US2581822A - Gas blast circuit breaker having parallel connected impedance - Google Patents

Description

H. THOMMEN ETAL PARALLEL CONNECTED IMPEDANCE Filed July 15, 1949 GAS BLAST CIRCUIT BREAKER HAVING Jan. 8, 1952 764% ZMMW & M 7% JNVENTORS.

"Patented Jan. 8, 1952 GAS BLAST CIRCUIT BREAKER HAVING PARALLEL CONNECTED IMPEDANCE lions Thommen and Hans Meyer, Baden, Switlerland, assignors to Aktiengesellscliaft Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Application July 15, 1949, Serial No. 104,918 In Switzerland July 23, 1948 8 Claims.

The present invention relates to circuit breakers and in particular to those of the type in which the load contacts are separated under the action of a blast of pressure gas such as compressed air. In the usual arrangement one of the contacts is made hollow and the other in the form of a piston that is normally spring loaded into contact with and closes the mouth of the hollow contact to keep the circuit through the contacts closed. When the pressure gas is applied to the junction of the-contacts, the piston contact moves away from the stationary hollow contact thus opening the electrical load. The are created upon separation of the contacts is bathed on all sides by the gas flowing under pressure and hence the general arrangement is highly satisfactory for interrupting heavy loads.

For improving the operation of the breaker and also increasing its load rating as well as to prevent a rapid rise in the contact voltage after the load current wave has passed through the zero point, it has been the practice to arrange for the temporary connection of an impedance such as a resistance unit in parallel with the contacts of the breaker when the latter are opened.

The object of the present invention is to provide an improved construction for switching in the parallel impedance that features auxiliary contacts for this purpose, these contacts being arranged to be closed in a positive manner by the pressure gas simultaneously with opening of the load contacts and thereafter opened automatlcally after a predetermined time delay so that the auxiliary impedance is connected in parallel with the load contacts only for a limited period.

In the accompanyin drawings Fig. 1 is a vertical view of the improved circuit breaker with certain parts broken away to show structural details; and Fig. 2 is a fragmentary view in vertical section illustrating a modified construction for the auxiliary switch chamber that houses the impedance element and its associated control contacts.

Referring now to the drawings, the circuit breaker includes a hollow insulator column I upstanding upon a tank II that contains air under pressure. At an intermediate point along the column, a ring like plate I! of conductive material is interposed. This plate includes a terminal I 3 for the connection of line conductor L; it supports a conductive cylinder I 4 arranged concentrically within the insulator colman that carries a conductive piston contact 55 loaded by spring IS in an upward direction; and also serves as a. support for a transversely extending conduit 11 also of conductive material.

A cap member i8 also of conductive material and carried at the top of the insulator column l0 includes a terminal 1 9 for connection of the other line terminal L, a transversely extending conductive arm'2ll, and it also serves to support 2. depending hollow contact member 23. The latter is provided with a discharge outlet 26 leading to atmosphere and the outlet may if desired include a time delayed reclosing valve (not shown) as described and shown in the previously issued United States Patent No. 2,417,274 if the load contacts are to be maintained in a separated condition "by the pressure gas subse-- quent to their separation.

The parallel connected impedance and con tacts controlling the same may be arranged in various ways but the preferred way as illustrat= ed in the drawings is to arrange these components within an auxiliary insulator column supported in a vertical position between arm and the outer, enlarged end lid of conduit ll.

Upstanding upon the outer end of conduit ll within the auxiliary column. 25 and surround ing the conduit outlet lib is a stationary cylinder 26 of conductive material containing a conductive piston 27 loaded by spring 28 in a downward direction. A rod 29 carried by piston 2? extends upwardly through an opening 36 in the top end wall of cylinder 28 and terminates in a contact member 3i which is adapted to engage a stationary contact 32 supported in column 25. One end of the resistor element is connected to contact 32 and the other end to the outer portion 20a of arm 29 that is fashioned into a cap closing oil the upper end of the auxiliary column 25.

Cylinder 26 includes a port 34 which upon upward motion of piston 21 places the lower portion of the cylinder in communication with the interior of column 25 thus to permit the compressed air to flow into the column from conduit ll. Due to the opening 34 the air pressure on opposite sides of the piston 21 then becomes equalized and the latter is then free to move to its lowermost position under the restoring force of the loading spring 28. Below the latter position, a check valve 35 is placed in the wall of cylinder 26. This valve opens inwardly upon a drop of the air pressure in conduit I! to facilitate removal of the compressed air from the interior of the column 25 as well as from the interior of cylinder 26 above piston 21.

From the above detailed description it is believed that-operation of the device can now be clearly understood. Summarizing, however with the components in the positions shown in the drawings, the load circuit lines L-L' are electrically connected through closed contacts I5, 23, and resistor 33 is disconnected through the open contacts 3|, 32. To open the circuit lines L-L. compressed air admitted to column Ill from tank H through a valve (r ot shown) flows upwardly to the junction of contacts I5, 23 causing the piston contact Hi to move downwardly and thereby separate it from the hollowcontact 23. This breaks the load connections L--L' and the are formed upon separation of the contacts is bathed on all sides by the compressed 'air which now flows upwardly through the hollow contact 23 and is discharged to atmosphere through outlet 24.

Compressed air flowing upwardly through column It also passes into conduit ill and applies an upward pressure against piston 2T! causing the latter to move upward and effect closure of the auxiliary contacts Si, 32 thus switching in the resistor 33in parallelwith the main load contacts I5, 23 with its attendant advantages as previously pointed out. The auxiliary contacts til, 32 close substantally at the same instant that the load contacts i5, 23 open but open automatically after. a period determined by the position and size of the port M in cylinder 26 as well as the size of opening 30 since these factors govern the rate at which the difierential in air' pressure on opposite sides of the piston 2? decreases to an ultimate value or zero. When the differential in gas pressure acting upwardly on piston 2? falls below the pressure exerted downwardly on the piston by the loading spring 28, the latter'then causes the piston to move downwardly to the starting position shown in the drawings thus separating contacts 39, 32 and taking the resistor 38 outof the circut. When the supply of compressed air to column it is turned off, check valve opens to empty the auxiliary column 25 as well as the interior of cylinder 26 above piston 2?! of the pressure air to ready the circuit breaker for a repeat operation.

In the modified construction illustrated in Fig. 2 the auxiliary column 25 is provided with a. transverse partition 36 dividing the interior into an upper chamber Si in which the resistor 33 is placed, and a lower chamber 38 that houses the auxiliary contacts 3!, 32 and the remainder of the control components associated therewith.

In conclusiomit is to be understood that the illustrated construction while. preferred may nevertheless be departed from without however departing from the spirit and scope of the invention asdefined in the appended claims. Also while a circuit breaker with but a single set of load contacts. is illustrated, the novel construction of the parallel impedance connecting device may be applied equally as well to circuitbreakers having a plurality of series connected sets of load contacts arranged in superposed relation as for example as shown in the aforesaid Patent. No. 2,417,274.

We claim:

1. Circuit breaker apparatus comprising a pair of normally closed load contacts separable upon an applicationof pressure gas thereto, an impedance, a'set of normally openauxiliary con- .tacts actuated by said pressure gas and'closed upon an application of said pressuregas to said load contacts disposed within an insulator shut oil! from the atmosphere, said auxiliary contacts being i'or connecting said impedance in parallel with said load contacts upon opening of the latter, and time delayed means restoring said auxiliary contacts to openposition upon termination of a predetermined closure period thereof.

2. Circuit breaker apparatus as defined in claim 1 wherein the means restoring said auxiliary contacts to open position comprises a loading spring cooperative with one of said auxiliary contacts, the force applied by said spring being counter to that applied by said pressure gas.

3. Circuit breaker apparatus comprising a pair of. normally closed load contacts separable in response vtoan application of pressure gas thereto, an impedance, and means for connecting said impedance in parallel with said load contacts, said connecting means including a pair of normally open auxiliary switch contacts disposed within an insulator shut off from the atmosphere and means controlled by said pressure gas for closing said auxiliary contacts for a predetermined period thereby to temporarily connect said impedance in parallel with said load contacts, the closure period of said auxiliary contacts be,- ing independent of the flow of pressure gas.

4. Circuit breaker apparatus comprising a pair of normally closed load contacts separable upon an application of pressure gas thereto, a set of normally open auxiliary contacts disposed within an insulator shut off from the atmosphere, an impedance connected upon closure of said auxiliary contacts in parallel with said load contacts, means actuated by said pressure gas for affecting closure of said auxiliary contacts, and means applying a force counter to that applied by said pressure gas actuated auxiliary contact closure means and effective to reopen said auxiliary contacts upon expiration of a predetermined closure period.

5. Circuit breaker apparatus comprising a pair of normally closed load contacts separable .upon an application of pressure gas thereto, an impedance, circuit means normally open at a set of auxiliary contacts for connecting said impedance in parallel with said load contacts, a piston connected to one of said auxiliary contacts, a cylinder within which said piston is slidable, a spring loading said piston to a position of rest wherein said auxiliary contacts are separated, means for introducing said pressure gas into said cylinder at one side of said piston to efiect movement of said piston against the action of said loading spring closing said auxiliary contacts and time delay means eiiecting equalization of gas pressure on both sides of said piston thereby to permit said loading. spring to return said piston to said rest position.

56. Circuit" .br'eaker apparatus comprising a mainhollow insulator column, upper and lower Spaced conductive plate members carried by said column,"a pair of normally closed load contacts supportedrespectively by said plates within said column and which contacts are separable upon an application ofpressure gas thereto admitted to said column, a pair of conductive membersextending laterally from said plate members, an auxiliaryhollow insulator column supported between said' conductive members, one of 'said conductive' members being tubular and in communication with the'interior of said main insulator column for'also admitting said pressure "gas; to said auxiliary column, an impedance within said auxiliary column, a pair of normally open contacts disposed within a chamber portion of-said 5 auxiliary column shut off from the atmosphere, one end of said impedance being electrically connected to one of said conductive members and the other endthereof to one of said auxiliary contacts, and the other of said auxiliary contacts being electrically connected to the other of said conductive members. a cylinder into which pres- -sure gas is admitted, a piston connected to one 01' said auxiliary contacts and adapted to slide in said cylinder, a spring loading said piston to a position of rest wherein said auxiliary contacts are separated, said piston being movable upon application of the said pressure gas to one side of said piston against the counteraction of said spring to effect closure of said auxiliary contacts and time delay means effecting a gradual reduction in the difl'erence in gas pressure at opposite sides of said piston thereby to permit said loading spring to return said piston to said rest position.

7. Circuit breaker apparatus as defined in claim 6 wherein said time delay means is constituted by a port through the side wall of said cylinder and which places both sides of said piston in communication with each other upon a predetermined displacement of said piston.

8. Circuit breaker apparatus as defined in claim 6 wherein said impedance and auxiliary contacts are contained within separate chambers in said auxiliary column established by partition means in the same.

HANS THOMMEN. HANS MEYER.

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

UNITED STATES PATENTS Number Name Date 2,453,555 Thommen Nov. 9, 1948 FOREIGN PATENTS Number Country Date 538,672 Great Britain Aug. 12, 1941 546,399 Great Britain July 10, 1942

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