US3760132A

US3760132A - Enclosed switch device with cover interlock

Info

Publication number: US3760132A
Application number: US00245456A
Authority: US
Inventors: J Ellsworth; J Wallace
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1972-04-19
Filing date: 1972-04-19
Publication date: 1973-09-18
Anticipated expiration: 1990-09-18
Also published as: BR7302846D0; CA942806A

Abstract

A switch device characterized by a switch structure within an enclosure having an openable cover and having interlock means between the switch structure and a handle on the cover for preventing opening of the cover if the contacts of the switch structure are welded in the closed-circuit position.

Description

United States Patent [1 1 Ellsworth et al.

[ 1 Sept. 18,1973

[ ENCLOSED SWITCH DEVICE WITH COVER INTERLOCK Inventors: James P. Ellsworth; James B.

Wallace, both of Beaver, Pa.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: Apr. 19, 1972 Appl. No.: 245,456

Assignee:

US. Cl 200/50 A Int. Cl. H0111 9/20, HOlh 33/46 Field of Search 200/50 A References Cited UNITED STATES PATENTS v 3,609,261 9/1971 Rys 200/50 A Primary Examiner-J. R. Scott Attorney-A. T. Stratton et al.

ABSTRACT A switch device characterized by a switch structure within an enclosure having an openable cover and having interlock means between the switch structure and a handle on the cover for preventing opening of the cover if the contacts of the switch structure are welded in the closed-circuit position.

7 Claims, 3 Drawing Figures PATENTEDSEPIBIBB 5.760.132

SHEU 2 0F 2 FIG. 3

E i :l

El 0 o ENCLOSED SWITCH DEVICE WITH COVER INTERLOCK BACKGROUND OF THE INVENTION vided with openable covers having handles which more recently have been operatively connected to the enclosed switch for actuating the switch to the open position when the cover is to be opened. A disadvantage with some devices of the foregoing type. is that in the event that the contacts of the circuit breaker are welded in the closed circuit position the handles for the covers have nevertheless been operable to open the cover notwithstanding the closed circuit condition of the breaker, thereby creating an unsafe condition.

SUMMARY OF THE INVENTION In accordance with this invention it has been found that the foregoing problem may be overcome byproviding an electrical switch device having a switch structure and an enclosure therefore, the switch structure comprising stationary and movable contacts, a movable switch arm having the movable contact thereon, operating mechanism for the switch arm and comprising an operating lever and a switch handle thereon for manually moving the operating lever, an overcenter toggle operable by the operating lever to effect movement of the switch arm to open and closed circuit positions, the enclosure comprising an openable cover, a second handle on the external side of the cover and having first means engaging and operating the switch handle, said means disengaging the switch handle when the cover is opened, the switch handle being movable between on and off positionsto operate the contacts between closed and opened positions, the first means comprising a rotatable member having opposed strike surfaces forming an aperture, the switch handle extending into the aperture when the cover is closed, the switch handle including a projection facing the on position, the handle being biased to the on" position if the contacts fail to open when the second handle is moved to the off position, and the projection being located in a path of movement of the strike surface on the on side of the handle when the cover is opened.

The advantage of the switch device of this invention is the inability to open the cover if the stationary and movable contacts are welded in a closed circuit position, thereby providing a safety feature for the switch device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a switch device constructed in accordance with the principles of this invention;

FIG. 2 is a plan view of the handle with a portion of the cover brokenaway; and

FIG. 3 is a plan view of a circuit breaker with the cover removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. I of the drawings a switch device or circuit breaker is generally indicated at 10. It comprises a switch structure 12 which is mounted on a molded base 14 of electrically insulating material, an enclosure 16, and a removable cover 18 which is preferably hingedly mounted on the enclosure.

The switch device or circuit breaker 10 is of the multi-pole type and the mechanism may be of the general type disclosed in US. Pat. No. 2,508,178, issued May 16, 1950 to T. Lindstrom et al., and assigned to the assignee of the present invention. The device 10 includes a stationary contact 20 and a movable contact 22 for each pole of the device. A common operating mechanism, generally indicated at 24 (FIG. 1), is provided for simultaneously actuating three movable contacts 22 (FIG. 3) to open and closed circuit positions.

The stationary contacts 20 is rigidly mounted on the inner end of a conducting strip 26 which extends out of the end of the enclosure 16 and is connected to a line terminal (not shown). The movable contact 22 for each pole is rigidly mounted on a contact arm 28 supported on a switch arm 30 which is rigidly secured on the end of a tie bar 32 that extends across all of the poles (FIG. 3) of the breaker for movement together to opened and closed circuit positions. The contact arm 28 is connected by a flexible conductor 34 to a terminal 36 which is secured tothe base 14 in a suitable manner such as by a screw (not shown).

The operating mechanism 24 for the switch structure 12 is disposed in the center compartment of the housing and is supported on a pair of frames 38 (only one being shown in FIG. 1) which are secured to the base 14 by suitable means such as screws 40. The operating mechanism comprises a forked operating lever 42, a toggle comprising links 44 and 46, overcenter springs 48, and a pivoted releasable cradle 50. An arcuate insulating shield 52 is mounted over the operating end of the operating lever 42 and is provided with an integral switch handle 54. The shield 52 is mounted on an intermediate portion 56 of the operating lever 42 and is secured in place by suitable means such as screws 58 attached to the levers 42, only one of which is shown in FIG. v1.

The toggle links 44 and 46are pivotally connected together by a knee pivot pin 60. The toggle link 44 is pivotally connected by a pivot pin 62 to the cradle 50 and the toggle link 46 is pivotally connected to the switch arm 30 for the center pole by a pivot pin 64. The overcenter springs 48 are connected under tension between the knee pivot pin 60 and the outer end of the operating lever 42 at pivot pins 66.

The switch structure for circuit breaker 12 is operated to the open position by manipulation of the handle 54 in a clockwise direction to the off" position, actuating the overcenter springs 48 to cause collapse of the erally indicated at 68, is provided and comprises a handle 70 and a switch actuator 72. The handle 70 is secured to the switch actuator 72 by a pair of spaced screws 74 which extend through an opening 76 in the cover 18. The handle is rotatable between on and off positions of the switch and a stop pin 78 limits movement of the handle between those positions.

As shown in FIGS. 1 and 2, the actuator 72 comprises a planar portion 80 and a pair of

integral arms

82 and 84 which arms are spaced inwardly toward the switch from the planar portion 80. The planar portion 80 includes a pair of similar spaced

notches

86 and 88 which cooperate with the stop pin 78 for limiting clockwise and counterclockwise rotation of the handle 70. As viewed in FIG. 2 clockwise rotation of the handle 70 from the on to the off position rotates the switch actuator 72 in the same direction. During this movement of the actuator'72 the left arm 82 engages and moves the switch handle 54 in a clockwise direction from the switch on to the switch off position to effect opening of the switch contact. Conversely, movement of the handle 70 (FIG. 2) counterclockwise from the off to the on position reverses the direction of movement of the parts just described and moves the actuator 72 toward the left to the on position. This causes the right arm 82 to engage and move the switch handle 54 counterclockwise to the on position to close the

switch contacts

20 and 22.

Locking means may be provided to prevent opening of the cover 18 in all positions of the handle 70 except when the handle is moved from the ofl position to the open cover position. An open cover position is located between the on and off positions. To effect opening of the cover the handle is normally moved from the on to the off position in order to open the contacts after which the handle 70 is moved to the open cover position. The locking means comprises a bar 90 which is slidably mounted in a U-shaped mounting bracket 92 which is attached in a suitable manner 64 being held in the position shown in FIG. 1 by the welded contacts. As a result the handle 54 is springbiased in a counterclockwise direction and is therefore held against the left arm 82 as shown by the dashed line positions 544 of the handle in FIG. 1.

With prior-known constructions of the handle 54 it was possible to open the cover 18 notwithstanding the

contacts

20 and 22 being welded together simply by rotating the handle to the open cover position and manually pulling the cover from its closed position on the enclosure 16 as shown in FIG. 1, whereupon the

arms

82 and 84 would move with the cover in the direction of the arrow 102 without resistance from the handle 54. As shown in FIGS. 1 and 2 in accordance with this invention the handle 54 is provided with means for preventing opening of the cover which means include a knob or projection 104. The projection 104 is on the side of the handle 54 facing the on position of the switch handle so that in the event that the cover 18 is manually opened when the

contacts

20 and 22 are welded closed, movement of the left arm 82 of the actuator in the direction of the arrow 102 is prevented when the arm comes into contact with the projection due to the handle 54 being spring biased in the counterclockwise direction.

Where under ordinary conditions the

contacts

20 and 22 are openable, the contact arm 28 moves to the broken-line position shown in FIG. 1 and the handle 54 is movable to the dot-dash position 54b by manipulating the handle 70 to the open cover position, whereby the projection 104 is out of alignment with the arm 82 to the inner surface of the cover 18. As viewed in FIG.

2 the lower end of the bar 90 is adapted to engage under a locking bracket 94 which is secured to the inside wall of the enclosure 16. A coil spring 96 is disposed between the mounting bracket 92 and the bar 90 to hold the bar normally in the position of engagement with the bracket 94. The upper end of the bar 90 includes an in-tumed end portion 98 which is positioned below the switch actuator 72 so that when the actuator is rotated clockwise a down-turned member 100 of the actuator engages and moves the end portion 98 upwardly to a broken-line position 98a, thereby disengaging the lower end portion of the bar 90 from looking engagement with the bracket 94. When a handle 70 is subsequently rotated counterclockwise, the spring 96 returns the bar 90 to the lock position as shown in FIG. 2.

If an excessive overcurrent or a short-circuit current occurs while the switch is standing closed, the

contacts

20 and 22 may stick or weld closed. In that situation movement of the switch handle 54 by the handle 70 to the "open cover" or off" positions is resisted by the overcenter springs 48 and upon its release the handle 70 is spring-biased to the on" position. More particularly, movement of the handle 54 to the "off" position causes the overcenter springs 48 to move the toggle 44 46 only slightly overcenter in the opening direction but collapse of the toggle is prevented by the pivot pin when the cover 18 is opened.

As shown in FIG. 2 the

arms

82 and 84 are provided with oppositely disposed rounded portions 82a and 84a to minimize friction between the arms and the handle 54 when in contact with each other. More particularly, the rounded portions 82a and 84a provided for point contacts with opposite sides of the handle 54, thereby minimizing friction between the arms and the handle. Manifestly, the spacing or clearance between the rounded portions 82a and 84a is slightly greater than the total width of the handle 54 and the projection 104.

Accordingly, the cover interlock satisfied or overcomes problems inherent in some prior art structures of enclosed circuit breakers and provides a needed safety device in a simple and inexpensive manner.

What is claimed is:

1. A switch device for controlling an electric circuit comprising a switch structure and an enclosure therefor, said switch structure comprising a stationary contact and a movable contact, a movable switch arm having said movable contact thereon, operating mechanism for said switch arm and comprising an operating lever and a switch handle thereon for manually moving said operating lever, an over-center toggle operable by said operating lever to effect movement of said switch arm to opened and closed circuit positions, said enclosure comprising an openable cover, a second handle on the external side of said cover and having first means comprising a rotatable member for engaging and operating said switch handle, said means disengaging said switch handle when said cover is opened, said second handle being movable between on" and off positions to operate said contacts between closed and opened positions, said second handle being biased to said on position by said over-center toggle if said contacts fail to open when said second handle is moved to said off position, and said switch handle having second means comprising a projection engageable with said rotatable member for preventing opening of said cover if said contacts fail to open when said second handle is moved to said off position.

2. The switch device of claim 1 in which said projection is on said side of said switch handle facing said on position of said switch handle.

3. The switch device of claim 2 in which said rotatable member comprises a strike surface, said projection is disposed on the side of said switch handle adjacent to said strike surface and said projection is disposed in the path of movement of said strike surface when said cover is opened and when said contacts fail to open when said second handle is moved to said off position.

4. The switch device of claim 3 in which said rotatable member comprises aperture means through which said switch handle extends, and said strike surface defines one side of said aperture means.

5. The switch device of claim 4 in which said rotatable member also comprises a second strike surface engageable with said switch handle for moving said handle to said on position.

6. The switch device of claim 4 in which said rotatable member comprises two arrn portions defining a notch into which said switch handle extends and in which one arm portion comprises said strike surface and said other arm portion comprises a second strike surface and said strike surfaces being engageable with opposite sides of said switch handle for moving said switch handle between said on and off positions.

7. The switch device of claim 1 in which said rotatable member has opposed strike surfaces forming an aperture, said switch handle extending into said aperture when said cover is closed, said switch handle including a projection facing said on position, said handle being biased to said on position if said contacts fail to open when said second handle is moved to said off position, and said projection being located in the path of movement of said strike surface on said on side of said handle when said cover is opened.

Claims

1. A switch device for controlling an electric circuit comprising a switch structure and an enclosure therefor, said switch structure comprising a stationary contact and a movable contact, a movable switch arm having said movable contact thereon, operating mechanism for said switch arm and comprising an operating lever and a switch handle thereon for manually moving said operating lever, an over-center toggle operable by said operating lever to effect movement of said switch arm to opened and closed circuit positions, said enclosure comprising an openable cover, a second handle on the external side of said cover and having first means comprising a rotatable member for engaging and operating said switch handle, said means disengaging said switch handle when said cover is opened, said second handle being movable between ''''on'''' and ''''off'''' positions to operate said contacts between closed and opened positions, said second handle being biased to said ''''on'''' position by said over-center toggle if said contacts fail to open when said second handle is moved to said ''''off'''' position, and said switch handle having second means comprising a projection engageable with said rotatable member for preventing opening of said cover if said contacts fail to open when said second handle is moved to said ''''off'''' position.

2. The switch device of claim 1 in which said projection is on said side of said switch handle facing said ''''on'''' position of said switch handle.

3. The switch device of claim 2 in which said rotatable member comprises a strike surface, said projection is disposed on the side of said switch handle adjacent to said strike surface and said projection is disposed in the path of movement of said strike surface when said cover is opened and when said contacts fail to open when said second handle is moved to said ''''off'''' position.

5. The switch device of claim 4 in which said rotatable member also comprises a second strike surface engageable with said switch handle for moving said handle to said ''''on'''' position.

6. The switch device of claim 4 in which said rotatable member comprises two arm portions defining a notch into which said switch handle extends and in which one arm portion comprises said strike surface and said other arm portion comprises a second strike surface and said strike surfaces being engageable with opposite sides of said switch handle foR moving said switch handle between said ''''on'''' and ''''off'''' positions.

7. The switch device of claim 1 in which said rotatable member has opposed strike surfaces forming an aperture, said switch handle extending into said aperture when said cover is closed, said switch handle including a projection facing said ''''on'''' position, said handle being biased to said ''''on'''' position if said contacts fail to open when said second handle is moved to said ''''off'''' position, and said projection being located in the path of movement of said strike surface on said ''''on'''' side of said handle when said cover is opened.