US1737636A - Heavy-duty electric switch - Google Patents

Description

G. A. BURNHAM HEAVY DUTY ELECTRIC SWITCH Dec. 3, 1929.

Filed April 14, 1926 n Il V/AI... a. Il.

Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE GEORGE A. BURNHAM, OF SAUGUS, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRI- CAL MANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A COR- PORATION F MASSACHUSETTS HEAVY-DUTY ELECTRIC SWITCH Application led April 14,

This invention relates to oil immersed electric switches adapted for interrupting heavy currents at high voltages; and more particularly to heavy duty oil switches having separate enclosing casings for each phase and a common actuating mechanism.

In the switch embodying this invention, the switch operating mechanism for each phase unit, is disposed within an enclosed mechanism compartment or well, between which wells communicating passages are. provided to accommodate the mechanism rods by which the several units are operated conjointly. Under certain conditions of circuit interruption oil is thrown about in the switch casing and into the mechanism well, from which it may escape or may pass to adjacent switches of the set. A combustible mixture may also be formed in the gas expansion space above the oil which mixture under proper conditions,

may burn or explode.

An object of this invention is to isolate the mechanism well from the gas expansion space of the switch, whereby to keep the oil and combustible mixture, or explosive pressures, out

of the mechanism well and to isolate from each other. the oil compartments of the switches of a multi-phase switching set.

A further object is generally to improve the construction and performance of oil circuit breakers. i

Fig. 1 is a sectional elevation of an electric switch embodying the invention.

-Fig. 2 isa detailed sectional elevation of two adjacent switch units of a multi-phase switching set embodying the invention.

As here shown, the electric switch embodying this invention is adapted to control a multi-phase electric circuit and to this end is provided with several separate units, each comprising a switch casing and cooperating stationary Vand Amovable switch members. Said units are or may be'identical and consequently the description of but one unit will suiice. Each phase unit includes the enclosing casing 8 which is adapted to contain oil or other suitable arc quenching fluid. Said casing'comprises a vertical cylindrical shell 10 of substantial height open at both ends, 50 forming the side walls of said casing, and

1926. Serial No. 102,070.

the concave plate 12 which is secured by means of rivets or by welding in fluid tight relation within said shell near its lower end to provide a bottom closure for the casing.

A switch frame 14 is secured to the top of said casing and forms a top-closure therefore and has a peripheral flange 16 which depends over the top of the side wall of the casing. Said switch frame is provided with an enclosed mechanism compartment or well 18 of more or less rectangular shape which is disposed in the intermediate portion thereof and is formed by the parallel side walls 19 which extend both above and below the top wall of the switch frame. The' mechanism well is closed at the bottom by the integral bottom wall 20 and at the top by the removable wellcover 21.

Stationary switch members 22 ai'e cariied by said switch frame on opposite sides of the mechanism well and extend into the interior of the switch casing and into the oil therein contained. The movable switch member includes a bridging or brush member 211 which is adapted to be raised and lowered into and away from circuit-controlling relation with the lower ends of said stationary switch members. Said brush member is carried at the lower end of an insulating switch rod 2G which is extended upwardly and through an aperture 28 in the bottom wail 2O and into said mechanism well and is connected with the switch operating mechanism therein contained. Said operating mechanism may be of any usual oisuitable construction which, preferably is adapted to guide the switch rod for movement in a straight line. As heie shown, the mechanism includes a guide link 30 one end of which is pivotally connected with said switch rod at the upper end thereof and the other end of which is pivoted to the upper end of a strut-link 32, the lower end of which latter link is pivotally connected with the switch frame. A bell-crank lever 84 is pivoted at 86 to the switch frame on the opposite side of said switch rod; and the end of the long arm 38 of said lever is pivotally connected with an intermediate-point on said guide-link. The short arm 40 of said bellcrank lever is pivoted to an actuating rod 42 fri which is adapted to be moved in a substantially horizontal direction by switch actuating mechanism (not shown) whereby to raise and lower said operating rod and said brush members and thereby to close andy open the switches.

The mechanism wells of the several switch units are arranged to be connected by communicating" passa-ges 45 through which said actuating rod 42 is adapted to pass, by which the movable switch members of the several units are caused to be raised and lowered inunison. Said passages may be constructed of pipe-sections 46 whichxmay hwveflangesl at each end whereb they may be secured to the mechanism we ls of the several switch units in a fluid tight manner by means of boltsV 49:

In accordance with this invention, means are provided to isolate the`v mechanism well finemtheoil and:v gasspacev of the switch casing, whereby tokeep`r the oil' and? the' switch gases out of themechanism well' and also to isolatie; the: casingsiol'f the'fvarious switchunit-s ofi a multi-phase switching set. To' this end, an insulating tubular member is disposed to loosely'surround the switch; rod 26; The upper endofY said member 60= is fixed in a fia-ngc@ which is secured inia fiuid tight mannen to thebottom walllof the mechanism well about thel switchqod. opening therein. The lowerend 'o saidtubularfmember isextended beneath the level of the oil in the casing and is terminated at about the' level: of the brush member`24 andthe. lower ends ofthestationary. switch members 22 in a metaal nose 64 which functionsy as ai guide forv the` switch rod; Said'y tubulin` member and its fittings areiconnected together'in a substantially fluid tight mannerl so that a fluid tight conduit for theA switch rod isprovided whichl extends from'the-mechanism well to alpoint below the oil"` level inthe easing.v While'the lower open end ofisaid conduit which forms the opening for thel mechanism well', is freelyopen, or at least there is a freerunning clearance'between the switch rod and the inner wallof the conduit, gas trom the gas-expansionspace above the oii in the casing cannot enter the mechanism weil because of the body ofoil aboutthe lower end of the' conduit. No' appreciable amount ofoillcan enter the' mechanism well through the conduit because of the small clearance space about the switch rod, and the resistanceto fluid flew offered ther small clearance. 'Il-he gases in the gas expansion spaceabove the oil can escape through the vent 66.1

I claim:

1. An electric switch having an oil containing enclosing casing which has a gas space above the oil and af mechanism well in the` gas space which has an opening in its bottom: butl is otherwise sealedfrom the interiorofthe: casing, means providing an oil seal for said opening, whereby to pre1 vent access of gas into said well from the interior of said casing, and means independent of said well to vent the gas space of said casing.

2. An electric switch haiving'an enclosing casing adapted to contain oil and having a gas expansion space above the oil, and a mechanism well disposed mainly in said gas expansion space above the oil and' isolated from fluid communication therewith, said well having an opening in the bottom which is beneath the oil, said casing having a ventingf passage which. is independent of said mechanism well.

3. A multi-phase switch apparatuscomprising a plurality of switch' casngseach adapted to contain oil andi gas expansion spaces above thek oil, intercomniunicating mechanism wells carried by said casings, and

having switch-rod openings in the bottoms thereof, and means to isolate said wel-ls from fluid communication with the gas expansion spaces of said casings including-mea'nsto provideI oil seals for said openings, saidv wells thus being sealed from communicationwith tlie gas spaces of saidy casings, and said casings having venting passages for the gas spaces independent of said wells.-

4. A multipliase switching apparatus comprising a plurality ofV switch casings each adapted to contain oil and having gas expansionr spaces abovev the oil, intercommunicating mechanism wells carried by saidr casings mainly above the oil and isolated from said gas expansion spaces, said mechanism wells having openings in the bottoms thereof whichl are beneath the oil-in saidcasing's, said wells thus being sealed from communication with' the gas spaces of said casings, and said casings having venting passages for the gas spaces independent of= said wells.

5. An electric switch having an enclosing casing adaptedv to contain oil, a mechanisin well disposed entirely above the oil level and isolated from the interior of said oil containing casing, said mechanism well having a hollow extension depending into and terminated beneath the level of the oil, and a switch rod operable in said extensionsaid'casing having a venting passage which isindependent of said well.

6. An electric switch comprising the combinationof an oil containing enclosingicasing, stationary and movable switch members depending intotheoil'of said casing, a-mechanism well carriedlby. the-upper part offsaid casing', switclril operating mechanism contained therein including a' rod which depends through an aperture in the bottom of said well and supports said movable switch membefr atx itslower end', and anv insulating tube fixed dependently to saidmeehanism well in4 surrounding relation with said rod and terminated at the lower ends of said stationary switch members and constituting a guide for said rod thereat, whereby to guide said brush member into engagement with said stationary switch members.

7. An electric switch having an enclosing casing adapted to contain oil and provided with a gas expansion space above the oil, a mechanism well disposed above the oil level and sealed against gaseous communication with said expansion space, a switch rod depending from said well into the oil, and a tubular guide member surrounding said switch rod and having its upper end in gas tight connection with said well and depending from said well through the gas eXpansion space and into the oil in said casing, the lower end of said tubular guide member being open only beneath the oil, and the side wall thereof being imperforate.

8. An electric switch comprising an enclosing casing adapted to contain oil and having a gas expansion space above. said oil, an enclosed mechanism well disposed entirely above the oil and isolated from the gas eX- pansion space, switch operating mechanism disposed within said well and having an operative element extending through an opening in the bottom of said mechanism well and through the gas expansion space into the oil of said casing, and means to prevent the entrance of gas from said gas expansion space to said mechanism well through said opening comprising a depending casing for said operative element and surrounding said opening and having a fluid tight connection with 'said well and extended downwardly through said gas expansion space and termin ated only below the level of the oil within said casing, the side wall of said depending casing being imperforate in said gas eXpansion space.

9. In an electric switch, the combination of a pair of enclosing casings adapted to contain oil and gas expansion spaces above the oil, an enclosed mechanism well contained in the top of each of said casings entirely above the oil therein, means providing a. communicating passage extending between said mechanism wells7 switch operating rods extending through openings in the bottom walls of said mechanism wells, and means to isolate said mechanism wells from the gas expansion spaces in said casings, said insolating means including guide tubes for said operating rods, the upper ends of which tubes surround the openings in the bottom walls of said wells and are secured to said walls in a gas tight manner and the lower ends of which open only into the oil in said casings.

10. An electric switch having an enclosing casing adapted to contain oil and a gas er;` pansion space above the oil, a mechanism well disposed in the upper part of said casing above the oil therein and having a bottom wall which is located above the oil and has an opening therethrough, switch operating mechanism contained in said well including a switch rod which extends through said opening into the oil,and an insulating tube having an imperforate side wall loosely surrounding said switch rod and having a flanged upper end which surrounds said opening and is carried by and has a substantially gas tight connection with the bottom wall of said well and which has a metal rod guiding member at its lower end which is submerged in the oil of the casing.

ll. An electric switch having an enclosing casing adapted to contain oil, a mechanism well disposed above the oil and isolated from communication with the interior of the casing and having a bottom wall which is located above the oil and has an opening therein, and a tube liXed to and having a substantially gas-tight connection with said bottom wall about said opening and extended downwardly therefrom and having its lower open end terminated only beneath the level and sealed by the oil in said casing.

In testimony whereof, I have signed my name to this specification.

GEORGE A. BURNHAM.

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