US2325949A

US2325949A - Electric circuit breaker

Info

Publication number: US2325949A
Application number: US430024A
Authority: US
Inventors: John D Gayer
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1942-02-09
Filing date: 1942-02-09
Publication date: 1943-08-03
Anticipated expiration: 1960-08-03

Description

Aug. 3, 1943.

34 O\\ 3 J9 Q 44 43' InQentor: John D. Gaye-r,

is Attovney.

Aug. 1943- J. D. GAYER 2,325,949

ELECTRIC CIRCUIT BREAKER Filed Feb. 9, 1942 2 Sheets-Sheet 2 I Inventor: John D. Gayen His Attorney.

Patented Aug. 3, 1943 2,325,949 ELECTRIC CIRCUIT BREAKER John D. Gayer, Springfield, Pa., assignor to General Electri York Company, a corporation oi New Application February 9,1942, Serial No. 430,024 6 Claims. (01. 200-82) My invention relates to electric switches such s circuit breakers and the like and more particularly to a restraining latch for restraining the movement of the contacts of electric switches.

It has been found that, due to vibration and other causes, the relatively movable contacts of a circuit breaker often tend to separate when the circuit breaker is closed or the contacts tend to move toward one another when the circuit breaker is open. To reduce the operating force required to operate a circuit breaker, the friction of the operating mechanism is usually held to a minimum value and, consequently, undesirable relative movement of the contcts may result in the open or closed position of the breaker with consequent danger to apparatus and perhaps even to human life. In the copending application of Carl Thumim et al., Serial No. 317,564, filed February 6, 1940, and assigned to the same assigneee as the present application, there is disclosed and broadly claimed a restraining means for holding the contacts of an electric switch in a predetermined position with means for releasing said re straining means when it is desired to operate the switch. Also, in the copending application of Carl Thumim et al., Serial No. 367,789, filed November 29, 1940, and assigned to the same assignee as the present application, there is disclosed an electric switch in which two restraining latches are provided for holding certain contacts of the switch in the open and in the closed position with means for releasing these latches at cult breaker in either its closed or its open position and which includes simple means for releasing the latching means at the desired time.

Accordingly, it is an object of my invention to provide a new and improved restraining means for the contacts of an electric switch.

It is another object oi my invention to provide a single restraining means for holding the relatively movable contacts of an electric switch in a plurality of predetermined positions with means operative upon movement of said relatively movinvention, and

able contacts for releasing the restraining means.

Further objects and advantages of my invention will become apparent as the following description proceeds 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.

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1 is a schematic diagram partly in section of an electric switch embodying my Figs. 2, 3, 4, and 5 are enlarged views of a portion of Fig. 1 indicating operating positions of the restraining means embodying my invention.

Although my invention is applicable to any types of switches having relatively movable contacts whether single-phase or polyphase, I have chosen for purposes of illustration to show my invention as applied to an air-blast circuit breaker of the fluid-operated type. Accordingly, in Fig. 1, I have shown my invention as applied to a polyphase circuit breaker l0, only the structure Illa associated with one set of contacts of the circult breaker being shown since the other poles of the circuit breaker are identical. Where I have illustrated any operating mechanism for the various phases or poles which are identical for-each phase or pole, such parts are hereinafter characterized by the same reference numeral with the letters a, b, or 0, depending upon the particular phase or pole of the circuit breaker. Circuit breaker I0 is illustrated as of the cross-blast type and the pole Illa is illustrated as comprising a stationary contact Ha and a movable contact [2a arranged to be operated so as to rate, an arc is drawn between arcing tips l6a and l2'a. Immediately after separation of the cation.

Each of the movable contacts of the various poles or phases of circuit breaker Ill, such as I2a,

which alone is illustrated, is connected to corresponding individual operating rods, such as Illa.

These operating rods, only |9a of which is illustrated, are'connected to one end of suitable levers 20, which levers have the other ends thereof provided with crossheads 2| arranged to slide in guides 22. Only the mechanism including members 20a, 2Ia, and 22a of pole "la is illustrated, however. Each of the levers 20 has an intermediate point thereon pivotally connected to bell cranks 23a, 23b, and 230, respectively, which, in turn, are pivotally mounted on

fixed supports

24a, 24b, and 240. This arrangement of cranks 23 and levers I provides a straight-line motion of the contacts I2 in arc chutes I3. In order that the movable contacts I2 associated with all the poles of circuit breaker I0 are simultaneously actuated, bell cranks 23a, 23b, and 230, are interconnected by a horizontally reciprocating operating rod 25. As illustrated, each of the bell cranks 23 is provided with suitable bufiers, only 26a of which is illustrated, to cushion the closing and opening movements of the operating mechanism and movable parts of circuit breaker I0.

Any suitable means may be provided forproducing relative movement between the contacts II and I2 of circuit breaker III. In Fig. 1, this means is illustrated as a fluid motor, generally indicated at 21', including a'cylinder 28 and a piston 29 operatively connected through a connecting rod 30, links 3| and 32, and a crank 33, with the bell cranks 23a, 23b, and 230 for operating the contacts of circuit breaker III.

In order to operate fluid motor 27 as well as to supply a blast of fluid through conduits II, only IIa of which is shown, for arc-extinguishing purposes, a source of fluid under pressure 34 is provided, which may preferably be air under pressure. This source of air under pressure 34 is connected through a suitable blast valve 35 to conduit Ila as well as to the corresponding conduits for the other poles of circuit breaker III and, to this end, a manifold (not shown) may be provided between these conduits I1 and blast valve 35. Blast valve 35 is preferably constructed as disclosed in copendlng application Serial No. 343,002, filed July 28, 1940, on behalf of Carl Thumim, now Patent 2,315,991 and assigned to the same assignee as the present application. Any suitable means may be provided for operating blast valve 35 although, in Fig. 1, I have illustrated this operating means as comprising a sliding bar 36 operatively connected to piston 29 of fluid motor 21 and having one or more cams, such as 31, mounted thereon. Movement of piston 29 causes cam 31 to engage a cam follower 38 to open blast valve 35 through pivotally mounted lever 39. As illustrated schematically in Fig. l, cam 31 will produce a blast of the same duration during both the opening and closing movements of the circuit breaker. However, it may be desirable in certain cases to have no blast of fluid during the closing operation of the circuit breaker or to have a blast of shorter duration during such closing operation, in which case, an additional cam having,a different operating face than cam 31, will be provided with means for rendering cam 31 inefiective to open the blast valve 35 during the closing operation of the circuit breaker.

Such an arrangement is disclosed and claimed in United States Letters Patent 2,287,578, filed jointly for Carl Thumim and me, and assigned to the same assignee as the present application.

The source of fluid 34 is also connected with the respective ends of cylinder 28 through a solenoid-operated circuit-breaker opening valve 40 and a solenoid-operated circuit-breaker closing valve 4|. It should be understood by those skilled in the art that opening valve 40 and closing valve 4| are preferably interlocked mechanically as in copending application Serial No.

317,564, referred to above, or interlocked electrically so that the opening valve 40 is given preference to permit opening of the circuit breaker even though a fault exists at the instant of closing of circuit breaker III. The restraining means of my inventiornsenerally indicated at 42, comprises a single pivotally mounted member or latch 43 pivoted at 44 and biased to rotate in a clockwise direction by spring means 45. Asuitable stop 46 is provided to limit the maximum clockwise rotation of latch 43. Restraint or latching of the contacts I2 of circuit breaker I0 and the operating mechanism associated therewith is obtained by engagement of the cam face 43' of latch 43 with the roller 41 attached to the end of crank 33 associated with link 3|. With the latch 43 in the position indicated in Figs. 1 and 2, the contacts I2 and the operating mechanism are held or restrained in the position assumed when circuit breaker I0 is closed and vibration or the like cannot cause contact separation. In Fig. 4, on the other hand,

the latch 43 is indicated in the position where face 43' thereof engages the roller 41. so as to hold or restrain the operating mechanism and the contacts l2 of circuit breaker III in the posi ton which these members assume when the circuit breaker is open and again vibration or the like cannot cause relative movement of the contacts II and I2.

In order to release latch 43 and permit movement of contacts I2 so as to open the circuit between terminals I4 and I5 when the mechanism isin the position indicated in Figs. 1 and 2, I provide a lost-motion mechanism between link 3| and crank 33 which comprises a slot 48 in link 3| and a pin 49 cooperating therewith and mounted in crank 33. Also latch 43 is provided with a cam face 43" which cooperate with a roller 50 mounted on link 3 I. Upon initial movement of piston 29 to the left from the position indicated in Fig. 1, link 3| is moved to the left so that roller 50 operating on cam surface 43" causes counterclockwise rotation of latch 43 to the position indicated in Fig. 3. Also, by virtue of the slotted connection between link 3| and crank 33, no movement of the contacts I2 of circuit breaker III has resulted until latch 43 is completely released and such movement is permitted. It should also be noted, that, with this slotted connection between link 3| and crank 33, blast valve 35 is opened to insure a blast of fluid adjacent relatively movable contacts II and I2 prior to any movement of the contacts as is disclosed and broadly claimed in the copending applicatiomSerial No. 317,564, referred to above.

In order to release latch 43 from the restraining position indicated in Fig. 4 when the circuit breaker I0 is open, I again use the same tripping means, namely, the slotted connection between 3| and crank 33 for release of latch 43. The end 3| of link 3| is adapted to engage the projecting tip 5| of the back plate 5| of latch 43.

With this arrangement, the initial movement to the right of piston 29 when the circuit breaker is open by virtue of the lost-motion connection between link 3| and crank 33 will cause the end 3| of link 3| to rotate latch 43 in a counterclockwise direction to the position indicated in Fig. 5, whereupon roller 41 is released so that subsequent closing movement of circuit breaker l may be permitted.

In view of the detailed description included above, the operation or my double-latched restraining means will be obvious to thos skilled in the art. By means of a single latch 43, I have provided an arrangement in which an electric switch may be held in either its open or its closed position without danger of movement or the relatively movable contacts due to vibration or the like. Furthermore, th lost-motion connection between link 3| and crank 33 eifects the unlocking of latch 43 from either 01' its two restraining positions.

It will be apparent to those skilled in the art that my invention is not limited to the particular construction shown but that changes and modifications may be made without departing from the spirit and scope or my invention and I aim in the appended claims to cover all such changes and modifications.

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

1. In combination with an electric switch comprising a plurality of relatively movable contacts, means for producing relative movement between said contacts, a restraining means comprising a single movable member constructed so as to hold said relatively movable contacts in a plurality of predetermined positions, and means operative upon operation of said first-named means for releasing said restraining means at each of said predetermined positions of said relatively movable contacts.

2. In combination with an electric switch comprising a plurality of relatively movable contacts, means for producing relative movement between said contacts, a restraining means comprising a single movable member constructed so as to hold said relatively movable contacts in either the fully open or the fully closed position, and means operative upon operation of said first-named means for releasing said restraining means at either the fully open or the fully closed position 01' said electric switch.

3. In combination with an electric switch comprising a pair of relatively movable contacts, means for producing relative movement between said contacts, a single restraining means constructed so as to hold said relatively movable contacts in either the fully open or the fully closed position 01 said electric switch, and a lostmotion connection interposed between said firstmentioned means and one of said relatively movable contacts for releasing said restraining means at both the fully open and fully closed position oi said electric switch.

4. In combination with an electric switch comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a single pivotally mounted restraining latch constructed so as to lock said electric switch open against closing movement due to vibration or the like when in one position and to hold said electric switch closed when in another position, and means including a lostmotion connection interposed between said motive means and one of said relatively movable contacts for releasing said restraining latch from either of its locking positions upon initial operation of said motive means.

5. In combination with an electric switch comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a single pivotally mounted restraining latch constructed so as to lock said electric switch open against closing movement due to vibration or the like when in one position and to hold said electric switch closed when in another position, and means including a lost-motion connection comprising a pin and slot arrangement interposed between said motive means and one of said relatively movable contacts for releasing said restraining latch from either of its locking positions upon initial operation of said motive means.

6. In combination with an electric switch comprising a pair of relatively movable contacts, a fluid motor for producing relative movement between said contacts, an operating mechanism for interrelating said fluid motor and one of said relatively movable contacts, a pivotally mounted latch including a pair of cam faces constructed so that one or said cam faces engages with said operating mechanism to lock said electric switch against closing movement due to vibration or the like when in the substantially fully open position and the other of said cam faces engages with said Operating mechanism to lock said electric switch against opening movement when in the substantially fully closed position, and means including a lost-motion connection interposed between said fluid motor and one of said relatively movable contacts for causing disengagement of each of said cam faces from said operating mechanism in either of the locking positions of said latch upon initial operation or said motive means to permit subsequent relative movement of said contacts.

' JOHN D. GAYER.