US2667554A

US2667554A - Operating mechanism for electric circuit breakers

Info

Publication number: US2667554A
Application number: US233542A
Authority: US
Inventors: Ronald B Shores
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1951-06-26
Filing date: 1951-06-26
Publication date: 1954-01-26
Anticipated expiration: 1971-01-26
Also published as: GB723156A

Description

R. B. SHORES 2,667,554

OPERATING MECHANISM FOR ELECTRIC CIRCUIT BREAKERS Jan 26, 1954 Filed June 26, 1951 9 7 8 M m m w m a m M u m q IO k z w Z i l. M Z Z 57 4 M U i m IN M x M Z m J 1 a 7 k? it 7 Inventor: Ronald B. Shores,

His Attorney.

Patented Jan. 26, 1954 UNITED STATS OPERATING MECHANISM FOR ELECTRIC CIRCUIT BREAKERS Ronald B. Shores, Lansdowne, Pa., assignor to General Electric Company, a corporation of New York Application June 26, 1951, Serial No. 233,542

6 Claims.

This invention relates to operating mechanisms for electric circuit breakers and more particularly to a system for controlling the circuit opening operations of circuit breakers of the gas blast type.

Particularly in high voltage gas blast circuit breakers, the circuit interrupting contacts frequently are biased into engagement so that after separation by a blast of gas, thes contacts reclose when the gas blast is shut off. For this reason, it is necessary to provide isolating contact means in series with the interrupting contacts and to open such isolating means before the interrupting contacts reclose in order to complete a circuit opening operation.

In Patent 2,418,739, Thumim et al., granted April 8, 1947, an operating system for multipole gas blast circuit breakers is disclosed wherein circuit isolating switch means is arranged to be opened only after a blast of pressure fluid has been supplied to the circuit interrupting units forming each pole of the breaker. To this end, a pneumatic interlock system is provided. My in vention concerns an interlock system of the general type disclosed and claimed in the above-mentioned Thumim et al. patent.

A principal object of my invention is to provide an improved operating mechanism for circuit breakers of the gas blast type which is characterized by simplicity of construction and a high degree of reliability of performance as compared with presently known arrangements.

In carrying out the invention in one ,form as applied to a multipole gas blast circuit breaker in which a separate blast valve is provided for each pole of the breaker for supplying a blast of gas to the associated interrupting contacts, a separate control interlock valve for each pole is opened after opening of the associated blast valve. Gasconduits are utilized to connect these control valves in series between a master opening control valve and separate pressure responsive means for operating the isolating contacts of the breaker. Opening of the master valve supplies fluid for operating both the blast valves and their associated control interlock valves so that only after all the blast valves are open can pressure gas be supplied through the series control valves to the pressure-responsive means for operating the isolating contacts. The principles of the invention are also applicable to a single-pole breaker in which a single control valve comprising an undercut portion of an extension of the spindle of the associated'blast valve is directly connected between a source of gas pressure and pressureresponsive means for operating the isolating contact means only after opening of the blast valve.

For a better understanding of the invention, reference may be had to the following description taken in conjunction with the accompanying drawing, the single figure of which represents schematically a multipole circuit breaker and its operating system in which the principles of the invention are embodied.

In the drawing, the numerals I, 2 and 3 designate generally the three poles of a polyphase gas blast circuit breaker. Each pole comprises finger-type contacts 4 biased by spring means 5 into engagement with a tubular contact 6. The finger contacts t comprise the interrupting contacts, while the tubular contact 6 is an isolating contact. Finger contacts 4 are supported on metallic structure generally designated by the numeral l which in turn is mounted on an insulating tubular member 8. Disposed at the top of the unit is a cover structure 9 in which is mounted suitable arc-cooling material such as the foraminated structure I9. Insulating cylindrical casing t is secured at its lower end to a metallic base member I! which conveniently constitutes the blast valve housing. Interrupting contacts 4 are moved out of engagement with isolating contacts 5 against the bias of springs 5 by means of a blast gas introduced into the lower portion of base member II. This blast, proceeding axially around the isolating contact 5, pivots the interrupting contacts 4 out of engagement therewith and extinguishes the are drawn therebetween as the blast flows in the direction of the arrows to atmosphere through the exhaust passage I2. Such finger-type interrupting contacts are disclosed and claimed in U. S. Patent 2,427,195 to Cox et al. The details of construction of each of the units I, 2 and 3 are disclosed and claimed in application Serial No. 233,637 Beatty filed June 26, 1951, and application Serial Nurnber 202,100 Beatty, filed December 19, 1950, now Patent No. 2,545,697, discloses and broadly claims a unit similar to units I, 2 and 3, both applications being assigned to the assignee of this invention.

A blast of fluid is supplied to the interrupting units a, 2, and 3 through the blast valves 53. Each valve 53 is of the balanced type comprising a pair of similar disks it which are secured to their common valve spindles I5 and which are biased toward engagement with their respective seats by means of compressional springs I5. Pressure fluid stored within the air receiver I? is supplied to each of the valves I3 through conduits I8, shown schematically by a single dotted line.

For the purpose of imparting opening lift to the blast valves l3, a piston is is arranged to drive each spinde I5 upwardly when air from receiver I1 is supplied through conduit upon the opening of the master opening control valve 2 I. Master valve 2 l is shown schematically as being of the electromagnetically operated type. Obviously, this valve could be automatically or manually operated or could be a combination valve which would operate either manually or automatically. As is well known, suitable condition-responsive means could be utilized to energize the coil-of the master valve 2| so as to cause opening thereof. Stop means 22 is provided for limiting the travel of the valves I3 and for protecting the return springs l6 from the hazard of being compressed solid under impact.

As is well understood, interruption of the circuit due to the blasting of the are drawn by the self-opening interrupting contacts i is accompished when blast valves it are opened. The blast iscut oil by the reclosure of valves l3 due to the'action'of compressional springs I5 following the-closingof master valve 2| and will result in the returnof finger-contacts 4 to their normal positions indicated.

For the purpose of establishing an isolating gap at each'of the interrupting units l, 2 and 3, it is necessary to move the contacts t-downwardly. To this end, pressure-responsive device 23 is arranged so as to 'eiiect simultaneous downward motion of each of the isolating contacts 6 in proper sequence after the opening of the interrupting contacts -4. Contacts 6 are secured at their lowerextremities to an insulating-operating rod flywhichcooperates at its lower-end with a straight-line linkage mechanism comprising an actuating crank 25-supportedat a pivot 26, a switch lever 2-1 which is pinned at 28 to a guide link '29 "mounted at a fixed pivot til. cranks25 are coupledby pins 3| to a horizontally disposed connecting link :or rod 3%. For biasing the isolating'contacts open the rod 32 is biased by means of compressional spring -33 toward the right. Such bias exerts a clockwise monientcn crank-arms 25 tending to turn thosecranks about their fixed pivots 23 for rotating the levers 2T downwardly or counter-clockwise. Such movement will drawtheconnecting rods 24 downwardly in 3a straight-line motion since the cranks 25 are-pinnedto'the levers 21 at -34 so that the arouatemovement of the crank 25 is neutralized by that of the switch lever 21 in known manner. This spring bias tending to move the isolating contacts downwardly to the open position is not effective so long as the hold-close toggle connected to the middle linkage mechanism and comprising the

links

35 and 36 is in the overcenter position indicated. The link35 isinounted about afixed pivot 31 and is pinned to the link 36 by apin 38. This holding toggle is arrangedto be tripped by actuating it through dead center by the initial movement of pressure responsive means 23 when actuated so as to impart downward movement to its piston rod 3t. Once the

toggle comprising links

35 and 3% is broken, the kick-off action of compressional spring 33, aided by the action of fluid pressure and gravity, effectively draws the interrupting contacts 5 downwardly at high speed to establish a sufficient isolating gap. The dotted line positions of link 21 and thelower portion of rod 24 for pole lare in dicative of the positions of these parts for the open position of the breaker. The momentum of the moving parts is dissipated by suitable bufiing All. of the means schematically indicated at 40, which bufiing means engage the rollers 4| mounted on the cranks 25.

In order to break the

toggle comprising links

35 and 35, fluid pressure must be supplied above the piston member 42 of the pressure responsive device 23. Such pressure is supplied through conduit 43.

Since it is not desirable to initiate downward movement of the isolating contacts 6 until pressure fluid .is established for opening and blasting the contacts 4 within the interrupting units, the

blast valves I3 and their individual operating fluid motors comprising pistons l9 are each providedwitha control valve the operation of which controls the fiowof fluid through the conduit 43 into the pressure responsive device 23 to initiate movement of the isolating contacts 6. In accordance with the invention, each of the valve stems I5 is provided with an undercut portion M which operates as a sleeve valve within thesuitable enclosing structure 45, each enclosure 45 being provided with an inlet port-flt-and an outlet :port 4,1. Connection between themasteropening control valve 2! and the inlet port 46 of one of the valves, such-as that associated with pole l is supplied through aconduit 48. Outlet port fl'lof the control valve associated with ,pole I is connected by means of a conduit 49 with inlet port 4 5 of the control valve associated with pole 2, while outlet port. of this control valve is connected bymeansofaconduit 5i) withiinlet port 45 of the control valve associated with pole Is. As is indicated, the'conduit 43 isiconnected to outlet port El of the control valve associated with .pole 3.

Thus, when master valve 2| is opened, fluid pressure is supplied to the three -fluid:motorscomprising pistons H] which move upwardly to open the blast valves l3. Lifting of the blast valves l3 causes the undercutportions 44 of each of the control valves to move upwardly a suilicient l distance to establish communication through these control valves between the inlet ports 45-and the outlet ports 47. :It will beobserved that-a substantial upward i-movement oi .eachcf the valves l3 occurs before the undercut portions 44 of each of the valve spindles l5 opens theinlet ports 45 to the outlet :ports -47. Thus, according to the invention a positiveopening of :each of the three valves 13 must have resulted .for establishing a blast of fluid within the :three interrupting units before fluid is permitted :to pass through the

conduits

44, 49, I50 and 43 to operate thepressureresponsive "device 23 to cause actuation of all the isolating contacts -6.

As :already mentioned, 'reclosing .of .the :master opening control :valve .21 cuts .off the blast zvalves but, because the blast valvescontrol the passage of pressure :fiuid through the control valves 44 l to the isolating motor 23, "the reclosing .of the master valve 2| must not take place 1.1111311313516318; the piston 42 has efiected the breaking of the hold-close .toggle135, .36. Accordingly, .a :cut-ofi switch for the control circuit of the valve 21 -.is

arranged to he operated accordance with the downward movement of the piston rod 3 9 ortsome other convenient :moving member. With the reclosing ofrthe blast valves l3, residual pressure behind the piston 42 canfeed backtoatmosphere through the :vents reopened by the slide valves 44 which are shown openiin the drawing.

If it is desired to have the interrupter operate as a .reclosing .breaker, it .-is .only necessary to provide means :for preventing the .operation of the pressure-responsive device 23. LTOithls "end,

a suitable valve such as 5| may be provided. Such a valve would be arranged to be closed automatically or manually by any well-known means so that opening of blast valves l3 would simply operate interrupting contacts 4 and extinguish the arcs drawn thereby and after closure of valves !3 these contacts 4 would re-establish a circuit through the interrupter.

The terminals of the circuit breaker could be arranged in any suitable manner known to the art. For example, one terminal of each unit could be formed on the structure I as indicated by the numeral 52, while another terminal could be arranged so as to establish contact with the isolating contacts 6 by a flexible braid connection or by a sliding contact connection of known construction such as is indicated by the numeral 53.

The arrangement a shown on the drawing and as described above utilizes a single fluid motor in the form of pressure-responsive device 23 for operating all poles of the circuit breaker. Obviously, each pole of the breaker could be provided with its own fluid actuated operating mechanism for operating the isolating contacts. For example, assuming that the fluid motor 23 shown in the drawing is for the purpose of operating only the isolating contact of pole 2, the horizontally-disposed connecting rod 32 would be eliminated except insofar as it is necessary to afford an opening bias through the agency of the compression spring 33. Conduit 49 could be directly connected to conduit 48 and conduit 5%) could be directly connected to conduit 53. Each of the other two poles of the breaker, such as l and could be provided with its own fluid responsive device such as 23 connected as indicated above in connection with pole 2. With such an arrangement, opening of the interrupting contacts of one pole, such as 2, would be accomplished and operation of the isolator would be possible only after the associated blast valve had operated.

The isolating contacts are reclosed by opening valve 5 so as to sup-ply pressure fluid from receiver ll through a conduit indicated schematically by the dotted line 55 to the underside of piston :32. Valve 56 is arranged to facilitate downward movement of piston 42 during an isolating operation or the breaker since this valve vents the motor to atmosphere when the valve is closed.

While I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that certain changes and modifications may be made without departing from the invention, and it is therefore intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope or the invention.

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

1. An operating system for a multi-pole gas blast electric circuit breaker having an interrupting contact and an isolating contact for each pole of the breaker, said system comprising a plurality of mechanically-independent biased-closed blast valves each arranged to control the flow of gas to one pole of the breaker, a plurality of fluid motors each having a movable part arranged to open one of said blast valves, a master valve arranged to supply gas under pressure to said plurality of motors, means including pressure-responsive motor means for opening said isolating contacts, a plurality of normally closed control valves each movable simultaneously with one of ill , 6 said fluid motors toward the open position during opening of the associated blast valve, each of said control valves being structually interconnected with and movable by said movable part of one of said fluid motors, and conduit'means forming a series path from said master valve through all of said control valves to said pressure-responsive motor means.

2. An operating system for a multi-pole gas blast electric circuit breaker having an interrupting contact and an isolating contact for each pole of the breaker, said system comprising a plurality of mechanically-independent biasedclosed blast valves each arranged to control the flow of gas to one pole of the breaker, a plurality of fluid motors each arranged to open one of said blast valves, 2. master valve arranged to supply gas under pressure to said plurality of motors, means including pressure-responsive motor means for opening said isolating contacts, a plurality of normally closed control valves each movable toward the open position by one of said fluid motors when opening its associated blast valve, and conduit means forming a series path from said master valve through all of said control valves to said pressure-responsive motor means, so that pressure gas is supplied through said master valve and said control valves to said pressure-responsive motor means to cause opera tion thereof.

3. An operating system for a multi-pole fluid blast electric circuit breaker having interrupting contact means and isolating contact means for each pole of the breaker, said system comprising a plurality of mechanically-independent biasedclosed blast valves each being arranged to control the flow of fluid to one pole of the breaker, a plurality of fluid motors each being arranged to open one of said blast valves, each of said motors comprising an operating cylinder and a piston having a piston rod projecting outwardly from said cylinder, a master valve arranged to supply fluid under pressure to said plurality of motors, means including pressure-responsive means for opening said isolating contact means,

a plurality of normally closed control valves each being movable toward the open position by one of said fluid motors when opening its associated blast valve, each of said control valves including an enclosing structure through which the associated one of said piston rods is movable and in which inlet and outlet ports are formed, movement of the associated piston rod during an opening operation of the associated fluid motor being effective to establish communication between said inlet and said outlet ports after commencement of its opening movement, and conduit means forming a series path from said mas ter valve through all of said control valves to said pressure-responsive means, said conduit means being connected to said control valves at said inlet and outlet ports.

l. An operating system for a multi-pole gas blast electric circuit breaker having interrupting contact means and isolating contact means for each pole, said system comprising a plurality of mechanically-independent biased-closed blast valves each being arranged to control the flow of fluid to one pole of the breaker, a plurality of fluid motors each being arranged to open one of said blast valves, each of said motors comprising an operating cylinder and a piston having a piston rod, a master valve arranged to supply fluid under pressure to said plurality of motors, means including pressure-responsive means for opening saidis latine contact means. a plurality dine man l sed control valves each bein movab ard he composi on hy on of sa d u d motors when 0116111 18 .1 95 155 13 9 6, vblast v e eachrof said control valves including anenclosing structure having inletand outlet ports and an undercut portion of th a ci ted pi t arranged to uncover said inlet ports after predetermined opening movement thereof, and conduit means forminga seriespath from "said master .valve through all of said control valves to said pressure-responsive means.

5. vAn operating system for a 'multi-pole gas blast electriccircuit breaker having interrupting contact means and isolating contact means for each pole, saidsystem comprising a plurality of mechanically-independent biased-closed blast valves each being arranged to control the flow of fluid to one pole or the breaker, a plurality of fluid motors each ein arr n ed to op n on of said blast valves, each of said motors comprising an operatingcylinder and a piston havin a piston rod, a master .va'lve arranged to supply fluid under pressure tosaid plurality of motors, means including pressure-responsive means for opening said isolating contacts, a plurality of normally-closed control valves .each being movable toward the open position by one of said fluid motors when opening its associated blast valve, each of said control valves includin an enclosing structure having an .inlet portandan t t p a dan und rcut portion of th associated piston rod for establishing communication between said ports upon ,movementof said rod by its associated motor, and-conduit means formin a serie path from said ma ter a ve through all of said control valves to said ,pres, sure-responsive means.

6. A r ting sy tem ffora as blast elect c c cui b fi ik l havin *8/11 is l ting .3mm; an

an interrupting contact arranged in series, said system comprising a blast valve biased 'to the closed position and arranged when opened to supply ablast of gas .to 'saidinterrupting contact to cause opening thereof and to extinguish the are drawn thereby, a fluid motor for operating said blast valveto the open position, .saidmot'or including a cylinder and an operating piston having a piston rod projecting outwardly from said cylinder, an opening valve arranged to supply pressure gas 'to said fluid motor to cause operation thereof, means including pressureresponsive means for opening said isolating contact, a normally-closed control valve "movable toward the open position in response to operation of said fluid motor when opening said blast valve,,said control valve vjbeing closed until after predetermined opening movement thereof, said control valve including an enclosing structure separate from said cylinder through which the projecting portion of said piston rod is movable and in which inlet and outlet ports are formed on an undercut portion of said piston rod, movementof said piston rod during an opening operation of said piston being effective to establish communication between said ports through said .undcrcut portion of said rod after a predetermined portion of the opening movement of said piston is accomplished, and conduit means directly connected between said opening valve and said inlet port and between said outlet port and said pressure-responsive means.

RONALD B. SHORES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,364,254 Thommen et a1. Dec. 5, 1944 2,418,739 Thumin et al Apr. 8, 194'? Mitts-w