US2078145A - Circuit breaker - Google Patents

Description

1935 2 Sheets-Sheet l G. R. LNGLEY CIRCUIT BREAKER Filed Dec. l2,

April 20, 1937.

April 20, 1937. G. R. LANG-LEY CIRCUIT BREAKER 2 Sheets-Sheet 2 Filed Dec. 12, 1935 mow.

leg,

lrvertor'. Gordon RLm bg 8x9 is ttorrweg.

Patented Apr. 20, 1937 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Application December l2, i935, Serial No. 54,067 In Canada March 20, 1935 Claimsa l My invention relates to circuit breakers, and

J more particularly to circuit breakers of the heavy duty type having circuit breaking contacts immersed in an insulating medium such as oil, com- 5 monly used for the interruption of heavy currents at high voltages, and wherein the arc drawn in breaking the circuit may create pressures within the circuit breaker ranging to a very high order.

-Circuit breakers of the type above referred to have been constructed on the principle that in order to withstand the high pressures generated therein, the walls of the pressure conning conLV talner should approach the form of a sphere as closely as is practically possible. To this end,

the upper part of the circuit breaker has been made in the form of a dome adapted to -be attached to a cylindrical tank, the bottom of which has been dished or bulged outwardly to conform tothe generally spherical outline.

Too close adherence to the above principle has resulted in excessive labor costs in the construction of heavy duty circuit breakers. The dorne shaped top is in itself costly to manufacture, and because of its shape has increased the diiliculty and cost of locating inserts therein. For example, the-circuit breaker conductor studs which pass through the dome and areI secured thereto, are most readily secured to suitable inserts and the inserts are then welded or otherwise secured in suitable apertures in the dome. 'Ihe locating ci' the apertures, which must be done with great accuracy, is rendered diiilcult because of the shape of the dome, and the welding necessary satisfactorily to secure the inserts in the dome gives y rise to strains within the material of the dome which at times distort the spacing of the conductor studs. Furthermore, the provision of means for securing the dome shaped top to the cylindrical tank and the provision of a dished-out bottom for the tank add considerably to the cost of manufacture.

r It is an object of my invention to provide an improved circuit breaker of the type above referred to, capable of interrupting heavy currents at high voltages and of withstanding the high pressures generated therein, and which will obviate many of the difculties encountered in the manufacture of circuit breakers of the prior art. X It is a further object of my invention to provide a circuit breaker, of the type havlng'oil ini5 mersed contacts, which will be oil-tight and ex- A ploslon-proof, which will be economical of manui'acture and which will readily permit the aww rate location of parts.

(Cl. Z-150) It isy a still further object of my invention to provide a circuit breaker construction which lends itself to userin metal clad switchgear installations now commonly employed in power distribution stations. for which the circuit breakers 5 must be accurately assembled in order to be iri-s terchangeable with other breakers of the same type and rating in the metal clad installation.

My invention will be more fully/set forth in the following description referring to the accom- 10 panying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part or this specification.

Referring to the drawings, Fig. 1 is a top plan 15 View oi a cire t breaker embodying my inven tion; Fig. 2 is a view, partly in section, on the line .A-A of Fig. i; Fig. 3 is a sectional 'view on the line B--B oi Fig. l; and Fig. fi is an enlarged isometric view or an operating element incorr- 20 porated in the circuit breaker.

In the drawings, Figs. i, 2, and 3, there is shown a circuit breaker tank having a top member formed of a hat plate i oi manganese bronze, cold. rolled steel, or other suitable materiali. The plate El when suitably selected as to thickness will withstand satisfactorily pressures higher than would be encountered during the operation of the cir1J cuit breaker, and at the same time aords a conn siderable saving in rst cost over the dome typt structures heretofore used. At the same time the plate l may be provided with accurately machined edges to serve as base lines for the location oi parts on the plate i.- Suitable apertures are out in the plate l through which the conductor studs 35 2 pass.

Each conductor stud comprises a conducting rod of copper' or similar metal suitably insulated, preferably with a laminated, impregnated insuflating material known to the trade as Herko ,w lite. Each conductor stud 2 is provided at its lower end with a stationary contact structure 3 to be later described, and at its upper end the cop:n per rod of each conductor stud extends beyondl the insulation and may be screw-threaded to per@ 45 mit the ready connection thereto of suitable conrn ductors (not shown), or it may be finished other4 wise, for instance with a silver contact ferrule for plugging intoa socket contact.

Intermediate ithe ends'of eachconductor stud 5@ 2, the insulation may be partly cut away and a flanged clamping member l formed in two halves secured about the conductor stud by means of the bolts 5. Each clamping member i is formed with an axially extending portion S adapted to fit 55 snugly within the aperture through which the conductor stud passes, and is also provided with a flange 1 arranged to abut the lower side of.A

plate I and to be secured thereto by the bolts 8. An alternative construction would employ a threaded clamping member arranged to screw into the top plate.

The stationary contact structure shown comprises contact ngers 9 and butt contacts I0 which 1o co-operate respectively with wedge shaped portions II and butt contact portions I2 of a movable bridging member I3. The stationary contact structures 3 are arranged in pairs, each pair being bridged by one bridging member I3 and all the bridging members are arranged to be operated between their open and closed circuit positions simultaneously by means to be later described.

In the structure illustrated, the butt contacts I8 of the stationary contact structures 3 are biased to their lowermost positions by means of springs I4 and are also arranged to move to a lowermost position during the circuit opening movement of the bridging member such that any arcing between the stationary contact structure -and the bridging member occurs between the butt contact portions of the respective members. In

this manner, the contact surfaces of the contact y fingers 9 are preserved for current carrying duty during the circuit closed position of bridging member I3 and the destruction of the contact surfaces of iingers 9 by arcing is substantially prevented.

The breaker tank I5 is formed in the regular manner from a piece of sheet steel rolled into a cylinder and welded at .the edges. A reinforcing and securing band I6 is welded to the outer side of the tank I5 adjacent its upper end'and a fiat bottom I1 is welded to the inner side of the tank I5 adjacent its lower end. The band I6 and iiat bottom' I1 are conveniently and economically made by irst selecting a substantially rectangular piece of metal plate having the required thickness Aand strength, and then cutting from said plate a circular aperture equal in diameter to the outer diameter of the tank I5. 'I'he width of the out may be arranged to substantially equal the thickness of the steel sheet used in tank I5, and the remaining circular piece of steel plate thus is adapted to fit within the lower/ end of tank I5 and is welded thereto to form the bottom thereof. v

The outer contour'of band I6 may be made as shown in Fig. 1, and in the Wider corner portions thereof suitable tapped holes are made for the reception therein of bolts I8 extending through the under side of plate I for the reception therein of y the upper edge of tank I and the groove provided with a gasket to form an oil and pressure-proof jointwhen the tank I5 is secured to plate I. It will be apparent that the top plate lends 'itself readily to the use of a structural steel supporting frame, the plate itself forming the top horizontal frame member. The plate may also be extended to' form an economical support for a solenoid or motor operated mechanism indicated generally at 36.

Each of the bridging members I3 is rigidly secured to the lower end of an operating rod 20, the upper end of which is secured to a horizontal cross bar 2I. g The operating rods 20 and -the bridging member I3 are moved in a vertical direction by means of the links 22 pivoted at 23 in an L-shaped bearing member 24 secured to the under side of the plate I. The links 22 are connected plate I and adapted to secure said plate I to tank at one end to the cross bar 2I through a sliding ball connection 25 and at their other end the links 22 are provided with a cross arm 26 arranged to be engaged by the lower end of a plunger 21 operating through registering apertures in plate I and 5 bearing'member 24.

The sliding ball connection, as is shown most clearlyin Fig. 4, comprises a block 28 secured to the cross bar 2I and having a horizontally extending cylindrical hole or slot 29 and a central verti- 10 cal slot 30 therethrough. The end of each of the links 22 is provided with a circular aperture 3I of a size to receive a steel ball 32 therein, and in assembled relation the end of the link operates in the slot 30 and the ball 32 operates in the cylindri- 15 cal hole 29. This slidable interlocked connectIon provides for an arcuate motion of the ends of links 22 while the cross bar 2I and block 28 move in a vertical straight line.

The plunger 21 extends through plate I and is 20 connected at its upper end to one end of a link-33, pivoted at 34 in a bearing block 35 on the upper side of plate I. The other end of link 33 may be connected to any suitable operating mechanism, either manual or electrically operated, mounted 25 conveniently on plate I and indicated generally by the rectangle 36. Bearing member 24 is provided with a collar of leather or other suitable material located around plunger 21 so that the plunger moves freely through the collar, but when 30 pressure develops in the tank the collar closes in on the plunger 21 and prevents escape of oil.

The interior of the tank I5 adjacent the contacts of the breaker is lined with a layer 31 of insulating material and, in the embodiment of my ,35 invention illustrated, an oil blast chamber 38 is provided enclosing all of the stationary contact structures 3 and bridging members I3. The oil blast chamber 38 comprises a topwall 39 and a. side wall 40, the top Wall 39 having apertures .40 through which the conductor studs 2 and the operating rods 28 pass, and the side wall 4I) being provided with apertures 4I adjacent the end of each bridging member I3. 'I'he principle underlying the operation of the oil blast chamber is well.- 45 understood in the art and further discussion thereof is not deemed necessary. In the embodiment shown, an aperture 42 is provided in the top wall 39, opening into a cylinder 43 mounted on the top of the wall 39, and a piston 44 is mounted to 50 slide vertically in the cylinder 43 for a'purpose which will appear more fully hereinafter. The piston 44 and cylinder 43 have a diameter which is relatively large compared with the diameter of the operating rods 20 and the piston 44 is pro- 55 vided with a vertically extending portion 45 arranged under certain conditions to co-operate with the cross arm 26 of link 22.

As is shown most clearly in Figs. 1 and 3, the cross arm 2I and operating rods 20 secured there- 60 to, are guided for movement in a vertical plane by the frame comprising the four rods 46 which are secured at their lower ends tov the top wall 3l of chamber 38. 'I'he rods 46 are arranged in pairs,

one pair at each end of the cross bar 2 I, and cross 65 members 41 are provided at each end of the cross bar 2I 'and arranged to co-operate with the rods 46 and 'guide the cross bar between them. Springs 48 are also provided at the upper ends of 70 rods 46 so arranged that the upward movement of cross bar 2I during the circuit closing operation of the circuit breaker compresses them. When the operating mechanism indicated generally at 36 is released, the springs 48 and I4 operate to -75 aovaifis provide an initial impulse in the opening direction to the bridging members I3.

With the foregoing detailed description of the co-operation of parts in the construction oi the circuit breaker according to my invention, the operation of the circuit breaker will be readily understood by those skilled in the art. Assuming thatthextank I5 is filled with an insulating fluid,

-.suchlas oil, to a level somewhat higher than the top of the oil blast chamber 38, and that the bridging members I3 are in the circuit open position illustrated in dotted lines in Fig. 2, the circuitl breaker is closed by operating the mechanism indicated generally at 36 to depress the plunger 2 1, thereby, through links 22 and operating rods 20, raising the bridging members I 3 to the position illustrated by full lines in Fig. 2.. In this position, the wedge-shaped portions lll of the bridging members I3 engage the contact fingers Sand depress the butt contacts IB against the bias of the springs I4.' In this position also, the cross bar 2l is at its highest position and compresses the springs 48.

The circuit breaker is held closed by the operating mechanism shown generally at 36and may be opened by releasing the operating mechanism,

either manually or in response to a suitable electrical control.

When the operating mechanism 36 is released, the springs 48 and I4 immediately apply an impulse in the opening direction to the bridging members I3, and the bridging members I3 very quickly move to the position illustrated in dotted lines in Figs. 2 and 3. As the butt contacts I and I2 separate, an arc is drawn, a relatively high pressure is generated within the chamber 38, and a iiow of oil is forced across the arcing contacts and through the apertures (it, thereby minimizing the arcing and giving rapid circuit interruption.

During the circuit opening operation, the occurrence of a relatively high pressure within the chamber 38 gives rise to a pressure differential acting on the operating rods 20 and opposing the opening movement of the bridging members i3. When the opening impulse imparted by the springs 48 and I4 is exhausted, this piston effect on the operating rods 20 may result in a tendency toreclose the circuit breaker and in order to overcome this, there is provided the pressure responsive piston 44 acting-within the cylinder i3 in response to an increase of pressure within the chamber 38. The upwardly extending portion d of the piston 44 is arranged, when moved upwardly to abut the cross arm 26 of links 22, thus applyinga force in the opening direction tothe links 22 over-balancing the piston effect on operating rods 20 and serving to hold the bridging members I3 in fully opened position.

In the operation of oil circuit breakers of the `type above described, it has occasionally occurred that during the circuit opening operation an arc y has struck between the stationary contact structures of adjacent phases. In the circuit breaker construction of my invention, I prevent this occurrence by securing to the inner sides of each of the stationary contact structures3 of the outermost phases a ilap 49 (see Fig. 3) of suitable insulating material extending downward somewhat below the lowermost portion of the adjacent stationary contact structure. As is shown most clearly in Fig. 3, these iiaps 49 are secured to the stationary contact structure by means of the bolts already provided for Csecuring this structure to the conductor stud. I have found that this type of barrier is superior to existing types in that the presence of this insulating ap 49 substantially eliminates any interphase arcing, and, being preferably nonrigid or exible in construction, is free from the tendency of a sti barrier to shatter and at the same time is sufiiciently supported so that its flexibility does not interfere with the moving parts adjacent.

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

l. An electric circuit breaker of the liquid-break type comprising a casing including a cylindrical metal portion, a disc-like metal plate secured within one end of said cylindrical portion to form the bottom wall of said casing, a metal reinforcing band, the outer periphery of which is substantially rectangular, secured `to the outer peripheral wall of said cylindrical portion at the opposite end thereof and a dat metal plate forming the cover structure of said casing, said plate having a circular groove in registry with the upper end of said cylinder, said plate constituting a unitary support for the complete circuit breaker structure, and means iordetachably securing said plate to diagonal portions of said reinforcing band 2. An electric circuit breaker of the liquid-break type comprising a metal casing, a flat plate provided with a lateral `extension forming the cover structure of said casing, lead-in conductor studs mounted in and extending through said cover plate, stationary contacts mounted at the lower ends of said conductor studs, a movable bridging member coacting with said stationary contacts and connected to lever structure supported with respect to said plate within said casing, operating mechanism mounted on said lateral extension exteriorly of said casing, and a plunger connected to said mechanism and guided for vertical reciprocal movement in said plate for engaging within said casing said lever structure.

3. An electric circuit breaker of the liquidbreak type comprising a casing, a flat metal plate having a lateral extension forming the cover structure of said casing, lead-in conductor studs mounted inand extending through said casing, stationary contacts mounted at the lower ends of said studs, a movable coacting bridging member operable through a lift-rod to closed and open circuit positions, a lever pivotally supported in depending relation to said plate, said lever operatively connected at one end to said lift-rod and provided at its other end with a roller, an operating mechanism mounted on the lateral extension of said cover plate exteriorly of said casing, a plunger connected to said mechanism guided in said plate for vertical reciprocal movement for engaging said roller and an antireclosing device in said casing including a piston adapted to engage said roller.

4. In an electric circuit breaker including relal lll transmitting straight line movement theretd comprising a member having a longitudinal slot and a coacting member slidable in and interlocked with respect to said slot, one of said members being pivotally mounted so that the other bridging members, and means for preventing member can be. restrained for rectilinear moveinterphase short circuits between the stationary 'nient. contacts of separate phases comprising ilexible 5. An electric polyphase circuit breaker of the insulating aps secured to the stationary contact 5 liquid-break type comprising a casing, a pluralstructure and extending to the lower extremities 5 ity of pairs of stationary phase contacts mounted of said stationary contact structure. in s aid casing, a plurality of movable coacting GORDON R. LANGLEY.

Images