US3748420A

US3748420A - Terminal member for circuit interrupter

Info

Publication number: US3748420A
Application number: US00245066A
Authority: US
Inventors: J Rexroad
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: FR2186746B1; ZA732300B; IT986979B; DE2318958A1; BR7302847D0; AU5413673A; DE7314251U; CA942808A; FR2186746A1; GB1423531A

Abstract

A terminal structure for a circuit interrupter with a stepped top surface and a stepped bottom surface by which the structure is divided generally into upper and lower portions. At least one horizontal opening extends through each upper and lower portion, one opening being above and another opening being below the stepped bottom surface. A substantially vertical threaded aperture extends from the top surface of each portion into each horizontal opening and a setscrew is disposed in each vertical aperture for securing electric cables in place.

Description

United States Patent 1191 Rexroad 1 July 24, 1973 [54] TERMINAL MEMBER FOR CIRCUIT 3,632,939 l/l972 Yorgin 200/168 R INTERRUPTER H h [75] Inventor: James 0. Rexroad, Beaver, Pa. $E:; 3 5,1 [73] Assignee: Westinghouse Electric Corporation, Attorney-A. T. Stratton. L. P. Johns et al.

Pittsburgh, Pa. 22 Filed: Apr. 13, 1972 [571 ABSTRACT A terminal structure for a circuit interrupter with a [21] 245066 stepped top surface and a stepped bottom surface by which the structure is divided generally into upper and 52 s 1 200 1 3 200 1 CT, 339 272 R lower portions At least one horizontal opening extends [51] Int. Cl H0lr 7/12 through each PP and lower Portion, one opening [58] Field of Search 200/166 CT, 168 R; being above nd another opening being below the 339/272 R, 272 A, 272 UC stepped bottom surface. A substantially vertical threaded aperture extends from the top surface of each [56] Ref ren es Ci d portion into each horizontal opening and a setscrew is UNITED STATES PATENTS disposed in each vertical aperture for securing electric 3,588,413 6/1971 Stanback 200/166 CT cables m place 3,113,822 12/1963 Sorflaten 339/272 UC 9 Claims, 10 Drawing Figures TERMINAL MEMBER FOR CIRCUIT INTERRUPTER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to circuit interrupters and more particularly to a terminal member therefor.

2. Description of the Prior Art Multiple cable terminals of the type disclosed in Canadian Pat. No. 693,476,'issued Sept. 1, 1964, have been provided for the purpose, among other things, of increasing the rating of circuit breakers without requiring proportionate increase in the sizes of the breakers. A disadvantage of the type of multiple cable terminal disclosed in that patent has been the limited accessibility to setscrews which hold the cables in place. It has been found in the past that after a cable has been inserted in a cable socket of a terminal for a period of time, the setscrew holding the cable in place requires retightening due to stress relief of adjacent metal parts. After repeated off" and on" cycles, the metal comprising the stranded cable as well as the terminal member become fatigued and cause the cables to become loose in their sockets for which reason the setscrews require retightening.

Prior known terminal members have been unsatisfactory because most terminal members or blocks have setscrews for some sockets which are accessible only by the removal of setscrews and cables for adjacent sockets. It is inconvenient and frequently difficult to have to remove one setscrew and cable in order to obtain access to a second setscrew which is aligned with the first setscrew.

SUMMARY OF THE INVENTION It has been found in accordance with this invention that the foregoing problems may be overcome by providing a terminal member having a stepped top surface including upper and lower top surface portions, a stepped bottom surface including upper and lower bottom surface portions, the member having at least two generally horizontal cable-receiving openings with an opening being above the upper bottom surface portion and another opening being above the upper bottom surface portion, the terminal member having a generally vertical tapped opening for each horizontal opening, the generally vertical opening to the upper horizontal opening extending from the upper top surface portion and the generally vertical opening to the lower horizontal surface extending from the lower top surface portion, and a setscrew in each vertical tapped opening for securing cable within the corresponding horizontal opening.

The advantage of the improved terminal member of this invention is that it minimizes the time and effort required to periodically retighten the setscrews for holding cables in place in a multiple cable terminal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a circuit breaker employing the principles of the invention;

FIG. 2 is a view taken along the line IIII of FIG. 1;

FIG. 3 is a plan view of one of the terminal structures of the invention;

FIGS. 4-7 are views of another embodiment of a terminal structure of the invention; and

FIGS. 8-10 are views of another embodiment of a terminal structure of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1 of the drawings, the circuit breaker enclosure or housing shown therein comprises a base 3 and a removable cover indicated generally at 5, both of which may be molded from a suitable insulating material. The cover 5 includes a main portion 7 (FIGS. 1 and 2) and a raised portion 9 which raised portion is provided to furnish room for a handle portion 71 and for longer overcenter springs 61 which will be described hereinafter in connection with the operating mechanism for the circuit breaker. Two slots 11 are provided in the cover 7, at opposite ends thereof, to receive the flanges of panelboard plates (not shown) in a well known manner. The breaker is of the three-pole type, each pole being provided with terminal structures indicated generally at 15 and 17 which are mounted at opposite ends of the base 3.

The circuit breaker includes, for each pole unit, a stationary main contact 21, a stationary arcing contact 22, a movable main contact 23, a movable arcing contact 24, and an arc extinguisher indicated generally at 25. A common operating mechanism indicated generally at 27 is provided for simultaneous actuation of the three movable contacts to open and closed positions. A trip device indicated generally at 29 serves to effect automatic opening of the circuit breaker contacts in response to predetermined overload conditions in the circuit of any pole unit of the circuit breaker. The terminal structure 15 is mounted at the outer end of a terminal conducting strip 31 which extends into the housing and rigidly supports the stationary contacts 21 and 22.

The movable contacts 23 and 24, for each pole unit, are mounted on a rigid contact arm 33 supported on a switch arm 35 which is secured to a tie bar 37 that extends across all of the pole units of the circuit breaker. The tie bar 37 supports the switch arms 35 of the several pole units of the breaker for unitary movement to the open and closed positions. Each of the contact arms 33 is connected by means of flexible conductors 39 to an intermediate conducting strip 41. The conducting strips 41 are each connected to a trip unit conducting strip, which is indicated generally at 43, by a bolt 42 which connects the

conductors

43 and 41 to the base 3 of the breaker. Each of the trip unit conducting strips 43 passes through the trip unit 29 and is supported at its outer end on a conducting block 45. The load terminal structures are connected to the conducting strips 43 in a manner to be hereinafter described.

When the circuit breaker is connected for operation, the circuit through each pole unit extends from conducting cables 47 through the terminal structure 15, conducting strip 31, stationary contacts 21 and 22, movable contacts 23 and 24, movable contact arm 33, flexible conductors 39, intermediate conducting strip 41, trip unit conducting strip 43, terminal structure 17, and three conducting cables 47. As shown, the conducting cables 47 are insulated at 50, the insulation being cut away for electrical connection of the cables to the circuit breaker.

The operating mechanism 27 (FIG. 1) is disposed in the center compartment of the housing and is supported by a pair of spaced frame members -53 (only one being shown) secured to the base 3. The operating mechanism comprises a pivoted formed operating lever 55,11 toggle comprising two toggle links 57 and 59, two overcenter springs 61 (only one being shown) and a pivoted releasable cradle 63 controlled by the trip device 29. An insulating shield 67, for substantially closing an opening 69 in the cover 13, is mounted on the outer end of the operating lever 55 and has the integral handle portion 71 extending out through the opening 69 to permit manual operating of the breaker.

The toggle links 57 and 59 are pivotally connected together by a knee pivot pin 73. The toggle link 57 is pivotally connected to the cradle 63 by a pin 75, and the toggle link 59 is pivotally connected to the switch arm 35, of the center pole unit, by a pin 77. The overcenter springs 61 are connected under tension between the knee pivot pin 73 of the toggle 57, 59 and the outer end of the operating lever 55. The circuit breaker is manually operated to the open position by movement of the handle 7l (FIG. 1) in a clockwise direction to the of position, which movement actuates the overcenter springs 61 to cause collapse of the toggle 57, 59 and opening movement of the switch arms 35 for all of the pole units in a manner well known in the art.

The circuit breaker is manually closed by reverse movement of the handle 71 from the off to the on" position, which movement causes the springs 61 to move overcenter and straighten the toggle 57, 59, thereby moving the switch arms 35, for all of the pole units, to the closed position.

The trip device, which is indicated generally at 29, serves to effect automatic release of the cradle 63 and opening of the breaker contacts for all of the pole units, in response to predetermined overload conditions in the circuit breaker through any or all pole units of the circuit breaker, in a manner specifically described in Canadian Pat. No. 693,476, and assigned to the assignce of the instant application.

Improved terminal structures and 17 are provided at opposite ends of the circuit breaker. Referring to the three-pole circuit breaker illustrated in FIGS. 1 and 2, there are three terminal structures 15 and three terminal structures 17, all of which are identical in construction. Each of the terminal structures 15, 17 comprises a block or member 81 of conducting material, a mounting bolt 83 (FIG. 1), and two connecting members or setscrews 85 and 86 (FIGS. 2 and 3). Two openings or

sockets

87 and 88 pass horizontally into each of the conducting blocks 81 for receiving-two conducting cables or lines 47 (FIGS. 1 and 2). As shown in FIGS. 2 and 3, the

openings

87 and 88 are spaced to permit connection of the two large cables 47, and the openings are tapped to receive the threaded setscrews 85.

As shown more particularly in FIG. 1, the member 81 has a stepped top surface including an upper top surface portion 90 and a lower top surface portion 92 with a vertical end surface 94 disposed therebetween. Likewise, the bottom surface of the member 81 is stepped and includes an upper bottom surface portion 96 and a lower bottom surface portion 98 with a vertical end portion 100 disposed therebetween. A vertical end portion 102 is disposed between the

surface portions

90 and 96.

The mounting bolts 83 extend through vertical apertures 104 for securing the member 81 to the conducting block 45. One of the openings 89 extends from the upper top surface portion 90 vertically to the horizontal opening or socket 87 and the other opening 89 extends to the horizontal opening 88. Thus, separate access is available to-each setscrew and 86 by a suitable tool such as an Allen wrench.

More particularly, the

horizontal openings

87 and 88 extend inwardly from the

vertical end portions

102 and 100, respectively. Although two

openings

87 and 88 are provided in the member 81, more than two openings may be provided as shown in other embodiments of this invention.

The stepped bottom surface of the member 81 whereby the vertical end portion is recessed from the vertical end portion 102 by the width of the surface 96 enables an installer to remove equal lengths of insulation 50 from the conducting cables 47 before inserting the cable into the

openings

87 and 88. Otherwise, without the recess with the end surface in alignment with the end surface 102, a greater amount of insulation 50 would have to be removed from the lower cable than from the upper cable.

Another embodiment of the invention is that shown in FIGS. 4, 5 and 6 in which parts similar to the embodiment of FIGS. 1-3 are identified with similar reference numerals. Manifestly, the embodiments of FIGS. 4-7 include three horizontal openings for

sockets

106, 108, and 1 10. The upper opening 106 is disposed in the upper portion of the terminal member and extends inwardly from the end surface 102.

The

horizontal openings

108 and 110 extend into the member from the critical end portion 100 in the lower portion of the member. The

openings

106, 108, and 110 are provided with

setscrews

112, 114, and 116, respectively, which in turn are threadedly seated in

openings

118, and 122 which openings may be vertical or inclined (as shown) at an angle to the vertical axis. Thus, the

openings

120 and 122 extend downwardly from the lower top surface portion 92 and the opening 112 extends substantially downwardly from an inclined top surface 124 which extends from the surface 90.

Another embodiment of the invention is shown in FIGS. 8-10 in which similar parts are identified with similar reference numbers as the embodiment shown in FIGS. 1-3. More particularly, the embodiment of FIGS. 8-10 is provided with four horizontal openings or

sockets

126, 128, 130, and 132, of which the

openings

126 and 128 are disposed in the upper portion of the member and extend inwardly from the vertical end surface portion 102. The

openings

130 and 132 are disposed in the lower portion of the member and extend inwardly from the vertical end surface portion 100.

Like the other embodiments, each opening 126-132 is provided with a

separate setscrew

134, 136, 138, and 140, respectively, each setscrew in turn being seated in a separate vertical threaded

opening

142, 144, 146, and 148. It is pointed out that like the previous embodiments, the embodiment of FIGS. 8-10 is provided with setscrews which are accessible through separate openings which extend from external surfaces of the terminal structure.

Accordingly, the terminal structure of this invention provides a multiple cable terminal in which each cable opening or socket is provided with a separate clamping screw which is accessible without the necessity of first removing another cable. Finally, the terminal structure provides the additional advantage of fitting into confined spaces within existing circuit breakers for interrupters and thereby provides for continued use of such breakers with the added advantage of the terminal structure with separately accessible clamping means for each cable.

What is claimed is:

l. A terminal structure comprising a terminal member of electrically conducting material and having a stepped top surface including upper and lower top surface portions, the member having a stepped bottom surface including upper and lower bottom surface portions, the member having at least two generally horizontal cable-receiving openings with an opening being above the upper bottom surface and another opening being below the upper bottom surface, the terminal member having a generally vertical opening for each horizontal opening, each vertical opening passing from an outer surface of the member, a first connecting member adapted to be positioned in one vertical opening to secure a first conducting line to said member when said first conducting line is positioned in the corresponding horizontal opening, and a second connecting member adapted to be positioned in another vertical opening to secure a second conducting line to said member when said second conducting line is positioned in the corresponding horizontal opening.

2. The terminal structure of claim 1 in which each vertical opening passes into only one of the horizontal openings.

3. The terminal structure of claim 1 in which the vertical openings are tapped openings, and in which the first and second connecting members are adapted to be screwed into said tapped vertical openings.

4. The terminal structure of claim 3 in which the member is provided with at least one aperture adapted to receive a mounting bolt.

5. The terminal structure of claim 3 in which the member includes a stepped top surface including upper and lower top surface portions, in which at least one of the horizontal openings is disposed between the lower bottom surface portion and the lower top surface portion, and in which at least one of the horizontal openings is disposed between the upper top surface portion and the upper bottom surface portion.

6. The terminal structure of claim 5 in which the generally vertical opening to the upper horizontal opening extends from the upper top surface portion and in which the generally vertical opening to the lower horizontal opening extends from the lower top surface portion.

7. A circuit interrupter comprising an insulating housing, a circuit interrupter mechanism disposed within the housing and comprising a pair of contacts operable to open and close an electric circuit, a conducting strip within said housing at one end thereof and connected in electrical series with said contacts, a terminal structure comprising a terminal member of conducting material and having a stepped top surface including upper and lower top surface portions, the members also having a stepped bottom surface including upper and lower bottom surface portions, the terminal structure having at least two generally horizontal cablereceiving openings with an opening being above the upper bottom surface and another opening being below the upper bottom surface, said terminal member having a generally vertical opening therein for each horizontal opening, each vertical opening passing from an outer surface of the member and into only one of said horizontal openings, a first connecting member adapted to be positioned in one vertical opening to secure a first conducting line to said member when the first conducting line is positioned in the corresponding horizontal opening, and a second connecting member adapted to be positioned in a second vertical opening through said one end to secure a second conducting line to a conducting member when said second conducting line is positioned in the corresponding horizontal opening.

8. The circuit interrupter of claim 7 in which one of the horizontal openings is in an upper portion of the member and substantially above another horizontal opening in a lower portion of the member.

9. The circuit breaker of claim 7 in which the member includes an upper offset portion in which at least one upper horizontal opening is disposed, in which the member includes a recessed surface adjacent to the offset portion, and which recessed surface comprises one of the outer surfaces from which the vertical openings extend.

Claims

1. A terminal structure comprising a terminal member of electrically conducting material and having a stepped top surface including upper and lower top surface portions, the member having a stepped bottom surface including upper and lower bottom surface portions, the member having at least two generally horizontal cable-receiving openings with an opening being above the upper bottom surface and another opening being below the upper bottom surface, the terminal member having a generally vertical opening for each horizontal opening, each vertical opening passing from an outer surface of the member, a first connecting member adapted to be positioned in one vertical opening to secure a first conducting line to said member when said first conducting line is positioned in the corresponding horizontal opening, and a second connecting member adapted to be positioned in another vertical opening to secure a second conducting line to said member when said second conducting line is positioned in the corresponding horizontal opening.

7. A circuit interrupter comprising an insulating housing, a circuit interrupter mechanism disposed within the housing and comprising a pair of contacts operable to open and close an electric circuit, a conducting strip within said housing at one end thereof and connected in electrical series with said contacts, a terminal structure comprising a terminal member of conducting material and having a stepped top surface including upper and lower top surface portions, the members also having a stepped bottom surface including upper and lower bottom surface portions, the terminal structure having at least two generally horizontal cable-receiving openings with an opening being above the upper bottom surface and another opening being below the upper bottom surface, said terminal member having a generally vertical opening therein for each horizontal opening, each vertical opening passing from an outer surface of the member and into only one of said horizontal openings, a first connecting member adapted to be positioned in one vertical opening to secure a first conducting line to said member when the first conducting line is positioned in the corresponding horizontal opening, and a second connecting member adapted to be positioned in a second vertical opening through said one end to secure a second conducting line to a conducting member when said second conducting line is positioned in the corresponding horizontal opening.