US2404957A

US2404957A - Circuit interrupter

Info

Publication number: US2404957A
Application number: US543910A
Authority: US
Inventors: Howard W Graybill
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1944-07-07
Filing date: 1944-07-07
Publication date: 1946-07-30
Anticipated expiration: 1963-07-30

Description

July 3o, 1946.

H. W. GRAYBILL CIRCUIIF1 INTERRUPTER Filed July '7, 1944 2 Sheets-Sheet 1 Magg 1 H.- r i &

WITNESSES'.

INVENTOR ikTTORNEYZ July 30, 1946 H. w. GRAYBILL. 2,404,957

C IRCUIT INTERRUPTER I Filed July 7, 1944 2 Sheets-Sheet 2 www? qdj/ Patented July 30, 1946 CIRCUIT INTERRUPTER Howard W. Graybill, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 7, 1944, Serial No. 543,910

(Cl. 20D- 48) 15 Claims. l

This invention relates generally to electric circuit interrupting devices, and more especially to disconnect switches which are capable of interrupting load currents,

A recent development in the electric switch art are load break disconnect switches. These switches, in addition to performing the function of ordinary disconnect switches, that is, being capable of inserting a readily visible safe air gap in the circuit, must also be capable of safely interrupting load currents. Load break disconnect switches may take several general forms, but regardless of the particular form, all require some means for extinguishing the arc drawn during interruption of load currents. This invention comprehends certain improvements in arc-extinguishing means ior load break disconnect witches, and is disclosed herein as incorporated in a switch ci the type having a set of disconnect contacts and a set of interrupting contacts connected in series circuit relation, with actuating means for sequentially actuating the two sets oi contacts so that all arcing occurs at the interrupting contacts for which arc extinguishing means is provided.

One object of this invention, therefore, is to provide a load break disconnect switch having a novel structural arrangement of circuit interrupting contacts and disconnect contacts electrically connected in series circuit arrangement.

Another object of this invention is to provide novel actuating means for a load break disconnect switch of the type described which includes an overcenter spring for actuating the interrupter contacts of the switch.

Another object of this invention is to provide a novel arrangement of arc-extinguishing means and circuit-interrupting contacts.

Still another object of this invention is to provide novel actuating means for a load break disconnect switch having a set oi interrupter contacts and a set of disconnect contacts, for actuatsoid sets oi contacts in a predetermined sequence.

These and other objects ot this invention will become re apparent upon consideration of the following detailed description of a preferred ernbodiinent thereof, when taken in connection with the attached drawings, in which:

Figure l. is a side elevation View a switch embodying this invention, with the stationary contact structure shown in section;

Fig. 2 is an enlarged partial section view taken substantially centrally through the movable support for the switch blade shown in Fig. 1;

Fig. 3 is an enlarged plan view of the portion of the switch shown in Fig. 2;

Fig. 4 is a View similar to Fig. 3, but with a part of the switch enclosing casing removed, and with certain of the parts shown in section; and

Fig. 5 is a sectional view taken substantially on the line V-V of Fig. l,

This invention is particularly disclosed herein as incorporated in a disconnect switch of the type shown inl L. Rawlins Patent No. 2,303,496, issued December l, 1942, to the same assignee as this invention. This type of switch comprises, in general, a supporting base 2 onwhich is mounted a stationary insulator as by bolts t! which engage a supporting post on base 2. A contact housing ill is secured on the upper end of stationary insulator il, for example, by through bolts l2. Contact housing ld preferably has openings at opposite sides thereof, with one opening adapted to receive a terminal plate I4 which is secured in the opening by bolts it. Terminal plate l extends outwardly of contact housing IB so as to have a line conductor secured thereto. Preferably, contact jaws I8 are also secured within Contact housing IFJ by bolts l, with the jaws maintained in spaced relation by terminal plate I4 interposedtherebetween. lThe Contact jaws i8 terminate within housing lil short oi theopp-osite opening therein, and are provided adjacent their free ends with a bolt 2li extending therethrough, to limit separation of the free ends of the contact jaws. Preferably, each contact jaw is provided with a limited area projecting contact portion 22 for engagement with a movable switch blade. It will be noted that the opening in contact housing lil adjacent the free ends of contact jaws i3 is provided with a side entrance 23 (Fig. 5) permitting the entrance of the movable switch blade from one side.

Supporting base 2 also has mounted thereon a rotatable insulator 24 in a bearing 2S, which is secured to base 2 by bolts 21. Rotatable insulator 24 has a shaft portion rotatably received in bearing 2t, and an actuating crank 28 may be secured to this shaft portion in any desired manner, for example as by bolts 3B provided through crank 28 and through flanges in separate parts of the shaft portion. The outer end of rotatable insulator 24 is provided with a housing bracket having a base plate 32 secured to rotatable insulator '25, as by bolts 3:3. An up- Astanding connecting portion 36 is provided integral with base 32 of the housing bracket, and a top plate 38 is provided integral with the other end of portion 36. Rotatable insulator 24 is provided with a central aperture in the outer end thereof for receiving a supporting shaft 48, which extends through the top and bottom plates 38 and 32 of the housing bracket, to rotatably support a terminal plate 42. The inner end of terminal plate 42 is preferably forked to form opposed bearing portions for receiving supporting shaft 48, and the shaft is maintained in the position shown by pins 44 engageable with the inner sides of the forked portion of terminal plate 42. A line conductor 43 may be secured to terminal plate 42 by bolts 45.

An interrupter housing, generally designated 46, is adapted to be mounted between top and bottom plates 38 and 32 of the housing bracket mounted on rotatable insulator 24, at the opposite side of connecting portion 36. The interrupter housing is preferably formed of complementary, generally cup-

shaped halves

48 and 58 of insulating material, such for example as a synthetic resin, porcelain, or the like. The

portions

48 and 58 of the interrupter housing are secured together in opposed relation, with the flanges thereof in engagement, by through bolts 52. Each portion of interrupter housing 46 is provided with a generally cup-

shaped liner

54 and 56, adapted to have the flanges thereof in abutting relation when the housing sections are secured together.

Liners

54 and 56 are also of insulating material, preferably an insulating material which is capable of evolving an arc-extinguishing gas when ln proximity with an electric arc such as liber, boric acid, or a synthetic thereto, as by welding or the like, an interrupter blade 68. Preferably, washers 56 are interposed between the interrupter housing 46, and the top and bottom plates 38 and 32 of the supporting bracket.

A main switch blade 62 is mounted at one end in interrupter housing 46, with recesses being provided in each

housing portion

48, 58, adjacent one side of the base portion of the housing, for receiving switch blade 62. Correspond ingly shaped recesses are also provided in

housing parts

48 and 56, for receiving a bolt or rivet 66, which is adapted to secure contact jaws 64 to opposite sides of blade 62 at the point where the blade passes through opposed flanges of

sections

48 and 58 of the interrupter housing. Obviously, when

housing portions

48 and 58 are secured together by bolts 52 with blade 62 and securing means 66 received in the recesses provided in the housing sections, switch blade 62 and contact jaws 64 will be held in fixed relation with respect to interrupter housing 46. As shown in Fig. 2,

liners

54 and 56 of the interrupter housing are also recessed as at 68, to form a chamber in which the outer ends of contact jaws 64 are located. Interrupter housing 46 is provided with a slot 'i8 (Fig. 1) tc the exterior thereof through a portion of the base of the housing, so as to direct gases escaping from the housing in a direction at an angle to main switch blade 62.

60, a crank 12 is provided on the upper end oi actuating shaft 58, and this crank has an eccentric crank pin 14 which is connected to one end of an overcenter spring 16, the other end of which is anchored to pin 18 secured on top plate 38 of the housing bracket. Preferably, a cover 88, generally cup-shaped in form, is inverted over top plate 38 of the housing bracket, and is secured thereto as by screws 8|, to protect the overcenter spring and other parts from the weather.

In the closed circuit position of the switch, the circuit therethrough extends from terminal plate I4 through contact jaws I8, main switch blade 62, contact jaws 64, interrupter blade 68, actuating shaft 58, crank l2, crank pin 14, and through a fiexible shunt 82 connecting crank pin "i4 and terminal plate 42. Preferably, flexible shunt 82 extends through an opening provided in cover 88 and is secured to the terminal plate and crank pin by

screws

84 and 86, respectively.

It will be noted that in the closed circuit position of the switch, overcenter spring 'I6 lies at one side of actuating shaft 58, to hold interrupter blade 66 in engagement with contact jaws 64,v and to also hold the interrupter housing against stop portion 88 formed integral with the vertical part 36 of the housing supporting bracket. In opening the switch, insulator 24 is rotated in a clockwise direction, and since main blade 62 is frictionally held in engagement between contact jaws 22, and since interrupter housing 46 may rotate on actuating shaft 58 relative to insulator 24, initial rotation of the insulator merely results in shifting of the axis of actuating shaft 58 to the other side of overcenter spring 16, while the free end of main blade 62 is held in engagement with contact jaws I6. Shifting of the axis of actuating shaft 58 to the other side of overcenter spring 'I6 causes the spring to exert a force to rotate interrupter blade 68 in a counterclockwise direction to move it out of engagement with contact jaws 64. This opens the circuit Within interrupter housing 46, and results in the drawing of an arc in the narrow slot formed between

housing liners

54 and 56. Since the liners are of a gas-evolving material, this will result in the production of a quantity of arc-extinguishing gas which must escape from slot 'F8 of the housing and thus pass through the arc and replace the ionized particles in the arc path by the un-ionized particles of such gases. This, coupled with rapid elongation of the arc due to the action of overcenter spring 16, results in an extremely eflicient arc-extinguishing action, to thereby interrupt the circuit within housing 46 before main blade 62 is separated from contact jaws I8, as shown in Fig. 5. After the circuit has been interrupted within interrupting housing 46, stop shoulders 88, also integrally formed with the housing bracket portion 36, will engage the opposite side of interrupter housing 46 to prevent further relative movement of rotatable insulator 24 and the housing 46, so that continued clockwise rotation of insulator 24 causes the interrupter housing and main blade 62 to move with the insulator. .This results in main blade 62 being moved out of engagement with fixed contact jaws i8 to insert a readily visible, safe air gap in the circuit.

In the open circuit position of the switch, where main blade 62 is separated from fixed contact jaws i8, overcenter spring 16 holds interrupter blade 60 at its open position spaced from interrupter contact jaws 64, and against one end of the narrow slot within interrupter housing 46,

In order to actuate interrupter switch blade i5 and consequently this spring also holds interrupter housing 4S in engagement with stop portion 90 of the housing supporting bracket. Accordingly, in closing the switch, switch insulator 24 will be rotated in a countercloclrwise direction, and

blades

60 and 62 will be held by spring 16 substantially at the position relative to insulator 24 shown in Fig. 5. When main blade 62 enters side opening 23 in xed contact housing I0 and engages between contact jaws I8, the circuit will not be completed, because interrupter blade 60 is still held in open circuit position.

However, as soon as full engagement of blade 62 with contact jaws I8 occurs, blade B2 will be held against further movement at its outer end, and consequently continued counterclockwise rotation of insulator 24 results in relative movement of blade 62 and housing 46 with respect to the rotatable insulator. This relative movement causes the axis of actuating shaft 58 to be moved to the Vopposite side of overcenter spring 1S, whereupon this spring will move interrupter blade 6) with a snap action into engagement between contact jaws 64, to thereby nally close the circuit.

It will be noted that according to this invention, a disconnect switch blade S2 is provided in series with an enclosed circuit interrupter blade B0, so that the circuit is always opened by the interrupter blade within its special arc-extinguishing enclosure, and o-n closing the switch the circuit is iinally made by the interrupter blade 60, so that all arcing will occur between interrupter blade EB and contact jaws G4, thus relieving main blade 62 and contact jaws I8 0f all arcing. In view of the foregoing, it is also apparent that use is made of relative movement between the actuating means and switch blade 62 for causing an overcenter spring 'l5 to actuate the interruptor switch blade '69 with a snap action, both in opening and in closing the circuit. The particular cooperation and relationship of the circuit interrupting blade 60 and its arc-extinguishing means with the switch actuating means and main blade 62, results in obtaining sequential operation of the interrupting blade and main blade by the use of relatively simple operating mechanism, and yet results in efhcient extinguishing of the arc within interrupter housing 45, with substantially no external display.

Having described a preferred embodiment ci the invention in accordance with the patent statutes, it is desired that this invention be not limited to this particular embodiment, inasmuch as it will be apparent to persons skilled in the art that many changes and modifications may be made in this particular species 0f the invention without departing from the broad spirit and scope of the invention. Accordingly, it is desired that this invention be interpreted as broadly as possible, and that it be limited only as required by the prior art.

I claim as my invention:

1. In a circuit interrupter, a line contact, a switch blade adapted to frictionally engage said line contact, movable supporting means for said blade with said blade mounted on said supporting means for limited relative movement while said blade is held in frictional engagement with said line contact, said blade also being movable with said supporting means into and out of engagement with said line contact, separable interrupting contacts arranged in series circuit relation with said blade, an overcenter spring for actuating said interrupting contacts into and out oi engagement with a snap action, and means responsive to said relative movement between said blade and supporting means to actuate said spring overcenter to thereby actuate said interrupting contacts while said blade engages said line contact.

2. In a circuit interrupter, a line contact, a switch blade adapted to frictionally engage said line contact, movable supporting means for said blade with said blade mounted on said supporting means for limited relative movement while said blade is held in frictional engagement with said line contact, said blade also being movable with said supporting means into and out of engagement with said line contact, separable interrupting contacts carried by said blade and arranged in series circuit relation with said blade, anovercenter spring for actuating said interrupting contacts into and out of engagement with a snap action, and said spring reacting between at least one of said. separable contacts and said supporting means so as to be actuated overcenter in response to relative movement of said blade and supporting means, to thereby actuate said interrupting contacts while said blade engages said line contact.

3. In a circuit interrupter, a line contact, a switch blade adapted to frictionally engage said line contact, pvotally movable supporting means for said blade with said blade pivotally mounted on said supporting means for limited relative movement on an axis offset from the pivot axis of said supporting means while said blade is held in irictional engagement with said line contact, said blade also being pivotally movable with said supporting means into and out of engagement with said line contact, separable interrupting contacts carried by said blade and arranged in series circuit relation with said blade, an overcenter spring for actuating said interrupting contacts into and out of engagement with a snap action, and said spring reacting between at least one of said separable contacts and said supporting means so as to be actuated overcenter in respense to relative movement of said blade and supporting means.

4. In a circuit interrupter, a line contact, a switch blade adapted to frictionally engage said line Contact, pivotally movable supporting means for said blade with said blade pivotally mounted on said supporting means for limited relative movement while said blade is held in frictional engagement with said line contact, said blade also being pivotally movable with said supporting means into and out of engagement with said line Contact, separable interrupting contacts carried by said blade and arranged in series circuit relation with said blade, an overcenter spring for actuating said interrupting contacts into and out of engagement with a snap action, and said spring reacting between at least one of said separable contacts and said supporting means so as to be actuated overcenter in response to relative movement of said blade and supporting means.

5. In a circuit interrupter, a line contact, a

' switch blade adapted to fricticnally engage said line Contact, pivotally movable supporting means for said blade with said blade pivotally mounted on said supporting means for limited relative movement while said blade is held in irictional engagement with said line contact, said blade also being pivotally movable with said supporting means into and out of engagement with said line contact, separable interrupting contacts arranged in series circuit relation with said blade, one of said interrupting contacts being mounted on said 7 blade and the other of said interrupting contacts being pivotally mounted on the same axis as said blade, means responsive to said relative movement between said blade and supporting means to actuate said spring overcenter to thereby actuate said interrupting contacts while said blade engages said line contact.

6. In a circuit interrupter, switch blade means, rotatable actuating means for said blade means, said blade means pivotally mounted on said actuating means on an axis oiset from the axis of rotation of said actuating means, means limiting pivotal movement of said blade means relative to said actuating means, interrupting means mounted on one of said first two mentioned means and comprising a housing having spaced parallel walls of insulating material forming a narrow slot therebetween, contact means in said slot adjacent one end thereof, a pivoted switching member also in said slot mounted for pivotal movea ment through said slot into and out of engagement with said contact means, and. overcenter spring means reacting between said switching member and the other of said rst two mentioned means for actuating said switching member in response to relative movement of said blade means and actuating means.

'7. In a circuit interrupter, switch blade means, rotatable actuating means for said blade means, said blade means pivotally mounted on said actuating means on an axis offset from the axis of rotation of said actuating means, means limiting pivotal movement of said blade means relative to said actuating means, interrupting means mounted on one of said first two mentioned means and comprising a housing having spaced parallel walls of insulating material forming a narrow slot, contact means in said slot adjacent one end thereof, a pivoted switching member also in said slot mounted for pivotal movement through said slot into and out of engagement with said contact means, said housing having an opening for venting gases from said slot to direct such gases in a direction at an angle to said blade means,

and overcenter spring means reacting between said switching member and the other of said first two mentioned means for actuating said switching member in response to relative movement of said blade means and actuating means.

8. In a circuit interrupter having spaced terminals, bridging means for said terminals comprising a housing having a contact projecting from one side thereof, said housing adapted to be movably mounted at the other side thereof adjacent one of said terminals for movement of said contact into and out of engagement with the other of said terminals, said housing having spaced parallel walls of insulating material therein forming a narrow slot, contact means on the inner end of said contact in said slot at one side thereof, a pivoted switching member adapted to be electrically connected with said one terminal at least in the closed circuit position of said interrupter, said switching member being mounted in said slot to pivotally move through said slot into and out of engagement with said contact means, and common actuating means for said bridging means and lswitching member.

9. In a circuit interrupter having spaced terminals, bridging means for said terminals comprising a housing having a contact projecting from one side thereof, said housing adapted to be movably mounted at the other side thereof adjacent one of said terminals for movement of said contact into and out of engagement with the other of said terminals, said housing having spaced parallel walls of insulating material therein forming a narrow slot, contact means on the inner end of said contact in said slot at one side thereof, a pivoted switching member adapted to be electrically connected with said one terminal at least in the closed circuit position of said interrupter, said switching member being mounted in said slot to pivotally move through said slot into and out of engagement with said contact means, said housing having an opening for venting gases from said slot to direct such gases in a direction at an angle to said blade means, and common actuating means for said bridging means and switching member.

10. In a circuit interrupter having spaced terminals, bridging means for said terminals comprising a housing substantially triangular in form, a contact projecting from the base of said housing at one side thereof, said housing adapted to be pivotally mounted substantially at the apex thereof adjacent one of said terminals for movement of said contact into and out of engagement with the other of said terminals, said housing having spaced parallel walls of insulating material therein forming a narrow slot, Contact means on the inner end of said Contact in said slot at said one side thereof, a switching member pivotally mounted in said slot substantially at the apex thereof and adapted to be electrically connected with said one terminal at least in the closed circuit position of said interrupter, said switching member being mounted in said slot to pivotally move through said slot into and out of engagement with said contact means, and common actuating means for said bridging means and switching member.

l1. In a circuit interrupter having spaced terminals, bridging means for said terminals comprising a housing substantially triangular in form, a contact projecting from the base of said housing at one side thereof, said housing adapted to be pivotally mounted substantially at the apex thereof, adjacent one of said terminals for movement of said Contact into and out of engagement with the other of said terminals, said housing having spaced parallel walls of insulating material therein forming a narrow slot, contact means on the inner end of said contact in said slot at said one side thereof, a switching member pivotally mounted in said slot substantially at the apex thereof and adapted to be electrically connected with said one terminal at least in the closed circuit position of said interrupter, said switching member being mounted in said slot to pivotally move through said slot into and out of engagement with said contact means, common actuating means for said bridging means and switching member, and the base of said housing being open at least at the other side thereof to vent gases from said slot.

12. In a circuit interrupter, a substantially fiat housing which is generally of triangular shape in outline, said housing having at least inner walls of insulating material forming a narrow arc slot of substantially the same shape and form as said housing, a switch member in said slot and pivotally mounted substantially at the apex of said housing, a contact in said slot adjacent the base of said housing and at one side thereof, means for actuating said switch member into and out of engagement with said Contact, and said housing being closed except for a vent in said base at a point spaced from said contact so that gases accumulated under pressure in said housing during arcing will pass through the arc in escaping from said housing.

13. In a circuit interrupter, a substantially flat housing which is generally of triangular shape in outline, said housing having at least inner walls of insulating material which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc forming a narrow arc slot of substantially the same shape and form as said housing, a switch member in said slot and pivotally mounted substantially at the apex of said housing, a contact in said slot adjacent the base of said housing and at one side thereof, means for actuating said switch member into and out of engagement with said contact, and said housing being closed except for a vent in said base at a point spaced from said contact so that gases accumulated under pressure in said housing during arcing will pass through the arc in escaping from said housing.

14. In a circuit interrupter, a pair of spaced supporting insulators one of which is rotatably mounted, a line contact mounted on the other of said insulators, switch blade means adapted to frictionally engage said line contact, said blade means mounted on said rotatable insulator for relative limited pivotal movement on an axis oirset from the axis of rotation of said rotatable insulator while said blade means is held in frictional engagement with said line contact, said blade means also being rotatable with said rotatable insulator into and out of engagement with said line contact, separable interrupting contacts carried by said blade means and arranged in series circuit relation therewith, an overcenter spring for actuating said interrupting contacts into and out of engagement with a snap action, and said spring reacting between at least one of said separable contacts and said rotatable insulator so as to be actuated overcenter in response to relative movement of said blade means and said rotatable insulator.

15. In a circuit interrupter, a pair of spaced supporting insulators one of which is rotatably mounted, a line contact mounted on the other of said insulators, switch blade means adapted to frictionally engage said line contact, said blade means mounted on said rotatable insulator for relative limited pivotal movement while said blade means is held in frictional engagement with said line contact, said blade means also being rotatable with said rotatable insulator into and out of engagement with said line contact, separable interrupting contacts carried by said blade means and arranged in series circuit relation therewith, an overcenter spring for actuating said interrupting contacts into and out of engagement with a snap action, and said spring reacting between at least one of said separable contacts and said rotatable insulator so as to be actuated overcenter in response to relative movement of said blade means and said rotatable insulator.

HOWARD W. GRAYBILL.