation and effect as those of the first embodiment are exhibited.

The present invention is not limited to the above embodiments, but can be embodied by being modified into the following modes, for example.

(1) The conductor 23 may be attached only to the pressure discharge ports 5h and 3h of either the upper discharge end 5a or the lower discharge end 3a to reduce the insulation resistance.

(2) The conductor 23 may be attached to the pressure release ports 5h and 3h by any means, for example, the base end portion may be directly attached by bolts and nuts without using the support shaft 35. You can When the support shaft 35 is used, it can be fixed by any means.

(3) The shape, expansion and contraction characteristics, etc. of the conductor 23 can be variously modified within the scope of not significantly impairing the effect, while following the technical idea of the present invention. For example, the metal foil 23a can be formed in a flat tubular shape.

Further, if the conductor 23 has a structure which is expanded by the arc jet when the pressure is released, it is not necessary to provide the pressure receiving body 34.

(4) The spacer 8 is formed of a heat-resistant insulating material such as porcelain into a solid rod shape, and Sn, Pb, Al, Cu and other low melting point metals or at least one of them is formed on the side surface from the lower end surface to the upper end surface. It is possible to provide a substantially linear fusing conductor made of a low melting point alloy or the like and melt the fusing conductor when a follow flow flows to facilitate the transfer of the internal arc path to the outside.

(5) Other than the coil spring 19, a short-circuit member for short-circuiting the lower lid 4 and the lower electrode 25 may be provided outside the coil spring 19.

(6) The present invention can be widely applied to the arrester 1 using the non-linear resistance element 7.

Effects of the Invention As described above in detail, according to the present invention, when an arc jet blows from a porcelain tube due to an abnormal voltage exceeding the duty, the conductor having elasticity is stretched on the arc jet, and the upper and lower discharge ends are extended. The excellent effect that the arc generated in the porcelain tube can be easily transferred to the outside by reducing the insulation resistance between them. As a result, it is possible to prevent the insulator from being broken by being heated by the follow-current arc after the pressure is released.

[Brief description of drawings]

1 to 7 are drawings according to the present invention, FIG. 1 is a perspective view of an essential part of the first embodiment, FIG. 2 is a partial vertical sectional view of the first embodiment, and FIG. 3 is an upper or lower cap fitting. Of FIG. 4, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, FIG. 5 is a sectional view taken along line VV of FIG. 3, and FIG. 6 is a sectional view taken along line VI-VI of FIG. FIG. 7 is a side view of a main part of the second embodiment, and FIG. 8 is a partial vertical sectional view of the prior art. 3 ... Cap fitting (lower cap fitting), 5 ... Cap fitting (upper cap fitting), 3h, 5h ... Pressure release port, 23 ... Conductor, 23a ... Metal foil as conductor, 2
3b ... same metal wire, 34, 34a ... pressure receiving part,

Claims (3)

[Claims] 1. Pressure release ports (3h, 5h) for arc jets are provided in cap metal fittings (3, 5) attached to both ends of the porcelain bushing (2) so as to face each other, and the pressure release ports (3h, 5h) are provided. 5h)
At least one side of the pressure receiving part (3
The conductor (23) provided with the conductors (4, 34a) is housed in a contracted state, and the base end of the conductor (23) is attached to the cap fitting (3, 3).
Lightning arrester characterized by being attached to 5). 2. The conductor (23) is a spiral metal foil (23).
2. The lightning arrester according to claim 1, wherein the lightning arrester is a), and the tip side thereof is a pressure receiving portion (34a) wound in a spiral shape around the core member (36). 3. The lightning arrester according to claim 1, wherein the conductor (23) is a spirally wound metal wire (23b), and a pressure receiving portion (34) is attached to the tip thereof.