US2376818A - Disconnecting contact - Google Patents

Description

May 22, 1945. M. J. RUBEL DISCONNECTING CONTACT Filed Jan. 6, 1943 2 Sheets-Sheet 1 INVENTOR Maxffubel.

I ATTO EY May 22, 1945. M. .1. RUBEL 2,375,813

DISCONNECTING CONTACT Filed Jan. 6, 1943 2 Sheets-Sheet 2 INVENTOR Maxjeubel.

v f 0 Arro1$ EY WITNESSES:

Patented May 22, 1945 mscommcrmc CONTACT Max J. Rubel, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company,

Pittsburgh, Pa., a corporation of Pennsylvania Application January 6, 1943, Serial No. 471,444

9 Claims.

My invention relates, generally to electric switches and, more particularly, to the disconnecting contact members 01' electric switches suitable for disconnecting removable circuit breakers and similar apparatus from the current conductors of a power system.

A conventional disconnecting contact assembly of the type disclosed in Patent No. 2,265,006, issued December 2, 1941, to M. J. Rubel and H. H. Rugg, utilizes circular or garter springs wrapped around the contact segments or fingers to exert radial contact pressure on the contact fingers. There is a possibilityof a garter spring breaking and grounding the circuit breaker or the bus.

Furthermore, as a practical matter, there is a design limitation on the capacity of a contact with which garter springs can be utilized, since the effective radial pressure on the contact fingers decreases as the numberof contact fingers increases. This function is expressed by the formula:

Pc=contact pressure P.=garter spring pressure n=number of contact fingers Therefore, there isa rather definite limitation on the current-carrying capacity of disconnecting contacts utilizing circular or garter springs.

In order to avoid the use of garter springs, it has been proposed to utilize flat springs for ap-- plying radial pressure to the contact fingers of a disconnecting contact of the circular type. For example, in the disconnecting contact assem bly disclosed in Patent No. 2,300,893, issued November 3, 1942, to B. I. Hayford, the contact members are disclosed'by'a cylindrical sleeve which also functions to maintain the contact fingers in spaced relation. A fiat spring is disposed between each of the contact fingers and the sleeve to provide contact pressure between the contact fingers and the round studs or conductors which are bridged by the contact fingers. However. the foregoing structure is rather difiicult to manufacture and assemble.

An object of my invention, generally stated, is to provide a disconnecting contact assembly which shall be simple and efilcient in operation and which may be economically manufactured and installed.

provide a disconnecting contact assembly which may be designed for any desired current-carrying capacity.

Another object of my invention is to provide a disconnecting contact assembly which may be easily assembled.

A further object of my invention is to improve the conductivity between the contact fingers and the curved surface of the conductors of a disconnecting contact assembly.

Still another object of my invention is to provide for retaining the contact fingers and their associated springs in position in a disconnecting contact assembly.

A still further object of my invention is to prevent the possibility of accidental disengagement of the contact assembly from its supporting member.

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

In accordance with one embodiment of my invention, ridges are provided on the portions of each of the plurality of contact fingers which engage a round stud, thereby securing a definite double point contact with the curved surface of the stud. The contact fingers and the pressure springs are retained in position by a spacing ring which is so disposed that there is a biasing force in the direction of the stud on which the fingers are mounted, thereby preventing the possibility of accidental disengagement of the contact assembly.

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, partially in section and partially in elevation, of a disconnecting contact assembly embodying my invention;

Fig. 2 is a view in section, taken along the line II-II of Fig. 1;

Fig. 3 is a view, in elevation, of one of the springs utilized in the disconnecting contact assembly;

- IV-IV of Fig. 1;

Fig. 5 is a view, in elevation of a modification of the invention;

Fig. 6 is a view, in section, taken along the line VI-VI of Fig. 5;

Fig. "7 is a view, in elevation. of one of the springs utilized in the structure shown in Fig. 5; and

. the stud I1, a

Fig. 8 is a view, in elevation, oi. one oi. the

- contact fingers utilized in the structure shown in Fig. 5.

Referring to the drawings, and particularly to Figure 1, the disconnecting contact assembly shown therein comprises two parts, a movable contact III and a stationary contact II. The stationary contact I I comprises a round stud I2 that is mounted in a porcelain bushing I3. The stud I2 is provided with a shoulder I4 that is disposed on one side of a partition I5, in the bushing I3. A nut I6 may be threaded onto the stud I2 on the other side of the partition I5, thereby securely fastening the stud I2 in the bushing I3.

The movable contact I comprises a round stud I1, which may be part of a circuit breaker structure (not shown), and a plurality of contact fingers I8 disposed around the periphery of the stud I1. In order to improve the conductivity between the contact fingers and the curved surfaces of the round studs, the end portions of each finger are provided with longitudinal ridges I9 which engage the studs. Since two ridge are provided at each end of a finger, a definite double point contact is secured with each round stud, provided the distance between ridges is less than the diameter of the stud.

As shown in Figs. 1 and 2, an individual spring 2|, of a fiat type, is provided for each one of the contact fingers I8. As shown in Fig. 3, a slot 22 may be provided at one end of each spring and a hole 23 may be provided near the other end. A pin or projection 24 may be provided near one end of each finger for the slot 22 and a similar pin or projection 25 may be provided near the other end for the hole 23. In this manner lateral movement of the spring relative to the finger is prevented but a slight longitudinal movement is permitted when the spring is compressed.

A groove 26 is provided near the end of the stud I1 for receiving an inwardly extending projection 21 on each of the contact fingers I8, thereby retaining the fingers on the stud when the movable contact III is disengaged from the stationary contact I I. The groove 26 is preferably formed by reducing the diameter of the end of the stud I1 and securing a plate 28 on the end of the stud by means of screws 29. In this manner all 01' the fingers may be placed on or removed from the stud I! as an assembled unit.

In order to retain the contact fingers in their correct angular position around the periphery of spacing ring 3| is provided. As shown in Fig. 1, the ring 3| is of a reversed Z shape in cross ection and is provided with suitably shaped openings 32 for the contact fingers I8 and the springs 2 I. Suitable projections or shoulders 33 are provided at the top of each opening 32 for notches 34 disposed near the middle of the edges of each spring 2|. In this manner longitudinal movement of the spring and the contact finger through the ring 3| is prevented after they are assembled in the ring and the point of application of pressure on the spring is definitely fixed.

When the movable contact I0 is disengaged from the stationary contact I I, the fulcrum point 35 of each finger I8 on the ring 3| at the bottom of the opening 32 is offset from the center of the finger and also from the point of application of pressure on the spring 2|. In this manner the exerted spring pressure is definitely biased in the direction of the circuit breaker stud I'I, thereby preventing the possibility of accidental disengagement of the contact fingers from the stud I1. Furthermore, the contact fingers I8, the springs 2| and the ring 3| can be assembled together as a unit and then slipped over the end of the stud prior to the attaching oi the plate 28, which, as explained herelnbei'ore, retains the fingers on the stud.

In the modification of the invention shown in Figs. 5, 6, '7 and 8, in which like parts are designated by the same reference characters as in Figs. 1 to 4, pressure is applied to the springs 2| by a ring 4| which encircles the springs at their midpoint. A depression 42 is provided in each of the springs 2| for the ring 4|.

The contact fingers I8 may be equally spaced around the periphery of the stud II by means of a spacing plate 43 having radially extending pro- J'ections 44 thereon. As shown, beveled notches 45 are provided in opposite sides of each finger for the projections 44. In this manner the fingers are maintained in spaced relation and in a radial position. The spacing plate 43 is retained in position by the notches 45.

It will be noted that the spacing plate is so located with reference to the ring 4I that the exerted spring pressure is biased toward the stud I'I when the moving contact is disengaged from the stationary contact. The spacing plate limits the inward movement of the disengaged ends oi the contact fingers, thereby preventing collapsing of the contact assembly. When the contact is in the engaged position, the spacing plate 43 fioats between the fingers and does not function as a fulcrum point.

In the present structure the groove 26 is cut in the stud I1 and the end portion 28 is integral with the stud. The contact assembly may be placed on the stud I! by compressing the upper ends of the fingers I8 together sufiiciently to permit the projections 21 to pass over the stud and into the groove 26.

From the foregoing description, it is apparent that I have provided an improved disconnecting contact which is simple in structure, low in cost and has a higher current-carrying capacity than previous contacts of a similar type. Furthermore, the present contact may be made in any desired size without overstressing any of its members.

Since numerous changes may be made in the above described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a ring encircling said fingers at substantially their midpoint, a fiat spring disposed between each of said fingers and said ring for maintaining contact pressure between the stud and the finger, each of said springs having means therein at substantially its midpoint for retaining said ring in position, means on the fingers for positioning the springs on the fingers, and means for retaining the contact fingers in spaced relation around said stud.

2. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a ring encircling said fingers at substantially their midpoint, a flat spring disposed between each of said fingers and said ring for maintaining contact pressure between the stud and the finger, each of said springs having means therein at substantially its midend of the point for retaining said ring in position, means on the fingers for positioning the springs on the fingers, means on the stud cooperating with means on the fingers for limiting longitudinal movement of the fingers, and means for retaining the contact fingers in spaced relation around said stud.

3. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a ring encircling said fingers at substantially their midpoint, a fiat spring disposed between each of said fingers and said ring for maintaining contact pressure between the stud and the finger, each of said springs having a depression therein at substantially its midpoint for retaining said ring in position, means on the fingers for positioning the springs on the fingers, means on the stud cooperating with means on the fingers for limiting longitudinal movement or the fingers, and means disposed inside or the fingers for retaining the fingers in a radial position and in spaced relation around the stud.

4. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a ring encircling said fingers at substantially their midpoint, a fiat spring disposed between each of said fingers and said ring for maintaining contact pressure between the stud and the finger, each of said springs having a depression therein at substantially its midpoint for retaining said ring in position, means on the fingers for positioning the springs on the fingers, and means on the stud cooperating with means on the fingers for limiting longitudinal movement of the fingers, a floating plate disposed inside of said fingers for equally spacing said fingers in a radial position, said plate having radially extending projections thereon, and said fingers having notches therein for said pro- Jections.

5. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a ring encircling said fingers at substantially their midpoint, a flat spring disposed between each or said fingers and said ring for maintaining contact pressure between the' stud and the finger, each of said springs having a depression therein at substantially its midpoint for retaining said ring in position, means on the fingers for positioning the springs on the fingers, means on the stud cooperating with means on the fingers for limiting longitudinal movement oi the fingers, and a floating plate disposed inside of said fingers for equally spacing the fingers in a radial position, said plate being offset from said ring a predetermined distance.

6. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a floating spacing ring having an opening therein for each of said fingers, a fiat spring disposed in each of said openings between the finger and the ring for maintaining contact pressure between the stud and the finger, each or said springs having means therein at substantially its midpoint cooperating with means on the ring for retaining said ring in position, and means on the fingers for positioning the springs on the fingers. T

7. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a floating spacing ring having an opening therein for each or said fingers, a fiat spring disposed in each of said openings between the finger and the ring for maintaining contact pressure between the stud and the finger, each of said springs having means therein at substantially its midpoint cooperating with means on the ring for retaining said ring in position, means on the fingers for positioning the springs on the fingers, and means on the stud cooperating with means on the fingers for limiting longitudinal movement of the fingers.

8. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery of the stud, a spacing ring having an opening therein for each oi. said fingers, a flat spring disposed in each or said openings between the finger and the ring for maintaining contact pressure between the stud and the finger, the cross section of said ring being such that the bottoms of said openings are offset from the tops of the openings a predetermined distance.

9. A disconnecting contact comprising, a round stud, a plurality of contact fingers disposed around the periphery oi the stud, a spacing ring having an opening therein for each of said fingers, a flat spring disposed in each of said openings between the finger and the ring for maintaining contact pressure between the stud and the finger, said ring being a reversed Z shape in cross section, thereby oil'setting thebottoms or said openingsa predetermined distance from the tops of the openings.

MAX J. RUBEL.

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