US2310755A

US2310755A - Electric circuit breaker

Info

Publication number: US2310755A
Application number: US422387A
Authority: US
Inventors: Thumim Carl
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1941-12-10
Filing date: 1941-12-10
Publication date: 1943-02-09
Anticipated expiration: 1960-02-09

Description

C. THUMIM ELECTRIC CIRCUIT BREAKER Feb. 9, 1943.

Filed D80. 10, 1941 Inventor: Carl Thumim,

b Hi5 Attorney.

Patented Feb. 9, 1943 ELECTRIC CIRCUIT BREAKER Carl Thumim, Yeadon, Pa., assignor to General Electric Company, a corporation of New York Application December 10, 1941, Serial No. 422,387

(Cl. Nt -82) 6 Claims.

My invention relates to electric circuit breakers and more particularly to circuit breakers which depend for their operation at least in part upon a source of fluid under pressure.

Where the operation of the circuit breaker depends to some extent at least upon a source of fluid under pressure, there is always the possibility of a reduction or complete failure of the pressure of this source of fluid and, if the circuit breaker under these conditions was permitted to operate to close or open the circuit, great damage both to the circuit breaker and associated apparatus might result.

Accordingly, it is an object of my invention to provide an electric circuit breaker depending at least in part upon a source of fluid under pressure for proper operation thereof in which the breaker is mechanically locked in the open or closed position in the event that the pressure falls below a predetermined value.

It is a further object of my invention to provide a new and improved electric circuit breaker which depends at least in part upon a source of fluid under pressure for proper operation thereof.

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 drawing in which Fig. l is a schematic diagram partly in section of an electric circuit breaker embodying my invention, and Fig. 2 is an enlarged perspective view partly in section of a portion of the apparatus shown in Fig. 1.

For explanatory purposes, I have illustrated my invention as applied to a circuit breaker of the cross fluid-blast type, such as is disclosed and claimed in United States Letters Patent 2,284,842, granted June 2, 1942, and assigned to the same assignee as the present application. It will, of course, be understood by those skilled in the art that my invention is equally applicable to other types of circuit breakers which depend for their operation to a certain extent atleast upon a source of fluid under pressure.

Referring now to Fig. 1 of the drawing, I have illustrated my invention as employing a fluidblast circuit breaker ID of the cross-blast type comprising a stationary contact II and a movable contact I2 arranged to be operated so as to draw an arc in an arc chute I3. The fixed contact I I is connected to the line terminal I4 while the movable contact I2 is connected to the line terminal I5. Fixed contact II is provided with spring-pressed contact fingers Ila and longer arcing contact fingers I I, while movable contact I2 is provided with arcing tip I2 so that, when the contacts separate, an arc therebetween occurs between arcing tips I i and I2. Immediately after separation of the contacts, one terminal of the arc is transferred by a blast of fluid, preferably air, issuing out of conduit I5, from contact fingers I I to the contact I I" which is provided with a tip of arc-resistant metal. The air blast from conduit I6 upon opening of the breaker drives the arc into the arc chute I3 against the edges of a plurality of partitions I! in the arc chute, which partitions are transverse to the air gap and the ends of which extend close to the path of movement of the arcing tip I2- of the movable contact I2. The circuit breaker I ii, illustrated by way of example in order to describe my circuit-interrupting system, is not my invention but is described and claimed in United States Letters Patent 2,284,842 referred to above.

In order to operate circuit breaker It automatically by fluid pressure, there is provided motive means comprising a cylinder is with a piston I9 connected through a rod 23 to operate a lever 2! secured to the shaft 22. The shaft 22 has attached thereto an arm 23 of insulating material for operating the movable contact I2' of the circuit breaker. Although circuit breaker II] is described with respect to a single phase, it will, of course, be understood by those skilled in the art that it may just as well comprise a plurality of phases, in which case, a plurality of arms 23 would be provided for operating the movable contacts I2 of the various phase The arm 23 is shown provided with apin 24 operating the member 25 secured to the outer end of movable contact I2. Member 25 is arranged to slide on a pair of rods 26, only one of which is shown in the drawing since the other is obscured from view thereby. It will be apparent that, when the shaft 22 is rotated in a counteris reciprocated. This type of operating mechanism is described in detail in United States Letters Patent 2,218,797, granted October 22, 1940,

upon the joint application of Leonard J. Linde and Torild Andersen, and assigned to the same assignee as the present application.

In order to operate the circuit breaker I as well as to supply a blast of fluid through conduit l6 for arc-extinguishing purposes, a source of fluid pressure 21 is provided which is preferably air under pressure. This source of air under pressure 21 is connected through a suitable blast valve'28 to conduit l 6 for supplying a blast of air adjacent contacts II and [2 of circuit breaker IQ for arc-extinguishing purposes. Blast valve 28 is normally biased to the closed position by means of spring 29 and is operated by means of solenoid 35 which may be energized at the desired time by any suitable control circuit. The source of fluid 21 is also connected with the respective ends of cylinder 18 for operating circuit breaker It through a four-way control valve 3!. This valve is arranged to control the closing of circuit breaker ID by connecting source 21 with the righthand end of cylinder 1 8 through conduit 32; For opening the circuit breaker, on the other hand, valve 31 is adapted to interconnect the source of fluid under pressure 12'! with the left-hand end of cylinder l8 through conduit '33. Valve 31 is so constructed as to vent one end of cylinder 18 to atmosphere through conduit 34 whenever the other end of cylinder 18 is subjected to pressure from source 27. A suitable spring means 35 is provided to bias valve 31 to the closed position shown in the diagram. Valve 31 is arranged to be operated for opening circuit breaker M3 by means of an opening solenoid 36 which may be energized from any suitablecontrol circuit. Similarly, valve '31 is arranged to be operated to control the closing of circuit breaker 1:0 by means of a closing solenoid '3! which may also be energized from any suitable. control circuit. Opening solenoid 36 and closing .solenoid 31 are preferably controlled in the manner disclosed in United States Letters Patent 2,255,496, granted September 9, 1941, upon an application of Bryce W. Wyman, and assigned to the same assignee as the present application.

In order to prevent operation of circuit breaker I 0 which might result in considerable damage thereto as well as to associated apparatus in the event that the pressure in source 2] fell below a predetermined amount, I provide a mechanical locking means generally indicated at 38 in Figs. 1 and 2 which is connected to the source of pressure 21 by means of a conduit 39. This mechanical locking means 38 may be applied to any movable part of the circuit breaker operating mechanism as will be understood by those skilled in the art. However, I have chosen to apply it to operating rod 20 which, as illustrated in Fig. 1. includes a portion of rectangular cross section 29'. Portion 20' of rod 20 is provided with two pairs of side notches and 4 l the pair of notches 40 being in registry with the mechanical locking means 38 when the circuit breaker is in the closed position shown in Fig. 1 and the notches 6| being in registry with the mechanical locking means 38 when the circuit breaker is moved to its fully open position.

Referring now to Fig. 2 where the mechanical locking means 38 is shown in enlarged perspective view, it is observed that it includes means comprising a pair of interference plungers 42 which are reciprocally mounted in a fixed cylinder block 43. In order to operate interference plungers 42 together, I provide a crosshead 44 which interconnects one end of one of the plungers 32 with the corresponding end of the other plunger 42. Fixed cylinder block 43 has cooperating openings within which plungers 32 are mounted and these openings are spaced so that interference plungers 42 are adapted to engage with the notches 48 or M, depending upon whether the circuit breaker is in the closed or open position. The fixed cylinder block 43 is provided with extensions 13 including semicircular grooves or notches which are adapted to be in registry with the notches 49 or H of the portion 253 of rod 20 when the circuit breaker I0 is in either its fully closed or fully open position. When the interference plungers #32 are moved into the notches as or M and the corresponding semicircular notches in fixed cylinder block 43, rod 29 is mechanically locked in either of its extreme positions and circuit breaker It} can not be operated.

In order to make crosshead 43 and interference plungers 42 responsive to the pressure of source 2?, I provide a fiuid motor in fixed cylinder block 23 comprising a cylinder 55 connected to source p 27 by conduit 39 and a piston 4'! reciprocally mounted in cylinder 45. Piston 31 is preferably connected to crosshead t l as by operating rod 68. Operating rod GB extends through crosshead M and includes force-transmitting shoulders 49 and by which 'forces either opposing or aiding the fluid pressure in cylinder &6 may be applied to piston ii. Locking means 38 should lock circuit breaker it in either its open or closed position if the pressure in source 2! falls below a safe operating value. Accordingly, I provide means including a compression spring 5i operatively connected through an eyebolt 5-2 .and a clevis-type bell crank 53 to piston 4'! by means of shoulder 49 on operating rod 43 for opposing the fluid pressure of source 2? acting on piston M. Bell crank 53 is movable about fixed pivot 54 and has forked ends 55 which fit into a groove in operating rod 48 between shoulders t9 and 56 so as to move operating rod 48 in either direction or be moved by piston -l acting through operating rod -58. Bell crank 53 also has forked ends 5 3 for connection with eyebolt 52 as at 5?. Eyebolt 52 extends through compression spring 5| which is supported by spring-retaining member 58 mounted on fixed cylinder block 63. Any suitable means for adjusting the compression of spring 5! may be provided. As illustrated in Fig. 2, I have provided a nut 59 on eyebolt 52 by which the compression of spring tl is adjusted to such a value as to move interference plungers 52 into engagement with notches 49 or BI whenever the pressure in source 21 falls below a predetermined minimum value below which safe operation of circuit breaker It may not be obtained with any degree of assurance. Bell crank 53 is constructed so that the forked ends 55 are adapted to engage with the corner 43" or fixed cylinder block 53, which acts as .a stop means to prevent pressures in excess of the minimum pressure in source 21 which is satisfactory for operating circuit breaker I i frommoving the interference plungers d2 beyond the limiting position shown in Fig. 2 in which the plungers are just clear of the portion 20' of reciprocating rod 2@. With the above described arrangement, locking means 33 is adapted to lock circuit breaker If) in either the open or closed position whenever the pressure in source 2! falls below a predetermined value considered safe for operating circuit breaker It, which pressure is determined by the setting of .compression spring 5| as maybe accomplished by adjusting nut 59.

Under certain conditions, it might be desirable to be able mechanically to lock circuit breaker ID in either its open or closed position; for example when repair work is done thereon or under certain test conditions. Accordingly, I provide means for accomplishing this purpose by utilizing locking means 38 which must be capable of mechanically locking circuit breaker l even though the pressure in source 2'! is sufliciently high to maintain interference plungers 42 out of engagement with notches 40 or 4| of the portion 20 of operating rod 20. To permit mechanically locking circuit breaker ID in one of its extreme positions, I provide a hand lever 60 pivotally mounted on pivot 54. Preferably the hand lever is provided with a curved end which, when lever 60 is rotated about pivot 54, engages at 60 with the portion 53' of bell crank 53 to rotate bell crank 53 in a clockwise direction about pivot 54 as viewed in Fig. 2 and move interference Iplungers 42 against the force of the fluid pressure in cylinder 46 acting on piston 41 into their locking position. Hand lever 60 may be mechanically held in this downward position holding interference plungers 42 in their locking position by means of an extension lug 6| supported from fixed cylinder block 43 and adapted to extend through a saw-cut notch 62 in hand lever 60. A suitable padlock or pin may be placed through

openings

63 and 64 in extension lug BI and hand lever 60 respectively to hold hand lever 60 in this downward position and consequently maintain interference plungers 42 in their locking position even though the fluid pressure in source 21 is sufiiciently high for safe circuit breaker operation.

In order to operate circuit breaker 16 manually under no-load conditions, for example when the pressure in source 21 is below the value to maintain interference plungers 42 out of their locking position, I provide openings or apertures 65 in bell crank 53 so that, by moving hand lever 60 downwardly and inserting a pin through apertures 55, hand lever 60 may then be moved upwardly to cause bell crank 53 to rotate in a counterclockwise direction about fixed pivot 54 as viewed in Fig. 2, whereupon the forked ends 55 of bell crank 53 engage with the shoulder 50 of operating rod 48 to withdraw interference plungers 42 from their locking position against the force of spring means The operation of the circuit breaker and mechanical locking means illustrated in Figs. 1 and 2 will be obvious to those skilled in the art in view of the detailed description included above. If, for any reason, the pressure of source 2! falls below a predetermined value so that it is impossible or undesirable to open circuit breaker Ill safely in the event of an abnormal current condition, spring means 5| is adapted to overcome the force acting on piston 41 and interference plungers 42 are moved to engage notches 40 or 4| depending upon the particular position of circuit breaker l 8 and consequently the circuit breaker is locked in either its fully open or fully closed position. However, means including a manual or hand lever 60 are provided whereby locking means 38 may be controlled so that operation of circuit breaker it! under certain conditions may be obtained even though the pressure has fallen below the Predetermined safe value for such operation or the circuit breaker I 0 may be mechanically locked in one of its extreme positions by manual means even though the pressure in source 21 is above the predetermined safe value.

While I have shown and described a particular embodiment of my invention as applied to an electric circuit breaker, it will be obvious to those skilled in the art that various changes and modiflcations may be made without departing from my invention in its broader aspects and I, therefore, in the appended claims aim to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. In an electric circuit breaker of the type depending at least in part upon fluid under pressure for operation thereof comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a source of fluid under pressure, a member associated with said motive means and movable thereby, and mechanical locking means responsive to the pressure of said source for looking said member in a predetermined position and consequently preventing operation of said circuit breaker when the pressure of said source falls to a value below which safe operation of said circuit breaker might not be obtained.

2. In an electric circuit breaker of the type depending at least in part upon fluid under pressure for operation thereof comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a source of fluid under pressure, a member associated with said motive means and movable thereby, and mechanical locking means responsive to the pressure of said source for locking said member in either one of two predetermined positions and consequently locking said circuit breaker in either the fully open or fully closed position when the pressure of said source falls to a value below which safe operation of said circuit breaker might not be obtained.

3. In an electric circuit breaker of the type depending at least in part upon fluid under pressure for operation thereof comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a source of fluid under pressure a member associated with said motive means and movable thereby, mechanical locking means responsive to the pressure of said source for locking said member in either one of two predetermined positions and consequently locking said circuit breaker in either the fully open or fully closed position when the pressure of said source falls to a value below which safe operation of said circuit breaker might not be obtained, and manual means for operating asid mechanical locking means to lock said circuit breaker in either its fully open or fully closed position even though the pressure of said source is above the value below which safe operation of said circuit breaker might not be obtained.

4. In an electric circuit breaker of the type depending at least in part upon fluid under pressure for operation thereof comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a source of fluid under pressure, a member associated with said motive means and movable thereby, mechanical locking means responsive to the pressure of said source for locking said member in either one of two predetermined positions and consequently locking said circuit breaker in either the fully open or fully closed position when the pressure of said source falls to a value below which safe operation of said circuit breaker might not be obtained, and manual means for operating said mechanical locking means to permit operation of said circuit breaker under predetermined conditions even though the pressure on said source falls to a value below which safe operation of said circuit breaker might not be obtained.

5. In an electric circuit breaker 'of the type depending at least in part upon fluid under pressure for operation thereof comprising 'a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a source of fluid under pressure, a member associated with said motive means and movable thereby including a notch therein, mechanical locking means including an interference plunger adapted to engage with said notch for locking said member, and consequently said circuit breaker in a predetermined position, a fluid motor associated with said interference plunger responsive to the pressure of said source of fluid and tending to force said plunger out of engagement with said notch, and means operatively connected to said fluid motor for opposing the action of said fluid under pressure, said lastmentioned means being so adjusted relative to the action of said fluid under pressure on said fluid motor to cause said interference plunger to engage said notch whenever the pressure of said source falls to a value below which safe operation of said circuit breaker is not assured.

6. In an electric circuit breaker of the type depending at least in part upon fluid under pressure for operation thereof comprising a pair of relatively movable contacts, motive means for producing relative movement between said contacts, a source of fluid under pressure, a member associated with said motive means and movable thereby having two pairs of spaced side notches therein, mechanical locking means including movable plungers for engagingone or the other of said pairs of side notches to lock said member and consequently said circuit breaker in either the fully open or the fully closed position, a fluid motor operatively connected to said plungers and responsive to the pressure of said source for forcing said plungers out of engagement with said notches, spring means for opposing said fluid motor to tend to cause engagement of said plungers with said notches, and means for adjusting said spring means to cause said plungers to engage either of said pairs of notches whenever the pressure of said source falls below a predetermined safe operating value.

CARL THUMIM.