EP1821379B1 - Gas filled surge absorber with exterior short circuit device - Google Patents

Description

The invention is in the field of electrical components and is to be applied in the structural design of a gas-filled surge arrester, which is provided with an external short-circuiting device. Such shorting devices are common in both two-electrode and three-electrode surge arresters. They serve to protect the surge arrester with long-term loads; such a short-circuiting device usually contains a fusible at higher temperatures construction element by which the two electrodes or the center electrode and one or both end electrodes are short-circuited.

In a known two-electrode arrester of this type, a spring contact and a drain contact are arranged electrically parallel to the two electrodes, wherein the spring contact is kept at a distance from the drain contact by means of a spacer applied to the insulator of the arrester and softening at elevated temperature. This spacer consists of a dimensionally stable at normal operating temperature and at elevated temperature softening, glass fiber reinforced plastic, such as polycarbonate ( EP 0 548 587 A1 ).

For two-electrode arrester, an external short-circuit device is further known, which is provided for such applications, in which a larger number of arresters in chambers of an existing insulating plastic magazine or a cassette are arranged. The short-circuit device in the form of a surge arrester axially not superior, electrically conductive strap with two right angles angled ends is in each case located in a immediately adjacent to the respective arrester lying, the holding device of the bracket forming separate chamber, wherein the one chamber wall forms the fusible spacer. The bracket is preformed so that a spring force is exerted on its angled ends when inserting the bracket in the chamber, under the action of the ends of the spring clip in case of overload penetrate the chamber wall ( EP 0 312 729 A1 ).

For three-electrode arrester, an external short-circuiting device is known which consists of an attached to the center electrode clamp of an open ring, one end of which together with laterally formed arms forms a shorting bar. The free ends of the two arms are held by means of a arranged between the center electrode and shorting bar spacer made of a fusible insulating material radially at a distance from the end electrodes of the arrester. The free ends of the two arms can be provided with special contacts. Instead of using a spacer between center electrode and shorting bar, the contacts mentioned may also be coated with an insulating coating ( US 4,984,125 A ). - In a similarly designed external short-circuiting device, which can be used for both three- and for two-electrode arrester, the free ends of the two arms of the shorting bar are angled such that they rest against the peripheral edge of the respective electrode, said have free ends in the region of the contact point a heat-meltable insulating coating ( FR-A-2 670 624 ).

A surge arrester is described in which the spacer is arranged between the middle part of the shorting bar and the insulator.

Such a configuration of the short-circuit device makes of the known ( US 4,984,125 ) Construction of a short-circuit device use, but in this case the clip is not on an electrode, but - in a known manner ( FR-A-2 670 624 ) - placed on the insulator between two electrodes. As a result, the shorting bar is arranged floating; This can have an advantageous effect in narrow installation conditions (magazine or cassette), as in unilateral contact of the shorting bar with a potential-carrying contact terminal no disturbing short circuit can occur. - Since the spacer between the shorting bar and the insulator is arranged, the spacer can be made relatively thin; Incidentally, a relatively inexpensive thermoplastic material can be used for the spacer, since the insulator heats up delayed with respect to the short-circuited electrodes.

Such a trained surge with short-circuiting device is thus characterized by a very compact and with respect to the insertion of a larger number of such arresters in cassettes very space-saving design, the short-circuiting device may consist of a parts and is easily adaptable to different Ableitergeometrien as a result of their simple design. The short-circuit device can also be retrofitted; It can also be exchanged after a response, provided that the actual arrester is still intact.

The described short-circuit device can be used for two-electrode arresters.

The open, snap-on ring of the new shorting device can be made of a heat-resistant plastic or a less electrically conductive, resilient metal (eg spring steel or a copper alloy), wherein on one end of the open ring a metallic, electrically very conductive ( made of copper, for example), shorting bar is attached or otherwise fastened. Preferably, however, the open ring consists of the same material as the actual shorting bar and is formed integrally therewith, wherein the open ring is provided to form the shorting bar at one end with two laterally molded tabs. To improve the contact, these tabs may be slightly angled at their free ends.

As a spacer for the short-circuiting device comes in a known manner a fusible plastic part into consideration. In the same way, a spacer made of a solder material can be used. These spacers may, for example, have the form of a rivet which is fastened to the middle part of the stirrup. Alternatively, a plastic clip attached to the middle part of the bracket can also be used.

Figur 1

einen mit einer Kurzschlußeinrichtung bestückten gasgefüllten Überspannungsableiter mit zwei Elektroden,

Figur 2

die Kurzschlußeinrichtung ohne Ableiter,

Figuren 3

einen Überspannungsableiter, bei dem der Abstandhalter der Kurzschlußeinrichtung aus einer Niet besteht,

Figur 4

einen Überspannungsableiter mit einer Kurzschlußeinrichtung, bei der der Abstandhalter aus einem Kunststoffklipp besteht,

Figur 5

eine Kurzschlußeinrichtung mit besonderer Ausgestaltung der Elektroden des Ableiters und

Figur 6

einen nicht zur beanspruchten Erfindung gehörigen Drei-Elektroden-Ableiter mit zwei auf die beiden Isolatoren aufgesetzten Kurzschlußeinrichtungen.

Examples of the understanding of the invention are in the FIGS. 1 to 6 shown. It shows

FIG. 1

a gas-filled surge arrester with two electrodes equipped with a short-circuit device,

FIG. 2

the short-circuit device without arrester,

Figures 3

a surge arrester, in which the spacer of the short-circuiting device consists of a rivet,

FIG. 4

a surge arrester having a short-circuiting device in which the spacer consists of a plastic clip,

FIG. 5

a short-circuit device with a special configuration of the electrodes of the arrester and

FIG. 6

a not belonging to the claimed invention three-electrode arrester with two placed on the two insulators shorting devices.

FIG. 1 shows a surge arrester 1, which consists of the insulator 2 and the two end electrodes 3 and 4. On the insulator 2, a short-circuiting device 10 is placed, which consists of a in FIG. 2 separately shown open ring 11 made of spring-hard metal and an insulating spacer 20 consists. The open ring 11 is formed at its one end as a shorting bar 12 and has a flat central part and two laterally molded, slightly angled at the ends tabs 14 and 15. The axial length of the shorting bar 12 is chosen so that the short circuit bar does not protrude beyond the surge arrester (see also FIG. 5 ). The spacer 20 could also consist of a solder material.

According to FIG. 3 consists of the short-circuiting device for the arrester 1 also from an open, on the insulator of Arrester aufschnappbaren ring, wherein a plastic rivet 21 is provided as a spacer for the actual shorting bar 13, which is fixed in a bore of the central part 13 of the shorting bar. - According to FIG. 4 can be used as a spacer plastic clip 22 which is pushed onto the middle part 13 of the shorting bar.

According to FIG. 5 the electrodes 31 and 32 of the surge arrester are provided with a larger outer diameter than the insulator 2. As a result, it is unnecessary to bend the ends of the actual short-circuiting device 16 at the ends.

FIG. 6 shows a not belonging to the claimed invention arrester, wherein between the end electrodes 3 and 4, a center electrode 5 is still arranged, wherein the arrester has two insulators 6 and 7. On each insulator a short-circuiting device 10 is placed, as well as for the arrester according to FIG. 1 is used.

Claims (6)

1. Gas-filled surge arrester having precisely two electrodes (3, 4) and having an insulator (2) arranged between the two electrodes, and having overload protection in the form of an external short-circuiting device (10, 16), in which the short-circuiting device comprises an electrically conductive short-circuiting link (12, 13), which runs in the axial direction of the surge arrester, the ends of the short-circuiting link being held at a radial distance from the electrodes by means of a holding device, which exerts a spring force, and a spacer (20; 21; 22), which is fusible in the event of a supply of heat, and in which the holding device comprises an open ring (11) which can be snapped onto the insulator and consists of a strip-shaped, resilient material, with the short-circuiting link being arranged at one end of said ring, the spacer (20, 23) being arranged between the central part (13) of the short-circuiting link (12) and the insulator (2), characterized in that the short-circuiting link (12) does not protrude axially beyond the surge arrester.
2. Surge arrester according to Patent Claim 1, wherein the open ring (11) which can be snapped on consists of metal and is designed to be integral with the short-circuiting link (12), the open ring being provided with two lugs (14, 15), which are integrally formed laterally, at the short-circuit-side end.
3. Surge arrester according to Patent Claim 1 or 2, wherein the ends (14, 15) of the short-circuiting link (12) are bent back slightly.
4. Surge arrester according to Patent Claims 1 to 3, further characterized in that the spacer comprises a rivet (21), which is fixed to the central part (13) of the short-circuiting link and consists of a plastic or of a solder material.
5. Surge arrester according to Patent Claims 1 to 3, further characterized in that the spacer comprises a plastic clip (22), which is positioned on the central part (13) of the short-circuiting link.
6. Surge arrester according to Patent Claim 1, in which the spacer is a fusible plastics part.

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