US2155276A - Quenching chamber for electric gas switches - Google Patents

Description

April 18, 1939. H. KoRNDoRr-'ER QUENCHING CHAMBER FOR ELECTRIC GAS SWITCHES Filed Jan. 31, 1938 Inventor: Hubert Korndrer,

His Attorney.

Patented Apr. 18, 1939 UNITED STATES PATENT Aori-ICE Hubert Komdrfer, Berlin, Germany, as'slgnor to l General Electric Company, a corporation of New York v Application January 31, 1938, Serial No. 188,011

In Germany May 28, 1936 8 Claims.

This invention relates to quenching chambers for electric gas switches of the type wherein the compressed gas requisite for the quenching of an arc is liberated from gas-producing material forming the walls of the quenching chamber by the switching-oil arc itself.

With the known constructional forms of quenching chambers of the above mentioned type Y the walls of saidv chambers which give off a gas, as stated, are generally formed by tubes through which the movable contact is drawn after separation from its counter contact. This design has the drawback that the chamber walls are strongly affected not only thermically by the switchingoff arc, and mechanically by the rapidly generated high pressure, but are also subjected to additional mechanical strains due to movable switch members. These strains may become very considerable especially if beads of fused metal form at the inner walls of the tubes or, also at the movable switch members, as a consequence, of the switching operations.

Furthermore, in the known constructional forms, as long as the tip of the movable contact 26 is located still within the quenching tube, the current of gas under pressure is confined solely at the lower r-,ims of the movable switching member, as the switching gases which are underva high'pressure can escape outwardly and in a restricted' quantity only at said rims through the narrow annular space necessary for the requisite play between the movable switch pin and the inner walls of the quenching tube. Finally, there exists in the tube, in which the arc is burning between the stationary switch member and the movable one approximately static pressure conditions which are not so serviceable for the quenching of the arc as compared with a gas current.

A principal object of my invention is the provision of an improved quenching chamber of the aforesaid typev wherein the arc-extinguishing gas is produced by the action of the arc on a solid gas-producing material so located with respect to the arc chamber that the chamber structure is not subjected to severe mechanical strains. 'I'he development of the quenching gas takes place at said place on a large surface and from an easily evaporated material, so that large quantities of a gas having a comparatively low temperature are obtained. Furthermore, provision is made to insure that soon after the commencement of the separation of the contacts a current of quenching gas is produced and so conducted that the arc is drawn into an existing quenching current, where- (C1. zoo-149) by it is quickly and reliably quenched. The conducting members for the current of the gas can be designed in the manner of a Laval-nozzle so that a favorable fiow of the quenching gas, as well as complete relief of pressure, and therefore, also a complete cooling of the hot switching gases is obtained and special cooling devices at the quenching chambers can be dispensed with.

The invention is illustrated diagrammatically and by way of example by the accompanying drawing in which Fig. 1 is an axial section through a quenching chamber designed according to this invention, and Fig. 2 is a similar fragmentary view of a slightly modified form of the quenching chamber.

This quenching chamber consists in the present instance of a cylindrical member I of an insulating material in which a hollow space 2 having the shape of a Laval-nozzle is provided. The member or insulating body I may be reinforced if desired by metallic insertions or by similar members and is closed at one end by a lid l. In the thus formed space 5 between the narrowest place 6 of the insulating body I and the lid 4 is arranged a contact chamber l consisting of an sulating material which, if desired, may be reinforced, The chamber l contains the stationary Contact 8 which co-operates with the movable switching member 9 that is tubular in the exam'- Jple shown. I'he unoccupied space in the passageway of the contact chamber is closed by an insulating bolt I0 which forms, together with the passagebore of the chamber l a restricted annular passage II for the movable switching member and which may be, like said chamber, provided with insertions consisting of a material giving off gas in a certain extent under the infiuence oi'I the heat of the arc.

The lower end of the contact chamber is open and is provided with a structure I2 having a large surface, and consisting of a substance that readily gives off an arc-extinguishing gas under infiuence of the arc heat. As shown in Fig. l the structure I2 comprises broken or granular material having interstices of such size that gas flow is not impeded. In the case of Fig. 2, a grid or honeycomb-like structure is shown. The particular gas-producing material used can be chosen tosuit operating requirements. Examplesof such materials are bre, urearesin and carbonates in general. Between the stationary contact 8 and the structure or grid I2 is an intermediate wall I3 in which a return-valve I4 is inserted.

The manner of operation of a quenching chamber designed according to this invention is as follows:

When the contacts 8 and 8 are separated from one another the volume of air contained in the aiutava with a non-return-valve. This second part is utilized for thel generation of gas only when the pressure of the gas present in the contact chamber 1 has attained a certain value, as above decontact chamber 1 is heated and thereby subscribed, and has opened the valve. Also the 5 jected to pressure which cannot, however, he rereverse valve operation is suited for the purpose in leased along the movable switch member. The view, in that that part of the honeycomb-shaped. pressure increases during the further course of insertion which is enclosed by means of the inthe switching stroke of said switch member. termediate wall is Withdrawn from the hot gases 10 thepassage opening of the chamber 1 is also by closing the val"e only when the pressure in 10 constructed of a material which is evaporated the contact chamber has attained a certain defiby the heat of the arc, then the formation of a nite value. In Fig. 1 there is shown by way of highly compressed hot gas also in this manner is example a simple arrangement for replacing the promoted without an essential wear of the ininsertion l2 in the manner of a cartridge. A

sertec` members. cap I2 to which the insertion is secured is screwed 15 These hot switching gases open the non-return into the end cover 4 so that removal of the cover valve I4 and stream along the honeycomb or is unnecessary when the insertion including the granular structure l2 which consists of a mategas-producing material is to be replaced. In F18. rial that readily gives oi gas'when subjected to 2 the cover 4 is first removed after which the the action of heat. While said switching gases insertion l2 can be removed by suitable means, 20

'are thus streaming along said structure they give such as a Spanner wrench.

rise to a quick development of large amounts of Accordingly, I have provided an improved elecquenching gas escaping from the large surface of tric switch of the automatic gas-producing type the said structure,there also taking place at the that is effective to interrupt arcing throughout same time a reduction of the high temperature. a wide current range, and that is both simple and 25 While this takes place, the pressure of the gas rugged in construction with respect to strains contained in the chamber 1 increases quickly-and to which this type of switch is usually subjected. the gas flows with a high velocity around the con- Also, since the gas-producing material naturally tact chamber at the outer surface thereof through deteriorates with use, depending on the severity 3o the passage 5 to the narrowest place 6 ofthe of arcing and number of opening operations, the 30 quenching chamber body i beyond which place replaceable feature is important from the standthere is a great drop in pressure by reason of the point of maintenance and continuity of operation. correspondingly shaped nozzle piece llying above Another possibility is to make the one part said narrowest section. of the honeycomb-like insertion of a material As soon as the arc is drawn from the contact that is gasiable only with difliculty and the other 35 chamber l it is exposed to the action of a powerpart of said insertion of an easily gasiable malful gas current which surrounds it in hose-like terial. It is then possible to provide, when the manner and quenches it. The entrance of the honeycomb-like insertion is suitably designed and arc in said current of gasvis at the zone of the the valve is appropriately arranged, for the most most favorable quenching conditions shortly in favorable switching-off'condltions at every range o front of the narrowest nozzle section. At this of current. point a small amount of the switching gas which Finally it is preferable that the lid or end cap 4, has been highly heated directly by the arc is the inner wall of which is designed to serve as liberated and when it passes along the structurev a direction-changing member for the gas stream,

I2 such as the honeycomb-insertion which conbe gas-tight, but conveniently detachable with re- 45 sists of easily gasifiable substances, there takes spect to the quenching chamber body i. This place, with the present improved quenching chamcan readily be accomplished by designing the ber, a reliable quenching of the are with weak parts for screw-threaded engagement as illuscurrents, as well as strong ones. The gas blast trated. Accordingly the insertion I2, as well as including the are extinguishing gases produced the contact chamber 1, are easily accessible and 50 from the material I2 is therefore initially directed exchangeable. In Fig. 1 there is shown by way away from the lower portion of the arc by the of example a simple arrangement for replacing arc pressure to return to a subsequently formed the insertion l2 in the manner of a cartridge. A portion by way of the passages 5 and 2. Thus the cap I2 to which the insertion is secured is screwed gas blast is delivered to the arc by a recurrent into the end cover 4 so that removal of the cover 55 path that is in shunt with part of the arc. is unnecessary when the insertion including the The arrangement of the stationary contact, the gas-producing material is to be replaced. In Fig. intermediate partition I3 with its non-return 2 the cover 4 is first removed after which the valve, and the honeycomb-insertion relatively to Y insertion I2 can be removed by suitable means,

G0 one another as shown by Fig. l may, of course, such as a Spanner wrench. 60 also be designed in another manner than that de- Accordingly, I have provided an improved elecscribed above and illustrated by way of example. tric switch of the automatic gas-producing type It may, for instance, be suited to the purpose that is effective to interrupt arcing throughout in view to provide the gas-producing material, a widecurrent range, and `that is both simple 6,-, such 'as the honeycomb insertion between the staand rugged in construction with respect to strains (.5 tional-y contact and the valve rim.or to dispense to which this type of switch is usually subjected. with it altogether, where cooling means for the Also, since the gas-producing materially natuhot arc gases is provided and where additional rally deteriorates with use, depending on the segas is not required. verity of arcing and number of opening opera- It is also possible to subdivide said insertion tions, the replaceable feature is important from 7u l (l2) and to subject a part of the gas-producing the standpoint of maintenance and continuity of surface at the outset to the action of the hot operation. gas current `produced directly by the arc, whereas What'I claim as new and desire to obtain by the other part of the subdivided insertion is en- Letter-system; of the Umd States is: closed in part by an intermediate wall provided 1. An arc-quenching chamber for an electric 76 switch including relatively movable contacts adapted to form a single arc, comprising a material adapted to yield an arc-extinguishing gas when subjected to the arc heat generated upon separation o! said contacts, and casing means `for deiining a passage leading away from one portion of said arc to said gas-yielding material, and fromsaid material tovanother portion of said arc.

2. An arc-quenching chamber for an electric switch including relatively movable contacts, comprising a material adapted to yield an arcextinguishing gas when subjected to the arc heat generated upon separation oi' said contacts, said material defining a plurality of passages for permitting substantially unobstructed ow oi said gas through said material, and casing means for defining a passage leading away from the point of initial arc formation, through said material to return' by another path to a subsequently formed portion of said arc.

3. An arc-quenching chamber for an electric circuit interrupter including means for lforming a single arc upon opening o1' the circuit, comprising a material adapted to yield an arc-extinguishing gas when subjected to the arc heat, said material having a comparatively large surface area for contact with the heated arc gases,

and casing means for dening a passage leading away from one part oi' said arc, to Asaid material and returning by a shunt path to another part of said arc.

4. An arc-quenching chamber for an electric circuit interrupter including means for forming an arc upon opening of the circuit, comprising a material adapted to yield an arc-extinguishing gas when subjected to heated arc gases, casing means for vdefining a passage leading away from one part of said arc to said material and by a recurrent path to another part of said arc, and a non-return valve positioned in said passage between said arc and gas-yielding material so that said passage is' opened in response to predetermined arc pressure.

5. AAn arc-quenching chamber for an electric circuit interrupter including means i'or forming an arc upon opening of the circuit, comprising a material adapted to yield an arc-extinguishing gas when subjected to heated arc gases, a replaceable unit including said material, said unit being interposed in and substantially lling a passage interconnecting diierent parts oi' said arc, and a valve also disposed in said passage between one part of said arc and said unit.

6. An arc-quenching chamber for an electric circuit interrupter including means forming an arcupon opening of the circuit, comprising a material adapted to yield an arc-extinguishing gas when subjected to the arc heat, casing means defining a passage for directing heated arc gases into the arcK path, said material being incorporated in a cartridge-like unit substantially blocking said passage except for gas iiow adapted to be inserted in said passage through a wall of said casing means,

l 7. An arc-quenching chamber for an electric circuit interrupter including means forming an arc upon opening of the circuit, comprising casing means defining a passage for directing heated arc gases from the arc path, and a material adapted to yield an arc-extinguishing gas when subjected to said heated arc gases, said material constituting a unit of substantially honeycomb configuration for deiining a plurality of separate paths for said gases so that a comparatively large surface area is presented for contact with said heated arc gases, and means for detachably securing said unit in said passage.

8. An arc-extinguishing chamber for an electric circuit interrupter including iixed and mov` able contacts, comprising casing structure having an exhaust passage through which the movable contact is operated, said casing means likewise defining a passage leading away from said fixed contact at the initial part of the arc to said exhaust passage by a recurrent shunt path for directing a gas blast into another part of the arc path, and a gas-yielding material constituted as a renewable unit positioned in said passage between said iixed contact and exhaust passage, said material having a comparatively large surface area for contact with the heated arc gases `traversing said passage whereby additional arcextinguishing gas is generated for arc interruption.

HUBERT KORN'DRFER.

CERTIFICATE OF CORRECTION.

Patent No. 2,155,276. April 18, 1959.

HUBERT KORNDRFER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first colmnn, line 6, for "he" read be; and second column, line 12, beginning with "In Fig. l" strike out all to and including the wordand period "operation Ain line 52, and insert instead the following sentence with this arrangement, the total gas-producing surface is available at low pressures, and hence low currents, for

yielding the required gas volume, whereas but a limited surface is required for heavy arc currents where the pressure is already high.;

line 67, for "materially" read material; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 6th day of June, A. D. 1959.

Henry Van Arsdale (Seal) Acting Conmissioner of Patents.

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