US2089050A

US2089050A - Electric circuit interrupter

Info

Publication number: US2089050A
Application number: US122773A
Authority: US
Inventors: Burmeister Hermann
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1936-05-16
Filing date: 1937-01-28
Publication date: 1937-08-03
Anticipated expiration: 1954-08-03
Also published as: GB476368A

Description

Aug. 3, 1937. H. BURMEISTER ELECTRIC CIRCUIT INTERRUPTER Filed Jan. 28, 1937 Inventor: Hermann Bun e'lste'r", y iVm z is Attor'neg.

Patented Aug. 3, 1937 ELECTRIC INTEBBUP'IEB Hermann Burmeiatcr, Berlin-Spandau, Germany, 'aseignor to General Electric Company, a corporation of New York Application January 28, 1937, Serial No. 122,773 In Germany May 16, 1936 5 (Cl. 200l 44) This invention relates to electric circuit interrupters of the air-break expulsion type wherein a 'gas formed by decomposition of a material by the are upon opening of the circuit is utilized to interrupt the arc.

In a well-known form of circuit interrupter of the aforesaid type, the arc is drawn in a confining insulating structure, such as a tube composed of material which under the influence of the are heat emits gases or vapors tendingto extinguish the arc. The interrupting capacity of a circuit breaker of this type wherein the gas forinterrupting the arc is released by the are heat from solid materials forming the walls of the confining insulating structure, depends primarily on the rapidity with which appreciable amounts of arc-extinguishing gas can be released under the influence of the arc, particularly in the case of low current interruptions. The interrupting capacity also depends on the characteristics of the gas so formed. I In the latter case, it is known that carbonic acid has many advantages as an arc extinguishing medium. In practice, however, the use of carbonic acid has been limited because of the comparatively complicated and expensive switching installations heretofore considered necessary.

" With reference to the rapidity of generation of the arc extinguishing gas in appreciable quantities under the influence of the are, fiber has proved satisfactory. However, due to the hygroscopic characteristics of the fiber, this material has not stood up well in operation. An-

other known material for releasing gas by action of the arc is boric acid which contains chemically combined water. In the circuit opening process the water is released under infiuence of the arc and is evaporated to form an are extinguishing vapor. In this case, however, the evaporation is not free of residue so that the original properties of the wall surfaces adjacent the arc are not obtained after repeated circuit interruptions.

It has also beenproposed to make the arc-extinguishing tube of fibrous material impregnated with a urea artificial resin. In this case, wherein mainly nitrogen acts as the arc extinguishing gas, the fibrous materials or carriers must be so selected that they readily disintegrate to form gas underinfluence of the are without leaving undesirable residue as soot. Accordingly,the cost of the arc extinguishing material in this case is an important factor.

In accordance with the present invention the advantages inherent in the use of carbonic acid as an arc extinguishing medium and in a material capable of releasing gas at a high rate for interrupting the are are obtained without disadvantageous results by the use of oxalic acid as the gas emitting material. The oxalic acid may either contain water or be free of water and may be used either with or without materials giving ofi oxygen, such as organic peroxide or per-salts.

Under the influence of the arc, the oxalic acid disintegrates to carbonic acid and water at a high rate. The caTbonic acid which is suitably utilized to interrupt the arc in a manner hereinafter described is released immediately and in large quantities, while the solvent water present evaporates without being essential to or materially influencing the arc interruption. Since oxalic acid readily disintegrates upon the addition of oxygen and by the addition of materials gas may be considerably increased.

or without the addition of a binding agent in powder form. As examples of binding agents, inorganic agents, such as plaster of Paris, clay, etc. and organic agents such as highly oxidized oils, such as, for example, linseed oil and wood oil, or prepolymerized artificial resin, as, for in- I stance, a. urea artificial resin may be used.

Referring more particularly to the drawing which illustrates a simple form of circuit interrupter to which the present invention is applicable, the single figure thereof is an elevational view partly in section of a circuit interrupter of the air-brake expulsion type.

In a structural embodiment of the invention it is preferable, particularly when the gas-emitting material for confining the arc is in tubular shape, to provide a strong reinforcing tube therefor because of the stresses incident to circuit interruption.

As illustrated, a mechanically strong reinforcing tube I composed of a suitable fibrous material, for example, is provided with an inner lining at 2 composed of the oxalic acid gas-emitting material above described. The are which is formed upon opening of the circuit is drawn through the tubular structure by the movable rod contact 3 which coacts with the fixed contact 4 at the upper closed end of, the tubei The tube has a sleeve fit with respect to the rod contact so that the arc is either in close proximity to or What I claim as new and'desire secure by Letters Patent of the United States is: v

1. An electric circuit interrupter comprising 15 means for opening the circuit so as to form an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said arc being composed of oxalic acid.

20 2. An electric circuit interrupter comprising means for opening the circuit so as to form an arc, and an insulating tubular structure within which said are is drawn, said tubular structure being in confining relation to said are and consisting of a reini'orcing material having an inner lining composed chiefly oi. oxalic acid.

3. An electric circuit interrupter comprising means for opening the circuit so as to form an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said arc being composed of oxalic acid and a per-salt.

4. An electric circuit interrupter comprising means for opening the circuit so as to form an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said are being composed of oxalic acid, and a binding agent consisting of a highly oxidized oil.

5. An electric circuit interrupter comprising 'means for opening the circuit so as to form an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said arc being composed of oxalic acid, and a binding agent consisting of a prepolymerized artificial resin.

HERMANN BURMEIS'I'ER.