US2520258A - Secondary breaker - Google Patents

Description

Aug. 29, 1950 R. R. PITTMAN ETAL 2,520,253

SECONDARY BREAKER Original Filed June 28, 1945 5 Sheets-Sheet 1 INVENTORS Aug. 29, 1950 R. R. PITTMAN ETAL SECONDARY BREAKER 3 Sheets-Sheet 5 Original Filed June 28. 1945 Fig. 5

TO LOAD .3); m o m INVENTORS QM/A A Patented Aug. 29, 1950 SECONDARY BREAKER Ralph E. Pittman, North Little Rock, and Carroll H. Walsh, Pine Bluif, Ark.

Original application June 28, 1945, Serial No.

602,056. Divided and this application November 5, 19459, Serial No. 125,694

2 Claims. 1

This invention relates generally to circuit breakers, and in particular to an outdoor type of low voltage breaker adapted for use in connection with the secondary windings of outdoor distribution transformers. This application is a division of pending application Serial No. 602,056, filed June 28, 1945.

Among the objects of the present invention may be noted the provision of: an outdoor type of secondary breaker construction adapted for mounting on the bushing terminal of an outdoor transformer, and suitable for manipulation with a linemans switch hook; a secondary breaker having an operating characteristic coordinated with the heating characteristic of an associated transformer; a breaker having a latch lever of semaphore type for visibly indicating when the breaker has automatically opened; a breaker having a snap-action movement when manually opened; a breaker having a trip-free mechanism; a breaker embodying a contact movable about a double pivoted mounting to provide high contact pressure and fast opening movement; a breaker having a resilient stationary contact normally under high pressure to provide energy for opening movement, an integral portion of the stationary contact being formed to provide an arcing contact; and a breaker of simple design, rugged strength and inexpensive construction.

Heretofore secondary breakers have been combined. with outdoor transformers, the most popular arrangement being one in which an indoor type of breaker is mounted inside of the transformer tank. This arrangement has the serious defect of inaccessibility, so that inability to close the breaker for any reason renders the transformer useless until it is disassembled and the condition remedied. For example, a breaker inside of a transformer tank and submerged in hot oil cannot be reclosed until the whole mass has cooled, even if the load is reduced. if the necessary thermally-responsive element is embodied in the tripping mechanism. In the meantime, serious results due to th long attendant service interruption may occur. Attempts have also been made to mount housed indoor breakers on the outside of the tank of the transformer, re-' sulting in an expensive construction unadapted to the service requirements. So far as we are aware, no satisfactory outdoor type of secondary breaker having the important advantages present in our invention and necessary to meet the service conditions, has been heretofore constructed.

With the above objects in View, our invention resides in the novel features of design and disposition of the various constituent elements, and in the novel apparatus provided by one combination of our breaker with an outdoor transformer, and the scope of the invention will be indicated in the appended claims.

An embodiment of the invention is illustrated in the accompanying drawing, in which: Fig. 1 is a side elevational view of the breaker, shown partly in section; Fig. 2 is a sectional view of the breaker, taken along the line 22 of Fig. 1; Fig. 3 is another sectional view of the breaker, taken along the line 33 of Fig. 1; Fig. 4 is another sectional view of the breaker, taken along the line 4-4 of Fig. 1; Fig. 5 illustrates the combination breaker and transformer, showing the breaker in the open position; and Fig. 6 fragmentarily illustrates in plan the supporting and connecting structure.

Referring to the details of construction illustrated in Figs. 1 through 4, a block 26, of weatherresistant insulating material, such as porcelain, has mounted thereon the metal supporting member [3, by means of the bolts 21. The supporting member [3 embraces respective opposing sides of the block 25, and is formed to provide a pair of arms I4 and [5, extending in parallel relationship downwardly and outwardly beyond the block 26. The member [3 also extends upwardly above and across the top of the block 26 in vertical spaced relationship therewith. Preferably the supporting member I3 is formed as a U-shaped piece from a fiat strip of copper, the respective arms of which are rigidly bolted to the block 26.

The bayonet-type terminal 10 extends downwardly through the top of the supporting member l3, the flange H resting on the bushing insulator I2, the latter serving to insulate the terminal l0 in its passage through the member l3. The bimetallic current-responsive element, shown more clearly in Fig. 3, extends horizontally outward beyond the block 26, from the terminal [0. The bimetallic element includes the bimetallic strip 11, one end of which is connected to and supported by the lower end of the terminal It] by the nut l8, and the other end of which is connected to and supported from the supporting member [3 by means of the bolt IS, the nut 20, and the metal spacing washer 2!. At its outer end, the latch detent 23 extends along the unfastened end of the strip ll, being rigidly attached thereto by the rivets 22, and insulated therefrom by the insulating material 24, which is conveniently formed from a strip of mica. The bimetallic element is so arranged that the latch detent 23 moves upwardly when the strip bends in response to heating. If desired, the cover l6 may be provided over the bimetallic element.

At a point spaced from the supporting member 13, a stationary contact support 3| is mounted at the rear of the block 26, by means of the bolt 29 and the nut 30, the head of the bolt 29 being positioned a substantial distance. within the block 25 in the recess 28. The stationary contact support 3! extends both downwardly and upwardly along the rear side of the block 26 beyond the nut 30, and is provided with a threaded opening at its upper end, through which a set screw 32- is extended to engage the rear surface of the block 26, for the purpose of adjusting the position of the downwardly extending portion of the support 3|. The stationary contact '33 conveniently formed from a looped strip of resilient conducting material, such as Phosphor bronze, is mounted on the support 3| by means of the rivets 34, extending outwardly and forwardly therefrom below the lower end of the block 26. For convenience of connection, the stationary contact support 3i extends below the stationary contact 33, and at its lower end is provided with the load terminal 53.

A latch lever 25, formed as a semaphore, is mounted for rotative movement about the pivot All on the extended arms I4 and it, being held midway between the arms by the ppositely disposed spacers it and ll, and. extending upwardly to normally engage the latch detent '23 of the bimetallic element. The movable contact, including the pair of laterally spaced, inwardly extending legs and 37 joined at their respective outer ends by the operating eye 52 and the rivets straddles and. is pivotally mounted on the latch lever 25 for rotary movement about the pivot 63, the latter extending laterally from each side of. the latch lever 25 at a point slightly above and inwardly with. respect to. the pivot 68 The relationship of the pivot points is and is such that the inwardly extending portions 35 and 31 of the movable contact engage and resiliently deform the stationary contact 33 when the latch lever 255' is in. the normal position in engagement with the latch 23. The resilient stationary contact is so formed. that when deformed a pressure acting outwardly and upwardly is provided tending to concurrently rotate both. the latch lever 25 about the pivot point 58 and the movable contact about the pivot point 43. Normally the engagement of the latch lever 25 with the detent E8 of the bimetallic element restrains rotative movement of the latch lever 25, and engagement of the movable contact with the pivotal mounting of the latch lever restrains rotative movement of the movable contact.

A pair of aligning washers M and 62 maintain the alignment of the movable contact with respect to the stationary contact, and the spring All is arranged to continually urge the movable contact and latch lever to jack-knife to the relative positions shown by the broken lines of Fig. 1, or the solid lines in Fig. 5.

The lowermost ends of the arms is and are joined and held in the desired spaced relationship by means of the spacing sleeve 49, through which is extended the bolt 5! The sleeve 49 also provides a stop to limit movement of the movable contact, for the purpose of preventing engagement withthe terminal 53. If desired, the flexible' conductors 44 and 45 may be utilized to directly electrically connect the movable contact to the supporting member l3.

As shown in Figs,v 1 and 2, an integral portion 35 of the stationary contact 33 extends outwardly beyond the face of the contact between the legs 36 and 3'! of the movable contact to engagement with the sleeve 38, the latter being mounted for rotation about the shaft or pivot 39. In its movement to open position, the ends of the legs 35 and 3! disengage the face of the contact before the portion 35 disengages. the sleeve 38, the latter elements constituting an arcing contact arrangement functioning to avoid arcdamage to the principal current-carrying contacts;

The apparatus shown in Figs. 5 and 6 includes the breaker in the tripped-open position, which might result from an overload on the transformer winding suppliedv through the load conductors t9 and 66. In this construction the bushing terminal 5'! is insulated from the tank wall 54 by means of the bushing 56, and the breaker is both sup-ported from and connected t the bushing terminal 51 by clamping the bayonet terminal iii of the breaker between the eye bolt 58 and the terminal 5'! (Fig. 6).

The current path. through the breaker when in closed position is from the terminal it tothe bimetallic strip ll, thence to the mechanism support 23, thence through the flexible conductors M and .5 to the movable contact, thence through the stationary contact 33' to the other terminal 53.

When a predetermined current passes through the breaker; the bimetallic element moves upward at its outer end, releasing the latch lever 25 for rotative movement about its pivot 48. Under the bias of the resilient contact 33*, the movable contact moves about its pivot 43 concurrently with its movement substantially end'wise bodily away from the stationary contact 33 about the pivot es, the breaker assuming the tripped-open position indicated by the broken lines of Fig. 1. Concurrently the spring 40- effects the jack-knifing of the latch lever 25' with respect to the movable contact, and the latch lever semaphorically indicates that the breaker has automatically tripped to the open position. While not essential to operation, it is desirable that the" bimetallic element be suchthat its heating characteristic parallels closely that of the associated transformer.

Toreclose thebreaker, the eye 52 may be urged upwardly with a linemans switch hock until the latch lever again engages the bimetallic element, as shown in Fig. l, and thenpulled down to engage and seat the contacts. While the movable contact and the latch lever are inf'ol'ded position, the contacts cannot be engaged, because the movable contact is sufliciently retracted to prevent contact engagement. The contacts are therefore not engaged as the latch lever is latched to the bimetallic element, but only when the eye 52 is pulled down after latching the latch lever. In the event that an excess current passes through the breaker at the instant of contact, the downward pull is in the direction to urge the breaker to open position. Since the spring 40 continuously urges the movable contact to fold against the latch lever, the breaker is trip-free, for the reason that contacts cannot be engaged if these elements are in folded position, and cannot be maintained in any other position unless latched to the bimetallic element.

If it is desired to manually open the breaker, this is accomplished by urging the eye 52 upwardly until the contact-ends of the movable contact pass downwardly over-center of the face of the stationary contact, at which time the spring 40 opens the breaker with snap action. The latch lever does not move when the breaker is manually opened.

It may be seen that our breaker is of such simple and rugged construction that the components may be readily formed of common inorganic materials, such as porcelain, copper and copper alloys, and for this reason is an effective outdoor type of device for the purpose, requiring no container, and functionally capable of accomplishing the objectives stated above.

It is intended that the description and drawing of the preferred embodiment of the invention herein presented will be regarded as illustrative rather than limiting.

We claim, as our invention:

1. A secondary breaker comprising relatively movable contacts including a deformable and resilient stationary contact and a contact movable to engage and deform said stationary contact, said stationary contact when deformed continuously urging the movable contact from engaged to open circuit position, said stationary contact being formed as a loop of flat resilient conducting material having a face extending first outwardly and downwardly and thence inwardly and downwardly and a centrally positioned integral portion extending outwardly beyond said face, said movable contact when in closed position engaging said stationary contact at a point on each side of said centrally positioned portion and at 6 an arcing-contact on said portion and disengaging at said points and said arcing-contact in sequence named when moved from the closed to the open position.

2. A secondary breaker comprising relatively movable contacts including a deformable and resilient stationary contact and a contact movable to engage and deform said stationary contact, said stationary contact when deformed continuously urging the movable contact from engaged to open circuit position, said stationary contact being formed as a loop of flat resilient conducting material having a face extending first outwardly and downwardly and thence inwardly and downwardly and a centrally positioned integral portion extending outwardly beyond said face, said movable contact including a pair of legs extending to contact said face and straddling said centrally positioned portion and a rotatable arcing sleeve extending between said legs and normally engaging said portion, said arcing sleeve being arranged to disengage said portion after the contact with said face is disengaged when said movable contact is moved from closed to open position.

RALPH R. PITTMAN. CARROLL H. WALSH.

No references cited.

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