US3748609A

US3748609A - Circuit interrupter

Info

Publication number: US3748609A
Application number: US00245064A
Authority: US
Inventors: J Wallace; A Maier; R Hill
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1972-04-18
Filing date: 1972-04-18
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24
Also published as: JPS4929460U; CA973914A; JPS5340672Y2

Abstract

A circuit interrupter, such as a switch or a circuit breaker, comprising relatively movable contact means, operating means releasable to open the contact means, and trip means which may be responsive to ground fault currents through the contact means to effect the release of the operating means to open the contact means upon the occurrence of ground fault currents.

Description

United States Patent 1 Wallace et al. a

[111 3,748,609 [4 1 July 24, 1973 CIRCUIT INTERRUPTER [75] Inventors: James B. Wallace; Alfred E. Maier;

Robert 11. Hill, all of Beaver Falls,

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Apr. 18, 1972 [2]] Appl. No.: 245,064

[52] U.S. Cl. 335/174, 335/18 [51] Int. Cl. H01h 9/20 [58] Field of Search 335/174, 175, 20,

[ 56] References Cited UNITED STATES PATENTS 2,285,040 6/1942 May 335/175 3,470,507 9/1969 Hall et al. 335/174 3,453,568 7/1969 Murphy et al. 335/20 2,508,178 5/1950 Lindstrom et al. 335/40 Primary Examiner-Harold Broome Attorney-A. T. Stratton, Lee I. Johns et al.

[57] ABSTRACT A circuit interrupter, such as a switch or a circuit breaker, comprising relatively movable contact means, operating means releasable to open the contact means, and trip means which may be responsive to ground fault currents through the contact means to effect the release of the operating means to open the contact means upon the occurrence of ground fault currents.

12 Claims, 4 Drawing Figures PAIENIEU JUL 24% 3. 748 .609

sum-'2 or 2 FIG. 4

cracurr INTERRUPTER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to circuit interrupters having an energizable release device for opening the contacts in the interrupter upon the occurrence of ground fault current through the contacts or upon the application of an energizing current for any purpose.

2. Description of the Prior Art Recently electrical wiring circuits have been installed with circuit interrupters such as switches and circuit breakers that are provided with ground fault trip means for opening the circuit when a ground fault occurs. Indeed, the desirability of providing ground fault protection has been widely accepted in recent years and has resulted in the production of ground fault devices of the various kinds. Among other things, many such devices including ground fault protection that are currently available are unable to open a current or circuit interrupter, such as a conventional residential circuit breaker, clue to insufficient force generated by the ground current. Accordingly, there is a need for a device for tripping a switch or current interrupter by means of a shunt trip actuated by a ground current or other energizing current.

SUMMARY OF THE INVENTION In accordance with this invention it has been found that the foregoing problem may be overcome by providing a circuit interrupter having relatively movable contact means and means releasable to effect opening of the contact means, trip means including first and second levers operable for effecting automatic release of the releasable means when a ground fault occurs or energizing current is applied for any purpose, the levers being operable between latched and unlatched positions relative to the releasable means, the trip means also including an electromagnetic trip device responsive to ground fault currents through the contacts or the application of an energizing current to effect movement of the first lever to the unlatched position, the trip means being biased in the latched position, the releasable means including a releasable lever having an end portion movable between said positions, the second lever having a roller engageable with the end portion in the latched position and being rollable to a nonengaging position of the end portion in the unlatched position, and a connecting link extending between the first and second levers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical sectional view taken on the line I-I of FIG. 4 and embodying the principles of the invention;'

FIG. 2 is a vertical sectional view taken substantially along the line II-II of FIG. 4 and showing the circuit interrupter in the tripped position;

FIG. 3 is a vertical sectional view taken on the line Ill -III of FIG. 1 and embodying the principles of the invention; and

FIG. 4 is atop plan view of the switch shown in FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 of the drawings a circuit interrupter or switch is generally indicated at 10. It comprises a switch structure 12 which is mounted on a molded base 14 of electrically insulating material, and which is disposed between spaced electrical conductors l6 and 18.

The switch 10 is of the multi-pole type and the mechanism may be of the general type disclosed in U.S. Pat. No. 2,508,178, issued May 16, I950 to T. Lindstromet al., and assigned to the assignee of the present invention. The switch 10 includes a stationary contact 20 and a movable contact 22 for each pole of the device. A commonoperating mechanism, generally indicated at 24 (FIG. 1 is provided for simultaneously actuating three movable contacts 22 (FIG. 4) to open and closed circuit positions. The stationary contact 20 is rigidly mounted on the inner end of the conductor 16 which has a line terminal (not shown) connected to the outer end. 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. 4) of the switch for movement together to open and closed circuit positions. The contact arm 28 is connected by a flexible conductor 34 to the conductor 18 which is se cured to the base 14 in a suitable manner such as by a screw (not shown). 3;

The operating mechanism 24'for the switch structure 12 is disposed in the center compartment (FIG. 4) of the mechanism and is supported on a pair of laterally spaced

frames

36 and 38 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 releasable lever or pivoted cradle 50. An arcuate insulating shield 52 is mounted over the operating and of the operating lever 42 and is provided with an integral switch handle 54. The shield 52 is mounted over an intermediate portion 56 of the operating lever 42 and is secured in place by suitable means such as screws 58 attached to the forked portions of the lever 42, only one of which is shown in FIG. 1.

The

toggle links

44 and 46 are 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 and the outer end of the operating lever 42 at pivot pin 66.

The switch structure for the circuit breaker 12 is operated to the open operating position by manipulation of the handle 54 in a clockwise directionto the oft position, actuating the overcenter springs 48 to cause collapse of the toggle links 44 and 46 (FIG. 2), thereby causing opening movement of the switch arms 30 for all of the poles-of the switch in a well-known manner.

Trip means are provided for automatically opening the switch 10 when a ground fault occurs or an energizing current is applied. The trip means being generally indicated at 63 comprises a "knuckle" type linkage which is movable between latched and unlatched positions with regard to the cradle 50. In the latched position, the knuckle linkage goes overcenter" and the linkage is held in tension (FIG. 1) by the springs 48 of the operating mechanism 24. More particularly, the trip means 63 includes (FIG. 2) a lever 65, a lever or bellcrank 67, a roller 68, and a biasing spring 70. In addition, the trip means 63 includes an electromagnetic device such as a solenoid 72 (FIGS. 2 and 4) having a plunger 74. The solenoid 72 is suitably mounted such as by a bracket 76 on a supporting frame of the circuit breaker, as shown in FIG. 4, where the plunger 74 is adapted to move the lever 65 in response to any abnormal current occurring through the

contacts

20 and 22 as the result of a ground fault.

The lever 65 is mounted on the frame 36 (FIG. 1) by a pivot pin 78. The lever 65 is provided with a flange 80 by which the lever is moved clockwise to the position shown in FIG. 2 by the plunger 74 when the solenoid 72 is actuated. The bellcrank 67 is pivotally mounted on the frame 36 by a pivot pin 82 and cooperates with a shaft support member 84 for mounting the shaft 86. The preferred construction of the bellcrank 67 and the shaft support member 84 includes an interconnecting portion 88 which with the bellcrank and support member form a U-shaped unit that is disposed between the

frames

36 and 38. The shaft support member 84 is pivotally mounted on the upper end of the frame 38 by a pivot pin 90 (FIG. 3). The shaft 86 supports the roller 68 which is rotatably mounted on the shaft and which cooperates with the cradle 50 in a manner set forth below.

The bellcrank 67 includes an outturned portion 92 which extends to the right as viewed in FIGS. 1 and 2. A connecting link 94, as best shown in FIG. 2, extends between the bellcrank 67 and the lever 65. A pivot pin 96 connects the link 94 to the bellcrank 92 and a pivot pin 98 connects the link to the lever 65. The spring 70 which is mounted on the pivot pin 96 has opposite end portions connected to the lever 65 and the bellcrank 67 for biasing the trip means 63 in the counterclockwise or latched position as shown in FIG. 1.

During normal operation of the circuit breaker the trip means 63 is disposed in the latched position with the roller 68, composed of a hard material such as hardened steel, disposed over an end portion 50a on the upper side of the cradle 50 to hold the cradle in the lowermost (latched) position. In that position, the contacts and 22 may be opened and closed in a normal manner by manual manipulation of the handle 54 in the clockwise and counterclockwise directions. Thus, the cradle 50 is retained in the latched position under normal electric current conditions. When an abnormal operating condition occurs such as a ground fault, the condition is detected by conventional ground fault detection device (not shown) which device transmits an electric current to the solenoid 72, causing the plunger 74 to move outwardly (to the right as viewed in FIG. 2) and to thereby rotate the lever 65 clockwise to the position shown. This action moves the roller 68 away from the latched position of FIG. 1 and the cradle 50 is thereby free to rotate counterclockwise about its mounting shaft 102 the ends of which are seated in the spaced-

frames

36 and 38. Upon release of the cradle 50, the springs 48 operate to pivot the cradle counterclockwise about its pivot and to change the line of action of the springs so that the springs collapse the toggle links 44 and 46 from the extended positions of FIG. 1 to the collapsed position of FIG. 2 and to thereby raise the contact arm 28 to the open position in a conventional manner.

Upon opening of the

contacts

20 and 22 the energizing current may be discontinued or the ground fault which tripped the mechanism is corrected and the plunger 24 moves to the left or retracted position,

whereupon the spring acts to return the trip means 63 to the latched position. However, inasmuch as the roller 68 is now disposed against an end 104 of the cradle 50 (FIG. 2), it is necessary to manually move the handle 54 to a resetting position in a manner well known in the art. Thus, the handle 54 is manually rotated clockwise until a flange 106 of the intermediate portion 56 is brought into contact with an end 108 of the cradle 50 to rotate the cradle clockwise until the end 104 is lowered and the end portion 50a drops below the roller 68 to the latched position. The switch 10 is then in condition for reclosing the

contacts

20 and 22 by rotating the handle 54 counterclockwise to the position shown in FIG. 1.

Accordingly, the device of the present invention satisfies problems that existed in the prior art with regard to ground fault phenomena. The device is particularly adapted for tripping a fusible switch by means of a shunt trip actuated by a ground current or an energizing current whereby a solenoid uses a minimal amount of force (ounces) to actuate a relatively much higher latch load (pounds); i.e., the device provides a highly satisfactory and advantageous mechanical advantage. Finally, prior art circuit interrupters of the general type described have not included suitable means for tripping the breaker upon the occurrence of a ground fault through the contacts or application of an energizing current.

What is claimed is:

l. A circuit interrupter comprising relatively movable contact means and means releasable to effect opening of the contact means, the releasable means comprising a releasable lever, trip means comprising tension linkage including first and second levers and a connecting link operable for effecting automatic release of the releasable means, the first and second lever being pivotally mounted respectively on first and second pivot pins, the connecting link being pivotally mounted on the first and second levers respectively on third and fourth pivot pins, the first and second levers being operable between latched and unlatched positions relative to the releasable lever, the trip means also including an electromagnetic trip structure adapted to respond to an energizing current to effect movement of the first lever to the unlatched position, and the second lever being movable by the first lever from latch to unlatched positions of the releasable lever upon operation of the electromagnetic trip structure.

2. The circuit interrupter of claim 1 wherein the trip structure is biased in the latched position.

3. The circuit interrupter of claim 1 wherein the electromagnetic trip structure is operable to move the first lever to the unlatched position.

4. A circuit interrupter comprising relatively movable contact means and means releasably to effect opening of the contact means, the releasable means comprising a releasable lever, trip means comprising tension linkage including first and second levers and a connecting link operable for effecting automatic release of the releasable means, the first and second lever being pivotally mounted respectively on first and second pivot pins, the connecting link being pivotally mounted on the first and second levers respectively on third and fourth pivot pins, the first and second levers being operable between latched and unlatched positions relative to the releasable lever, the trip means also including an electromagnetic trip structure responsive to abnormal ground fault currents to effect movement of the first lever to the unlatched position, and the second lever being movable by the first lever from latched to unlatched positions of the releasable lever upon operation of the electromagnetic trip structure.

5. The circuit interrupter of claim 4 wherein the trip structure is biased in the latched position.

6. The circuit interrupter of claim 4 wherein. the electromagnetictrip structure is operable to move the first lever to the unlatched position.

7. The circuit interrupter of claim 4 wherein the releasable lever is movable between latched and unlatched positions when the trip means is released, and the second lever having means engageable with the releasable lever in the latched position.

8. The circuit interrupter of claim 7 wherein the engageable means is a roller engageable with the releasable lever in the latched'position, and rollable to a nonengaging position of the end portion in the unlatched position.

9. The circuit interrupter of claim 7 wherein the trip means are biased in the latched position.

10. The circuit interrupter of claim 9 wherein the second'lever is a bellcrank.

11. The circuit interrupter of claim 9 wherein the application of a small force by the electromagnetic trip structure on the first lever effects a substantially larger force on the second lever.

12. The circuit interrupter of claim 9 wherein the contact means comprise a stationary contact, a movable contact, and a movable switch arm having the movable contact thereon; the releasable means comprising an operating lever, a switch handle, the releasable lever, an overcenter toggle operable by the operat ing lever to effect movement of the switch arm to opened and closed circuit positions, and the overcenter toggle being operatively connected between the releasable lever and the movable switch arm.

Claims

1. A circuit interrupter comprising relatively movable contact means and means releasable to effect opening of the contact means, the releasable means comprising a releasable lever, trip means comprising tension linkage including first and second levers and a connecting link operable for effecting automatic release of the releasable means, the first and second lever being pivotally mounted respectively on first and second pivot pins, the connecting link being pivotally mounted on the first and second levers respectively on third and fourth pivot pins, the first and second levers being operable between latched and unlatched positions relative to the releasable lever, the trip means also including an electromagnetic trip structure adapted to respond to an energizing current to effect movement of the first lever to the unlatched position, and the second lever being movable by the first lever from latch to unlatched positions of the releasable lever upon operation of the electromagnetic trip structure.

6. The circuit interrupter of claim 4 wherein the electromagnetic trip structure is operable to move the first lever to the unlatched position.

8. The circuit interrupter of claim 7 wherein the engageable means is a roller engageable with the releasable lever in the latched position, and rollable to a non-engaging position of the end portion in the unlatched position.

10. The circuit interrupter of claim 9 wherein the second lever is a bellcrank.

12. The circuit interrupter of claim 9 wherein the contaCt means comprise a stationary contact, a movable contact, and a movable switch arm having the movable contact thereon; the releasable means comprising an operating lever, a switch handle, the releasable lever, an overcenter toggle operable by the operating lever to effect movement of the switch arm to opened and closed circuit positions, and the overcenter toggle being operatively connected between the releasable lever and the movable switch arm.