US2451669A - Gas blast circuit breaker - Google Patents

Description

E. EICHENBERGER GAS BLAST CIRCUIT BREAKER Filed March 27, 1945 Patented ca. is, less UNITE GAS BLAST CIRCUIT BREAKER Ernst Eichenberger, Wettingen, Switzerland, as-

signor to Aktiengesellschaft Brown, Boveri &

Cie., Baden. Switzerland Application March 27, 1945, Serial No. 585,031 In Switzerland September 15, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires September 15, 1963 9 Claims.

Switching devices usually employed for interrupting alternating current cannot generally be used for the interruption of direct current, because with direct current the current and voltage are substantially constant and do not pass through zero values, a phenomenon which in the case of an alternating current can be utilized in a favourable manner. In order to ensure that a direct current is certain to be interrupted it is necessary that the arc should be so long that the voltage drop in the arc is greater than the driving electromotive force in the circuit. Switching devices are known where the rupturing arc is lengthened by locating transverse walls of metal or insulating material in the path of the are so that the arc can establish itself along the edges of these walls in a wave-like manner. It is also known to assist the rising of the arc loop between the transverse walls by a supplementary gas blast, whereby due to the substantial lengthening of the are it is more easily extinguished. With direct current switches ofthis kind the arc lengths are already very considerable, even with small currents, so that with larger currents there is a danger of backarcing occurring.

The present invention concerns a gas blast circuit breaker with blast chamber where the arc root points are blown from the switch contacts to auxiliary contacts and the arc loop against insulating walls located across the path of the arc, the disadvantages referred to above being overcome according to the invention by probes being arranged in such a manner-one above the other in the direction of flow of the pressure gas in the space inside the blast chamber which is touched by the arc loop, that they form points of attachment for the arc loop so that this latter under the blast effect of the pressure gas can climb up these points in stages, so that the arc is lengthened whilst the root points remain stationary.

Constructional examples of the invention are illustrated diagrammatically in Figs. 1 to 6 of the accompanying drawing where circuit breaker blast chambers which are particularly suitable for interrupting direct current are shown in longitudnial and cross-section.

Fig. l is a central vertical section of one form of the invention;

Fig. 2 is a central vertical section of a slightly modified form of the invention;

Fig. 3 is a transverse section taken on lines 8-! of Fig. 2;

Fig. 4 is a central vertical section of another modification of the invention;

Fig. 5 is a transverse section taken on lines 5-5 of Fig. 4; and

Fig. 6 is a central vertical section of yet another modification of the invention.

In all the figures a1, a2 designate the switch contacts which are either both stationary and are bridged over by a movable contact element b, as

shown in Figs. 1 to 3 and 6 or one is a stationary hollow contact and the other a movable pin contact, as shown in Figs. 4 and 5. Auxiliary contacts 01-, 02 are metallically connected with the switch contacts and these former act as are catchers and secure the position of the root points of the arc. The blast chamber of insulating material is indicated by the reference letter (Z and has at its upper end an exhaust e for the pressure gas used to extinguish the arc, this gas being supplied to the contacts over f, and a pressure gas container and valve not shown in the drawing. In the blast chamber d are walls of insulating material which subdivide the chamber and serve as supports for the probes, these probes forming points of attachment for the arc, so that the latter which is subjected to a gas blast can climb upwards.

In the constructional example shown in Fig. 1 the blast chamber which has a rectangular section is fitted with two walls g1, 92 which are arranged transversely to the path of the arc. Metal bolts hi to he and hll to h18 respectively are inserted at intervals one above the other in these transverse walls, so that the probes in both walls are located opposite to each .other at the same height.

When a direct current is interrupted the rupturing arc is blown by the pressure gas from the main contact; oi, as to the auxiliary contacts c1, c2. Whilst the root points of the arc continue to adhere to the auxiliary contacts, the arc loop is driven in stages upwards over the pairs of opposing probes, whereby the arc wanders along the lateral spaces between the walls g1, g2 and the wall of the chamber thus forming a closed loop over the probes and is extinguished when it is sufllciently extended. Back arcing in the space between the walls g1, y: where the central portion of the arc loop is located is impossible because there is a constant supply of fresh pressure gas to this intermediate space, so that the space below the arc loop is deionized. Walls g1, 92 together with the probes can be arranged parallel as shown, or they can be made to diverge in the direction menace 3 of flow of the pressure gas whereby the extinction 01' the arc is assisted. The same purpose is achieved if the probes of both walls gr, 9: are connected over resistances as indicated by the broken lines in Fig. 1.

The rectangular shaped blast chamber shown in Fig. 1 can be replaced by a circular blast chamber as indicated in Figs. 2 and 3, where identical elements are designated by the same reference letters as in Fig. 1. The probes hi, ha and the like are supported by an insulating tube gu which is arranged coaxial with the blast chamber. The insulating tube is held in position by webs ii, i: which subdivide the annular space between the tube and the chamber wall. The probes are arranged diametrically opposite-to each other in the insulating tube in such a manner that their connecting line runs perpendicular to the webs. The effect is the same as that already described in connection with the arrangement shown in Fig. 1. Webs ii, in prevent the rupturing are from forming in the annular space without first touching the probes.

Figs. 4 and 5 show a constructional example where two concentric insulating tubes 921, on: are located within the circular blast chamber d. This circuit breaker has a fixed hollow contact a1 and a movable contact or. Metal rings her to has and hn to has, which are located in the cylindrical surfaces of the insulating cylinders gm, can, serve as probes. The operation of the circuit breaker is fundamentally the same as that shown in Fig 1. The are rises in the annular space between the blast chamber and the insulating tube gm as well as in the hollow space inside the insulating tube gas, the middle part of the arc loop lying in the anular space between the insulating tubes gm, Q22, whilst the lower part of this space is deionized by pressure gas so that back arcing is prevented.

In order to reduce the dimensions of the blast chamber, which with high voltages has a correspondingly great length, it is possible as is shown in Fig. 6 for instance, to arrange transverse walls in, kg inside the blast chamber d, metallic coatings m1, me being provided on the lower ends of these walls, so that the blast chamber is subdivided into three part chamber which are electrically in series. Each part chamber (11, (is, da contains two transverse walls of the same design which serve as special supports for the probes and are of the kind described in connection with Fig. 1. The eflect of this arrangement is again the same as that described for the constructional example shown in Fig. 1, with the additional advantage. however, that not only is the length of the chamber reduced for high voltages but the extension of the arc is accelerated and the extinguishing effect improved.

I claim:

1. Gas blast circuit breaker comprising switch contacts; a pair of auxiliary contacts constructed and arranged to catch and hold root points of the are formed upon opening of said switch contacts, a blast chamber disposed crosswise of the path 0! the are, said chamber being subdivided longitudinally by interior wall means into three compartments through which blast gas is adapted to flow, and said auxiliary contacts being located respectively at the entrance to the outer two of said compartments, a plurality of spaced probes arranged one above the otherv in each of the said outer two compartments, and similarly spaced probes in the middle compartment individual to and electrically connected with each of the probes in said outer compartments, said spaced probes forming successive points of attachment for the are intermediate the root points thereof upwardly through the blast chamber as the arc is lengthened by the blowing action of the blast gas.

2. Circuit breaker as in claim 1, characterized by the feature that said probes are supported by the wall means which subdivide the blast chamber.

3. Circuit breaker as in claim 1, characterized by the feature that said interior wall means coniprises at least two spaced walls and said probes are metal bolts arranged at intervals one above the other and extend through the respective walls.

4. Circuit breaker as in claim 1, characterized by the feature that said interior wall means comprises at least two walls spaced parallel.

5. Circuit breaker as in claim 1, characterized by the feature that said interior wall means comprises at least one main interior insulating wall initially dividing said chamber into longitudinal sections, the lower end of said wall being provided with an electrode, and that each chamber section is subdivided longitudinally by secondary interior walls into at least three compartments and on which said probes are supported.

6. Circuit breaker as in claim 1, characterized by the feature that the blast chamber is circular and that said interior wall means comprises an insulating tube built into the blast chamber by means of webs which subdivide the annular space between said tube and the internal wall of said blast chamber, and that said probes are located diametrically opposite each other in said tube in such a manner that their connecting line runs perpendicularly to said webs.

7. Circuit breaker as in claim 1, characterized by the feature that the blast chamber is circular and said interior wall means comprises at least two concentrically arranged insulating tubes that support said probes.

8. Circuit breaker as in claim 1, characterized by the feature that the blast chamber is circular, and said interior wall means comprises at least two concentrically arranged insulating tubes, and that said probes are metallic rings located in the cylindrical surface of each insulating tube.

9. Circuit breaker as in claim 1, characterized by.the feature that a resistance is connected between two probes in like positions at opposite sides of the same chamber.

ERNST EICHE'NBERGER.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 1,861,128 Milliken May 31, 1932 1,948,658 Gerin et al Feb. 27, 1934 2,049,995 Clerc Aug. 4, 1936 2,100,182 Clerc Nov. 23, 1937 FOREIGN PATENTS Number Country Date 540,927 Germany Jan. 7, 1932

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