US2152478A

US2152478A - Electric switch gear

Info

Publication number: US2152478A
Application number: US83663A
Authority: US
Inventors: Charles H Hill
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1936-06-05
Filing date: 1936-06-05
Publication date: 1939-03-28
Anticipated expiration: 1956-03-28

Description

March 28, 1939. H, HILL 2,152,478

' ELECTRIC SWITCH-GEAR Filed June 5, 1936 Fig. L I

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Charles H. Hill, by Hi Attorneg.

portion of Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE ELECTRIC SWITCH GEAR.

Charles H. Hill, Drexel Hill, Pa.., assignor to General Electric Company, a corporation of New York My invention relates to electric switchgear, more particularly to switchgear of the drawn-out type wherein a circuit breaker is bodily movable to connected and disconnected positions with respect to stationary circuit connections.

Heretofore in electric switchgear of the aforesaid type, and specifically the drop-down type, various methods and mechanisms have been employed for lifting and lowering the circuit breaker to connected and disconnected positions, respectively, such as, for example, motor operated gearing, manual notching or racking means, separate auxiliary trucks, etc. In general, these devices have proved expensive, particularly for circuit breakers of moderate size, and in many cases are slow and awkward when time is an important factor.

The principal object of my invention is the provision of an improved switchgear unit wherein the circuit breaker can be manually lifted and lowered, respectively, to connected and disconnected positions easily and quickly, and wherein the manual operating mechanism is simple, efficient and inexpensive.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claimed annexed to and forming a part of this specification.

Referring to the drawing, Fig. l is an elevational View illustrating a switchgear unit embodying my invention in the disconnected position; Fig. 2 is a side view, partly in section, of a Fig. 1; Fig. 3 is a view similar to Fig. 1 showing the switchgear unit in the connected position, and Fig. 4 is a graphical illustration of forces involved in the connecting or lifting operation.

The switchgear unit shown by Fig. l is of the so-called drop-down metal clad type comprising a stationary supporting frame I and a circuit breaker 2 of suitable interrupting capacity, such as an oil circuit breaker for example, mounted for vertical reciprocal movement within the frame. In the conventional design, a sheet metal structure i forms with the frame l an enclosing housing. Coacting with the circuit breaker 2 are stationary circuit connections 3 and i which are usually connected to busbars (not shown) mounted and supported in the upper part of the housing 5. The connections 3 and 4 terminate in stationary disconnect contacts (not shown) within cylindrical insulating shells 5 and 6, respectively, secured to the frame I for coaction with the movable disconnect contacts I and 8 beneath the shells 5 and B and carried by the circuit breaker 2 The disconnect contacts may be of any suitable form, such as of the plug and socket type for example, the contacts being in engagement within the lower portions of the insulating shells when the circuit breaker 2 is elevated as indicated in Fig. 3. The disconnect contacts 1 and 8 are carried at the upper ends of the circuit breaker lead-in bushings l and 8', which extend through the breaker cover 2 and are connected to the conventional oil circuit breaker contact structure within the breaker tank. These details are omitted in the interest of clearness since the type of disconnect contacts and the internal structure of the circuit breaker have no bearing on the present invention.

Suitable breaker operating means, such as a solenoid operating mechanism for example, generally indicated at 9, is mounted on and carried by the circuit breaker by means of a bracket l6 suitably connected to the breaker cover 2. Where the mechanism 9 is electrically controlled, coacting disconnect contact structure at H and 12 connects the mechanism with the secondary or control circuits when the breaker is elevated to the connected position as shown. by Fig. 3.

For the purpose of guiding and supporting the circuit breaker 2 within the frame l, the frame is provided at one side thereof with a pair of guide rods I3 secured at their upper and lower ends, respectively, to cross members l4 and I5 forming part of the frame I. The guide rods l3 have slidably mounted thereon a saddle plate or carrier member 16 having guide rings [6 on which the breaker is supported in a manner presently described, and in a preferred form of my invention the plate is normally biased upwards against the weight of the breaker by springs l1 mounted on the guide rods 13, the weight of the breaker, however, overcoming the spring resistance as shown by Fig. 1.

From the above it will be observed that the circuit breaker 2 is supported only at one side thereof in cantilever fashion, although it shall be understood that the above described supporting and guiding arrangement can be used at opposite sides of the breaker, if desired, to equalize stresses.

Referring more specifically to the breaker supporting arrangement, the plate [6 (Fig. 2) has secured thereto at its inner side a pair of lugs l8 each having a vertical extension l8 coacting with a notched lug l9 secured to the housing of the circuit breaker 2. Two or more spaced lugs l8 are provided for carrying the breaker as indicated in Fig. 1. The breaker is vertically positioned by means of adjustable studs 20 which are secured to the plate l6 beneath the lugs l8 and abut the side of the circuit breaker housing as clearly shown by Fig. 2.

Coacting with the springs I! for elevating and lowering the breaker 2 is a manual operating device comprising a toggle including a bellcrank 2| pivotally mounted at 22 on the stationary frame I, and a link 23 pivotally connected at 24 to the plate l6. One arm of the bellcrank 2i is pivotally connected at the toggle knee 25 to the link 23 and the other arm 26 is formed as a socket member for receiving a bar 21, as indicated in Fig. 3, for manual operation of the toggle. When the bellcrank 2| is rotated counterclockwise, as viewed in Fig. 1, the toggle 2 I-3 is straightened and the circuit breaker 2 raised on its. guides to its connected position as shown by Fig. 3. The raising and lowering of the circuit breaker is of course associated with suitable interlocking means for preventing opening or closing of the disconnect contacts on load current when the breaker is closed. Such means are well known in the art and may, for example, be of the char-- acter disclosed and claimed in Paxton et al. Patent No. 2,043,113, granted June 2, 1936, for Metal enclosed switchgear. Since such interlocking means forms no part of the present invention, illustration thereof is omitted in the interest of clearness.

In the operation of switchgear of this character, a single attendant may be called upon to perform the connecting or disconnecting operation and it is, therefore, highly desirable that a moderate application of force be effective to lift the comparatively heavy circuit breaker structure throughout its entire range of movement. That is, there should be no high resistance point in the operation.

To this end, the desirable characteristics of a toggle are combined with the characteristics of a coil spring under compression so as to produce by application of a moderate manual effort a uniformly high operating force throughout the entire range of operation. In other words, when the mechanical advantage of the toggle is at its lowest value, as shown in Fig. 1, the. compression springs I1 exert their maximum upward force. As the spring force decreases during the upward travel, the mechanical advantage of the toggle increases until it reaches its maximum just prior to its straightened position near the upward limit of travel.

It will, therefore, be noted that the springs and the toggle cooperate in the most effective man-- her to provide a smooth and uniform operating force. Knowing these factors, it is a comparatively simple matter to design the toggle and springs so that the switchgear can be easily operated by a single attendant.

This point can be more clearly brought out by reference to Fig. 4 illustrating graphically forces involved in lifting the breaker from disconnected to connected position. The force-distance curve a illustrates the manual effort which would be required to lift the breaker by the toggle alone. It will be noted that a high initial effort is required. Curve b represents the manual effort required to lift the breaker by the combined arrangement of toggle and spring. No high resistance point appears and near the end of the connecting operation where the resistance is nor mally high, due to engagement of the disconnect contacts, etc., the power available is greatly in excess of that required.

The circuit breaker 2 can be held in its upper connected position by the toggle when in an overset position, as illustrated by Fig. 3, the toggle being restrained in said overset position by an adjustable stop member 28 secured to the plate l6. If desired, a latch 25a pivotally mounted on the frame I and biased toward. latching position by a spring 252) can be provided for holding the toggle in such position as a precaution against accidental lowering of the breaker. This latch, of course, would be released such as by lifting of a trip rod 9a when the breaker is tripped manually at the trip lever 92) which is also adapted to trip the breaker mechanism (not shown) in the connected position shown by Fig. 1 preparatory to lowering. The lowering or disconnecting operation is performed simply by rotating the operating bar 21 clockwise.

Although, in the construction shown by Fig. l, the weight of the breaker 2 entirely overcomes the resistance of the springs I! in. the disconnected position, it is apparent that the springs may be in addition compressed somewhat by the manually operated linkage. A simple latch, such as shown at 30, for the linkage would then. be used as indicated in Fig. 1 to hold the springs compressed. The latch 30 can be pivotally supported on the frame I by a lug 3| for engaging the carrier guide ring 16'. A stop 32 secured to the frame coacts with the latch as shown. This arrangement would give an initial impulse or acceleration to the breaker when. the latch is released by the trip 9a, preceded of course by slightly depressing the carrier to provide clearance for the latch prior to the beginning of the lifting operation. Where such a latch is used, the carrier member 16 can also be held in its lower position against the bias of the springs when the breaker is removed for inspection or replacement.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

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

1. Electric switchgear of the draw-out type comprising a stationary supporting frame, a circuit breaker adapted to be tripped by manual means bodily movable in a vertical direction in said frame to connected and disconnected positions, a linkage forming a toggle including a manually operated bell crank pivotally supported on said frame and a link interconnecting said bell crank and said breaker, said toggle being collapsed in the lowered position of said breaker, a latch mounted on said frame for engaging said toggle and holding the same in extended position when said breaker is raised to connected position, and means for releasing said latch when said breaker is tripped. by said manual means.

2. Electric switchgear of the draw-out type comprising a stationary supporting frame, a circuit breaker bodily movable in a vertical direction in said frame to connected and disconnected positions, means for raising and lowering said circuit breaker between said positions including a toggle linkage and spring structure each operatively interconnecting said frame and breaker arranged so that in the lowered position of the breaker the spring structure is under maximum tension and the mechanical advantage of said linkage is a minimum, a latch coacting with said frame and breaker for holding said spring structure under compression in said iowered position, and means independent of said spring for applying an operating force to said linkage for raising said circuit breaker upon. reiease of said latch.

3. Electric switchgear of the draw-out type comprising a stationary supportin frame, a circuit breaker adapted to be tripped by manual means bodily movable in a vertical direction in said frame to connected and disconnected positions, a manually operated toggle linkage operatively interconnecting said frame and breaker, a latch pivoted on said frame and coacting with the knee of said toggle linkage for preventing accidental collapse of said toggle, and means for releasing said latch upon tripping of said breaker by said manual means, and spring structure normally biasing said breaker in the upward direction, the resistance of said spring structure being substantially overcome by the Weight of said breaker when said breaker is in its lowered disconnected position.

4. Electric switchgear of the draw-out typecomprising a stationary supporting frame, a circuit breaker adapted to be tripped by manual means bodily movable in a vertical direction in said frame to connected and disconnected positions, a pair of vertical guide rods secured to one side of said frame, a carrier member secured to and slidable on said rods, said breaker and carrier member having coacting supporting lugs by which said breaker is hung in detachable relation on said carrier member along the inner side thereof, means including a manually operated linkage interconnecting said frame carrier member for raising and lowering said breaker, a latch coacting with said frame and linkage for holding said linkage in extended position for precluding accidental lowering of said breaker, and means for releasing said latch upon tripping of said breaker by said manual means.

5. Electric switchgear oi the draw-out type comprising a stationary supporting frame, a circuit breaker bodily movable in a vertical direction in said frame to connected and disconnected positions, vertical guide rods secured to one side of said frame, a vertically positioned carrier so cured to and slidable on said rods, said breaker and carrier having coacting supporting lugs by which said breaker is hung in detachable cantilever relation on said carrier along the inner side thereof, an adjustable member mounted on said carrier beneath said lugs adapted to abut said breaker for adjusting the position of the vertical axis thereof, and means for raising and lowering said carrier.

CHARLES H. HILL.