US2249444A - Electric circuit breaker - Google Patents

Description

July 15, 1941. o. c. TRAVER l 2,249,444

ELECTRI C CIRCUIT BREAKER 35 37 by H15 Attorney.

July 15, 1941. o, Q TRAVER 2,249,444

" ELECTRIC CIRCUIT BREAKER Filed May 16, 1940 2 Sheetssheet 2 inventor: @live-1` C. Trave ,by fi/amy t-he Attorney.

Patented July 15, 1941 ELECTRIC CIRCUIT BREAKER liver C. Travel', Drexel Hill, Pa., assignor to General Electric Company, a corporation of New York Application May 16, 1940, Serial No. 335,485

14 Claims.

My invention relates to circuit breakers and more `particularly to electric circuit breakers'of the gas blast type.

An object of my invention is to provide an improved electric circuit breaker of the gas or vapor Iblast type.

Another object of my invention is to provide an improved breaker of the above-mentioned type in which the total amount of gas passing across the breaker contacts may be limited to any desired value.

A further object of my invention is to provide an electric cincuit breaker of the above-mentioned type which utilizes a pressure-forming arc to produce the desired. gas pressure to extinguish the interrupting arc wherein a substantially constant pressure willobtain regardless oi' the magnitude of `the arc current which is passing through the breaker at the moment of its opening operation.

I accomplish these and other objects by providing an electric circuit breaker with an arrangement for transforming a limited amount of anc-extinguishing liquid into a gas or vapor, this gas or vapor being then directed through the arc formed upon separation of the relatively movable circuit breaker contacts. In order to effect this result, I provide a gas generator having a gas accumulator chamber and a liquid reservoir. An arrangement, which includes a spring-biased piston, is provided for introducing a definite or predetermined amount of liquid into the gas accumulator when the circuit breaker contacts separate. I also provide in the gas accumulator relatively movable auxiliary contacts which are operated when the circuit breaker contacts move. Thus, when the blast of gas is desired for extinguishing the'arc formed upon separation of the relatively movablev contacts, the spring-biased piston injects a substantially definite quantity of liquid into the gas accumulator. An arc is also drawn between the auxiliary contacts which transforms the liquid into a gas. This gas is then conducted through anopening whose exit is adjacent the space between the relatively movable contacts. It will be seen, therefore, that regardless of the amount of current which is broken between the auxiliary contacts, a certain definite maximum pressure will obtain in the gas accumulator, because .there is only a certain measured amount of liquid in the vgas accumulator to be transformed into the anc-extinguishing gas.

Further objects and advantages oi my invenv tion will become apparent from the following (ci. zoo-14s) description referring to the accompanying drawings, 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.v

In the drawings, Fig. 1 is a partial sectional side elevation of au electric circuit breaker of the gas blast type being provided with an embodiment oi.' my invention; Fig. 2 is a sectional side elevation of a portion of the circuit breakerillustrated in Fig. 1, the parts being illustrated in their position after circuit breaker operation, and Fig. 3 and Fig. 4 illustrate modiiications of the electric circuit breaker illustrated in Figs. 1 and 2.

Referring to the drawings, in Fig. i I have illustrated an electric circuit breaker of the gas blast type having relatively movable contacts Ill and ii. The contact I ii is electrically connected to the terminal I2, while the contact Il is electrically connected to the terminal I3 through a conducting cross-head i4, auxiliary contact I5, auxiliary contact i6, and the piston on which it is mounted, and pig-tail i1. In order to provide an arrangement for directing a substantially denite quantity of arc-extinguishing gas through the arc formed upon separation ofthe relatively movable contacts I0 and Il to extinguish the arc, I provide a gas generator I8. I'he gas generator i8 is provided with a partition l! so as to form a liquid reservoir 20 and a gas accumulator or forming chamber 2i. The gas accumulator chamber and reservoir are connected together by a passage 22 which is formed by extending the sides oi' the partition I9 toward the reservoir. Ihe gas accumulator chamber communicates with an infterrupting chamber 23 through an insulating conduit 24. The exit end 25 of the conduit 24 is so spaced that it will be properly positioned with respect tothe gap formed upon separation of the contacts Il! and il. The reservoir ,20 contains an arc-extinguishing liquid 26 of any suitable type, such as dichlordiuormethane, commonly known as Ireon, water, or carbon tetrachloride.

` vIn order to provide an arrangement for introducing a definite or predetermined quantity of liquid from the reservoir 20 to the gas accumulator chamber 2|, I provide a piston 21 which is adapted to move inside a pistoncylinder 28.

The cylinder has an opening 29 inits top head through which a tubular extension 30 of the piston 21 extends. The tubular extension or stem 30 is of sufficient length that when the piston 21 is in its downward position, as shown in Fig. 1, the tubular extension will extend up into the passageway 22 between the chamber and the reservoir'. So that the liquid 28 from the reservoir may und its way into the space above the piston 2 in the cylinder 28, I provided a hole 3i in the lower portion of the side wall of the cylinder 2l which communicates with the interior of the reservoir. The piston is also provided with a passageway 32 which provides communication from the lower portion of the cylinder 2l. which is in communication with the reservoir through the hole 3i to the upper portion of the cylinder above the piston. A flap valve 33 is provided over the top of the passageway 12 which allows the passageway 32 to open when the piston is descending, but which provides a closure member for the passageway I2 during the tlmethe piston is ascending. The top portion of the cylinder communicates with the gas accumulator chamber through a transverse opening llt and a longitudinal communicating passageway 3E in the piston extension member It. The contact i5 which is carried by the stem 30 has a hole 3G through which it cornmunioates with the passageway 35 and the passage 22. A sp1-ing 3l is provided between the aumliary Contact member i8 and the top ci the liquid, which has been injected into the gas accumulator, into a gas. In order to make -sure that this pressure generating arc drawn between the auxiliary contacts i5 and i6 will not become undesirably long, I provide an auxiliary statlonary contact I9 through which the contact I5 moves. As the end of the contact II is drawn inside this tubular contact 39, the arc will therefore transfer itself from the contact l5 to the tubular stationary Contact 39. With such a structure the-total amount of gas which is available for extinguishing the arc oi the circuit breaker will be limited to a certain maximum amount. Thus, under extreme conditions, that is, under severe short circuits, when all the liquid which is injected into the gas accumulator 2| has been transformed into a gas, the pressure developed will be limited to a maximum value whlchwill be safe for those parts of the breaker that must contain or control it. This maximum value will be determined by the amount of liquid which has been injected into the gas accumulator. Therefore, the total amount. of gas inie'cted across the interrupting contacts l0, l I may be limited to any desired value. Under light current conditions, the heat generated by the pressure-forming arc may not be suillcient to transcylinder which normally biases the piston to f move toward the gas accumulator chamber.

This piston, however, is .held in its downwardl position as shown in Fig, 'i by means of the auxihary movable contact it when the contacts It and il are in their closed position.

The operation of my improved circuit breaker is as follows: Upon relative movement of the contacts it and il through any suitableactuating mechanism which may be connected to the cross-head H by an insulating rod 38, the auxiary movable Contact i5 will tend to move away from the auxiliary contact I8 and piston stem 3D. Since this piston is biased to move towards the gas accumulator through the medium of the spring member 37 the piston will tend to move with the auxiliary movable contact i5, but wl be retarded somewhat by the work done in transferring the liquid from the cylinder 28 to the passage 22, the distance being limited by the available 'travel for piston 2 in cylinder 2l. Upon such movement of the piston member, the liquid in the space between the top oi the piston and the top of the cylhider will be displaced through the passageways 3l, 35 and 36, and inv jected into the gas accumulator 2i in the region of the arc which is drawn between auxiliary contacts i5 and i5. A. definite amount oi liquid will be so injected, this amount being determined by the capacity o1' the space between the top of the piston and the top o!4 the cylinder when the piston is in its downward position, as shown in Fig. 1. When the piston has moved a certain denite distance, or until it is stopped by contacting the inside surface of the top of the cylinder, this definite quantity of liquid will have been injected into the gas accumulator 2l. If an adjustment is desired for the purpose of altering this quantity, a screw 28a can be provided to vary the stroke of the piston 21. During this movement the auxiliary contact l5 will have moved away from the auxiliary contact i8.

Ii' current is ilowing between the terminals I2 and i3, an arc will, of course, be drawn between these relatively movable auxiliary contacts I! and I6 upon a gap being formed therebetween. This arc will produce heat which will transform the -form all the liquid injected into a gas in the accumulator. However, a suiilcient amount of gas will be present to extinguish the interrupting arc since, it, also, will be proportionally smaller. However, under all conditions of current, a limited amount of gas will be available for arc-extinguishing, and this amount will be a maximum when all the liquid which has been introduced into the chamber 2| has been transformed to a gas.

A vent 4U may be placed between the accumulator and the reservoir so as to equalize the pressure therebetween, thereby causing the rate of transfer ci' the liquid from cylinder 28 to passage 22 to be substantially independent of the amount of pressure in accumulator 2l.

rIlhereiore, the gas which has been formed in the gas accumulator 2i will pass through the conduit 24 into the space between the relatively movable contacts i0 and ll. This will cause the arc drawn therebetween to be blown into an arc chute Il and extinguished. The arc-extinguishing gases will also pass into the arc chute 4i.-

The arc chute Il forms no part o! my invention, it being described and claimed in a copendlng application Serial No. 313,126 to David C. Prince et al., tiled November 6, 1939, and assigned to the same assignee as the present invention. This arc chute includes a fan-shaped portion 42 with barriers 4l. 'I'he arc drawn between the relatively movable contacts Il! and Il will therefore be blown by the gm which passes out through the conduit 24 into this fan-shaped passageway 42. The arc will be bent around the converging edges of the barriers I3 and blown into the space between these barriers and extinguished. A pipe Il is provided at the large end of the fanshaped arc chamber so as to provide a vent for thev exhaust gases.

I have described above, a structure in which I the total amount of gas available for arc extinguishing may be limited to any desired value. This is accomplished by introducing a denite quantity oi' liquid inw a gas-forming chamber, the amount of gas developed up to a maximum value, being dependent upon the amount of current passing through the breaker at the time of circuit-opening operation, or upon the heat of the pressure-fornung arc.

I may also provide a breaker structure in which. the gas pressure in the accumulator is kept to a substantially constant value throughout the en.- tire range of current rating of the breaker. This result may be accomplished with a structure similar to that shown in Fig. l, except that the vent 46 is stopped up or suiiiciently restricted. This structure is illustrated in Fig. 4. As has already been pointed out, the function of vent 40 is to equalize the pressure in chambers 20 and 2| so that the rate of transfer of liquid from cylinder 28 to passage 22 is independent of the pressure inside of 2|, and dependent on the characteristics of the spring 31. Therefore, this rate of transfer can be made dependent on the pressure developed in chamber 2| by causing this pressure to create a force against which the spring must push in order to raise the piston 21. This is accomplished by having only one communication between chambers 20, 2| and this being through the passage 22 through which the piston extension 30 and auxiliary contact I6 extends. Thus, when the pressure developed in the accumulator is equal to the force which the spring can bring to bear against the contact I6, the piston 21 will stop moving and no more liquid will be injected into the chamber 2|. until the gasf already developed passes out through the passage 24. Thus, assuming that the pressure-forming arc is hot enough totransform into gas all the -liquid injected into it, the\ pressure developed in the accumulator will remain at a determinable approximately constant value, or within a predetermined operating range, from the time that the pressure has built up to this value, until the circuit breaker interrupting arc has been extinguished.

In case the circuit breaker should be operated with n.0 current flowing therethrough, the liquid introduced into the chamber 2| will not be transformed into a gas. Under such conditions there must be a way of removing the injected liquid or when the breaker operates again twice the measured liquid will be available. .Thus I provide a hole 45 in the passageway 22 which is so placed in the partition I9 that it is just above the convtact I6 when thebreaker is in its fully closed position, as shown inA Fig. 1. 'I'his provides a drain, but the hole 45 will be closed by the side of the contact I6 after the breaker starts to open, so that it will not interfere with normal operation.

In Fig. 2 I have illustrated the gas generator parts and the interrupting contacts intheir circuit open position.

In Fig. 3 I have illustrated a modification of the gas blast circuit breaker which includes relatively movable contacts 46 and 41. `The contacts 46 and 41 are placed in a container 43 which is provided with transverse barriers 49 and 50. The

f barriers 49 and 5D are placed a short distance apart so that the relatively movable contacts 46 and 41 will separate in the space between the transverse barriers. The contact 41 has an extension 5| which cooperates with a tubular contact member 52. Thus auxiliary contacts 5| and `52 provide upon separation a pressure generating arc. At the base of the tubular contact 52 there is provided a piston member 53 which is adapted to move in a cylinder 54. The piston member 53 and cylinder 54 provide an arrangement for injecting a definite amount of liquid into the space between the contacts 5| and 52.

The piston is provided with a passageway 55 and a check valve 56 similar to the passageway 32 and valve 33 illustrated in Fig. 1. The tubular extension 52 is also provided with a transverse passageway 51 and a longitudinal passageway 58 similar to the passageways 34 and 35 in the piston illustrated in Fig. 1. 'I'he piston 53 is biased in an upward direction by means of a spring member 59, which also makes the electrical connection between contact 52 and cylinder 54. The contact 41 is also biased toward the contact 46 by a spring member 6I). The cylinder 54 communicates with the chamber formed between the barrier 50 and the bottom of the casing 48 by means of a pipe arrangement 6|. This chamber forms a reservoir, in which a liquid is placed, similar to the reservoir 20.

The operation of the electric circuit breaker illustrated in Fig. 3 is as follows: when the contacts 46 and 41 are moved to their closed position, contact 41 will force its extension 5| against the contact' 52, overcoming the force of the springs 59 and Sil-by means of the downward movement of the contact 46. Thus the piston 53 will rest against the bottom of the cylinder 54 and contacts 46 and 41 and piston 53 will be in electrical contact. Upon actuation of the electric circuit breaker, the contact 46 will move upwardly causing the contact 41 to tend to move with it fora certain limited distance. This will cause the upwardly biased piston stem 52 to move also. The delay caused by the dashpot action of piston 53 will cause a gap to form between the contacts 5| and 52, and ii' current is flowing, an arc will be formed therebetween. Since the upward movemenu of the piston 53 has caused a spray of liquid to be injected into the space between the contacts 5| and 52, the arc drawn therebetween will cause this liquid spray to be transformed into a gas. When piston 53 reaches the top of cylinder 54, no further liquid can be sprayed into the pressure-forming arc, thereby limiting the maximum gas pressure under the highest short circuit conditions permissible. The gas formed will move upwardly through a passageway 62 in the barrier 50, which communicates with the space between the barriers 49 and 56. Further movement of the contact 46 will cause an arc to be drawn between the interrupt- ' ing contacts 46 and 41, since further movement of the contact 41 is prevented by a stop member 63 on the contact extension 5| which contacts the bottom surface of the barrier 5U. The gas generated below the barrier 50 will passthrough the transverse passageway and interrupt the arc formed between the movable contacts 46 and 41 so as to open the circuit which is connected to the circuit breaker through lines 64 and 65.

In view of the foregoing it will be seen that I have provided an electric circuit breaker of the gas blastl type which is so constructed that the pressure of the arc-extinguishing gas which is developed by a pressure-forming arc will be limited to a maximum value of pressure, which value may be determined by the value which the gas accumulator vessel can safely withstand. This is accomplished since a definite amount of liquid is injected into the space surrounding the pressure-forming arc so that only a limited amount of liquid is present to be transformed into the gas, which is then directed through the interrupting arc formed upon separation of the main circuit breaker contacts to extinguish that arc. Furthermore, a substantially constant pressure canbe maintained in the gas accumulator during the time the interrupting arc is extinguished by allowing the pressure in the accumulator to limit the distance o! travel of the spring-biased piston which injects the liquid into the accumulator.

Modications of the particular arrangements which I have disclosed as embodying my invention will occur to those skilled in the art, so that I do not desire my invention to be limited to the particular arrangements set forth, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

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

l. An electric circuit breaker including relatively movable contacts, an arc extinguishing liquid, means for forming a pressure generating arc for transforming a portion of said liquid into a gas, said portion being limited to a predetermined part of said liquid, and means for directing said gas through the are formed upon separation of said contacts to extinguish the arc.

2. An electric circuit breaker including relatively movable contacts, an interrupting chamber for said relatively movable contacts, an arc extinguishing liquid, a gas forming chamber, means for introducing in accordance with the contact opening operation a denite quantity of said liquid into said gas forming chamber for transforming into a gas, and means for directing said gas into said interrupting chamber and through the arc formed upon separation of said contacts to extinguish the arc.

3. An electric circuit breaker including relatively movable contacts, an interrupting charnber, a gas forming chamber, an opening in said gas forming chamber communicating with said interrupting chamber, said contacts being separable in said interrupting chamber substantially adjacent said opening, means for introducing a definite quantity of liquid into said gas forming chamber, and means in said gas forming chamber responsive to the movement of said contacts for transforming liquid into a gas so that the gas will fiow out o said opening and through the gap formed upon separation of said contacts for interrupting the arc at said gap.

4. An electric circuit breaker including an interrupting chamber, relatively movable contacts in said chamber, an arc extinguishing liquid, a gas forming chamber for transforming liquid into a gas, and means for introducing a definite quantity of said liquid into said gas forming chamber so that a limited quantity of gas may be directed into said interrupting chamber and through the arc formed upon separation of said contacts to extinguish the arc.

5. An electric circuit breaker including relatively movable contacts, a gas forming chamber, an opening in said chamber, said contacts being separable substantially adjacent said opening, an

arc extinguishing liquid, means including a pressure generating arc within said gas forming chamber for transforming liquid into a gas, and means for introducing a predetermined portion of-said liquid into said-gas forming chamber so that the gas transformed will now out said opening and through the gap formed upon separation oi' said contacts for interrupting the arc at said gap.

6. An electric circuit breaker including relatively movable contacts, relatively vmovable auxiliary contacts, actuating means for said relatively movable contacts and relatively movable auxiliary contacts, said relative movement causing arcing between said contacts and between said auxiliary contacts, a gas generating chamber, said auxiliary contacts being separable in said chamber, an arc extinguishing liquid, means for introducing a definite quantity of said liquid into said chamber upon relative movement of said auxiliary contacts so that the arc therebetween will transform liquid into a gas, and means for directing said generated gas through the arc formed upon separation of said contacts to extinguish the arc.

r1. An electric circuit breaker including relatively movable contacts, a gas generator having a reservoir chamber and a gas accumulator chamber, an arc extinguishing liquid in said reservoir, means for introducing a definite quantity of said liquid from said reservoir into said accumulator chamber, means in said accumulator chamber responsive to the movement of said contacts tor transforming liquid into a gas, and means for directing said gas into the space between said relatively movable contacts.

8. An electric circuit breaker including relatively movable contacts, a gas generator having a reservoir and a gas accumulator chamber, an opening in said chamber, said contacts being separable substantially adjacent said opening, arc extinguishing liquid in said reservoir, a passage between said reservoir and said chamber, means including a spring biased piston for injecting a dennite quantity of said liquid from said reservoir through said passage into said chamber, and means in said chamber for transforming injected liquid into a gas at substantially the moment said contacts separate so that the gas will dow out said opening and through the gap formed upon separation of said contacts for interrupting the arc at said gap.

9. An electric circuit breaker including rela.- tively movable contacts, a gas generator having a reservoir and a gas accumulator chamber, an opening in said chamber, said contacts being separable substantially adjacent said opening, an arc extinguishing liquid in said reservoir, s. passage between said reservoir and said chamber, a cylinder within said reservoir, communieating means between said cylinder and said reservoir, a piston within said cylinder, said piston having a pOrtion extending into said passage between said reservoir and said chamber, a bore within said piston and extending portion, s. spring biasing said piston for movement toward said chamber, means for allowing said piston to move upon separation ot said contacts so that the measured quantity of liquid above said piston within said cylinder will be imected through said bore and passage into said chamber, and means in said chamber for transforming said injected liquid into a gas so that said gas will now out said opening and through the gap formed upon separation of said contacts for interrupting the arc at said gap. y

10. An electric circuit breaker including relatively movable contactsya gas generator having a reservoir and a gas accumulator chamber, an opening in said chamber, said contacts being separable substantially adjacent said opening, arc extinguishing liquid in said reservoir, a piston in said reservoir, spring means for moving said piston, means including said spring biased piston for injecting a definite quantity of said liquid from said reservoir into said chamber, vent means extending between said reservoir and chamber so as to substantially equalize the pressure therebetween, and means in said chamber for transforming said injected liquid into a gas at substantially the moment said contacts separate so that the gas will ilow out said opening and through the gap formed upon separation of said contacts for interrupting the arc at said gap.

11. An electric circuit breaker including relatively movable contacts, a gas forming chamber, means for forming a pressure generating arc in said chamber for transforming liquid into a gas, means for introducing a predetermined quantity of liquid into said chamber, the amount of said injected liquid which is transformed into a gas being determined by the amount of heat generated from said pressure generating arc, and means for directing said generated gas through the arc formed upon separation of said contacts :o extinguish the arc.

12. An electric circuit breaker including rela- ;ively movable contacts, a gas-forming chamber, neans in said chamber for transforming liquid nto a. gas, means for introducing liquid into :aid chamber at such a rate that the gas pres- :ure developed in said chamber remains below a maximum value, and means for directing said gas through the arc formed upon separation of said contacts to extinguish the arc.

13. An electric circuit breaker including relatively movable contacts, a .gas generator having a reservoir and a -ga-s accumulator chamber,

means in said accumulator chamber for transforming liquid into a gas, means including a lspring-biased piston for injecting liquid from said reservoir into said chamber at such a rate that the gas pressure developed in said chamber remains below a maximum value, and means lfor directing said gas into the space between within a predetermined operating range, andA means for directing said gas through the arc formed upon separation of said contacts to extinguish the arc.

OLIVER C. TRAVER.

Images