US1976484A - High potential switch apparatus - Google Patents

Description

Filed: April 19. 1932 IhvehtoT": PichaW-d Cr'meT",

His AttOT'hGH.

Patented Oct. 9, 1934 PATENT QFFHIE HEGH POTEN'EEAL SVVETCH APPARATUS Richard Criimer, Generai Eiec New York Application April 19, l

out],

Stegiitz, Germany, assignor to tric Company, a corporation of Serial No. 606,253

In Germany April 21, 1931 4 Claims.

My invention relates to high potential switch apparatus, more particularly to static shielding means for preventing flashover or arcing in oil circuit breakers.

The use of insulation, as compressed paper cylinders and the like, for surrounding the potential bearing portions of explosion chamber switch contact structure of the high tension type is well known in the art. However as usually applied in the form of a sleeve surrounding the high potential portions of the stationary contact structure, there may occur electric discharges or flashovers between said contact structure and grounded conducting portions, as the metallic switch tank or casing, or between the separated contact portions along a path shunting the normal course of the arc during the circuit interrupting operation. The above difficulties may, of course, be overcome by increasing the spacing between the metal and insulating structure in the main oil body, thereby increasing the size of the apparatus, or by wrapping or taping the affected parts in the manner of insulating high tension cables, the latter method however being impractical in the case of circuit breakers since the contact structure should be readily detachable for inspection or replacement.

The principal object of my invention is the provision of improved shielding means for the Q stationary contact structure of oil circuit breakers which shall effectively prevent electric discharges between the same and adjacent conducting structure.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is a fragmentary view, partly in section, of oil circuit breaker contact structure embodying the present invention, and Fig. 2 is a partial view illustrating another form of my invention.

In Fig. 1 there is illustrated, by way of example, oil circuit breaker structure of the so-called explosion chamber type comprising a lead-in conductor bushing l which extends in a well known manner through the cover structure of the circuit breaker, and explosion chamber contact structure 2 supported by an adapter 3 mounted at the lower end of the lead-in bushing. The adapter 3 which is suitably connected to the lead-in conductor 1' is of metal, as is the member 4 supporting the stationary contact 4 within the explosion cham- Cal her. The movable contact 4" carricd by the con,- ventional bridging member extends upwardiy through the bottom of the explosion chamber to engage with the stationary contact in a well known manner. The aforesaid structure may be of the conventional type and need not be described further for a clear understanding of the present iii-- vention.

For the purpose of preventing electric discharges at high operating potentials at the con- 1 tact structure, as for example between the adapter 3 and, the grounded circuit breaker tank or between the stationary contact structure .and the movable contact 4" along a path shunting the normal course of the arc during the circuit interv rupting operation, there is provided a metallic cylindrical shield 5 which is ccnductively connected in any suitable manner, as by a sliding contact strip 3, with the metallic portions of the explosion chamber or adapter, the aforesaid con nection interfering in no manner with the replacement or detachment of the apparatus. The metallic shield 5, as illustrated, has a close sliding fit over the explosion chamber structure 2, the shield surrounding the metallic portions of the upper part of the explosion chamber, the adapter and the lower part of the lead-in bushing 1.

In the present instance an insulating coating 6 completely surrounds the shield 5. The outer wall of the explosion chamber structure may comprise an insulating cylinder 7, the lower part of which may support in any suitable manner, as

by insulating rings 7, the concentric insulating cylinders 8 and 9.

High resistance of the shielding means to puncture at excessive potentials is obtained by the above arrangement while permitting ready replacement of the apparatus involved.

It may be advantageous in certain cases from the viewpoint of economy to use a metallic pro tecting shield insulated only in part. In Fig.

2 there is shown an arrangement wherein a metallic protecting shield 10 is mounted, as in the previous instance, on the explosion chamber structure 2, the opposite ends of the cylinder being provided with comparatively thick walled insulating bands, each comprising a metallic band 11 and an insulating coating 12. Each band 11 is electrically connected as at 11' to the shield 10. Accordingly by this arrangement, the bare 105. shield 10 is provided with thick walled extensions encased in insulating material, thereby serving to prevent discharge at the outer ends of the shield. As in the previous instance, the metallic shield projects a certain distance beyond the metallic potential bearing portions and the shield is suitably electrically connected by the conducting strip 3 to said metallic portions. It will be apparent that the thick-walled end portions may comprise turned-over edges of the shield itself.

An oil circuit breaker having a metallic static shield of the aforesaid character may be comparatively compact in construction since a smaller oil tank may be used. Likewise the opening stroke of the breaker may be shortened. In the event of inspection or repair of the contact structure the static shield, which is slidably mounted on the stationary contact structure, may be readily detached, there being no permanent electrical connections with the adapter structure to interfere.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art Without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an oil circuit breaker including. a lead-in conductorbushing and stationary contact structure mounted at the lower end of said bushing, a metallic static shield surrounding and having a detachable sliding fit with respect to said contact structure, said shield and contact structure being electrically connected by sliding electrical connections.

2. In an oil circuit breaker including a lead-in conductor bushing and stationary contact structure mounted at the lower end of said bushing, a metallic static shield insulated at its opposite ends surrounding and having a detachable sliding fit with respect to said contact structure, said shield electrically connected to said contact structure.

3. In an oil circuit breaker including a lead-in conductor bushing, bare metallic structure including an adapter mounted at the lower end of said bushing and stationary contact structure supported by said adapter, a cylindrical metallic shield provided with an insulating coating detaohably mounted over said metallic structure, said shield electrically connected to said metallic structure and extending beyond the extremities thereof.

4. In an oil circuit breaker including a lead-in conductor bushing, bare metallic contact structure mounted at the lower end of said bushing, a protecting metallic static shield forming a cylinder. detachably mounted over and electrically connected to said contact structure and extending beyond the extremities thereof, and metallic bands electrically connected to said shield and provided with an insulating coating mounted on and disposed at the opposite ends of said cylindrical shield forming thick-Walled end portions.

RICHARD CRAMER.

Images