US2962569A

US2962569A - Circuit breaker

Info

Publication number: US2962569A
Application number: US664758A
Authority: US
Inventors: Francis L Gelzheiser; Robert H Flick
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1954-10-28
Filing date: 1957-06-10
Publication date: 1960-11-29
Anticipated expiration: 1977-11-29
Also published as: FR1137849A

Description

NOV- 29, 1950 F. L. GELzHElsER ETAL 2,952,569

cmcurr BREAKER Original Filed Oct. 28, 1954 5 Sheets-Sheet 1 Nov. 29, 1960 F. L. GELZHEISER ETAL CIRCUIT BREAKER Original Filed Oct. 28, 1954 3 Sheets-Sheet 2 Fig.5.

Nov. 29, 1960 F. l.. GELzHElsER ETAL 2,962,569

CIRCUIT BREAKER Original Filed Oct. 28, 1954 3 Sheets-Sheet 3 Fig. 8.

Vae

United States Patent() CIRCUIT BREAKER Francis L. Gelzheiser, Beaver, and Robert H. Flick, Brighton Township, Beaver County, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Original application Oct. 28, 1954, Ser. No. 465,262. Divided and this application June 10, 1957, Ser. No. 664,758

4 Claims. (Cl. 200-144) This invention relates to circuit breakers and more particularly to circuit breakers for controlling lighting and moderate power circuits.

This application is a division of our application Serial No. 465,262, tiled October 2S, 1954, now Patent No. 2,904,655, and assigned to the assignee of the instant application.

An object of this invention is to reduce the cost of a circuit breaker which may embody an improved thermally and magnetically responsive trip device by using an improved housing construction.

Another object of the invention is to provide a circuit breaker having a two-piece housing of molded insulating material comprising a base and cover, the base being molded with ledges so arranged as to receive a cover plate which is retained on the housing after being merely formed by two adjoining openings therein, one of said openings being formed from the top of said base and the other from the bottom, said openings adjoining to form a horizontal passage.

Another object of the invention is to provide a circuit breaker embodying a housing in which a separate portion of the housing such as a cover plate is inserted and firmly held in place without being positively fastened to .the main part of the housing.

The invention both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

Figure 1 is a vertical sectional View taken substantially on line I-I of Fig. 3 of a circuit breaker embodying the principles ot the invention;

Fig. 2 is a vertical sectional View taken substantially on line Il-II of Fig. 3;

Fig. 3 is a vertical sectional view taken on line IIL-'III of Fig. l and looking in the direction indicated by the arrows;

Figs. 4, 5 and 6 are elevational views respectively showing trip members for one, two and three-pole breakers;

Fig. 7 is a bottom view of the circuit breaker showing the insertable plate for the housing;

Fig. 8 is a detailed view of the insertable bottom plate;

Fig. 9 is a sectional view of the trip device showing the adjustment for the thermal trip element beforefthe insulating sealing cement is applied; Y

Fig. l0 is a fragmentary detailed view of the calibrat ing device and biasing spring for the magnetic trip means, and

Fig. ll is an end elevational view of a part of the cover showing the slot molded therein for receiving the adjusting screw and the mounting ,screw for securing some of "ice the parts thereto. This view shows the end of the breaker before the insulating cement is applied.

Referring to Fig. 1 of the drawing, the circuit breaker generally comprises a two-piece housing of molded insulating material including a base 11 and cover 13, a stationary contact 15 and movable contact 17 for each pole of the breaker, an operating mechanism 19 and a trip device 21. The housing is divided into two separate compartments by means of matching

barriers

23 and 25 molded integral respectively with the base 11 and the cover 13.

The stationary contacts 15 for each of the two poles of the breaker are mounted on the inner ends of conducting members 27 integral with a plug-in or other terminal connector 29 supported in the base 11 of the housing. The moving contact 17 for each pole is rigidly secured to a U-shaped switch or contact arm 31. Both of the contact arms 31 (Figs. 1 and 2) are operated to open and closed positions by the operating mechanism 19 to open and close the contacts.

The operating mechanism 19 comprises an operating member 32 having an integral operating lever 33 for each pole of the breaker and a single operating handle 35, an over-center spring 37 for each pole of the breaker and a releasable trip member 39. The operating member 32 including the handle 35 and the operating levers 33 for both poles of the breaker comprises a single member of molded insulating material so that operation of the handle simultaneously moves both of the levers 33. Molded on the operating member 32 is a central bearing surface 41 for pivotally supporting the member in the barrier 25 in the cover 13. Similar bearing surfaces 42 (Fig. l) on the ends of the member 32 are provided for pivotally supporting the ends of the member in the side walls of the cover 13. The barrier 25 is provided with a slot 43 having a semi-circular bearing portion at its upper end for securing and positioning the operating member. After the operating member 32 is inserted in the slot 43, a support and closure member 45 of insulating material is inserted in the slot and suitably secured thereon. The upper end of the member 45 has a semicircular bearing surface engaging and supporting the 'bearing portion 41 of the member 32. The end bearing portions 42 of the member 32 are similarly secured and supported in the side walls of the cover 13.

The releasable trip member 39 (Figs. l and 2) comprises a spring support lever or trip arm 47 for each of the poles of the breaker, each of the spring supports or trip levers being secured adjacent its pivot axis to a tie rod or cross bar 49 of molded insulating material for unitary pivotal movement. The tie rod 49 is provided with a central bearing portion 51 (Fig. 2) for pivotally supporting the releasable trip member 39 in the barrier 25 and end bearing portions 52 (Fig. l) for supporting the ends of the releasable trip member 39 in bearing portions (not shown) in the side walls of the cover 13. The spring support or trip lever 47 for one of the poles of the breaker extends toward the right (Fig. 1) and has a latch end 53 which is normally engaged and releasably held by a single latch element of the trip device 21 (to be later described) to releasably hold both of the trip arms 47 of the releasable trip member 39 in operative position.

Each of the operating levers 33 is bifurcated and the spaced legs 55 thereof are provided with notches 57 in which are seated the inner ends of the legs 59 of the U-shaped switch members 31. The switch -members 31 are held in place by the cover-center operating springs 37 which are connected under tension between the switch members 31 and the corresponding spring supports 47 of the releasable trip member 39. In ythe position shown in Fig. 1 the spring 37 biases the switch member 31 t0 the closed position, and when in open position the spring 37 biases the switch member 31 to the open position.

The circuit breaker is opened manually by moving the yoperating member 32 (Fig. 1) by the handle 35 clockwise from the on to the oif position. During this movement the inner ends of the switch arms 31 are Carried over to the left of the line of action of the overcenter springs 37 whereupon the springs move the switch arms to the open position with a snap action. The contacts are closed by reverse movement of the operating member 32, that is, from the oir to the on position. During this movement the inner ends of the switch members 31 are moved over to the right of the line of action of the overcenter springs which then move the switch ymembers to the closed position with a snap action.

An arc extinguisher 61 for each pole-or" the breaker vmay be disposed in openings or arc chambers 60 formed from the top of the 'base adjacent one end thereof for Vquickly extinguishing the arc drawn when the circuit is interrupted. The arc extinguishers may be of any suitable type, the one shown comprising a series of spaced slotted plates of magnetic material into which the arc is drawn and quickly extinguished. The arc gases are drawn into a vent passage 62 along the bottom of the base 11 under a cross barrier 67 and vented out the end of the housing opposite the stationary contacts. The vent passage is formed by the opening 6i) formed from ythe top of the base 11 at the left end thereof and an opening 117 formed from the bottom of the base 11 adjacent the right hand end. These two openings adjoin to form the horizontal passage extending along the bottom of the base. With this arrangement the horizontal vent passage 62 Imay be Imolded in the base 11 by two vertically separable mold parts without any drilling or other operation to form the horizontal passage.

The circuit breaker is tripped open automatically in response to overload currents by operation of the trip device 21. A trip device 21 is provided for each pole of the breaker but since the trip devices are alike only one will be described. The trip device comprises a bimetal element 63 having one end rigidly secured to the inner lend of a conducting strip 65 with the high expansion side of the bimetal element on the outside of the loop. The conducting terminal strip 65 which is secured by means of a screw 66 to the end wall of the cover 13, extends out through an opening in the base 11 below the cover 13 and has a terminal connector 71 at its outer end.

As shown in Figs. 1, 2, 9 and 11 the cover 13 has a vertical slot 68 molded in the end wall from the lower edge thereof, for receiving the screw 66 which secures the conducting strip 65 and the magnet yoke 95 to the end wall. The slot 63 is wide enough to receive the shank of the screw, and the head of the screw engages the end wall of the cover on opposite sides of the slot to rigidly secure the parts thereto. An adjusting screw 101, the purpose of which will be later described, also extends through the slot 68 at the upper end thereof. In this manner the slot 68 provides an opening for the adjusting screw 101 and for the retaining screw 66 for rigidly mounting the parts on the end wall of the cover without the necessity of drilling holes therein. After the parts are mounted on the cover and the thermal trip device is calibrated by adjustment of the screw 191, the entire slot 68 is illed with a suitable material such as a cement to prevent tampering with the calibration and to insulate the live parts of the assembly, so that the user will be protected from receiving an electrical shock.

The free end 73 of the bimetal element is conductively connected to the switch member 31 by means of a flexible conductor 75. A movable trip bar 77 (Fig. 5) formed from a single piece of at sheet insulating material extends across both poles of the breaker to be actuated by the trip device 21 for either pole. The trip bar 77 is supported at its ends in notches 79 formed by projections 81 molded in the base 1,1 adjacent the sidewalls thereof.

The barrier 23 in the base 11 is provided with a V-shaped opening 83 for receiving the trip member 77 which at this point terminates just below the barrier 25 in the cover 13 so that when the cover is in place it will hold the trip member in place by preventing it from moving upwardly. As shown in Fig. 9 the trip member 77 has an opening 85 therein into which extends the angular upper end of a latch member 87 suitably secured to the side of the trip member. The latch member 87 normally engages latch end 53 of the trip arm 47 and restrains the releasable trip member 39 in operative position. A spring 89 (Figs. l and 10) is compressed between a spring seat 90 in a recess in the barrier 23 and the trip member and biases the trip member to its latching position.

In each of the compartments the trip member 77 has an upwardly extending projection 91 which at its upper end has rigidly secured thereto by means of a rivet 92 an armature 93 for cooperating with a U-shaped magnet yoke 95. rl`he magnet yoke 95 is mounted on the end wall of the cover 13 With the yoke portion thereof disposed between the conducting strip 65 and the end wall and surrounds three sides of the conducting strip 65. The magnet yoke is rigidly secured in place by the screw 66 which also secures the conducting terminal strip and the bimetal and magnet assembly to the end wall of the cover of the housing.

Upon the occurrence of an overload current of, for example, up to 1000% of normal rated current the bimetal element 63 becomes heated and when heated a predetermined amount bends rearwardly in a direction to close the loop, since the high expansion side is on the outside of the loop, and moves the free end 73 thereof toward the right. This causes the bimetal to engage the rounded head of the rivet 92 and rock the trip member 77 clockwise disengaging the latch member 87 from the releasable trip arm 47 thus releasing the entire trip member 39. As soon as the releasable trip arm 39 is released, the springs 37 for both poles of the breaker rotate the releasable structure 39, including the spring support or trip member 47 for each pole, in a clockwise direction to the position where it is arrested by engagement by the latch end of the spring support or trip arm 47 with a projection 97 on the base 11 of the breaker housing. This movement of the releasable trip member 39 carries the line of action of the springs 37 for both poles of the breaker over to the right of the associated switch members 31 and the springs 37 then move the switch members to the open position with a snap action. When the springs 37 move overcenter, they act through the switch members 31 to move the handle 35 to an indicating position between the on and ofi positions, giving a single indication that both poles of the circuit breaker have been tripped open.

Upon the occurrence of a heavy overload current, of, for example, 1000% or more of rated current or a short circuit current, the armature 93 is attracted to the magnet yoke 95, actuating the trip member 77 to disengage the latch 87 to instantaneously trip the breaker. If the circuit has been heavily loaded, but not quite to the point where the bimetal would cause tripping, the bimetals 63 will be heated and will move the armatures 93 toV a posi- Vtion closer to the yokes or pole pieces 95. Under these conditions the magnetic trip will take place at a lower value of current than when the circuit has not .been heavily loaded. Also, by having the plurality of armatures mounted on the single trip bar,.the force of the magnetic attraction is the sum of forces exerted by all the pole pieces, so that magnetic tripping will be faster if several poles are overloaded rather than just one.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving thehandle 35` and the operating member 32 to a position slightly beyond the oi position. During this movement the legs 55 of the levers 33 engage pins 86 in the releasable trip members 47 and restore the entire releasable structure 39 for both of the poles to the latched position. The contacts are then closed in the previously described manner by movement of the handle 35 and the levers 33 to the on position.

The position of the movable end of the bimetal and, hence, the thermal tripping time of the trip devices is adjusted by means of screws 101, there being a screw 101 for each pole of the breaker. The screws 101 threadedly engage upwardly extending portions 103 of the steel magnet yokes 95 and their rounded inner ends apply a pressure to the supported legs of the bimetal elements 63 at the point where they are secured to the inner ends of the conducting strips 65. Just below the point of engagement of the screw 101 with the bimetal element the conducting strips 65 are provided with lateral projections 105 (Figs. l, 2 and 3) which are adapted to engage spaced hooked portions 107 formed on the upwardly extending projections 103 of the magnetic yoke and extending inwardly therefrom. The point at which the projections 105 engage the hooked portions 107 forms a pivot or point indicated at X about which the upper end of the conducting strip 65 will bend when the screw 101 is turned. As shown in Fig. 9 the screw 101 has been turned slightly clockwise increasing the pressure on the upper end of the conducting strip 65 causing it to bend and bodily displace the bimetal element in a counterclockwise direction about the point X. During this adjustment, the -free end 73 of the bimetal moves closer to the rivet 92, reducing the amount of bimetal movement required on heating before the latch end of the releasable trip member 47 will be released by the latch portion 87. Upon counterclockwise rotation of the screw 101 the inherent resiliency of the conducting strip 65 will cause it to move back toward its normal position, thus pivoting the bimetal element 63 about the .point X in a clockwise direction.

Means is provided for adjusting the unattracted position of the armature 93 relative to the magnet yoke 95 independently of the adjustment of the bimetal element. This means includes a plurality of notches 109 (Figs. 1 and l0) molded in the center barrier 23 of the base 11 for receiving headed rivets 111 of different lengths. As shown in Fig. 10, the head of a rivet 111 is placed in one of the notches and the body of the rivet extends toward the trip bar 77 slightly to the right of the left hand edge of the V-shaped notch 83 in the barrier 23 of the base 11. The rivet 111 is held in place by the lower edge of the barrier 25 in the cover and provides a stop for the trip bar 77. By varying the length of the rivet 111 or by placing a longer rivet in one of the other notches 109, the unattracted position of the trip bar 77 may be varied thus varying the position of the armature 93 relative to the magnet yoke 95.

While there has been specifically described a two-pole circuit breaker, the invention may readily be adapted for use in either a single-pole breaker or a three-pole breaker. A single-pole circuit breaker is provided by omitting the left hand pole unit (Fig. 2) and the parts therein and substituting a trip member 113 as shown in Fig. 4 for the trip bar 77. A three-pole circuit breaker is provided by adding a pole unit like the pole unit shown in Fig. 2 to the right of the breaker (Fig. 3). The operating member 32 (Fig. l) would be extended to provide an operating lever 33 for the third pole and the releasable trip member 39 is also extended to provide a trip arm 47 for the third pole. In the three-pole breaker the trip bar 77 (Figs. 3 to 5) would be replaced by the trip bar 115 (Fig. 6). The operation of the single-pole and three-pole breakers would be the same as that described for the two-pole breaker illustrated.

Tn molding the base 11 it has been found advantageous to provide the opening or openings 117 (Figs. l, 2, 3 and 7) in the bottom wall 69 of the base 11 to permit the passage of a die member in order to mold the vent passage under the cross barrier 67 and theprojection 97. After the breaker is assembled it is necessary to close the openings 117 by means that is resistant to internal and external pressure and which is strong mechanically and electrically.

As shown in Figs. l and 2, the base 11 is molded with ledges 121 on the bottom wall 69 of the base and extending across each compartment of the base. Ledges 123 are also molded on the bottom wall 69 of the base 11 extending lengthwise of the compartments. Near the center of the side edges of the opening 117, projections 125 are molded on the ledges 123 near the center thereof and of slightly less width than the ledges so that the projections do not extend into the openings 117 as can be seen in Fig. 3. f

Plates 127, one of which is shown in Fig. 8, are adapted to be inserted in the openings 117 and locked in place. The plates 127 are made from a suitable insulating material and have notches 129 in the side edges thereof for engaging the projections 125 (Fig. 7) on the base 11. The plates are installed by inserting one end thereof in the opening 117 so that it rests on the left hand ledge 121. The plate 127 is then bowed slightly and the other end is inserted inthe opening 117 so that it rests on the right hand ledge 121 after which the plate is slid toward the right until the notches 129 register with the projections 125 at which time the plate, due to its resiliency, snaps into place and is locked against removal by engagement ofthe notches 129 with the projections 125.

vThere is provided a circuit breaker embodying a thermally and magnetically responsive trip device wherein the thermally responsive element is rigidly supported on a conducting strip mounted on one end wall of the breaker housing and is pivotally movable by bending the conducting strip about a Xed point for purposes of calibration. The magnetically responsive element is calibrated independently of the thermally responsive element by the insertion of stop members of various lengths in recesses provided therefor in the breaker housing. An opening provided in the bottom of the housing for facilitating manufacture thereof with a horizontal vent passage is closed by the insertion of a suitable insulating member which, when placed in position is automatically locked in position.

While the invention has been specically disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from the spirit of the invention.

We claim as our invention:

1. In a circuit breaker, a housing of molded insulating material, relatively movable contacts in said housing for opening and closing the circuit, a trip device for initiating an opening operation of said contacts, an opening in the molded housing, a pair of ledges at opposite sides of said opening, a closure plate insertable into said opening having a dimension between one pair of opposed edges greater than the distance between said pair of ledges, said pair of ledges overlapping said pair of opposed edges at the outer side of the closure plate to prevent its movement outwardly from the opening, and interlocking means integral with the housing and closure plate preventing edgewise movement of the closure plate olf either of said ledges.

2. In a circuit breaker, a housing of molded insulating material, relatively movable contacts in said housing for opening and closing the circuit, a trip device for initiating an opening operation of said contacts, an opening in the molded housing, a pair of ledges at opposite sides of said opening, an insertable closure plate in said opening having a dimension between one pair of opposed edges greater than the distance between said pair of ledges, said pair of ledges overlapping said pair of opposed edges at 7 the outer side of the closure plate to prevent its movement outwardly from the opening, a second pair of ledges at other opposite sides of said opening, said closure plate having a dimension in the direction of the space between said second pair of ledges greater than the distance between said second pair of ledges, and said second pair of ledges overlapping edges of said closure plate at the inner side thereof to prevent its movement into the opening.

3. In a circuit breaker, a housing of molded insulating material, relatively movable contacts in said housing for opening and closing the circuit, a trip device for initiating an opening operation of said contacts, an opening in the molded housing, a pair of ledges at opposite sides of said opening, a closure plate in said opening having a dimension between one pair of opposed edges greater than the distance between said pair of ledges, said pair of ledges overlapping said pair of opposed edges at the outer side of the closure plate to prevent its movement outwardly from the opening, a second pair of ledges at other opposite sides of said opening, said closure plate having a dimension in the direction of the space between said second pair of ledges greater than the distance between said second pair of ledges, said second pair of ledges overlapping edges of said closure plate at the inner side thereof to prevent its movement into the opening and a notch in said closure plate and a projection on the housing fitting in said notch to limit edgewise movement of the closure plate in one direction.

4. In a circuit breaker, a housing of molded insulating material, relatively movable contacts in said housing for opening and closing the circuit, a trip device for initiating an opening operation of said contacts, an opening in ape-aride 'a e Y 'the molded housing, a pair of ledges at opposite sides of said opening, an insertable closure plate in said opening having a dimension between one pair of opposed edges greater than the distance between said pair of ledges, said pair of ledges overlapping said pair of opposed edges at the outer side of the closure plate to prevent its movement outwardly from the opening, a second pair of ledges at other opposite sides of said opening, said closure plate having a dimension in the direction of the space between said second pair of ledges greater than the distance between said second pair of ledges, said second pair of ledges overlapping edges of said closure plate at the inner side thereof to prevent its movement into the opening, and said closure plate being flexible at the time when it is being positioned on said housing thereby permitting its positioning on said housing.

References Cited in the le of this patent UNITED STATES PATENTS 2,020,331 Sachs Nov. 12, 1935 2,020,332 Sachs Nov. 12, 1935 2,233,187 Van Hoorn Feb. 25, 1941 2,320,437 Jennings June 1, 1943 2,324,155 Haynes July 13, 1943 2,387,724 Elman et al. Oct. 30, 1945 2,444,149 Aldridge June 29, 1948 2,532,083 Brenner Nov, 28, 1950 2,626,335 Landin Jan. 20, 1953 2,719,203 Gelzheiser et al. Sept. 27, 1955 2,797,277 Dorfmann et al. June 25, 1957