US2159764A - Circuit breaker contact - Google Patents

Description

May 23, 1939. c, D 2,159,764

I v CIRCUIT BREAKERVCONTACT Original Filed Nov. 21, 1935 2 Sheets-Sheet l Inventor" Charles H. Hill.

iS' Attorney.

May 23, 1939.

C. H. HILL CIRC UIT BREAKER CONTACT Original Filed NOV. 21, 1935 2 Sheets-Sheet 2 Inventor: Charles HHHI; by Hi Attorney.

Patented May 23, 191 39 PATENT OFFICE CIRCUIT BREAKER CONTACT Charles H. Hill, Drexel eral Electric York Hill, Pa., assignor to Gen Company, a corporation of New Original application November 21, 1935, Serial No. 50,915. Divided and this application August 11, 1936, Serial No. 95,394

4 Claims.

10. other object of my invention is to provide an improved contact structure for eliminating the foreign matter which is rubbed loose during the wiping action.

The current carrying capacity of electric 15 switches is reduced as a result of the accumulation of .foreign matter, such as dust, oxides, etc., on the contact engaging faces. It is not always convenient or safe to remove such foreign matter because the switch may have to be dis- 20 connected from all live conductors or cleaned under hazardous conditions. In accordance with my invention, I provide an improved means for effecting the cleaning action and disposal of the foreign -matter during the regular operating movements of the switch.

This application is a division of my application Serial No. 50,915, filed November 21, 1935, for Electric switches, now Patent No. 2,141,272, patented December 27, 1938.

My invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings, Fig. 1 is a side elevation partly broken away and partly in section of a circuit breaker embodying my invention, the circuit breaker being shown in the closed position; Fig. 2 is a detail in perspective of the 40 movable contact structure shown in Fig. 1; Fig.

3 is a partial side elevation of the opera-ting and tripping mechanisms of the circuit breaker shown in Fig.1 with the parts in the trip'ped position;

and Fig. 4 is a partial side elevation of the op- 45 erating and tripping mechanisms of the circuit breaker shown in Fig. 1 with the parts'positioned in the reset condition preparatory to closing the circuit breaker.

In the illustrated embodiment of my inven- 50 tion, a base or switchboard panel ll) of suitable insulating material has secured thereto to fixed contacts, shown as pairs of strips or bars H and I2. These may be of copper, and the outer bars a may be provided with silver inserts l3 to provide 55 the actual contact engaging surfaces. The bars l2 in the lower fixed contact are preferably separated as shown for cooling purposes. The fixed contacts are arranged to be bridged by a movable contact shown as a block-type contact I4, which may be of copper and which may have silver inserts I5 to provide the contact engaging surfaces. Secondary and tertiary cooperating contacts l6 and I] may also be provided, as is customary in air circuit breakers. As shown, the movable contact I4 is connected to one of the fixed'contacts l2 by a'fiexible lead l8 and also to the movable contacts of the secondary and tertiary pairs by a-flexiblelead I9 in order to provide a suitable current conducting path whereby the are or arcs will be interrupted, at the contacts 3 and I! provided for this purpose. As shown, the movable contact I4 is pivotally mounted at 20 on a contact carrying arm 2|, which also serves to support the movable contacts of the secondary and tertiary pairs l6 and II. This arm is pivotally supported at 22 on a frame 23, which is suitably supported on the base I 9 and which, as shown, constitutes the support for the operating and latching mechanism s'of the circuit breaker.

In order to provide a wiping contact action, the movable contact M has, in accordancewith my invention, a lost-motion mounting, as shown.

Thus, its pivot pin 20 may be set in a slot 20' which is inclined downwardly towards the fixed contacts as shown or is oblique to the face of the contact M. Then as the circuit breaker opens, the resilient action of-suitable means such as backup springs 2! tends to force the contact l4 downward in the slot 20' so that, when the circuit breaker is closed, the'contact I4 is caused to rise upward and thus produce a wiping action on the silver insets l3 and IE to clean them. These insets may be grooved or slotted transversely or diagonally as at 15' to provide a place or channel for foreign matter to go when the wiping action takes place on the closing of the circuit breaker.

As shown in Fig. 1, I provide means employing the principle of the toggle and the inclined plane for actuating the movable contact to and holding it in the circuit closed position. The toggle comprises a link 24, one end of which is pivotally connected to the circuit controlling member 2|,

as at 25, and a link 26, one end of which is pivotally connected to a fixed support, such as a pivot 21, in the frame 23. Resilient means, such as a helical spring 28 may be connected between the pivots 25 and 21 to expedite the circuit opening movement of the contact arm 2|.

' breaker, the wedging member 29 is suitably' supported or guided by a movable abutment 32 and is provided with suitable cam faces 33 and 34, which respectively engage the roller on the toggle and a roller on the abutment 32.

. For actuating the cam member 29 between the toggle and the abutment in order to move the cam faces 33 and 34 along their respective rollers 30 and 35; the cam member may be pivotally mounted as at 36 on an arm of an operating member or crank 31, which may bepivotally supported at 21 co-axially with the toggle link 26. For connecting two or more poles together .to form a multipole breaker, the toggle link 26 may be in 'the form of a crank having an arm 38 whereby the toggle mechanisms'of the difierent poles can feature of the latch. .In order to restore the abutment 35 to its thrust transmitting positionon the reset movement of the circuit" breaken be interconnected through a cross-bar 39 for si multaneous operation by a single operating mechanism, the connecting bar 39 preferably being of suitably insulating material or so constructed that the different poles are insulated each from the other'b In order to prevent the opening of the circuit breaker by a counterclockwise movement of .the operating member 31; whether done intentionally or byjars or vibration, a latching member 49 pivotedonthe frame 23 at 4| may be biased by suitable means, such as a spring 42, to engage a projection 43 on the cam member 29 whereby to prevent movement of the cam-member in such 34mg as to permit the collapse of the toggle In order to secure the desired trip-free action and at the same time provide a shockproof mechanism, I support the movable abutment 32 by a collapsiblemechanism. As shown this comprises an underset toggle including links 44 and 45 which are respectively pivoted to the abutment Since the 32 at 46 and to the frame 23 at 4'I.- toggle 44--45 is underset and the pressure opening tendency of the circuit breaker against-the wedging member 29 is in a direction to turn the abutment 32 clockwise about its pivotal support 48, I provide a, shockproof latching mechanism for preventing this collapse of the abutment support. As shown, this latching mechanism includes a latch 49 mounted on a trip' shaft 59 and provided with a toggle supporting face 5| which is engaged by an extension of the toggle link 45 to the left of its pivot '46. The latch 49 is biased to latching position against a stop 52 by suitable means, such as a spring 53.

In order to insure the shockproof ability of the latch 49, it is pivoted substantially on its center of gravity axis so that there is no tendency for it to rotate. The reset biasing spring 53 besides overcoming friction also assists in the. shockproof I provide suitable biasing means, such as a spring 60, which exerts on the abutment'32. a force tending to rotate it counterclockwise about its pivot 48.

For tripping the latch 49 in response to predetermined circuit conditions so as to effect the opening of the circuit breaker, any suitable means may be employed. The particular arrangement illustrated is electromagnetic with so-called sucker type time lag 9. As shown this means includes an electromagnet 6| which is looped around the bars |2 of the lower fixed contact and which is provided with an armatureLGZ. In circuitbreakers of small capacity a {multiple turn series windingmay be used-as is well known to the art. The armature 62, upon-attraction, is arranged to actuate a tripping member 63 whichengages the tail 94 of the latch 49x andturns it counterclockwise to release thegtoggle link-44 from-the latching fa'ce- 5|.' The time lag feature is provided by a movable-disc 65 whichrests in oil against'a disc 66 so that the time ofrelease is dependentv on the time in which the oil film between the discs is'brokenr Suitable adjusting means are 'providedin the form of, a screw and spring means ill- 68 for controlling the pick-up of the armature 62. V

Assuming the parts positioned as shown in. Fig. 1 and that an abnormal circuit condition such as overcurrentthrough the circuitcontrolled by the circuit breaker causes the actuation of the tripping rod 63 and. thereby the release of the tripping latch 49, the abutment 32' will be no longer'maintained in its thrust transmitting position by the holding toggle 44-45 since the latch face 5| has been moved clear of the left-' I hand end of the link 44. Consequently, the opening action of the circuit breaker due to'the weight of the parts and the action of the springs 28 will act on the abutment 32 in a direction to turn it clockwise about its pivot.48 and the parts will move to the position shown in Fig. 3. In this position, the toggle 44-45 is collapsed, as shown, and the wedging member 29 is turned counterclockwise about its pivot 36 but is still engaging the rollers 39 and 32 of the toggle 24-26 and the abutment 3'2. 40

Before the breaker can be reclosed, the abutment must be restored to its thrust transmitting position. For this purpose, the operating handle or lever 31 is turned counterclockwise about its pivot 21, thereby effecting movement; of the switching member in a direction to permit the restoration of the abutment 32 to its thrust transmitting positionunder the action of its biasing spring 60. This spring also lifts, the 'free end of the switching member at the same time. During the resetting movement a roller 19 on the extended portion of the toggle link 44 moves up along the edge of the latch 49 to engage the latch face 5| and the latch is biased against the stop 52. The parts are now positioned as shown in Fig. 4 with the abutment 32 in its thrust transmitting position.

In order to close the circuit breaker, the operating handle 31. is turned clockwise thereby pulling the. switching ,member 29 to the right between the rollers 35 and 30 insuch a way as to present an increasingly. widening portion ,of the wedging member between these-rollers so as to straightentheoperating toggle 24- -26 and close the circuit breaker with the parts positioned as shown :in Eig; 1 Just, before the final closedposition, thejlatch 49 engages the projection 43 ,onthe switching member 29-so that any attempt auto move the operating lever 31 counterclockwise from its stop 69 while the circuit breaker is closed 7 cannot produce an opening of the circuit breaker. In other words, a slow opening of the breaker, in,-

tentional or otherwise, by manual operation of the operating handle or vibration causing the counterclockwise rotation thereof cannot occur. 75

While 'I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims allthose modifications that fall within the true spirit and scope of my invention.

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

1. An electric switch-comprising two spaced stationary contacts, amovable contact for brid ing said spaced stationary contacts, means for actuating said movable contact to engage said stationary contacts including a movable member,

and a pin and slot connection between said movable member and said bridging contact, the axis of the slot portion of said connection being oblique to the plane oi said stationary contacts when said contacts are engaged by said bridging contact for eflecting a relative sliding movetionary contacts when said contacts are engaged by said bridging contact and projections .on the bridging contact slidable in said slots, and means for "yieldingly maintaining the bridging contact positioned with its projections in the end or the slots adjacent the stationary contacts when the switch is open.

3. An electric switch comprising two spaced stationary contacts, a movable contact for brldg ing said spaced stationary contacts, means tor actuating said movable contact to engage said stationary contacts including a movable member, a pin' and slot connection between said movable member and said bridging contact for effecting a relative sliding movement between said stationary and bridging contacts upon engagement thereof, said connection including a slot in said movable member, a projection on said movable contact engaging said slot, and'means for maintaining the movable contact at a predetermined substantially fixed obliquity relatively to the axis of said slot in the circuit controlling positions 01' said movable contact.

4. An electric switch comprising two spaced stationary contacts, a movable contact member for bridging said spaced stationary contacts, means for actuating said movable contact member to engage said stationary contacts including a movable member, one of said members being provided with a slot and the other with a pin projecting into said slot toiorm a pin and slot connection between said members, the axis of said slot being oblique to the plane of said stationary contacts when said contacts are engaged by said bridging contact member for effecting a relative sliding movement between said stationary contacts and said bridging contact member upon engagement thereof.

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