US1740558A

US1740558A - ainsworth

Info

Publication number: US1740558A
Authority: US
Priority date: 1923-04-02
Publication date: 1929-12-24
Anticipated expiration: 1946-12-24
Also published as: US1837805A

Description

24, 1929. 5. D. AmswoRTH ELECTRIC SWITCH FiledApril 2,. 1923 5 sheets-sheet 2 Invenor. c/(LMm C). CM

Dec. 24, 1929. c. D. AlNswoRTH ELECTRIC SWITCH Filed April 2, 1925 5 Sheets-Sheet 3 Dec. 24, 1929. c. D. AlNswoRTH ELECTRIC SWITCH Filed April 2, 1923 5 sheets-sheet 4 Dec. 24, 1929. c. D. AlNswoRTH ELECTRIC SWITCH 5 sheets-sheet 5 Filed April 2, 1923 Patented Dec. p26, l'1929 *UNITED STATES PATENT OFFICE CHESTER D. A'INSWORTH, or WOIQLASTON, MASSACHUSETTS, ASSIGNOR, @Y MESNE ASSIGNMENTS, Tm.,CONn1TELECTmCALMANUFACTURING CORPORATION, OE nos- TON, MASSACHUSETTS, A CORTOHATION or MASSACHUSETTS ELECTRIC SWITCH4 I Application led April 2, 1923. Serial No. 629,252.

This invention relates to oil immersed electric switches especially adapted'for outdoor installations, although not necessarily lim1ted to such use. l

An object of this invention'is the provision of a switching apparatus made up of switch units of interchangeable construction so that one or several units may be connected together to form a unitary switching apparatus having a variable number of poles'.

A further object is to provide switch loperating mechanism adapted to permit the switch to have a relatively high rate of opening movement.

A yet further object is generally to 1mprove the construction and pperation of elec tric switches.

Certain features of this invention are d isclosed in my co-pending application Serial No. 606,678. filed December 13, 1922, which has eventuated into Patent No. 1,729,859, 1ssued October 1', 1929.

Fig. 1 is a side elevation of a Athree pole switch embodying my invention, the switch comprising the center pole being partially.

in section.

Fig. 2 is a front elevation of one of the su itch units of Fig. 1. n

Fi g. 3 is a sectional view of a modified form of switch unit, the unit being similar to a switch unit yillustrated in Fig. 1 but having added thereto a current transformer.

Fig. 4C is a sectional .detail illustrating the application of a 'bushing type transformer to the switch.

Fig. 5 is a detailed front elevation of an enclosing casing for the control mechanism of the switch. y u

Fig. 6 is a sectional detail along line 6 -6 of Fig. 5. illustrating the relative position of the component parts of the control mechanism in switch-closed position.

Fig. 7 is a detail illustrating the relative position of the component parts of the switch contr-ol mechanism when tripped electrically.

Fig. 8 is a similar view illustrating therelation of the parts of the control mechanism `when the switch is opened manually.

Fig. 9 is a view of the control mechanism adapted for manual control only, the dotted position of the mechanism illustrating the switch-open condition of the mechanism.

Fig. 10 is a detail illustrating especially an insulated fixed Contact member adapted for use with a core-type of current transformer. v

Fig. 11 is an elevation, in detail, of the oil immersed transformer and its supporting means. p

Fig. 12 is an end View of Fig. 11.

Fig. 13 is aperspective detail of one of the coil-supporting brackets.

Fig. 14 is a sectional detail illustrating the are defiector for the transformer. o

The switching apparatus here shown is adapted for the control of a three phase circuit and comprises three similar switch units. Each switch unit is or may be so constructed and arranged that a switching apparatus adapted to control circuits of various phases may be built up by assembling and connecting together in linea suitable number of switch units. Each. switch unit may comprise a frame 20 of more or less rectangular shape,

which frame is adapted to comprise a cover for the voil receptacle 21. Said oil receptacle isreceived within said frame and depends therebelow and may rest upon the cradle 22. Said cradle is or may be secured removably to the switch frame by suitable means as the rods 23 and nuts 23, Wliereb the oil receptacle is also secured removab y to the switch frame. The top walls 24 of said switch frame are preferably inclined downwardly from the the middle portion thereof and stationary switch members comprising the insulators 25 and the conducting studs 26 are inserted through said inclined Walls and secured theref to. Said studs 26 are or may be provided with the screw-threaded lower end portions on which the main stationary contact members 27 are secured. Auxiliary stationary contact members 28 may be detaohably secured to said main contact members 27 and are adapted to cooperate 'with the auxiliary contact'men'ibers.of the movable switch Inember in the usualmanner. f

Sai-d switch frame 20 is or may be provided with a transverse mechaniram-containing compartment 39 disposed between the stationary switch members; and the side walls 31 of said compartment may be extended laterally in opposite directions beyond the body of the switch frame and may terminate in vertically extended flanges 32 and 33 which are adapted to besecured to similar fianges 0f adjacent switch units by suitable means as the bolts 34, whereby to tie together the various switch units and form a unitary switch structure.

The movable switch member may include the insulating rod 36 provided with the brush member 37 at the lower end thereof. A metal rod 38 is or may be fixed to the upper end of said insulating rod 36 and extends slidably through an aperture in the bottom wall of the mechanism compartment and may carry a block 40 adjustably threaded on the upper end thereof. Said block 40 is'or may be disposed between and pvoted to the upper ends of guide links 41 of the switch mechanism. The lower 'end of said guide links are or may be pivotally connected with the pair of strut links 42; and said latter links are or may b'e pivoted on a pin 43 extended through the opposite walls 3l of the mechanism compartment. A pair of bell crank levers 45 are pivotally mounted on a pin 46 extended through the opposite end of the side walls 3l of the mechanism compartment and the long arms of said bell crank levers are pivotally connected by suitable means, as the pins 47, to an intermediate portion of the guide links 4l. This construction and disposition of mechanism provides means to guide the upper end of the movable switch member in substantially a straight line.

' purpose, the switch frames 20 may be formed or provided with the lateral extensions 5l adapted to rest upon said frame 50. Bolts 52 may be assed through said extensions 5l into said rame 50 whereby to secure the switch units to lsaid frame. The rear end ofthe mechanism compartment of the rear switch unit may be closed, preferably removably, by suitable means as the cover plates 53.

The switch mechanisms of all the switch units are or may be connected together for conjoint operation by the two spaced bars 55 which are extended through the upper portion ofthe connected mechanism compartments of the switch units and are or mayV be pivotally connected with the short arms 45 of the bell crank levers 45 of the separate switch mechanisms.

The switch operating or control mechanism is adapted to be contained mainly within a separate casing which is or may be secured against the free flange of the foremost switch unit. Said casing 60 is or ma be divided into an upper compartment 6l a apted to contain switch operating mechanism, two spaced Aof the switch. Said Various 'compartments may be closed by the cover plates and 66 and said cover plates may be secured removably in position by any suitable means as the thumb nuts 67.

The switch mechanism herein illustrated is adapted to provide for the manual opening and closing of the switch and also for the automatic tripping of the switch by electrically controlled tripping means.

The switch operating mechanism includes a pair of spaced bellfcrank levers which are or may be disposed between the bell-crank levers 45 of the foremost' switch unit and pivotally supported on the pivot pin 46 of said bell crank levers. The upper arms 7()a of said bell crank levers are or may be pivotally vconnected by the pin 72 to triangularly shaped and spaced plates 73 which constitute members of a lockin toggle for all of the switch units. A link 4 is or may be disposed between said plates and pivotally connected to said plates by suitable means as the pin 75. The other end of said link may be disposed between the arms 45 of said foremost bell crank lever 45 and pivotally connected thereto by the pin 76. The connections between said link 74 and the bell crank lever 45 and the plate 73, and between said plate 73 and the bell-crank lever 7 0 are adapted to be such as to form an inverted toggle which when substantially in an on-center position is adapted to hold the switch units closed. A latch roller 78 is or may be disposed between the lower' ends of said plates 73 and rotatably supported on a pin 79 )assed through said plates. A latch 80 may e disposed between said plates and pivotally supported on the pin 46. Said latch is arranged to engage said latch roller 78 and releasably hold the inverted toggle and consequently the switch closed; and said latch is adapted to be raised whereby to release said latch roller and permit the toggle to be broken by the Weight ofthe movable switch member, or accelerating springs 39, whereby to permit the switch to open. Said latch 80 is adapted to'be raised to trip the switch by means including the link 82 which is disposed beneath said latch and is formed or provided with an elongat. :l slot 83 in which the lixedly supported pin 82 is or ma be received. Said pin 82u is adapted to guide said link 82 in the tripping movellt lll':

.pins 87 may be adjustably extended for engagement with tripping members of the trip,- ping coils.

The trippmg coils are adapted to be contained in the compartments 62 and 62a and disposed beneath .the tripping frame 84. Each tripping coil may comprise the coil bobbin 90 in which a tube 91 is movably extended; and said tube 91 may contain the plunger of the coil. Said tube 91 may be formed or provided with a reduced upper end portion 92 which is adapted to be extended through an aperture in the top compartment 61 and a nut 93 may be threaded on said reduced portion 92 whereby to secure said tube 91 and consequently the coil bobbin in place.

Each coil compartment may contain a plu- 35|rality of, as two, coils. v Trippingpins 94 may be slidably extended through said tubes 91 into the top compartment and are adapted to be engaged by the movable plungers. A tripping plate 95 is extended between and .pivotally received or fulcrumed on eachpair of tripping pins and the arrangement is or may be such that each coil may act independently to raise said tripping plate to trip the switch or the coils may act conjointly to trip the switch. This arrangement may be substantially as set forth in my above-namedv co-pending application.

The lower or calibration ends of the tubes 91 of said tripping coils are extended slidably through the bottom walls 97 of the coil compartments and into the lowermost compartments 63 and 63EL and adjustments of the current settings of said coils may be made in these compartments. The bottom walls 98 of said lowermost compartments are or may be formed with apertures therein which are aligned with the tube apertures in the upper Wall 97. The trip coils may be removed from their enclosing compartments by first withdrawing the tubes 91 through said aligned apertures. Said apertures in said lowermost wallsi98 are or may be normally closed by the plug 99. l

The switch operating components adapted to provide for the manual opening and closing of the switch include the pairs of links 105 which are or may be pivotally connected to the lower arms b of the bell-crank lever 70. Said links 105 are also pivotally connected by suitable means as the pivotpin 106 with apair of links-107 and said links 107 are in turn pivotally supported on the fixed pin 82a. Said pairs of

links

107 and 105 constitute toggle members adapted to be actuated manually to effect .the opening and closing central passage 64 of the casing.

ends of said bars 110 are adapted to be pivoty pivotally supported ,on the pivot pin 106. The lower end of said link is or may be pivotally connectetlto the connecting bars orrods 110 which extend downwardly through the The lower ally'connected to an operating handle 111 and said handle is or may be pivoted to a bracket 112 secured to the lower wall 98 of the casing 60.

When the switch is closed, the switch operating mechanism is or may be in a position similar to that illustrated in Fig. 6. When the mechanism is tripped electrically, the bell-crank levers 70 and the toggle comprising the links 107 Vand 105 and the operating handle 111 are adapted to remain stationary and said members will be held in such position bythe

toggle links

107 and 105, which toggle is 'adapted to be in somewhat overshot positionand in contact with a 'stopmember as the pin 113.v "With this arrangement, the upper arin70`"t of the bell-crank lever 70 forms a pivotal support for the toggle comprising the plates 3 and the link 74. When the over-load coils are energized to trip the switch, the latch is raised from holding engagement with the latch roller 7 8 carried by the lower bend of the plates 7 3 and, in-

asmuch as the toggle including said plates a member is in a slightly under-shot position,

Athe weightof the switch members, or accelerating springs associated therewith, serves to move the movable switch members rapidly into open position. h

. The switch-open position of the mechanism when tripped electrically is or may be similar l to that illustrated in Fig. 7. It is to benoted that with this arrangement, the only part of the operating mechanism that moves is the toggle comprising t-he plates 73 and the link of the switch. A linkv108 is or may be dis- -posed between said

links

105 and 107 and 74. Inasmuch as said toggle may have very..

little weight and inertia, l this arrangement provides a switch havingl a relatively high rate of' opening movement.

As here shown, the switch is arranged to be closed manually after it has opened electrically. For this purpose, the handle is adapted to be raised whereby to break the toggle com! prising the

links

107 and 105 and rotate the bell-crank lever 70 ina clockwisedirection. This movement causes the plates 73 to rotate in a counter-clockwise direction whereby to move the latch roller 78 into holding engagement with the latch 80. The connection between the switch operating mechanism and the movable switchl mechanism is thereby restored and when said operating handle 111 is moved downwardly, the operating vmechanism is restored to a condition illustrated in Fig. 6.

When. the switch i opened manually, the handle 111 is raised as before and thebell crank levers remain connected with the switch mechanisms through the latch 80 to effeet the manual opening of the switch and remain connected therewith when the operating handle 111 is moved downwardly to effect the manual closing of the switch.

The switch mechanism herein illustrated may also be arranged solely i'or nunmal opening and closing and the switch mechanism so arranged is illustrated in Fig. 9. For this arrangement, the toggle comprising the plates 73 and link 74 maybe removed and a link 115 may be connected behveen the pivot pin 72 carried in the arms 7 0 of the bell-crank levers 70 and the pivot pin 76 carried in the arms 45 of the bell-crank levers 45. This arrangement serves to connect said bell-crank levers 70 iixedly to the bell-crank levers 45 whereby the operation of said handle 111 serves to open and close the switch units; and the switch units will remain in closed position until thc handle is moved downwardly as the toggle comprising thel

members

107 and 105, inthe switch closed condition, is adapted to be in slightly over-shot position.

It is to be noted that the stationary and movable switch n'iembers of the switch units are or may be unsymmetrically disposed with relation to the vertical axis ot' the switch frame and the oil receptacle, or displaced laterally toward anl end wall of the casing,.

whereby to provide an enlarged space A between a stationary switch member and the opposite end wall of the casingin which a transformer, as a current transformer, is adapted to be received.

Fig. 4 illustrates a bushing type transformer 120 contained within thc switch unit and disposed to encircle one of the stationary switch members adjacent the top wall ot the switch frame. The coil 121 thereof is ad anted to occupy the enlarged space provided by thel displacementof the switch members. The terminals of said coil may extend through ay suitable pipe 122 into a terminal box 123` secured to the upper end of said pipe wherebyl connectiol. may be made to a suitablecontrol or indicating circuit.

In Fig. 3 there is illustrated a core typecurrent transformer disposed in the enlarged space and vimmersed in'the oil o f the switch' and arranged substantially 1n ylmewith the stationary switch members. Said trans- `former may comprise the iron core 125 and the secondary coil 125, which latter is wound on said core, and the primary coil 125b which latter is or may be spaced from said secondary coil and also from the core` and insulated from Vboth bv the oil of theswitch, which oil is adapted to fillv the space between the primary coil and the lcore and secondary coil. The transformer core may be secured to t-he frame l126', which latter is or may be secured to and depend from the switch frame; and said frame may carry insulating members 126a adapted to engage and hold said primary coil. The stationary switch member may also be provided with insulating members 126", which latter also are adapted to engage and support said primary coil in position.

In connection with said oil immersed current transformer a modified arrangement of contact member is or may be provided (Figs. 10 and 11). The primary coil of said current transformer is adapted to be connected in series with the circuit through the switch. For this purpose, the lower end of the stud 26 is or may be provided with a conducting plate 130 (Fig. 13) which may be secured to said stud by the nut 131; and said plate is or may be arranged to support an insulating member 126". Said plate 130 is adapted to be connected with one terminal 132 of the primary winding of the transformer. A stationary contact member is carried by said stud and insulated therefrom. Said stationary contact member may comprise a substantially U-shapcd member 0r fra ne 135 having the lower arn'; 136 adapted to provide a contact lacc for the movable brush member. The upper arm 137 is or may be formed with an aperture therein in which an insulating bushing 138 is received. Said arm 137 of said contact member is received upon the lower end of the stud 26 and between insulating washers139. Nuts 140 are or may be threaded on said stud 26 on the opposite sides ol said insulating washers whereby to secure said contact member 135 firmly to said .stud but insulated therefrom. An' auxiliary contact member 142 may be secured to said contact member and a terminal 143 of the primary coil of the transformer may also be secured to said contact member 135 as, for instance,

through the bracket 160, and said bracket may be arranged to support an insulating member 126b for said primary coil. This arrangement provides means whereby the current transformer may be connected in series with the circuit through the switch and the terminals of the transformer may be carried v one 'of the stationary switch members.

Preferably, an arcing shield 165 is carried by said stud 26 and extended therefrom to a position below and spaced from the primary coil 125b of the transformer, whereby to protect said coil from the hot arc gases and divert said gases away from contact with the coil.

The open tops of the corI .iected switch mechanism compartments and 'the mechanism compartment of the casing 60 Amay he closed by a single "cover 150 which entends over all compartments: and said cover may be securedremovably in position by suitable means as the thumb bolts 151.

IThe structure may be otherwise modified without departing-from the spirit of the invention.

1,74o,5es

I claim: 4 v o 1. Electric switching apparatus comprising the combination of a plurality of switch casings having transversely disposed mechanism-containing compartments, said casmgsvv being arranged in line and in abutting relation with each other and secured in such relation'whereby to connect all mechanism-containing compartments, switch lmechanism contained in the mechanism compartment of each casing, and means extended through said compartments and operatively connected with said mechanisms, whereby to operate all mechanisms conjointly.

2. Electric switching apparatus compris-v relation with all ot said'compartments, switch mechanism contained in the compartment of each casing, and means extended through said compartments under said cover and opera` tively connected with saidy `mechanisms, whereby to operate all mechanisms conj ointly.

3. Electric switching apparatus comprising the combination of a plurality of switch casings having transversely disposed mechanism-containing compartments, said casings being arranged in line and in abutting relation with each other and secured in such relation whereby to connect all mechanism-containing compartments, said connected compartments being open at the top and at each end, a cover extended over said casings and arranged tocover the top of all of said connected compartments, a cover plate secured to the switch casingof an end switch over one open4 end of said connected compartments, a closure for the other open end of said connected compartments comprising a controlmechanism enclosing casing arranged in communication with said casing-compartments, inter-connected switch mechanism contained in each switch casing compartment, and control mechanism containec in said control casing and connected with said interconnected switch` mechanisms. 1

4. 'Electric switching apparatus compriscasing over an open end of said connected compartments, a closure for the other open end of said connected compartments compr1sing a control-mechanism 4.enclosing `casing' having an open top 'and secured tofa switch casing over said'other end of said connected compartments, ay cover extended over the open topof said connected lcompartments and said control-mechanismv casing, `inter-connected switch mechanisms contained in said switchv casing compartments, and control-mechanism contained in said. control-mechanism casing and connected operatively with said interconnected switch mechanisms,V A

5. In an electric switch, an cnclosing'casing for `the switch-operating mechanism having atop compartment forthe operating mechanism, two spaced'side compartments and a vertical lpassage extended between said side compartments and in communication with said top compartment, and removable covers for said compartments.

6. In an electric switch, an enclosing cas-v ing for the switch-operating mechanism having a top compartment for the `operating njlechanism, two spaced side compartments and a vertical passag'cextended'between said side compartments and in ycommunication with said top compartment, switch operating mechanism contained in said top compartment, an operating member connectedwith said mechanism and extended .downwardly throughsaid vertical passage, and trip coils contained in said side compartments having movable members extended in to said top comf partment and operatively associatedwith the mechanism contained therein. f f

,7. In an electric switch, an enclosing casing for theswitch-operating mechanism having a top compartment for the operating mechanism, two spacedside compartments land a verticalpassage extended between said side compartn'ients and in communication with said top compartment, switch operating mechanism contained in said top compartment, an operating member connected with said mechanism and extended downwardly through said vertical passage,an,operating handle disposed beneath and pivoted tothe bottom-wall of said casing and connected with said down, wardly extended operating member, and trip coils contained in said side compartmentS having movable members extended into said -top compartment and operatively associated lwith coils contained in said intermediate compartments and having movable members extended into said top compartment and operatively associated with the mechanism therein contained, said trip coils also having calibration members extended into said lower compartments.

9. In an electricv switch, an enclosing casing for the switch-operating mechanism having a top compartment adapted to contain the operating mechanism, pairs of bottom and intermediate compartment-s disposed below said top compartments, said casing having` a. vertical passage disposed between said pairs of compartments and communicating with said top compartment, switch `Jperating mechanism contained in said top compartment having an operating member extended downwardly in said vertical passage, and trip coils contained in said intermediate compartments and having movable members extended into said top compartment and operatively associated with the mechanism therein contained, said trip coils also having calibration members extended into said lower compartments, said compartments having l s openms at the sides, and removable covers for sal openings.

10. In an electric switch, an enclosing casing having a top compartment adapted to contain the switch operating mechanism, and having two spaced lower compartments and a vertical passage between said compartments communicating with said top compartment,'switch-operating mechanism contained in said top compartment including a tripping frame extended above both lower comartments, tripping coils contained in said ower compartments having movable members extended into said top compartment and arranged to actuate said tripping frame, and an operating member connected with said operating mechanism and extended downwardly in said vertical passage.

11. An electric switch having a substantially rectangular fluid-containing enclosing casing, and insulated stationary switch members carried by the top wall of and depending into said casing and laterally displaced within 1the casing toward a side wall thereof, whereb to provide an enlarged and unobstructe space between a stationary switch member and the opposite side wall, contact members carried by said switch members beneath the fluid, one of which contact members is insulated from its switch member, and a series transformer contained in said enlarged space of the casing beside said stationary'switch members and in the general plane thereof and above said contact member and having a connection with said ihsulated contact member and also with its switch member.

12. An electric switch having an enclosing casing, stationary and movable switch members carried by the top wall of and depending into said casing and displaced laterally therein toward a wall of the casing, whereby to provide an enlarged space between a stationary switch member and the opposite wall of the casing, a transformer disposed within said enlargedspace and supported by the adjacent stationary switch member, and a bracket connecting said transformer with the top wall of the casing.

13. An electric switch having an enclosing casing comprising an Aoil receptacle and a switch frame comprising a cover for said oil receptacle, meansl removably connecting said switch frame and oil receptacle, stationary and movable switch members carried by said switch frame and depending into and displaced laterally toward an end wall of the oil receptacle, whereby to provide an enlarged space between a -stationary switch member and the opposite end wall of the casing, a bracket secured to said switch frame between the aforesaid stationary switch member and opposite wall of the casing and depending therebelow, and a transformer carried by the lower end of said bracket and by said aforesaid stationary switch member and disposed in said enlarged space of said casing.

14. An electric switch includin a stationary switch member, a contact mem r carried by and insulatedfrom said switch member, a transformer connected between said stationary switch member and insulated contact member, and a movable switch member arranged to engage said insulated contact member, whereby to include said transformer in the circuit through the switch.

15. An electric switch including an enclosing casing, a pair of stationary switch members carried by said casing and extended therein, a contact member carried by and insulated from one of said stationary'switch members, a transformer disposed Within said casing and connected within said casing to said insulated contact member and the switch member supporting said contact member, and a movable bridging member arranged to conneet` said insulated'contact member and the other stationary switch member, whereby to include saidtransformer in the circuit through the switch.

16. An electric switch including a stationaryswitch member having a screw-threaded lower' end, a contact member comprising a U-shaped frame having spaced upper and lower arms through the upper arm of which the lower end of said stationary switch member is extended, a nut disposed between the arms of said frame and threaded on the end of said stationary switch member, and a second nut threaded on said stationary switch member above said upper arm of said frame, said nuts arranged to clamp said`frame to said stationary switch member, and a movable switch member engageable with said lower arm, and'means establishing an electric conumass nection between said contact member and'stat-ionary switch member. v 17. An electric switch including a stationary switch member` having a screw-threaded lower end, a contact member comprisingl a. U-

shaped frame having an insulation-hushed aperture in the upper arm thereof in which the lower end of said stationary switch member is extended, a nut disposed between the arms of and insulated from said frame and threaded on the end of said stationary switch member, and a` second nut threaded on said stationary switch member above said upper arm of said frame and insulated from said upper arm, said nuts arranged to clamp said insulated Contact member to said stationary 'switch member, a transformer' con,- ne'cted between the lower end of said stationary switch member and said insulated contact member, and a movable switch mem- ""`\ber@anged to engage said insulated contact membervhcrehy to include said transformer in the circuit througlt'l Switch-s..

18. An electric switch having thecombination vof an oil receptacle, movable and stationary contact members and a transformer immersed in the oil therein adjacent the arc zone and-above said stationaryfcontachmemf Y bers, and a deiiector plate arranged above one of said contact members and below `and in shielding relation with said transformer and in the npathof the arc gases from said contact members. A f 19. An electric switch having the combination of an oil receptacle, movable and stationary contact members and a transformer immersed in the oil therein adjacent the 'arc zone and above'said stationary Contact members and a deflector plate carried by a stationary VA4o contactmember and arranged above it and below and in shielding relation with said transformer and in the path of the arc gases from said contact members.

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

CHESTER D. AINSWORTH.