US3265833A - Electric circuit breaker operating mechanism and improved supporting plates therefor - Google Patents

Description

F. H. MURPHRY 3,265,833

Aug. 9,1966

ELECTRIC CIRCUIT BREAKER OPERATING MECHANISM AND IMPROVED SUPPORTING PLATES THEREFOR Filed June 3, 1964 2 Sheets- Sheet 1 I I I I7 2115 57 3| 1 FIG. 1

INVENTOR. /C;FANK H MURPHY A TTORNEY 2.Sheets-Sheet 2 INVENTOR. FRANK H MUR HY F. H. MURPHY FIGS ELECTRIC CIRCUIT BREAKER OPERATING MECHANISM AND IMPROVED SUPPORTING PLATES THEREFOR Filed June 3, 1964 FIGS United States Patent ELECTRIC CIRCUET BREAKER OPERATENG MECHANISM AND IMPROVED SUPPORTING PLATES THEREFOR Frank H. Murphy, West Hartford, Conrn, assiguor to General ElectricCornpany, a corporation of New York Filed June 3, 1964, Ser. No. 372,193 3 Claims. (El. 200-116) My invention relates to electric circuit breakers, and more particularly to multi-pole electric circuit breakers of high current capacity type including separable contacts operated by quick-make, quick-break type operating mechanism, which breakers are capable of interrupting short-circuit value currents as well as intermediate value overload currents.

It is a general object of the present invention to provide a multi-pole electric circuit breaker of the molded insulating case type having an electrical current carrying and short-circuit current interrupting rating substantially double that of comparable prior art circuit breakers of comparable size. More particularly, it is a general "object of the invention to provide an electric circuit breaker having a current carrying rating of 225 amperesat 240 volts, the external dimensions of which are not ap preciably greater than the dimensions of the most directly comparable prior art circuit breaker having a rating of 100 amperes at 240 volts.

Two basic problems are encountered in attempting to increase the electrical current rating of circuit protective devices of the short-circuit interrupting type. These are (1) to increase the size of the current carrying elements of the device, and especially of the contact members, so as to be able to carry the substantially increased current without'excessive heating, and (2) to provide in the limited space, an operating mechanism of sufiicient strength to furnish substantially increased contact pressure under normal conditions, and to be able to move the larger contact members to open position fast enough to interrupt the higher overload and short-circuit currents.

Electric circuit breakers of the multipole type ordinarily comprise an insulating casing having a plurality of side-by-side chambers. Each such chamber includes a stationary contact and a movable contact. Operating mechanism is also provided for moving the movable contacts between open and closed circuit positions. In accordance with the prior art a single operating mechanism is usually provided, positioned in one of the pole chambers, the movable contact members being ganged together on a common cross-bar for simultaneous operation by the single operating mechanism. The size of the operating mechanism which may be used is of course limited by the fact that the pole chamber in which the operating mechanism is located must'also providespace for a stationary contact and associated arc extinguishing chamber and also for a current responsive trip device.

Various attempts have been made to provide stronger operating mechanism for operating higher rated contacts, such attempts including (1) the provision of a separate operating mechanism for each pole of the multipole breaker, and (2) the provision of a separate chamber .alongside the contact-containing pole chambers, such additional chamber housing only the operating mechanism. The use of a separate mechanism for each pole chamber, however, is extremely expensive. The use of a separate pole chamber for housing the operating mechanism requires that the overall dimensions ofvthe device be increased by an amount necessary to provide this additional space. This, of course, is contrary to the overall objective which is to provide a breaker of increased rating till lesser volume.

In accordance with the present invention a more powerful and effective operating mechanism is provided in a pole space of comparable size of prior art breakers by using a part of the pole chamber for two purposes, that is, to house the stationary contact and associated arc extinguisher, and also to provide support for a portion of the operating mechanism. Thus a portion of the operating mechanism, in effect, overlaps the stationary contact area and projects over the arc extinguisher. This is true although the operating mechanism is supported on the base portion of a top-and-bottom divided insulating housing.

In accordance with the invention in one form, an electric circuit breaker is provided of the type including an insulating casing'having at least one pole chamber supporting a stationary contact and an associated arc extinguisher at one end portion of the chamber. An operating mechanism is also provided including a movable contact member, the operating mechanism being supported adjacent the arc extinguisher and arranged to move the movable contact into and out of engagement with the stationary contact. The operating mechanism, moreover,

includes a portion within the pole chamber extending over a portion of the arc extinguisher and over the stationary contact, and another portion supported on the same general plane as the stationary contact.

In accordance with another aspect of the invention, the operating mechanism includes a pair of side frames, each of which includes a supporting portion engaging the base of the insulating support at a point spaced from and generally co-planar with the stationary contact and a second supporting portion resting on the insulating base at a point substantially directly above the stationary contact, each of these supporting points representing points at which the operating mechanism rests on the base. Fastening means is also provided for drawing an intermediate part of the'mechanism toward the supporting base, but not into contact with it, to fasten the operaing mechanism in place in the casing. The mechanismside plates therefore incorporate a bridge-type mounting, with supports at either end and fastening means intermediate the supporting points.

In the drawings,

FIGURE 1 is an-elevational sectional view of an electric circuit breaker incorporating the invention, taken substantially along the line 11 of FIGURE 2, the supporting side plate of the operating mechanism nearest the viewer being omitted to show the parts better;

FIGURE 2 is a plan view of a three-pole elelctric circuit breaker incorporating the invention, a portion of the casing cover being broken away;

' FIGURE 3 is a side elevation view of the operating mechanism of the circuit breaker o f FIGURE 1, the parts being shown in the off condition;

FIGURE 4 is a perspective view of a portion of the operating mechanism of the circuit breaker of FIGURE 1, and v FIGURE 5 is a fragmentary elevational view of portions of the circuit breaker of FIGURE 1, showing particularly the mounting of the mechanism in the casing.

Referring to the drawings, the invention is shown in FIGURES 1 and 2 as incorporated in a three-pole electric'circuit breaker'includi ng a generally rectangular insulating casing comprising a base 10 and a cover 11. The base 10-includes opposed integral side wall portions 12'(only one shown) and intermediate partition portions 13 (only one shown) defining three elongated generally rectangular recesses or pole chambers 14 (only two shown). The cover includes corresponding side and partition portions, which correspond to the side and partition portions 12 and 13 of the base respectively to subminal conductor or strap stantially totally enclose the pole chambers 14. (The side portions of the cover 11 are not shown, and only one partition portion '13 is shown, see FIGURE 2.) The cover I I is attached to the base by suitable means such as by screws 11'.

Each of the pole chambers 14 has a stationary contact 15, supported on a line terminal conductor or strap 16. Each of the line terminal straps 16 is fastened to the base 10 by suitable means such as by pairs of screws 17, and carries a line connecting lug 18 attached thereto by suitable means, not shown. Each of the line lugs 18 is of the screw clamp type and includes a clamping screw 19.

The opposite end of the base 10 includes a load ter- 20 for each pole chamber, also attached to the base 10 by suitable means such as by pairs of screws 21, and support load connecting lugs 22 each including clamping screws 23.

Each of the load straps 20 has a heater conductor 24, including a U-shaped portion passing around a magnetic field piece 25, and having its inner end connected to a pair of flexible conductors 26 by means of a screw 27, which also serves tofixedly attach this end of the conductor 24 to the base 10.

The other end of each of the flexible conductors 26 is rigidly attached by suitable means, such as by brazing, to movable contact members 27. The movable contact members 27 are each pivotally carried by a generally U-shaped contact carrier 28 by means of an inverted U-shaped clamp 29 and a pivot pin 30. (Note: One side of the U-shaped carrier is broken away.) Each of the movable contact members 27 includes a contacting surface portion 27' disposed and arranged to engage a corresponding stationary contact 15. A compression spring 31 is disposed between the bight portion of each of the contact carriers 28 and an end portion of the corresponding movable contact member 27 to provide contact pressure when the mechanism is in the closed circuit position as indicated in FIGURE 1. A stop pin 32 is carried by the contact carrier member at the opposite side of the movable contact member 27 from the compression spring 31, to serve as a stop to limit rotation of the contact carrier member 27 under the influence of spring 31 when the parts are in the open circuit position as indicated for example in FIGURE 3.

The current path through each of the poles of the circuit breaker may therefore be traced as follows: current enters at line terminal 18, flows through line terminal strap 16 to stationary contact 15, to movable contact surface 27, to movable contact member 27, to flexible conductor 26, to heater conductor 24, to load terminal strap 20, to load lug 22.

, The contact carrier 28 for the central pole of the circuit breaker, as illustrated in FIGURE 1, is pivotally supported by a fixed pivot pin 33, which in turn is supported by a pair of mechanism side plates 34. The contact carriers 28 of each of the three poles are ganged together for simultaneous operation by a contact crossarm 35 which is generally square in cross-section, and comprises a metallic core member 35A and a generally rectangular insulating sheath 35B. Each of the contact carriers 28 is rigidly attached to the cross-arm 35 by suitable means such as by means of a generally U-shaped clamping member 36.

For the purpose of aiding in the extinction of an arc drawn between the movable contact surface 27' and the stationary contact 15, an arc extinguisher assembly is provided comprising a pair of side plates 38 of insulating fiber and a back wall 38' also of insulating fiber. A plurality of spaced ferro-magnetic metallic plates 39 are supported in spaced parallel relation [between the arc chute side plates 38. Each of the plates 39 is generally U-shaped and the aligned openings of the plates 39 define a passageway through which the outer end portion of the movable contact member 27 moves in going from 4 closed to open circuit position. An arc drawn between the contact members 27' and 15 is therefore drawn into the magnetic plates 39, and the arc ga-sses are vented through a screen member 40.

OPERATING MECHANISM For the purpose of moving the center contact carrier 28, and with it the two outside contact carriers 28, with a quick-make and quick-break action, an operating mechanism is provided, which will not be described. The operating mechanism not only serves to move the movable contact members 27 between open and closed circuit positions, but also moves the contact members from closed circuit to open circuit position upon the occurrence of predetermined overload and/or short-circuit conditions in the circuit, and indicates such a tripped condition by movement of the operating handle to a trip signalling position. In addition to the side plates 34, the mounting and operation of which will be described later, the operating mechanism includes a handle assembly comprising a handle member 41 which is supported on a manually operable member 42 of metallic material, pivotally supported on a pair of projections 43 carried by and projecting outwardly of the side plates 34 of the mechanism. The operating mechanism also includes a releasable cam member 44, which is pivotally supported on a fixed pivot pin 45 extending between the side plates 34. The releasable cam member 44 includes a curved cam surface or edge portion 46, for a purpose to be described, and a latched end portion 47.

The releasable cam member 44 is normally restrained from rotation in a counterclockwise direction as viewed in FIGURE 1 by means of a restraining latch 48 carried by a common trip bar 49 extending across all three poles of the breaker, and pivotally supported at its opposite ends by suitable means such as by pivot pins 50 journalled in corresponding recesses in the side walls of the casing of the base 10. The common trip bar 49 is adapted to be rotated, so as to cause release of the latch member 48, by the action of current responsive means associated with any of the three poles of the circuit breaker and comprising for each pole an elongated bimetallic strip 51 rigidly attached to the heater conductor 24 at one end by suitable means such as by welding or brazing. Each of the bimetallic strips 51 carries an adjusting or calibrating screw 52. Each of the bimetallic strips 51 is disposed and arranged so that when heated by the heater conductor 24, it warps so as to move the calibrating screw 52 to the left as viewed in FIGURE 1, rotating the trip bar in counterclockwise direction to release the latch 48. Magnetic current responsive means is also provided for each pole of the circuit breaker comprising a pivotally supported armature member 53 pivotally supported by lugs 53A extending sideways into corresponding pivot recesses 54 in opposed confronting portions of the side walls 12 and partitions 13 of the base 10. Each of the arma-v tures 53 includes extension portions or legs 53B which are disposed and arranged to be attracted by the end portions of magnetic field piece 25 upon the passage of predetermined currents through the conductor 24. Attraction of the legs 53 toward the field piece 25 causes counterclockwise rotation of the armature 53 and causes its upper end to engage the trip bar 49, rotating it in counterclockwise direction to cause tripping as previously described. A light biasing spring 55 is provided for biasing each of the armatures 53 in clockwise direction, each of the springs 55 extending between a lug portion 53C of the corresponding armature 53 and the lower edge portion of the magnetic field piece 25. Certain aspects of the thermal-magnetic trip construction disclosed herein are the subject of a separate application Serial No. 359,567, Iencks and Murphy, filed April 14, 1964, and assigned to the same assignee as the present invention.

The central contact carrier member 28 has a generally U-shaped operating yoke 57 which is pivotally connected thereto by pivot pin 30 which also pivotally supports the movable contact member 27 on thecontact carrier 28, the pin 30 passing through aligned holes 57A in the yoke member 57, see FIGURE 4. The upper ends of the legs of the yoke member 57 carry a cam roller supporting pin 58, which in turn supports a cam roller 59 and one end of each of a pair of tension type operating springs 60. Because of the use of a single integral member comprising the U-shaped member 57, there is substantially no danger of the pin 58 swinging about an axis perpendicular to its axis of rotation such as might occur if the two side portions 57B and 57C were separate link members.

The ca-rn'roller 59 includes a pair of opposed flange portions 59A which facilitate travel of the cam roller 59 along the cam surface 46 of the releasable cam member 44. The upper ends of the tension type operating springs 60 are supported by the bight portion of generally U- shaped manually operable member 42 by suitable means, such as by having a loop portion thereof extending through slots in the manually operable member and being trapped against movement therethrough by retaining pins 61.

In operation, when the parts are in the closed circuit position as shown in FIGURE 1, the tension type operating springs, acting between the supporting pin 58 and the bight portion of the manually operable member 42, tend to cause movement of the cam roller 59 toward the left as viewed in FIGURE 1 because the center of curvature of the cam surface 46 lies to the right of the line of action of the spring in this position. Movement of the cam roller 59 and its pivot pin 58 to the position shown in FIGURE 1 forces the contact carrier member in counterclockwise direction, bringing the'movable contact surface 27' of the movable contact member 27 into engagement with the stationary contact 15. As this occurs, the contact member 27 is rotated slightly clockwise about its pivotal support 30 on the contact carrier 28, compressing the contact pressure spring 31.

Movement of the handle member to the right as viewed in FIGURE 1, moves the upper ends of the springs 60 to the right, this movement continues until the line of action of the springs passes to the right of the center of curvature of the cam surface 46. When this occurs, the operating springs 60 move the cam roller 59 to the right, moving the contact carrier 28 and the associated movable contact members 27 clockwise about the pivotal support 33. Movement of the central contact carrier 28 inclockwise direction is limited by engagement of the pin 30 carried by the-central contact carrier 28 with edge portions of the side plates 34 forming a corner. See particularly FIG- URE 5. This movement takes place with a snap action, independent of the rate of movement of the handle 41.

When the parts are in the closed circuit position as shown in FIGURE 1, an overload or short circuit condition which causes rotation of the trip bar 49 as described above causes release of the releasable member 44 from the latch 48. When this occurs, the force of the operating springs 60 pulling upward on the cam roller pin 58 urging the cam roller 59 against the cam surface 46, causes counterclockwise rotation of the releasable member 44 about its pivotal support 45. This permits movement of the cam roller 59 upwardly and slightly to the right even though the handle member 41 is held in the on position, and so permits automatic opening of the contact members. Certain aspects of the mechanism construction described are set forth and claimed in my copending divisional application Serial Number 510,113, filed October 21, 1965 and assigned to the same assignee as the present invention. These aspects are illustrated particularly in FIGURE 4.

As illustrated in FIGURES 1 and 5, and particularly in FIGURE 5, the mechanism side plates 34 each includes a first leg portion 62, which rests against the back wall 16A of the base 10. The side plates 34 are also supported at the opposite end by means of a cross pin 63 which extends through the side plates 34 and has its end portions would existif this end of the frame resting in notches 64 in the inner sides of the partitions 13 of the base 10. It will be observed that the side plates 34 merely rest against the base 10 at the support points 62 and 63. The plates 34 are drawn toward the back wall 10A of the base 10 by means of screws 65 which thread into alternately offset portions 66 of the plates 34. The secrew 65 pulls the intermediate portion 67 of the side plates 34 toward the back wall 10A.

As shown in FIGURE 5, the side plates 34, and particularly the depending portions 62 and 67, are dimensioned so that the pin 63 engages the notch 64 and the leg 62 engages the back wall 10A of the casing 10 before the lower edge of the intermediate portion 67 can engage the back wall 10A of the casing. Thus, when the screw 65 is in fully tightened condition as shown in FIGURE 5, a small s ace 68 exists between the lower edge of the projection 67 and the back wall 10A of the casing base 10. Thus only a single fastening element is used for each side frame 34. It will also be observed that by means of the mounting structure shown, the side frames 34 are supported both at the extreme front and extreme rear portion, that is, at the opposite ends thereof, thereby providing a very secure mounting, although the space used at the back wall of the casing 10 for the mounting is relatively small. It will be observed that the pin 63 which rests in the notches 64 extends substantially directly over the stationary contact 15. Thus the forward part of this pole chamber is used for two purposes, (1) to house a portion of the arc extinguisher structure including the stationary contact, and (2) to contain and support a portion of the operating mechanism. Since the supporting point of the pin 63 is at the upper edge of the base portion 10, it is sufiiciently removed from the supporting point of the stationary contact 15 and the stationary contact supporting strap 16 to prevent the possibility of a dielectric oversurface failure between these two points which danger were supported adjacent the back wall of the casing.

The handle support member 42 is bifurcated at its lower end to fit over the supporting pivot pin 43. In addition, the handle member 42 includes enlarged portions 42A adjacent the lower end which serve the purpose of retaining the pin 30 in position when the parts are assembled in the center pole, thereby preventing the pin 30 in this pole from sliding lengthwise to a position where it might be struck by the edge of the handle support member 42. The corresponding pins 30 in the outside pole members are each retained in place by the corresponding side wall 12 and adjacent partition 13.

It will be observed that the entire mechanism assembly is held in assembled relation without the need for any special retaining means holding any of the pivot pins in their position. Thus the pins 30 and 32 are retained in place, although free to slide lengthwise, by the adjacent partitions and side wall portions of the base. Also, since the side portions 57B and 57C comprise integral parts of a single U-shaped member, no separate retaining means is required to retain these portions on the corresponding ends of the pin 58. In assembly, the pin 58 is snapped in between the side portions 57B and 57C by springing these parts apart slightly.

The entire circuit breaker therefore has its assembly greatly facilitated since virtually all of the parts may be assembled by hand and without any metalworking operations such as riveting, welding, brazing, etc. to hold the parts together. In accordance with the invention, an extremely compact high spring force mechanism is provided. Thus for example, the contact pressure of the most nearly similar prior art circuit breaker of this size is about 5 pounds, whereas in the construction in accordance with applicants invention, the contact pressure achieved is from 8 to 10 pounds.

While the invention has been disclosed in only one particular embodiment, it will be readily appreciated that numerous modifications thereof may readily be made. It

is therefore intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising:

(a) an insulating casing having a generally planar bottom wall and surrounding peripheral side walls extending substantially perpendicular thereto;

(b) at least one relatively stationary contact supported on said bottom wall of said insulating casing;

(c) at least one movable contact movable into and out of engagement with said stationary contact;

((1) operating mechanism for moving said movable contact, said operating mechanism comprising a pair of sheet metallic plates supported in generally parallel spaced apart relation in said insulating casing, each of said plates having a first end portion in engagement with said bottom wall of said insulating casing at a point spaced from said relatively stationary contact, each of said plates having an opposite end portion extending adjacent said stationary contact;

(e) means supporting said opposite end portions of said plates each on one of said side walls of said insulating casing at a point spaced away from said bottom wall in a direction perpendicular to said bottom wall, and

(f) fastening means positively anchoring each of said plates to said bottom Wall of said insulating casing, said fastening means engaging said plates at a point intermediate said end portions.

2. An electric circuit breaker comprising:

(a) an insulating casing having a generally planar bottom wall and surrounding peripheral side walls extending substantially perpendicular thereto;

(b) at least one relatively stationary contact supported on said bottom wall of said insulating casing;

'(c) at least one movable contact movable along a predetermined path of movement between a closed position in which it is in contact with said stationary contact and an open position in which it is out of con-3 tact with said stationary contact;

(d) are extinguishing means comprising a series of metallic plates supported in spaced apart relation along said path of movement of said movable contact;

(e) operating mechanism for moving said movable contact between said open and closed positions, said operating mechanism comprising a pair of sheet metallic side plates supported in generally parallel spaced apart relation, each of said side plates having a first end portion in engagement with said bottom wall of said insulating casing at a point spaced from said relatively stationary contact, said side frames each having an opposite end portion extending at least partially over said are extinguishing means;

(f) means supporting said opposite end portions each on one of said side walls of said insulating casing, and

(g) fastening means positively anchoring each of said side plates to said insulating casing, said fastening means engaging said side plates at a point intermediate said end portions.

3. An electric circuit breaker comprising:

(a) an insulating casing having a generally planar bottom wall and surrounding peripheral side walls extending substantially perpendicular thereto;

(b) at least one relatively stationary contact supported on said bottom wall of said insulating casing;

(c) at least one movable contact movable along a predetermined path of movement between a closed position in which it is in contact with said stationary contact and an open position in which it is out, of contact with said stationary contact;

(d) are extinguishing means comprising a series of metallic plates supported in spaced apart relation along said path of movement of said movable contact;

(e) operating mechanism for moving said movable contact between said open and closed circuit positions, said operating mechanism comprising a pair of sheet metallic plates supported in generally parallel spaced apart relation, each of said plates having a first end portion in engagement with said bottom wall of said insulating casing at a point spaced from said relatively stationary contact, said plates each having an opposite end portion extending at least partially over said are extinguishing means;

(f) means supporting said opposite end portions each on one-of said side walls of said insulating casing; (g) fastening means positively anchoring each of said plates to said insulating casing, said fastening means engaging said plates at a point intermediate said end portions, and

(h) said plates being dimensioned so that the engagement of said plates with said casing at said end portion-s prevents said intermediate portions of said side frames from contacting said bottom wall insulating casing.

References Cited by the Examiner UNITED STATES PATENTS 2,195,016 3/1940 Swingle 200116 2,214,695 9/ 1940 Jennings 200116 2,233,336 2/1941 Bentley 200-168 2,454,106 11/1948 Von Hoorn 200-1 16 2,989,604 6/ 1961 Wegh 200-116 3,105,132 9/1963 Jencks 200-168 3,171,929 3/1965 Jencks et a1 200116 3,174,024 3/ 1965 Strother et a1 2001 16 BERNARD A. GILHEANY, Primary Examiner.

Claims (1)

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) AN INSULATING CASING HAVING A GENERALLY PLANAR BOTTOM WALL AND SURROUNDING PERIPHERAL SIDE WALLS EXTENDING SUBSTANTIALLY PERPENDICULAR THERETO; (B) AT LEAST ONE RELATIVELY STATIONARY CONTACT SUPPORTED ON SAID BOTTOM WALL OF SAID INSULATING CASING; (C) AT LEAST ONE MOVABLE CONTACT MOVABLE INTO AND OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACT: (D) OPERATING MECHANISM FOR MOVING SAID MOVABLE CONTACT, SAID OPERATING MECHANISM COMPRISING A PAIR OF SHEET METALLIC PLATES SUPPORTED IN GENERALLY PARALLEL SPACED APART RELATION IN SAID INSULATING CASING, EACH OF SAID PLATES HAVING A FIRST END PORTION IN ENGAGEMENT WITH SAID BOTTOM WALL OF SAID INSULATING CASING AT A POINT SPACED FROM SAID RELATIVELY STATIONARY CONTACT, EACH OF SAID PLATES HAVING AN OPPOSITE END PORTION EXTENDING ADJACENT SAID STATIONARY CONTACT; (E) MEANS SUPPORTING SAID OPPOSITE END PORTIONS OF SAID PLATES EACH ON ONE OF SAID SIDE WALLS OF SAID INSULATING CASING AT A POINT SPACED AWAY FROM SAID BOTTOM WALL IN A DIRECTION PERPENDICULAR TO SAID BOTTOM WALL, AND (F) FASTENING MEANS POSITIVELY ANCHORING EACH OF SAID PLATES TO SAID BOTTOM WALL OF SAID INSULATING CASING, SAID FASTENING MEANS ENGAGING SAID PLATES AT A POINT INTERMEDIATE SAID END PORTIONS.

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