US3814878A

US3814878A - Circuit breaker operating mechanism

Info

Publication number: US3814878A
Application number: US00241714A
Authority: US
Inventors: D Weston; R Kupetis
Original assignee: PORTER CO H
Current assignee: PORTER CO H; PORTER H CO INC US
Priority date: 1970-03-31
Filing date: 1972-04-06
Publication date: 1974-06-04
Anticipated expiration: 1991-06-04

Abstract

A circuit breaker comprised of a shunt switch, vacuum tube interrupter switches and a disconnect switch blade housing said interrupter switches is operated by the mechanism of the invention in a switch opening sequence wherein the shunt switch is opened first, the interrupter switches are then opened at high speed and the disconnect blade is swung open immediately following opening of the interrupter switches, and in a closing sequence wherein the circuit is closed through the shunt switch to relieve the interrupters of circuit closing stresses.

Description

United States Patent [191 Weston et al. i.

[5 1 CIRCUIT BREAKER OPERATING MECHANISM [75] Inventors: Donald E. Weston, East Sebago,

Maine; Raymond F. Kupetis,

Chicago, Ill.

[73] ,Assignee: H. K. Porter Company, Inc.,

' Chicago, Ill.

[22] Filed: Apr. 6, 1972 [211 App]. No.: 241,714

Related US. Application Data I [62] Division of'Ser. No, 24.079, March 3|, 1970, Pat.

[521 us. Cl ..200/144 B, 200/15'3 L, 200/169 R 51 Int. Cl. ll0lh 33/66 [58] Field of Search 200/144 B, l53 L, 169 R 56] References Cited UNITED STATES PATENTS 3,532,842 10/1970 Fohrhaltz "ZOO/I448 I451 June 4, 1974 Primary Examiner-Robert S. Macon Attorney, Agent, or FirmGary, .luettner, Pigott & Cullinan [57] ABSTRACT A circuit breaker comprised of a shunt switch, vacuum tube interrupter switches and a disconnect switch blade housing said interrupter switches is operated by the mechanism of the invention in a switch opening sequence wherein the shunt switch is opened first, the

interrupter switches are then opened at high speed and the disconnect blade is swung open immediately following opening of the interrupter switches, and in a closing sequence wherein the circuit is'closed through the shunt switch to relieve the interrupters of circuit closing stresses.

9 Claims, 8 Drawing Figures 3,566,055 and copending. application Ser.

CIRCUIT BREAKER OPERATING MECHANISM CROSS REFERENCE BACKGROUND OF THE lNVENTlON:

U.S. Pat. No. 3,566,055, granted Feb. 23, 1971 to Donald E. Weston, discloses an isolating circuit breaker capable of performing circuit breaking functions though comprisedof what were previously known only aslow capacity interrupting" devices. This so-called isolating circuit breaker is comprised of a disconnect switch blade housing a plurality of interrupters and a main or by-pass switch in parallel with the interrupters and comprising the normal load carrying member of the assembly. ln switch closed position, the bypass switch carries the current and maintains the interrupters essentially inelectrically unstressed condition.When it is desired to break the circuit, the by-pass or shunt switch is opened first and the interrupters are opened momentarily thereafter to break the circuit.

Then the disconnect switch blade is opened to completely isolate the interrupters from the circuit. By virtue of this sequence of operation, the interrupters are isolated from circuit stress except at the moment of opening thereof and thus can be operated at their transient capabilities rather than their continuous service rating to perform circuit breaking operations. Also, further to relieve the interrupters from circuit stress, the circuit is remade through the by-pass or shunt switch and not through the interrupters.

Mechanism for performing the aforesaid sequence of operations is disclosed in U.S. Pat. No. 3,566,055. Other mechanisms for performing similar sequences of operations are disclosed in British Pat. No. 1,028,719 and U.S. Pat. No. 2,710,322, to which specific reference is made. Attention is also invited to the references cited against the identified patents and also to German Pat. No. 1,128,506 and U.S. Pat. No. 2,872,550.

SUMMARY OF THE INVENTION The object of this invention is to provide an improved and highly reliable operating mechanism for switches of the character above described.

THE DRAWINGS DESCRIPTION:

Referring to FIG. 1, the switch there shown is of a type commensurate with the disclosures of patent No.

I 2 54 connecting a depending shaft extension 55 to an operating bar 41.

The outboard insulators 51 and'52 mount the stationary contact assemblies of the switch, which in this case are comprised of a pair of metallic stanchions 56 each fixedly mounting a stationarycontact 65 for engagement by a respective end of a vacuum tube assembly 57 and also a stationary contact 58 for a rotatable, double break switch blade 59 comprising a shunt or by-pass for the vacuum tube assembly 57. This shunt switch blade is mounted on top of the rotatable insulator 53 immediately below the vacuum tube assembly 57.

' The shunt blade 59 is simply a cylindrical conductive tube closed at its ends and provided with thick walls and contactfingers generally correlated to the crosssectional area of the bus connectors leading to the switch and sufficient to carry continuously the current of the system. The blade is secured centrally of its length to the insulator 53 so as to be rotated thereby in such fashion that its opposite ends swing away from both of the contacts 5858 simultaneously and toequal degrees, whereby to provide two points of contact separation for inserting a large air gap between the contacts 58 -58. The blade is of such length that when rotated approximately to 55, the air gaps between it and the contacts 58 will be sufficient to prevent re-striking of an arc therebetween at the potential of the system.

The vacuum tube assembly 57 comprises a central operator section 60 of generally cylindrical configuration, a pair of insulator sections 61 extending to opposite sides of the central section, and conductive end bells 62 carrying contacts for engagement with the stationary contact members 65. As with the blade 59, the

blade or assembly 57 is mounted centrally of its length for rotation about the axis of the insulator 53 into and 119,51 1, filed March 1, 1971. As shown, the switch is comprised of a stationary base 36 and three mounting insulators; namely,

stationary outboard insulators

51 and 52 and a rotary central insulator 53 journaled on the base 36 and adapted to be operated by a crank arm out of engagement with the contacts 65. Mounted within each insulator 61 is one or more vacuum tube units of conventional construction. All of the vacuum tubes are connected in series circuit between the end bells 62, preferably in conjunction with-a voltage distributing and equalizing linkage for causing all of the vacuum tubes to break simultaneously. For a more de tailed discussion, reference may be had to U.S. Pat. No.

3,566,055. In the particular environment here consid ered, each insulator may carry a single vacuum tube 63 surrounded by air at ambient pressure and temperature, the two tubes being connected in series between the bells 62 and mounted in back-to-back relation.

In operation of the switch, the crank 54 is turned by the bar 41 to rotate the insulator 53 and thus the shunt blade 59. When the blade has been rotated to a predetermined degree to establish the necessary air gaps between it and the contacts 58, the vacuum tubes 63 are tripped to open circuit position by means of a shaft 64 extending from the blade 59 upwardly into the central section 60 of the vacuum tube assembly. This causes the circuit to be interrupted or broken. As explained in U.S. Pat. No. 3,566,055, the vacuum tubes until this time have been shunted by the blade 59, have had only momentary current carrying duty and thus are in prime condition to perform a circuit breaking function. As soon as the interrupters have been tripped to open circuit position, the shaft 64 effectively engages the blade or housing 57 and swings it away from the contacts 65, whereupon the circuit is fully open and the interrupters 63 are completely isolated from the circuit.

The operating mechanism provided by this invention for the switch is shown in FIGS. 2 and 3, and sequential positions in the operation thereof are depicted fragmentarily in FIGS. 4 through 8. Referring to FIGS. 2 and 3, the shaft 64 extending upward from the disconnect or-shunt blade 59 is provided within the central section 60 of the assembly 57 with a cam 71 intended primarily for closing the vacuum tubes. The hub portion of the cam includes a pair of upwardly extending spaced abutments 72. Rotatably mounted on the shaft 64 above the cam 71 is a rotary latch 73, the latch being trapped on the shaft proximate to the cam by a collar 74 secured to the shaft. The hub portion of the latch 73 is equipped with a pair of abutments 75 extending toward the cam 71 and complemental to the abutments 72 on the cam. The circumferential dimensions of the two pairs of

abutments

72 and 75 are such as to provide a predetermined spacing between opposing abutments providing a lost motion rotary connection between the cam and latch correlated to the degree of disconnect or shunt switch rotation desired prior to tripping of the vacuum tubes, in this case approximately 40 to 45.

Both the cam 71 and the latch 73 are elongate members having cam and latch surfaces (respectively) at the opposite ends thereof for cooperation with the vacuum tube switch means mounted in each of the insulators 61, only one of which is shown in FIG. 2. Each vacuum tube comprises a stationary tubular housing 76 containing a stationary contact (not shown) and a movable contact rod 77 extending from the tube and equipped to the exterior thereof with a transverse pin 78. Engaged with the pin is a collar 79 which is contacted by a compression spring 80 disposed between the collar and an operator 81 which is slidably mounted in a tubular guide and stop member 82 which may be bolted or otherwise secured to the tube 76 and the central section 60. The operator 81 is also slidably guided on the inner end of the contact rod 77, and a headed bolt 83 adjustably threaded into the inner end of the contact rod 77 serves to trap the operator 81 on the rod 77 with facility for adjustment of lost motion between the operator and the head 83. An operator driving compression spring 84 is confined between the tube 76 and the operator 81 in encircling relation to the spring 80.

lnwardly of the head 83, the operator 81 is equipped with a transversely mounted roller bearing 85 which parallels the shaft 64 for cooperation with the cam 71 and the latch 73. Also disposed for cooperation with the cam and latch area pair of abutments projecting from the housing section 60; namely, a closing direction abutment 86 extending into the path of the cam 77 on the closing side of the vacuum tube center line, and an opening direction abutment 87 extending into the path of the latch 73 on the opening side of the vacuum tube center line and spaced from the adjacent side of the latch by an angle equal to the rotary movement of the shaft 64 prior to tripping of the vacuum switches.

These two

abutments

86 and 87 are provided for the purpose of rotating the vacuum tube assembly 57 to isolated position, and the illustration and description thereof are given by way of example and not as the preferred structure for isolation of the vacuum switch assembly 57. In the latter regard, reference is made to copending application Ser. No. 119,511.

In the closed position of the switch, as shown in FIG. 3, the cam 71 and the latch 73 are in line with the vacuum tubes and the latch is engaged with the roller 85 to retain the vacuum tubes closed. At this time, the operator 81 closes the vacuum tube switch under predetermined spring pressure by virtue of the interposition of the compression spring 80, whereby to maintain a predetermined contact pressure between the vacuum tube contacts.

Upon opening movement of the rotary insulator 53 and shaft 64, the shunt or disconnect switch 59 is first rotated to swing clear of its contacts by an arcuate extent of 40 to 45, during which the cam 71 is rotated to clear the bearing 85 and to engage its abutments 72 with the abutments on latch 73, the latch still retaining the vacuum tube switches closed as shown in FIG. 4.

During the next 10 to 15 of shaft rotation, the cam 71 drives the latch 73 in opening direction, whereupon the latch releases the roller 85 and the spring 84 drives the operator 81 to switch open position, as shown in FIG. 5, at which time the shunt or disconnect switch has been opened about 55 60. During opening movement, the spring 84 initially drives only the operator 81 whereby to accelerate the same to high speed, and during this time, the pressure on spring is alleviated due to retraction of the operator 81. Then, the spring 84 drives the now accelerated operator against the head 83, with impact load to break any welding of the vacuum tube contacts, whereupon the contact rod 77 is snapped to full open position and the vacuum tube contacts are separated at a defined controlled rate whereby to insure effective interruption or breaking of the circuit, i.e., opening of the circuit.

As soon as the latch 73 has been moved sufficiently to trip the vacuum switches, the latch engages the abutment 87 and continued rotation of the shaft thereupon causes the housing 60 and thus the vacuum tube assembly 56 to rotate with the shaft to a sufficient arcuate extent to fully isolate the vacuum tubes from the circuit, i.e., to completely separate them physically from all electrical connections. In the illustration of FIG. 6, a suitable open position is given as one wherein the shunt has been rotated 1 10 120 and the vacuum tube assembly 55, 60.

When it is desired to close the switch, the insulator 53 and shaft 64 are rotated in the opposite direction, whereupon the shunt switch 69 and the cam 71 first rotate approximately 40 to 45 back toward closed position, during which the cam 71 will reclose the vacuum tube contacts as indicated in FIG. 7. Then, the abut ments 72 on the cam 71 engage the abutments 75 on the latch 73 and swing the latch into latching position relative to the roller as is shown in FIG. 8. At this time also, the cam 71 engages the abutment 86 whereupon continued rotation causes both the vacuum assembly 57 and the shunt switch 59 to be rotated back to the switch closed position shown in FIG. 3. The electrical closing stress is carried by the shunt switch by means of appropriate contact design.

Having thus described the purpose and function of the cam 71, latch 73, and

abutments

86 and 87, it will be apparent that the two

switches

57 and 59 could be operated individually from the base 36 of the switch assembly by means of concentric shafts, i.e., the insulator 53 and a shaft extending axially through the insulator and the shunt 59 and into the housing'60. Also,'the use mounted above the vacuum tube assembly 57 for operation by the inner one of the two shafts; in which case the assembly 57 could be operated individually by the insulator 53. The two shaft structure would aid in providing even greater assurance of avoidance of electrical stress on the vacuum tubes, especially switch closing stresses, in accordance with the teachings of US. Pat. No. 3,566,055 and application Ser. No. 1 19,51 1.

Also, as shown in our copending parent application Ser. No. 24,079, the shaft 64 can be rotated only so far as is necessary to open the shunt switch and trip the vacuum tube interrupters (approximately 50 to 60) for operation in relatively low load circuits and/or for circuit reclosure service. The cam 71 is so configured as to effect closing of the interrupters after closing of the shunt 59 when the switch is operated in this manner.

Thus,'while we have shown and described one embodiment of our invention, the additional examples given render manifest the ability of persons skilled in the art to make changes, rearrangements and modifications in said embodiment without departing from the scope of the invention, as defined by the appended claims. a

What is claimed is:

1. Operating means for a switch assembly including interrupter switch means and shunt switch means normally by-passing said interrupter switch means, comprising a shaft, a cam on said shaft having abutments thereon, a latch journalled on said shaft proximate to said cam and having abutments thereon for engagement with the abutments on said cam, said latch in the closed position of the switch engaging the interrupter switch means and maintaining the same closed and having the abutments thereon spaced circumferentially from the abutments on said cam so as to accommodate predetermined rotation of said shaft and said cam and opening of the shunt switch means before the abutments on said cam engage the abutments on said latch, said cam upon engagement of its abutments with those on said latch rotating said latch away from said interrupter switch means to accommodate opening of the interrupter switch means.

2. Operating means as set forth in claim I, said cam and said latch having juxtaposed faces each including an annular surface and a pair of diametrically opposed abutments projecting from said surface, each of said abutments being of less than 90 in arcuate extent, the abutments onsaid latch entering between the abutments on said cam and providing predetermined rotational lost motion between the cam and the latch in both directions of shaft rotation.

3. Operating means as set forth in claim 1, including a supporting structure for the interrupter switch means and a pair of stops projecting from said structure to opposite sides of said latch, said stops bieng spaced apart by a distance greater than the width of the latch to accommodate tripping and resetting of the interrupter switches prior to engagement of the latch with the respective ones of said stops.

4. Switch means comprising a spaced pair of stationary contacts, an insulated housing extending between said contacts and enclosing vacuum tube switch means normally bridging between said contacts, a shunt switch normally bridging between said contacts parallel to said vacuum tube switch means, means for moving said shunt switch into and out of engagement with said stationary contacts, a shaft projecting from said shunt switch moving means into said housing, a cam on said shaft for driving the vacuum tube switch means to closed circuit position upon rotation of said shaft in switch closing direction, a latch journalled on such shaft and having lost motion connection with said cam for latching said vacuum tube switch means in closed circuit position, and spring means on said vacuum tube switch means normally biasing the same to open circuit position,- said cam upon rotation of said shaft in switch opening direction having an initial lost motion relative to said latch to accommodate opening of said shunt switch and thereafter engaging and tripping said latch to accommodate opening of said vacuum tube switch means.

5. The switch means of claim 4, including abutment means on said housing engageable by said latch after tripping of said latch on switch opening movement for rotating said housing away from said stationary contacts upon further rotation of said shaft to isolate said vacuum tube switch means from the circuit.

' 6. The switch means of claim 5 including second abutment means on said housing engageable by said cam upon switch closing rotation of said shaft for rotating said housing and said vacuum tube switch means back into engagement with said stationary contacts.

7. Switch means comprising a vacuum switch, movable means projecting from said vacuum switch for opening and closing the contacts thereof, means for urging and movable means toward switch open position, a shaft, means for rotating said shaft about its axis, a latch journalled on said shaft and in latching engagement with said movable means in switch closed position, and trip means secured to said shaft, said trip means being spaced from said latch in switch closed po sition and engaging said latch upon a predetermined degree of rotation of said shaft to move said latch means out of said latching engagement.

8. The switch means of claim 7 wherein said movable v means comprises an axially movable rod having a terminal bearing surface, said rod moving outward from said vacuum switch to switch open position and inward toward said switch to switch close position, said latch being in latching engagement with said surface in closed switch position, and wherein said trip means further comprises cam means for engaging said bearing surface and moving said rod toward closed switch position.

9. The switch means of claim 7 further comprising spring means for urging said movable means toward switch closed position when said latch is in latching engagement therewith.

Claims

2. Operating means as set forth in claim 1, said cam and said latch having juxtaposed faces each including an annular surface and a pair of diametrically opposed abutments projecting from said surface, each of said abutments being of less than 90* in arcuate extent, the abutments on said latch entering between the abutments on said cam and providing predetermined rotational lost motion between the cam and the latch in both directions of shaft rotation.

4. Switch means comprising a spaced pair of stationary contacts, an insulated housing extending between said contacts and enclosing vacuum tube switch means normally bridging between said contacts, a shunt switch normally bridging between said contacts parallel to said vacuum tube switch means, means for moving said shunt switch into and out of engagement with said stationary contacts, a shaft projecting from said shunt switch moving means into said housing, a cam on said shaft for driving the vacuum tube switch means to closed circuit position upon rotation of said shaft in switch closing direction, a latch journalled on such shaft and having lost motion connection with said cam for latching said vacuum tube switch means in closed circuit position, and spring means on said vacuum tube switch means normally biasing the same to open circuit position, said cam upon rotation of said shaft in switch opening direction having an initial lost motion relative to said latch to accommodate opening of said shunt switch and thereafter engaging and tripping said latch to accommodate opening of said vacuum tube switch means.

6. The switch means of claim 5 including second abutment means on said housing engageable by said cam upon switch closing rotation of said shaft for rotating said housing and said vacuum tube switch means back into engagement with said stationary contacts.

7. Switch means comprising a vacuum switch, movable means projecting from said vacuum switch for opening and closing the contacts thereof, means for urging and movable means toward switch open position, a shaft, means for rotating said shaft about its axis, a latch journalled on said shaft and in latching engagement with said movable means in switch closed position, and trip means secured to said shaft, said trip means being spaced from said latch in switch closed position and engaging said latch upon a predetermined degree of rotation of said shaft to move said latch means out of said latching engagement.

8. The switch means of claim 7 wherein said movable means comprises an axially movable rod having a terminal bearing surface, said rod moving outward from said vacuum switch to switch open position and inward toward said switch to switch close position, said latch being in latching engagement with said surface in closed switch position, and wherein said trip means further comprises cam means for engaging said bearing surface and moving said rod toward closed switch position.