US1119971A - Circuit-interrupter. - Google Patents

Description

H. G. MACDONALD. CIRCUIT INTERRUPTER.

APPLIOATION FILED JUNE 8, 1907.

1,1 19,97 1 Patented Dec.8,1914.

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WlTNESStSt lNVENTOR 5M W8 2am ATIIORNEY H. G. MACDONALD.

CIRCUIT INTEBRUPTER. APPLICATION FILED JUNE 9, 1907 1 1 1 9,97 1 Patented Dec. 8, 1914.

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HOWARD G. MAGDONALD, OF PITTSBURGH, YENNSYLVANIA, ASSIGNO-R T0 WEST- INGHOUSE ELECTRIC & MANUFACTURING GOMIANY, A CORPORATION OF PENNSYLVANIA.

Application filed June 8, 1901*. Serial No. 377,957.

To all whom it may concern:

Be it known that I, HOWARD G. MACDON- ALD, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have. invented a new and useful Improvement in Circuit-Interrupters, of which the following is a specification.

My invention relates to circuit interrupters and has special reference to inclosed cir cuit breakers which are adopted to automatically interrupt electric circuits under overload conditions.

The object of my invention is to provide, in a device of the class above indicated, simple and conveniently disposed means for suspending the action of the overload release mechanism.

Switching devices which are arranged to automatically interrupt electric circuits under predetermined conditions are often employed for controlling the supply of energy for electric motors and other translating de vices. It is a wellknown fact that translnting devices of this character may be niaterin-lly overloaded for a short period of time when their terminals are first connected. to the line without any serious injury, While the samedoad, if applied for any considerable length of time after the device has been in operation, may bring about disastrous results. I

According to my present invention, i provide it manually operated device by which an attendant may prevent unnecessary in' terruption of the circuit'just after it has been completed. In this Way, the overload release mechanism may be sensitively adjusted for the protection of the translating device under normal conditions.

Figure 1, of the accompanying drawings, is a'view, partially in section, but mainly in elevation, of a circuit interrupter constructed in accordance with my invention. Fig. 2 is a plan view of the device shown in Fig. 1, and Fig. 3 is a detail view of a portion of the mechanism.

Referring to the drawings, the device here illustrated comprises a frame or body 1 which forms a casing for the operating mechanism 2. an insulating slab or plate 3, stationary and movable contact members 4. and 5, and an. inclosing casing 6 for the contnctmembers, in which a suitable insulating fluid may be disposed.

Specification of Letters Patent.

CIRCUITJNTERRUPTER.

Patented Dec. 8, 1914.

The stationary contact members 4 are secured directly to terminals 6, and the movnble contact members are connected to teri'uinals 7, by means of flexible ribbons or cables 8. The movable members are me chanically connected and electrically separated by means oian insulating bar or strip 9 and may be moved into and out of engagement with the stationary contact members by means of an operating lever 10 to which the her 9 is connected by means of the rod 11. ln-order that an excellent electrical contact me be obtained between the stationary an movable contact members, each of the latter comprises a cylindrical head or block 13, a screw-threaded shank 11, which passes loosely through a hole in the bar 9 end is connected to the flexible strip 8, and e. helical spring 12 which is interposed between the bar 9 and the cylindrical head 13.

T he operating lever 10, which is a part of the operating mechanism 2, is in the form of a bell-crank and is pivot-ally mounted on a stationary shaft 15. A bell-crank lever 16, having relatively short bifurcated arms 17 and 18, is keyed to a shaft 19 that is rot-stably n'iount-ed so that its center line is substantially parallel to the center line of the shaft 15. The shafts 15 and 19 are sup ported by a portion of the casing 1, the walls of which are relatively near together at this point and form a relatively small compartment 20 which communicates with a larger compartment 21 containing the terminals 6 and 7. One end of the shaft 19 projects materially beyond the wall of the compartment 20,'and an operating handle lever 22 is aflixed to this shaft extension. The arm 18 of the bell-crank lever 16 is connected to an arm 23 of the lever 10 by means of a link 24. A toggle connection is thus formed and the arrangement of parts is such that a predetermined rotation of the handle lever 22 effects engagement of the stationary and movable contact members.

The weight of thcinovnble contact members and their connecting-bar is suiiicient to separate these members "from the stationary members and,'. consequently, a latch mechanism 25 is provided for holding the switch closed. The latch mechanism 25 comprises a relatively light bell-crank lever 26, which is nihxed to a shaft 2-7, and is provided with a hook or latch 28 and a forked trigger 29. The latch 28 is pivotaliy at tached to aprojection 31 of the lever 96 by means of a pin 30 and is limited in its mo tion in one direction by an angle projectionv 32 which engages the body of the lever. A predetermined relation is normally maintained between the lever-Z6 and the latch 23 by means of a tension spring that is inter posed between the projection 32 and the le ver. The bifurcated projection 17 on the bell-crank lever 16 supports a. pin 3-1 which may be engaged by the latch 28 when the switch is closed.

In order that the switch may be automati- 'a.lly opened under overload conditions, electro-magnets35 and 36 are connected in series with the circuits completed through the switch in a well-known manner and comprise stationary core members 37, movable core members 38 and magnet windings 39. The movable core members 38 comprise magnetizable blocks that are attached to one end of hammer rhds 40 which pass loosely through holes in the stationary memher and which are adapted to strike the two parts of the lever arm 29 when the electromagnets are energized. -W hen the magnets are deenergized, the air gaps between the stationary and movable core members are determined by the positionot a calibrating device all which comprises a cross arm 42 having forked. extremities 42* and. pivotally n'iounted at'thc end of a calibrating lever 43. This calibrating lever is made up of two parts and '16, both'of which are affixed to a shaft 4 L that is rotatably mounted in a. manner similar to that of the shafts 15 and 19. The part 110 may be secured in any convenient position by incansof a'thunibscrew 2 8, by which its outer extremity is clamped to a stationary plate d7, The upper extremitiesof the hammer rods are provided with enlar ements which 'ci'igage the forked c-X- trc-miti T of the cross arm through which the hammer rods project. 7 p

One end of the shaft 27 extends through theavall of the compartmeritQO and a sec; 'ondary handle lever 27 is attached to this extremity. The latch 28 is normally held in engagement'with the pin 34 by reason of a spring 48 which is interposed between a stationary projection it) on the wall of the rasing and a. relatively short arm 50 which projects from the. lever 36.

The operation of the device is as follows: Assuming that theswitch is connected in the circuit of an electric motor and occupies its open circuit position, if the handle lever 32 is rotated so as to close the switch and rent plete the motor circuit. the first rush of curent will usually be suflicient to actuate the tripping magnets. When these magnets are actuated, the hammer rods 40 will strike the arms of the bell-crank lever- 26 and will more latch 28 out of engagement with the pin 3%. As soon as the bell-crank lever,16 is released, the movable contact members 5 will move out of engagement with the stationary contact members 4, thereby interrupting the circuit which was completed through the switch. 7

When an electric motor or other translating device has been standing idle so that its i windings and magnetizable core members are cold, it will, of course, carry a. consider able overload for a short'time without injury. In order that the tripping mecha msm of my'switchin'g device-may be calibrated to protect the motor under operating conditions, without beingactuated by the first rush of current when the switch is first closed, the bell-crank lever 26 may be prevented from rotating by the attendant who closes the switch. The auxiliary handlelever 27 is provided for this purpose, and it may also be employed for manually tripping the circuit breaker when it is desired to interrupt the circuit. Under normal conditions, if the current traversing the circuit which is completed .throughthe switch surges above the value at which the tripping device is actuated, for a very short interval of time, an interruptioh'of the circuitmay be prevented by dash-pots 51 'which com prise cylinders 52 and plunge s 53 that'are attached to theinovable core members 38 of the electro-ma'gnet-s. 36. i

I desire thatwa-riations in size and arrangemeut of details shall: be included within the scope ot-my' invention- I claim as my invention;

In a circuit breaker, the combination with stationary and movable contact members, and closing mechanism therefor comprising an operating lever, a'handle lever and a

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