US2331255A

US2331255A - Switchgear apparatus

Info

Publication number: US2331255A
Application number: US424905A
Authority: US
Inventors: Charles P West
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1941-12-30
Filing date: 1941-12-30
Publication date: 1943-10-05
Anticipated expiration: 1960-10-05

Description

Oct. 5, 1943. c. P. WEST 2,331,255

SWITCHGEAR APPARATUS Filed Dec. 30, 1941 2 Sheets-Sheet 1 Fig 1:1" A L INVENTOR L/LJ Q; LL mar/M W- ATTO EY Oct. 5, 1943.

c. P. WEST 2,331,255

SWITCHGEAR APPARATUS Filed Dec. 30, 1941 2 Sheets-Sheet 2 WITNESSES: INVENTOR M i (/mr/es F Wesf.

ATTO EY Patented Oct. 5, 1943 2,331.255 swn'cncma APPARATUS Westinghouse Electric pany, East Pittsburgh,

Pennsylvania West, Forest Hills, Pa., asslgnor to 8: Manufacturing Com- Pa., a corporation of Application December 30, 1941, Serial No. 424,905

6 Claims.

My invention relates, generally, to switchgear apparatus and, more particularly, to the disconnecting contact devices of removable circuit breakers which are suitable for disconnecting the circuit breakers from the current conductors of a power system.

In order to increase the current carrying capacity of the disconnecting contact devices for heavy duty circuit breakers, it is customary to provide a multiple number of contact members connected in parallel-circuit relation or to increase the number of contact fingers on each contact member. Since the contact'pressure between the stationary and the movable contact members is maintained by springs which engage the contact fingers, the force required to overcome the tension of the springs during the connecting operation increases with the number of springs, thereby making it difiicult to place the circuit breaker in service.

Accordingly, an object of my invention, generally stated, is to provide a disconnecting contact structure which shall be simple and efiicient in operation and which may be economically manufactured and installed.

A more specific object of my invention is to reduce the power required to force the contact members of a disconnecting device intoengagement.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with my invention, a disconnecting contact is so constructed that the floating contact fingers meet the corresponding fixed part of the contact at difierent times, thereby making it unnecessary to expand or compress all of the springs simultaneously and, consequently, reducing the power required to force the contact members into complete engagement.

For a fuller understanding of the nature and objects of my invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view, in side elevation, of a portion of a disconnecting contact device embodying my invention;

Fig. 2 is a view, in section, taken along the line IIII ofFig. 1;

Fig. 3 is a reduced view, in front elevation, of the movable portion of the contact device;

Fig. 4 is a view, in plan, of another modification of the invention; and

Fig. 5 is a view, in device shown in Fig. 4.

Referring to the drawings, and particularly to Figure 1, the disconnecting contact device shown therein comprises a movable member ID and a stationary member II. The movable member I0 is preferably carried by a circuit breaker 0f the movable type which is disposed for rectilinear movement relative to the fixed or stationary member ll.

As explained hereinbefore, in order to increase the current carrying capacity of the disconnecting contact device, it is customary to provide a plurality of groups of contact members which are connected in parallel-circuitrelation. Thus, as illustrated in Fig. 3, in the present structure, which is for a three-pole circuit breaker, there are six groups of contact members, two for each pole, with six contacts in each group, thereby making a total of thirty-six contacts per breaker.

In the embodiment of the invention illustrated in Figs. 1 to 3, each contact is of the type described in the copending application of M. J. Rube] and H. H. Rug Serial No. 294,118, filed September 9, 1939. Each moving contact comprises a round stud I2, which may be part of a circuit breaker structure (not shown), a plurality of contact fingers l3 disposed around the periphery of the stud l2, and a plurality of helical springs l4 bent into ring formation to bias the contact fingers inwardly to maintain contact pressure between the stud. l2 and the fingers ii.

A keyway I1 is provided in the stud l2 for receiving an inwardly extending projection 18 on each of the contact fingers l3. Thus the projection 18 engages the sides of the keyway I! to retain the fingers I3 on the studs I2. The contact fingers l3 may be equally spaced around the periphery of the stud l 2 by means of a spacing plate or washer 2|, as shown in Fig. 2. The spacing plate 2| is provided with equally spaced radial notches 22 for receiving the contact fingers 13, thereby maintaining the fingers in spaced relation and also keeping them in a radial position.

The stationary member H comprises a round stud 26 into one end of which copper blades 21 may be inserted to provide for the conventional method of connecting to bus bars. The stud 26 may be secured to an insulating panel 28 in any suitable manner.

When these contacts are being forced into engagement the contact fingers l3 meet the studs 26 and a large force is required at this point to expand all of the springs l4 simultaneously. This is particularly true in structures of the type elevation, of the contact w herein illustrated in which a large number of fingers are provided in order to increase the current carrying capacity of the device. Thus, instead of having to overcome the tension of the springs for two sets of contact fingers for each pole of a circuit breaker, it is necessary to overcome the tension of the springs for twelve sets of fingers for each pole, or a total of thirty-six sets of fingers for a three-pole breaker.

In order to reduce the force required to perform'the connecting operation, the studs 26 are so disposed in stepped relation that certain groups of the floating contact fingers meet the corresponding fixed part of the contact device at different times, instead of simultaneously as in prior structures. Since the power required to slide the fingers along the fixed studs, after the springs have once been expanded, is much less than that required to expand the springs, the total force required is greatly reduced if the floating contact fingers engage the fixed studs successively as the circuit breaker is moved into position along a rectilinear path.

In the modification of the invention illustrated in Figs. 1 to 3, the contact studs 26 are of three different lengths, and the studs are so disposed that one-third of the contact fingers engage at one time, another third engage when the circuit breaker has traveled a short distance further, and the last third engage at a still further point in the travel of the breaker. Thus, instead of having to expand all of the springs I l at one time, it is necessary to expand only one-third of the springs at any one time. In this manner the total force required to perform the connecting operation is greatly reduced, thereby permitting the use Of a lighter and cheaper mechanism for performing the connecting operation and also permitting lighter structural designs for the circuit breaker and the cell in which the breaker is mounted.

It will be understood that the present invention may be utilized in circuit breaker structures in which the contact fingers i3 are mounted on the fixed portion of the structure and the studs 26 are carried by the movable portion. It will also be understood that, if desired, the studs l2 on which the contact fingers l3 are mounted may be disposed in stepped relation instead of the studs 26, as herein illustrated. Furthermore, the grouping of the contact members may be changed as desired, and the number of contact members provided. may be changed as required for circuit breakers of difierent capacities.

In the modification of the invention shown in Figs. 4 and 5, the disconnecting contact device is of the type disclosed in Patent No. 2,254,914, issued September 2, 1941, to H. H. Rugg. The device comprises a movable member 30 and a fixed member 3!. The member 3! comprises a base member 32 having a cylindrical recess therein, a plurality of contact fingers 33 having one end disposed to engage the rectangular conductor or switch blade 30 and the other end disposed in the base member 32, and a plurality-of springs 3 disposed to bias the contact fingers 33 toward each other and into engagement with the conductor 38. A pair of conducting members 35 may be secured in the base member 32 for connecting the base member to bus bars or other suitable current conductors (not shown). 1

The contact fingers 33 are assembled in the base member 32 in oppositely disposed pairs, and, as shown in Fig. 5, the fingers are connected in groups, with two pairs of fingers in each group.

A comparatively heavy contact pressure is applied at the contact points by means of the springs 34 which are mounted on bolts 36. Crimp washers 31 are provided for engaging the upper and the lower contact fingers of the group connected by each one of the bolts 36. As shown in Fig. 4, the springs 33 are disposed between the lower crimp washers 31 and the heads of the bolts 36. In this manner one bolt and one spring serve to compress two pairs of contact fingers.

In order to reduce the force required to insert the rectangular member 30 between all of the contact fingers 33 to complete the connecting operation, the member 30 is provided with a sloping end 38. Thus, it will be seen that the fingers 33 come into engagement with the member 30 successively as the

members

30 and 31 are moved toward each other in a rectilinear path. In this manner, it is not necessary to energize all the springs 33 simultaneously as would be the case if the conductor 30 did not have the sloping end 38.

As explained hereinbefore, once the contact fingers 33 are separated to compress the springs 33, the force required to slide the fingers along the conductor 30 is considerably less than that required to compress the springs. Accordingly,

the total power required to complete the connecting operation is greatly reduced by providing for successive engagement of the contact fingers.

Obviously, it is immaterial which one of the members 30 or 3| is movable relative to the other member. Furthermore, if desired, the contact fingers of the different groups could be of difierent lengths in order to secure the successive or stepped engagement between the fingers 33 and the conductor 33.

From the foregoing description, it is apparent that I have provided a disconnecting contact device which is particularly suitable for use in switchgear apparatus having a high current-carrying capacity and which materially reduces the force required for operating the apparatus. Thus, when the device herein disclosed is utilized for connecting a removable circuit breaker to the bus bars of a switchgear structure, the power required for performing the connecting operation when the circuit breaker is placed in service is greatly reduced, thereby permitting the utilization of a lighter and cheaper operating mechanism.

Since many modifications may be made in the apparatus and arrangement of parts without departing from the spirit of my invention, I do not wish to be limited other than by the scope of the appended claims.

I claim as my invention:

1. In switchgear apparatus, in combination, a plurality of groups of contact fingers for slidably engaging cooperating contact members, spring means for biasing the contact fingers against the contact members, means for mounting said contact fingers and contact members for sequential engagement when moved in a rectilinear path, and means for connecting a plurality of said groups of contact fingers in parallel-circuit relation, all of said contact fingers being of the same size and having the same current-carrying capacity.

2. In switchgear apparatus, in combination, a plurality of groups of contact fingers for slidably engaging cooperating contact members by rectilinear movement, each group comprising oppositely disposed contact fingers and common spring means for biasing the contact fingers independently of the other groups, means for mounting said groups of contact fingers for successive engagement of their cooperating contact member when moved in a rectilinear path, and means for connecting a plurality of said groups of contact fingers in parallel-circuit relation, all oil said contact fingers being of the same size and having the same current-carrying capacity.

3. In switchgear apparatus, in combination, a plurality of groups of contact fingers for slidably engaging cooperating contact members by rectilinear movement, each group comprising a plurality of contact fingers disposed around the periphery of a circular stud for receivinga cooperating stud and spring means for biasing the contact fingers into engagement with said studs, means for mounting said groups of contact fingers for successive engagement of their cooperating contact member when moved in a rectilinear path, and means for connecting a plurality of said groups of contact fingers in parallel-circuit relation, all of said contact fingers being of the same size and having the same current-carrying capacity.

4. In switchgear apparatus, in combination, a plurality of groups of contact fingers for slidably engaging cooperating contact members by rectilinear movement, each group comprising a plurality of con-tact fingers disposed around the periphery of a circular stud for receiving a cooperating stud and spring means for biasing the contact fingers into engagement with said studs,

means for mounting said cooperating studs in ofiset relation for successive engagement by their cooperating contact fingers, and means for connecting a plurality of said groups of contact fingers in parallel-circuit relation, all or said contact fingers being of the same size and having the some current-carrying capacity.

5. 1n switchgear apparatus, in combination, a plurality of contact fingers for slidably engaging a cooperating contact member by rectilinear movement, spring means for biasing groups of the contact fingers against the contact member, means for mounting said contact fingers for successive engagement of the contact member when moved in a rectilinear path, and means for connecting a plurality of said groups of contact fingers in parallel-circuit relation, all of said contact fingers being of the same size and having the same current-carrying capacity.

6. A disconnecting contact device comprising contact members disposed for relative movement in a rectilinear path, a plurality of groups of springs for maintaining contact pressure between groups of said contact member's, means for so mounting said contact members that the spring groups are energized successively by the rectilinear movement of the contact members, and means for connecting a plurality of said springcontrolled groups of contact members in parallelcircuit relation, all of said contact members having the same current-carrying capacity.

CHARLES P. WEST.