US2057084A

US2057084A - Electrical interlocking switch gear

Info

Publication number: US2057084A
Application number: US685048A
Authority: US
Inventors: Elias S Cornell; Charles A Koerner; Joseph A Stoos
Original assignee: DELTA STAR ELECTRIC CO
Current assignee: DELTA STAR ELECTRIC CO; DELTA-STAR ELECTRIC Co
Priority date: 1933-08-14
Filing date: 1933-08-14
Publication date: 1936-10-13
Anticipated expiration: 1953-10-13

Description

Oct. 13, 1936. E. s. CORNELL. ET AL ELECTRICAL INTERLOCKING SWITCH GEAR Filed Aug. 14, 1933 4 Sheets-$heet l n 1936- 155. CORNELL ET AL ELECTRICAL INTERLOCKING SWITCH GEAR I Filed Aug. 14, 1935 4 Sheets-Sheet 2 5r. YMELLILIICLV EEEF-Ein L76 .IL i

Oct. 13, 1936- E. s. CORNELL ET AL ELECTRICAL INTERLOCKING SWITCH GEAR Filed Aug. 14, 1953 4 Sheets-Sheet 3 Get. 13, 1936. E. s. QZORNELL ET AL ELECTRICAL INTERLOCKING SWITCH GEAR Filed Aug. 14, 1933 4 Sheets-$heet 4 Patented Oct. 13, 1936 UNITED STATES PATENT OFFICE ELECTRICAL INTER/LO CKING SWITCH GEAR Elias S. Cornell, Evanston, Charles A. Koerner,

Chicago, and Joseph A. Stoos, Naperville, Ill.,

Application August 14,

24 Claims.

This invention relates to electric switching stations of the type wherein the circuit breakers are mounted on an elevator for raising and lowering the breakers into and out of their operative positions, and particularly to installations wherein the breaker terminals or bushings are provided with switching means whichserve as disconnect switches for the breakers, the disconnect function being attained by raising or lowering of the entire circuit breaker mechanism. Such installations include a stationary supporting structure containing an elevating housing mechanism for receiving the circuit breaker and elevating or lowering the same.

It is one of the objects of the present invention to provide a novel support for the breaker and the hoisting mechanism. When the circuit breaker is in its operative position it is desirable that the breaker be held firmly in place, in order that it may better be able to withstand the reactions incident to opening of the circuit under adverse conditions. In order to prevent upward movement of the circuit breaker head during circuit interruptions under extreme short circuit conditions, it has been customary to provide means for clamping the breaker to the hoisting mechanism. This is objectionable. In the first place, it means that the elevating or hoisting mechanism takes all of the reaction incident to a violent switch-opening operation. In the second place, it complicates the operation of placing the breaker on the elevating mechanism and the operation of removing the breaker from the elevating mechanism. We propose to cure these defects. We eliminate all clamping means for securing the circuit breaker to the elevating mechanism. In our improved arrangement the circuit breaker rests, by its own weight, on the elevating mechanism, which mechanism is free of any arrangement for holding the breaker head against upward movement with respect thereto under severe circuit interrupting conditions. When the circuit breaker is elevated to its operative position it abuts against a stop which is a part of the stationary structure, such stop serving to hold the breaker against upward movement under the forces induced during violent circuit interruption. This frees the hoisting mechanism of the stresses that would be induced therein if the hoisting mechanism were relied upon to hold the breaker down during violent circuit interruption. The elevator mechanism comprises a pair of arms between which the circuit breaker, mounted on a truck, may be moved. The arms are then movable vertically upward to engage and elevate the breaker. The breaker is held on the elevator 1933, Serial No. 685,048

mechanism solely by its own weight. This facilitates the removal of the breaker from the elevator mechanism, because it is only necessary to move a truck under the breaker and then, by lowering the elevator mechanism, bring the breaker onto the truck and free the breaker from the elevator mechanism.

It is a further object of the present invention to provide a three-point support between the elevator mechanism and the breaker head. This provides a simple manner of mounting the breaker and assures the uniform distribution of stress due to the weight of the breaker.

It is a further object of the present invention to provide an improved interlock between the circuit breaker, the elevating mechanism, and the stationary structure, so as to prevent raising or lowering of the circuit breaker except when the breaker is in its switch-open position. We provide a structure, carried by the circuit breaker itself, for positively locking the hoisting mechanism to the frame whenever the switch is in its closed position. By this arrangement it is impossible to commence the circuit breaker lowering operation until the breaker has been tripped.

We are aware that it is old to provide for automatically tripping a circuit breaker upon the commencement of the lowering of the hoisting mechanism. Such arrangements of the past include a lever connected to the circuit breaker tripping mechanism and carrying a roller, which rests in a notch in the stationary supporting structure, so that upon the downward movement of the elevator mechanism the roller is pushed out of its notch and actuates the tripping mechanism for tripping the circuit breaker. Such mechanism is open to serious objection. If the circuit breaker happens to be carrying a heavy load at the time of lowering, the violent reaction resulting from the forces produced incident to the tripping operation must be carried by the elevator mechanism at a time when it is not locked to the frame but is moving downwardly. This imposes an undue strain upon the elevator mechanism. By our improved arrangement the lock between the elevating mechanism and the stationary structure cannot be released until the circuit breaker has been tripped. Thus, there is a definite assurance that, at the time of tripping of the circuit breaker, the elevating mechanism is locked in position.

It is a further object of the present invention to provide an arrangement which will prevent closing of the circuit breaker before the elevator mechanism has been locked against lowering, and to prevent unlocking of the elevator mechanism while thecircuit breaker is in its closed position. By this arrangement there is a definite assurance that the elevator mechanism is locked in position whenever the circuit breaker is closed, so that the elevator mechanism cannot be subjected to violent reaction incident to circuit breaker operation under adverse conditions when the elevator mechanism is unlocked.

It is a further object of the present invention to provide an arrangement wherein the interlock between the elevating mechanism and the stationary supporting structure will not be subjected to excessive strain in the event that an attempt is made to lower the mechanism when it is locked to the stationary structure. We accomplish this by providing an arrangement which will cause binding between the elevating mechanism and the stationary supporting structure if an attempt is made to lower one end of the elevating mechanism when the other end is held by the interlock against lowering.

The attainment of the above and further objects of the present invention will be apparent from the following specification, taken in conjunction with the accompanying drawings forming a part thereof.

In the drawings:

Figure 1 is a side view of a switching unit embodying the principles of our invention, said view being taken along the line i-l of Figure 3;

Figure 2 is a top view taken along the line 2-2 of Figure 1;

Figure 3 is a view taken along the line 3-3 of Figure 1 and illustrating the front of the mechanism when the front cover plate is removed;

Figure 4 is a right side view of the mechanism, with the cover removed, and illustrating the circuit breaker in its elevated position, said view being taken along the line 4--4 of Figure 3;

Figure 5 is a sectional view of the interlock between the circuit breaker operating shaft and the transfer switch operating shaft, said view being taken on the line 55 of Figure 1;

Figure 6 is a perspective view of the elevator mechanism;

Figure 7 is a diagrammatic view illustrating the operation of the shutter mechanism;

Figure 8 is a view taken along the line 88 of Figure 7 Figure 9 is a fragmentary sectional view of the transfer plug used on the circuit breaker;

Figure 10 is a fragmentary View illustrating the rear of the circuit breaker;

Figure 11 is a fragmentary perspective view illustrating the interlock between the circuit breaker and its support; and

Figure 12 is a fragmentary sectional view taken along the line I2-I2 of Figure 1.

Each unit is metal enclosed, with self-contained factory assembled switch gear and busses wired and ready for installation. Each unit comprises a stationary element or cubicle and a removable element comprising an oil circuit breaker of the vertical lifting and lowering type. The stationary element or cubicle is indicated at I, and comprises a rigidly braced welded structural steel supporting frame with heavy sheet metal enclosures. The cubicle is divided into an upper compartment 2 containing the busses and the transfer switching equipment, and a lower compartment 3 containing the elevator mechanism for the oil circuit breaker, the switch control apparatus, the shutter control apparatus, the interlocks, and, optionally, the metering transformers. The lower compartment is provided with a removable rear panel 5 for permitting access to the rear of the cubicle. It is also provided with a front recessed door 6 formed of stretcher level steel hung on concealed hinges so that the door face is flush with the front of the unit when closed. The sides of the lower compartment are enclosed by sheet metal panels 'l8. The enclosure for the upper compartment is separate from the enclosure for the lower compartment, and comprises side panels 9 and ID which are provided with openings for extending connections tothe busses, front and rear panels H and I2, and top panels comprising three separate sections, l3, l4 and I5. All the panels are secured to and removable from the structural steel frame.

A three-phase main bus it and a three-phase transfer or reserve bus I! are mounted in the upper compartment and extend the full width thereof, being separated by a barrier 98 of Bakelite or other suitable insulation. Each set of busses is rigidly supported by two pairs of bars i9-I9 of suitable insulation, such as Bakelite, which embrace the bus bars and securely clamp them in place, the bars l9--I9 being, in turn, rigidlysecured together by metal cross members 20-20 and suitable hangers. Laminated copper taps 22 are welded or otherwise secured to the respective bus conductors I6, each of the taps terminating in a cylindrical plug 2! which constitutes the male terminal of a primary plug disconnect switch 23, as will be more fully described as this description proceeds. Each bus conductor, with its associated tap, is enclosed in wrapped insulation comprising a laminated paper insulation wrapped under tension, each layer being coated with phenolic varnish, solidly pressed, and cured in heated molds. This insulating method eliminates voids, looseness, warps and cracks. A three-phase bus unit comprises the bus, its support, bus taps and stationary ends of plug 2| with their insulating bushings 23A. This is assembled before installation in the cubicle and may be easily removed as a unit. The ends 26 of the busses are silver plated and, with their bolted connections between splice plates that extend the connections to or from the busses, insure permanently high conductivity.

Each of the plug disconnectors 23 for the main bus includes a tube of insulation 23A of suitable insulation such as the material known as Bakelite, which tube is divided into upper and lower parts by an internal web 2313 having an opening through which the male plug 2| extends. The plug is secured to the web by a suitable nut. The three tubes of insulation 23A of the main bus extend through openings in an escutcheon plate 230 and are secured thereto, the lower portion of each tube of insulation extending through the escutcheon plate. This completes the main bus unit for mounting within the upper compartment of the cubicle. In assembling the bus within the cubicle the escutcheon plate is se cured to the base of the upper compartment 2. The upper part of the tube of insulation 23A is filled with insulating compound after assembling of the bus. The auxiliary or reserve bus disconnector 23' and the line disconnector '34 are of a construction similar to that of the main bus disconnector 23.

The reserve or transfer bus I! is of a construction substantially identical to that of the main bus It. The taps 25 that are connected to the reserve bus correspond to the taps 22 of the main bus, and are each provided with an additional tap 26, covered. With insulation as are the taps 22, and extending the electrical connection from the reserve bus, through insulating bushings 2'! supported by a plate 28, to a stationary terminal 29 of a transfer switch 30. There are three such switches, one for each phase. The blades of the disconnect switches are mounted upon hinge terminals 3| supported by insulators 32. The hinge terminal 3| of each transfer switch 30 is connected, by way of an insulated tap 33, to a male plug similar to the plug 2|, and comprising a part of the plug disconnectors 34. Insulating barriers 35 and 36 of the material known as Bakelite, or the like, separate the taps 33 from the taps 25 and 26. The hinge terminals 3| of the transfer switches 30 are connected to an incoming or outgoing line conductor by way of insulated taps 40 that extend through current transformers 4|, to outgoing potheads 42. The transformers 4| are for metering purposes or the like.

The three switch blades are connected by insulating links and cranks 46 to a shaft 41, Rotation of the shaft operates the three switches in unison. The shaft is rotated by a crank 48, a reciprocating rod 49, a crank 50, and a rotatable transfer switch operating shaft 5|. The transfer switch operating shaft extends from the rear of the cubicle, through an interlock 52, to the front of the cubicle. The interlock 52 looks the shaft 5| against rotation in either direction except when the circuit breaker is in its elevated and closed position, as will be more fully described as this description proceeds.

The interlock 52 comprises an interlock sector keyed to the shaft 5| and cooperating with an interlock latch lever 6| which is pivoted about a stationary pivot 62 and includes a projection 64 that extends in the path of movement of the interlock sector 60, as may be seen from Figures 1 and 5. An arm 65 is formed integrally with the interlock latch lever BI and is engaged by a spring 66 for biasing the latch lever to its locking position. The interlock sector 60 is shown in the position it occupies when the transfer switch is closed. To open the transfer switch it is nec essary to rotate the shaft 5| in a clockwise direction as seen in Figure 5. The interlock sector 60, however, abuts against the projection 64 of the interlock latch lever 6| and locks the shaft 5| against clockwise rotation. In order to free the interlock sector it is necessary to rotate the interlock latch lever 6| clockwise, as seen in Figure 1. This is accomplished by a link 6! which engages the arm 65 and, upon upward movement of the link, moves the arm 65 and the interlock latch lever clockwise until the projection 64 clears the interlock sector 60. This movement is against the action of the spring 66. Upward movement of the link 61 is obtained by means of a cam 68 which is mounted on the operating shaft of the oil circuit breaker and is brought into the position shown in Figure 1 when the oil circuit breaker is fully elevated. The cam 68 is shown in the position which it occupies when the circuit breakeris open. In this position it has not raised the latch 67. To release the interlock latch lever 6| it is necessary to operate the circuit breaker, thus rotating the cam 68 counterclockwise. This forces the link 61 upward, whereby the projection 64 clears the interlock sector to permit movement of the sector and rotation of the transfer switch operating shaft 5|. The shaft 5| may now be rotated to open the transfer switch 30. If this is done, the sector 66 is brought into a position where its lower edge is immediately above the upper edge of the projection 64 of the interlock latch lever. If the circuit breaker is then operated to its open position the cam 56 permits the spring to return the link 61 and arm 65 to the position shown in Figure l, and thus return the interlock latch lever to the position shown in Figure 1. The interlock sector 69 is now immediately above the projection 64, whereby the projection 64 locks the shaft 5| against counterclockwise rotation, that is, against rotation in the switch closing direction. By this arrangement the transfer switch 30 can be operated to its open or to its closed position only when the circuit breaker is in position and is closed.

An explanation will now be given of the circuit breaker hoisting or elevating mechanism, and the supporting and operating means therefor.

The elevator supporting and operating mecnanism comprises a worm gear of the jackscrew type, including a worm 15 supported against longitudinal movement and carrying a nut 15 which is held against turning with the worm l5, whereby the nut rides up and down on the worm as the worm is rotated. The lower end of the worm I5 is supported in a ball thrust bearing ll which is, in turn, supported by a structural metal member 78 that extends upwardly from the bottom of the cubicle midway between the right and left sides thereof, and is suitably braced adjacent its top and bottom by cross members l989. At its upper end the worm shaft extends into a gear box 82 which is bolted or otherwise suitably secured to a cross channel 83. The gear box includes an operating shaft 84 extending at right angles to the worm shaft 75, and coupled thereto by bevel gears within the box. A sprocket wheel 85 is mounted on the shaft 84 for rotating with the same, the sprocket wheel being driven by a chain 86 which, in turn, is driven by a smaller sprocket wheel 81 keyed to a hoisting mechanism operating shaft 88 that extends to the front of the cubicle. The forward end of the shaft 88 is squared for receiving an operating handle or an electric drill motor.

The circuit breaker holding and elevating mechanism is shown in Figure 6. It comprises a pair of angle iron members 99-99 welded or otherwise secured to a lower plate 9| and an welded to the side arms and to the angle iron members, respectively. Each of the side arms 93 has a trunnion receiving groove 95 and interlock bar receiving slot 96. A locking lug 9! is welded or otherwise secured to one of the arms 93 for receiving a padlock to lock the elevator mechanism in its raised or lowered p051- tions. The upper angle member 92 is provided at its center with an upstanding lug 98 having a curved upper surface constituting one point of support for a movable circuit breaker, as will be more fully set forth as this description proceeds. A slot 99 at the rear of the angle member 92 permits the angle member to embrace the worm shaft 75. The two side arms 9393 are provided with outwardly extending lug projections IOU-I00 bolted or otherwise secured thereto. Flanged rollers |0| are secured to the outer sides of the bracing plates 94 and in alignment with the respective lug projections I06. A bar I02 is welded or otherwise secured to one of the shaft "I extending upwardly through the slot 09 arms 93. This bar constitutes a support for a shutter-clutch operating cam, as will be more fully set forth as this description proceeds.

The elevator mechanism is assembled in the cubicle so that the horizontal flange of the angle member 92 rests upon the nut I6, with the worm in the angle member 92. At this time the flanged rollers IIlI on the two bracing plates. 94 bear against upright guides I05-I05 which are a part of the stationary cubicle structure. After the elevator unit has been placed in the cubicle, a second pair of flanged rollers I06, similar to the rollers I0 I are secured to the outer sides of the side arms 93, said rollers IOI engaging the upright guides I05. Likewise, lug projections I01 are secured to the outer sides of the bracing plates 94, said lug projections also engaging the upright guide I05. Also, a shutter operating cam or runway assembly H0 is bolted or otherwise rigidly secured to the bar I02 of the elevator mechanism so as to move up and down with the elevator mechanism.

The shutter operating cam IIO comprises a fiat plate having a guideway I II secured thereto and extending almost, but not quite, to the top of the plate, and a short guideway II2 secured at the opposite edge and adjacent the top of the plate.

An explanation will now be given of the shutter mechanism and the means for controlling and operating the same. For this purpose reference may be had more particularly to Figures 1, 7 and 8. The shutters are of identical construction and are indicated at I20, I2I and I22. Each of the shutters comprises a rectangular plate I25 mounted on pivoted brackets I23 that pivot about stationary pivots I2I. The shutters are adapted to be swung from a position covering the openings at the lower side of the plug disconnectors 23-23'34, to a position free of the openings. In Figure 1 the shutter I2! is shown in its closed position, that is, in a position covering the lower opening of the plug disconnector 23'. The shutters I20 and I22 are shown in their open positions, that is, in the positions uncovering the openings of the plug disconnectors 23 and 30, respectively. An operating shaft I controls the operation of the shutters. This shaft is connected to the shutter I22 by means of a link I 3I and a crank arm I32, so that rotation of the shaft I30 will always actuate the shutter I22. The shutters I20 and I2I are selectively operated from the shaft I30 through a clutch mechanism I33. For this purpose theclutch mechanism has two cranks I and I36 extending therefrom and selectively connected to the operating shaft I30 by a clutch operating lever I31 and a clutch collar I38, splined to and slidable on the shaft I30. The crank I35 is connected to the shutter I2I by means of a link I 40, whereas the crank I36 is connected to the shutter I20 by means of a link I 4 I. Rotation of the operating shaft I 30 will produce rotation of one or the other of the two cranks I 35--I 36, depending upon which one of the cranks is clutched to the shaft I30, as determined by the position of the clutch collar I38. This will produce an opening or closing of the corresponding shutter I20 or I 2I. The clutch is manually operated by means of an operating rod I43 that extends to the front of the cubicle and is pivoted at I44 to an operating handle I45 which is itself pivoted at I46. A I80 degree clockwise rotation of the handle I05 shifts the clutch collar I38 from the position shown, where the main bus shutter I20 is operatively connected with the shaft I30, to its opposite position, where the reserve or transfer bus shutter I2I is operatively connected to that shaft, namely, from a position where the crankv I36 is clutched to the shaft I30 to a position where the crank I35 is clutched to the shaft I30. It is to be understood that operation of the handle I45 merely shifts the clutch, it does not produce operation of the shutters. The exposed edge I47 of the operating handle I45 may have a letter M marked thereon, indicating that in this position of the operating handle the main bus shutter will be operated. Likewise, the opposite end I08 of the operating handle may have the letter R marked thereon, indicating that in this position of the operating handle the reserve bus shutter is connected for operation.

The actual operation of the shutters is brought about by rotation of the shaft I30. This is accomplished through a crank I50 that is keyed to the shaft I30 and is pivotally connected to a link I5I (Figure 1) that is connected, at its opposite end, to one arm I52 of a two-armed lever. This lever is pivoted about a stationary pivot I53 and has asecond arm I54 which carries, at its outer end, aroller that rides against the guideway III of the shutter operating cam H0. The elevator mechanism, and with it the shutter operating cam H0, is shown in its uppermost position. As the elevator is lowered, the roller at the end of the arm I54 rides against the guideway II I until the elevator approaches its lowermost position. At that time the roller clears the upper beveled edge of the guideway I II and is forced to the right, that is, counterclockwise, by the lower beveled edge of the guideway I I2. Counterclockwise rotation of the two-armed lever causes a corresponding rotation of the shutter operating shaft I30 through the link I5I and the crank I50. This causes operation of the shutter I22 and, the particular one of the shutters I20-I2I that is clutched to the shaft I30, in this instance the shutter I20. This brings all the shutters to their closed position, that is, to a position the same as that of the shutter I2I. If the elevator is subsequently raised, the upper beveled edge of the guideway I I I rotates the crank arm I54 clockwise, thus producing a corresponding rotation of the shutter operating shaft I30. opening of the shutter I22 and of the connected one of the two shutters I 20 or I2 I, in this instance I20. The opening of the shutters is accomplished at the initiation of the upward movement of the elevator. The closing of the shutters is accomplished at substantially the completion of the downward movement of the elevator.

The shutter mechanism has two distinct functions. First, since the shutters are always closed when the elevator mechanism is in its lowered position, they prevent accidental contact with the plug disconnectors that are connected to the busses or to the incoming or outgoing line. Second, upon raising of the elevator mechanism, they uncover only the selected one of the two bus disconnectors and thus prevent accidental contact with the other bus. The operating handle I45 may be set in the position indicated in Figure 1, and padlocked against operation. This permits the uncovering of the shutter that controls connections to the main bus, but it definitely precludes the establishment of connections to the reserve or transfer bus I'I. Likewise, the operating handle may be locked in its opposite position to permit access to the transfer bus I! while precluding access to the main bus I6.

A circuit breaker I60 is provided for establishing connections between the conductor 33 (Fig- This causes an iire i) and the main bus or the transfer bus. The circuit breaker is here shown as a threephase breaker and includes three socket terminals I6I, one for each pole, for establishing connections with the corresponding phase conductors 33. It also includes three terminal studs I73 which, by means of an adapter or transfer plug I63, are adapted to cooperate with the

plug disconnectors

23 or 23 of the main or of the transfer bus. The socket terminals are of a construction such as shown in the pending application of Alfred Alsaker and Fred H. Cole, Serial No. 681,158, filed July 19, 1933.

Briefly, the socket comprises a large number of contact wires I64, swaged or otherwise suitably secured to a plug I65 that is threaded over a terminal stud I66 comprising one terminal of the circuit breaker. Coiled springs I67, in the form of rings, embrace the contact wire assembly and urge the wires inwardly into firm engagement with a plug. A plurality of internal rings I 68 limit the extent of inward collapse of the contact wires when the socket does not contain a plug. A sleeve I69 of suitable insulation surrounds the contact socket for preventing accidental contact therewith. It is to be noted that the terminal studs I73 are appreciably below the terminal studs I66. When the adapter I63 is mounted in place it brings the overall height of the corresponding terminal of the circuit breaker to that of the socket terminals I6I.

The adapter comprises a transfer stud support I70 and a transfer plug IN. The transfer stud support comprises a copper bar I72, one end of which is secured to the stud I73 that threads into a plug I74. The other end of the bar carries a stud that threads into a plug I75. The copper bar [.72 is enclosed in a body of insulation I76 which is, preferably, molded around it and may comprise any suitable insulation such as the material known as Bakelite. The body of insulation includes cylindrical pockets surrounding each of the plugs I74 I75. The transfer stud support includes a supporting leg comprising an insulating rod I78 and an insulating tubing I79 and a mounting base I80. The rod I78 is secured in place prior to baking of the insulation I76. The transfer plug is mounted in place with the male plug I74 connected to the threaded stem I73 of the breaker and with the base I80 resting upon and bolted to the circuit breaker head. A tube of insulation I 8| surrounds the plug I74. A similar tube of insulation I82 surrounds the plug [75.

The transfer plug I'II comprises a body of insulation in one end of which is secured a pair of oppositely facing sockets I85 and I86, of a construction similar to the sockets I6I. The opposite side of the transfer plug includes a cap I87 comprising an integral part of the main body of insulation and joined thereto by a bridge I88. A tube of insulation I89 surrounds the socket I 85, being press fitted over a cylindrical portion of the main body of insulation comprising the transfer plug. A spring clip I96, carried by the transfer stud support, extends through a centrally located opening in the bridge portion I88 of the transfer plug and serves to snap the transfer plug into its fully closed position when it is brought approximately to its fully closed position. In the position shown in Figure 9, the transfer plug covers the plug I74, the socket I85 being in a position to engage the plugZI of the main bus conductors 22 (Figure 1). If desired,

the position of the transfer plug may be reversed so that the socket I86 engages the plug I74, and the cap I87 covers the plug I75. In this position of the transfer plug the socket I85 will engage the stud of the tap 25 from the reserve bus I7 (Figure 1).

The head of the circuit breaker E60 has mounted thereon an operating and tripping mechanism I which may be of any preferred construction. All of the operating mechanism of the circuit breaker is carried by the head 296 thereof. A tank 20! is secured to the head 25!! and encloses the interrupting mechanism, said tank carrying the bath of insulating arc quenching oil. A pair of trunnions 205-406 are carried by

blocks

207 and 208, that are welded or otherwise secured to the opposite sides of the head of the circuit breaker adjacent the front thereof. A rear support 209 is secured centrally of the rear of the head 200 and includes a socket 210 which is adapted to seat on the lug 98 of the elevator mechanism, as shown in Figure 6.

Release bar pull rods 2I5 and 2I6 are carried by and slide in the

blocks

207 and 208. These pull rods are formed, at their forward ends, with eyes constituting handles. At their rear ends the release bar pull rods carry draw bar stops 2I7 and 2I8, which slide on draw bar support blocks ZIIa and 2I8a, respectively. These blocks are welded to the circuit breaker head 200. The draw bar stops carry cam projections 2I9220 that are engaged by stop cams 22I and 222, respectively, both of which are keyed to a shaft 223, constituting the main operating shaft of the circuit breaker. The stop cams include a curved surface 224 of variable radius and a curved surface 225 of fixed radius. They also each include a flat surface 226.

Figure 11 shows the interlock mechanism of the circuit breaker when the circuit breaker shaft 223 is in its switch closed position. The circuit breaker is held in the hoisting mechanism, the trunnions 205-206 resting in the trunnion grooves 95-95 in the side arms 93. At this time the draw bar stops extend within the interlock bar receiving slots 96 in the hoisting mechanism. The drawbar stops 2 II-2 I8 also rest on the upper surfaces of interlocking bars 230 that are welded or otherwise secured to each of two upright channel-shaped structural members 23I comprising parts of the stationary cubicle. As long as the drawbar stop 2I7 or 2I8 rests on the interlock bars 230 and within the slots 96 of the arms 93, it is not possible to raise or lower the hoisting mechanism. The drawbar stops 2I7-- 2I3 cannot be retracted from the position shown in Figure 11 unless the switch operating shaft 223 is rotated to its open position, that is, counterclockwise as seen in Figure 11, so that the stop cams 22I222 clear the cam projections 2i9-220 of the drawbar stops. Therefore it is not possible to lower the circuit breaker except when the breaker is in its open position.

As an additional precaution against any possibility of lowering the circuit breaker hoisting mechanism when the breaker is in its switch closed position, the release bar pull rod 2I5 is provided with a lug projection 240 which moves into engagement with and actuates a manual trip 24! (Figure 4) of the circuit breaker operating and tripping mechanism I95. Thus, even if the stop cam 22I were omitted so as to permit forward movement of the release bar pull rod 2I5 when the circuit breaker is in its closed position,

there would still be the definite assurance that the circuit breaker is tripped by the time the draw bar pull stop 2I1 clears the interlock receiving slot 96.

When the circuit breaker is elevated to its normal uppermost position the blocks 201-208 of the circuit breaker head bear against stops 2 56, which are welded to each of the channel upright members 23 I. This definitely limits the upward travel of the elevating mechanism and serves to hold the circuit breaker head firmly in place. The circuit breaker head is thus firmly held against all reactions incident to a violent circuit interrupting action. This rigid mounting for the circuit breaker does not require clamping of the breaker to the elevating mechanism and thus permits the easy mounting or removal of the breaker from its supporting and elevating structure.

When the circuit breaker has been raised to its elevated position it is necessary to lock the elevating mechanism in position before the breaker can be operated to its closed position. This'is done by pushing the drawbar stops 2ll--2|8 into theslots 96 in the arms 93 of the elevator mechanism and over the top surfaces of the interlock bars 230, to the positions shown in Figure 11. If an attempt is made to operate the circuit breaker before the drawbar stop 2!? has been pushed back, the flat surface 2 35 of the stop cam 22f will abut against the upper surface of the cam projection 219 and thus hold the shaft 223 against clockwise rotation to the switch closed position. If the operator should move the draw bar stop 21'! to its locking position and fail to move the draw bar stop 2|B to its locking position, an attempted operation of the circuit breaker Will be successful. Clockwise rotation of the shaft 230 brings the curved surface 224 of the stop cam 222 against the inclined surface of the cam projection 22D and forces this cam projection rearwardly to its locking position. This assures locking of the hoisting mechanism in its elevated position when the circuit breaker is in its closed position.

To lower the circuit breaker it is necessary first to trip it. Thereafter, the release bar pull rods 2I5-2I6 are pulled forward to bring the draw bar stops 2l'|2l8 out of the slots 96 and free of the interlock bars 230. The circuit breaker may then be lowered by rotating the hoisting mechanism operating shaft 88 which, through the mechanism previously described, rotates the worm 15 to cause the nut 16 to travel downwardly and thus lower the circuit breaker supporting and hoisting frame. When the circuit breaker reaches its fully lowered position the top surfaces of the draw bar stops are immediately below the bottom surfaces of the interlock bars 230. The draw bar stops may then be pushed back to a position beneath the interlock bars, as indicated in dotted lines in Figure 11, and thus lock the circuit breaker elevating mechanism against being raised. In this position the cam projections 2l9-220 again clear the stop cams 22l-222 and thus permit operation of the circuit breaker operating shaft 223, as may be necessary for test purposes. It is to be noted that the draw bar stops 2ll-2l8 can not be moved to a position clearing the cams 22l222 while the hoisting mechanism is only partially lowered, since at that time the interlock bars 230- prevent rearward movement of the draw bar stops 2l1-2I8. Thus it is impossible to reclose the circuit breaker when the same has been only partially lowered.

' slots 96 and resting on the interlock bar 230, the

front of the hoisting mechanism will be held against lowering. The attempted lowering of the rear end of the hoisting mechanism will cause the two angle members Hill to bind on the V upright guides I and prevent lowering of the hoisting mechanism. A similar binding action takes place if an attempt is made to raise the hoisting mechanism when the draw bar stops engagement of the lower face of the interlock bars 233 to lock the hoisting mechanism against elevation.

When the circuit breaker has been lowered and the draw bar stops 2l12l8 pushed back, it is possible to operate the circuit breaker. If the circuit breaker is operated to its switch closed position the stop cams 22l-222 prevent retraction of the draw bar stops and thus prevent elevating of the circuit breaker. The circuit breaker can be elevated only when it is in its switch open position.

When the circuit breaker supporting mechanism has been lowered to the disconnecting position, the locking lug 91 on the hoisting arm 83 is opposite alower clip angle 244 that is welded or otherwise secured to the outer flange of one of the channel members 23 i. This permits padlocking of the circuit breaker in its disconnecting position. An upper clip angle 245, which is also welded or otherwise suitably secured to the outer flange of the upright structural member 23 l, permits padlocking of the hoisting mechanism in its elevated position.

To completely remove the breaker element from the elevator element and frame, the breaker is lowered to the platform of a truck that may be inserted beneath the breaker and which then takes the weight of the breaker element. The elevator element can be lowered further until the breaker element is completely disengaged from the three points of support. The breaker can then be rolled forward and away from the structure.

From the above description it is apparent that we have invented an improved switching station comprising a compact structure having a high factor of safety since it is impossible to obtain an incorrect operation ofthe kind that might be destructive. The circuit breaker is supported in its hoisting frame on a three-point support, thereby assuring a firm support for the breaker even if one of the point support is slightly above or below the other two points. The circuit breaker is held against vertical upward movement in the elevator frame solely by its own weight whereby it may be inserted in place by simply lowering the elevator frame, moving the circuit breaker between the arms of the frame, and then raising the frame until the arms engage the breaker. It may be removed fro-m the frame in an equally simple manner. When the breaker is in its fully elevated position the hoisting frame is held against downward movement by the draw bar stops 2ll2|8 which are within the slots 95 and rest on the interlock bars 230. The circuit breaker is held against upward movement, under the explosive action that takes place during violent circuit breaker operation, by the stops 246-256. Therefore the hoisting frame is practically freed from stress incident to the tripping .of the circuit breaker.

While we have herein shown and described a 7t.

preferred. embodiment of our invention, it is to be understood that the invention is not limited to the precise construction herein shown, the same being merely illustrative of the principles of the invention. What we consider new and desire to secure by Letters Patent is:-

1. Electric switching apparatus comprising a stationary structure, a main switch unit mounted to have vertical movement therein, said structure and unit having cooperating disconnecting switch contacts separable by downward movement of the unit, a switch operating member forming a part of the main switch unit, means carried by the switching unit and movable into engagement with the stationary structure for locking the switching unit in its uppermost position to said stationary structure, means carried at the ends of said operating member for locking the member against switch closing movement whenever the first mentioned locking means is in its released position, and means for preventing operation of said switch unit locking means when said unit is in intermediate positions.

2. Electric switching apparatus comprising a stationary structure, a main switch unit, a frame supporting said unit and mounted to have vertical movement in said structure, said structure and said unit having cooperating disconnecting switch contacts separable by a downward movement of the unit, means carried by the unit and movable into engagement with said frame and stationary structure for locking the unit against downward movement and for rigidly securing said unit against upward movement with respect to said frame, means carried by said structure for preventing engagement of said locking means except when said unit is in fully raised or fully lowered position, and means carried by said unit for preventing release of the locking means while the switching unit is in its switch closed position.

3. Electric switching apparatus comprising a stationary structure having disconnecting switch contacts, a switch unit having cooperating disconnecting switch contacts adapted when the switch unit is raised, to engage the first mentioned disconnecting contacts, a hoisting mechanism for raising the switch unit, a pair of locking members for preventing vertical movement of the switching unit, and means for preventing closing operation of the switch unit when both locking members are in their released position and for moving one of the locking members to its locking position responsive to an attempted closure of the switch unit when the other locking member is in its locking position.

ifElectric switching apparatus comprising a stationary structure having disconnecting switch contacts, a switch unit having cooperating dis connecting switch contacts engageable with said first disconnect contacts when said unit is raised, a hoisting mechanism supporting said unit for raising and lowering movement, abutment means on said structure for limiting the elevated position of said switch unit, and means responsive to a closure of the switch in its elevated position for preventing movement of said switch relative to said frame and movement of said frame relative to said stationary structure, said last named means being operable only when switch unit is in fully raised or fully lowered position.

5. In combination, a stationary structure, a hoisting frame vertically movable in the structure, a circuit breaker supported by said frame and separable therefrom as a completeunit, and

means carried by the circuit breaker for simultaneously locking the circuit breaker to the hoisting mechanism and the hoisting mechanism to the stationary structure.

6. In combination, a stationary structure, a hoisting frame vertically movable in the structure, a circuit breaker supported by said frame and separable therefrom as a complete unit, means carried by the circuit breaker for simultaneously locking the same to the hoisting mechanism and locking the hoisting mechanism to the stationary structure, and means controlled by the locking means for controlling the operation of the breaker.

7. Electric switching apparatus comprising a stationary structure, a switch unit adapted to be raised and lowered therein, said stationary structure and said switch unit having cooperating disconnecting switch contacts adapted to engage when the unit is in its raised position, a hoisting mechanism supporting the switch unit, said unit resting upon the hoisting mechanism and depending therefrom and held against upward movement with respect to the mechanism solely by its own weight whereby the hoisting mechanism may be freed of the switch unit by a. relative vertical movement, abutment means carried by the stationary structure and holding the switching unit against upward movement from its normal elevated position under the reactions incident to a violent circuit interruption, and means for simultaneously locking the switch unit and hoisting mechanism against downward movement from their uppermost position and resisting the downward reaction incident to a violent circuit interruption, said last-named means preventing closure of switch unit in said uppermost position except when said locking means is in looking position.

8. In combination, a circuit breaker including a head and a tank depending therefrom, supporting trunnions on the opposite sides of the head adjacent the front thereof, additional supporting means at the rear of the head, vertically movable supporting means for the breaker comprising a frame open at the front for receiving the breaker, said frame having a pair of parallel side arms each of which has a trunnion receiving groove cooperating with the trunnions on the breaker head, and means at the rear of the frame cooperating with the supporting means at the rear of the circuit breaker head.

9. In combination, a circuit breaker including a head, line conductors extending therethrough, and a tank depending from the head, said head having three supporting projections extending therefrom, and an elevator mechanism for the breaker, said elevator mechanism including a pair of arms adapted to embrace the breaker and engage two of the supporting projections, and a cross arm between the pair of arms, said cross arm engaging the third projection.

10. Electric switching apparatus comprising a stationary structure having disconnecting switch contacts, a switch unit having cooperating disconnecting switch contacts adapted when the switch unit is raised, to engage the first mentioned disconnecting contacts, a hoisting frame supporting the switch unit, means at the rear of the frame for supporting and raising it, means adjacent the front of the frame for looking it to the stationary structure, cooperating guides on the stationary structure and on the hoisting frame, and means for causing a binding action at the guides if an attempt is made to move the hoisting frame vertically when the front end thereof is locked.

11. Electric switching apparatus comprising a stationary structure, a hoisting frame mounted in said structure, vertically movable means supporting the rear of the hoisting frame, means for locking the front of the frame to the structure, and means at the rear end of the frame for causing a binding between the hoisting frame and the stationary structure if an attempt is made to move the rear of the hoisting frame vertically while the front thereof is locked against movement.

12. In a switch gear cubicle having vertical side channels therein, a switch unit adapted to be vertically raised and lowered within said cubicle, a hoisting mechanism therefor having roller means engaging in said channel and having means for supporting said switch unit thereon, slidable latch means carried by said unit and adapted to lock said unitto said mechanism, and means in said cubicle preventing actuation of said latch means in positions intermediate the upper and lower positions of said hoisting mechanism 13. In a switch gear cubicle, a hoisting mechanism having guided vertical movement therein, a switch unit adapted to be supported in said hoisting mechanism, means carried by said unit for simultaneously locking said unit to said mechanism and said mechanism to said cubicle tive position, said means including a pair of latching members, and means responsive to operation of said unit when one of said members is in latching position for simultaneously moving the other of said members into latching position.

15. Electrical switching apparatus comprising a stationary cubicle structure having opposed guide channels formed in the sides thereof, hoisthoisting mechanism, and means on the switch engageable with the frame and the stationary structure for locking the switch to the frame and the frame to the cubicle structure in the elevated position of the frame and switch.

'16. In electrical switching apparatus of the class described, a circuit breaker comprising a head portion and a depending tank portion, said head portion having three supporting projections, hoisting mechanism for said breaker having means engageable by said projections, a pair of slidable latching members carried by the head of said breaker, interlocking means formed in said hoisting mechanism, and an operating shaft for said breaker, said latching members preventing rotation of said shaft toward operating position until said latching members are moved into engagement with said interlocking means.

17. Electrical switching apparatus comprising a circuit breaker having a head portion and a depending tank portion, a pair of trunnions extending from opposite sides of said head portion, a supporting member secured to the rear of said head portion, a hoisting mechanism mounted for vertical movement and having an open end portion, parallel side members having trunnion receiving portions, a cross arm between said side members opposite the open end of said mechanism and having supporting means for receiving the supporting member on said head portion, said breaker being supported on said hoisting mechanism, and means for locking said breaker with respect to said hoisting mechanism only in fully raised or fully lowered position of said mechanism.

18. Electrical switching apparatus comprising a circuit breaker having a head portion and a depending tank portion, a pair of trunnions extending on opposite sides of said head portion, a supporting member secured to the rear of said head portion, a hoisting mechanism mounted for vertical movement and having an open end portion, parallel side members having trunnion receiving portions adjacent said open end portion, a cross arm between said side members at the opposite end thereof and having supporting means for receiving the supporting member, said breaker being supported by said trunnions and supporting member on said hoisting mechanism, means for locking said breaker with respect to said hoisting mechanism only in fullyraised or fully lowered position of said mechanism, and means for preventing operation of said, breaker into switch connecting position until said breaker is locked to said hoisting mechanism.

19. In electrical switching apparatus of the class described, a stationary cubicle structure, a hoisting frame, means in said structure providing a guideway for vertical movement of said hoisting frame, supporting means formed in said hoisting frame, a switch unit, means carried by said unit and engageable with said supporting means to support said unit in position within said frame, said unit being vertically separable from said frame, and latching means carried by said unit and. adapted to lock said unit to said frame only in uppermost and lowermost positions of said frame.

20. In electrical switching apparatus of the class described, a stationary cubicle structure, a hoisting frame, means in said structure providing a guideway for vertical movement of said hoisting frame, supporting means formed in said hoisting frame, a switch unit, means carried by said unit and engageable with said supporting means to support said unit in position within said frame, said unit being vertically separable from said frame, and latching means carried by said unit and adapted to lock said unit to said frame only in uppermost and lowermost positions of said frame, said latching means simultaneously engaging said stationary structure for preventing movement of said frame. I

21. In combination, in switchgear of the class described having depending disconnect contacts mounted in the upper portion thereof, a, h ting frame mounted for vertical movement beneath said contacts, a switch unit detachably supported on said frame and having line terminal contacts adapted to engage said disconnect contacts, a rotatable operating shaft for said unit, latching means carried by said unit and adapted to lock said unit to said hoisting frame in uppermost position of said frame, said latching means having means for preventing rotation of said shaft into operating position when said unit is not locked to said frame.

22. In combination, a stationary frame structure, a hoisting mechanism therein, a circuit breaker movable into and supported on said hoisting mechanism, stop means on said frame limiting upward movement of said breaker, releasable means carried by said breaker and operable only when said breaker is in uppermost position to lock said breaker against downward movement with respect to said frame and simultaneously to lock said hoisting mechanism to said frame, and means for holding said locking means in looking position when said breaker is in switch closed position.

23. Electrical switching apparatus comprising a stationary cubicle structure having opposed guide channels formed in the opposite sides thereof, a hoisting frame mounted only for vertical movement in said cubicle comprising a pair of opposed side portions having guide means engaging the guide surfaces of said channels to prevent cooking of said frame in said structure, a switch unit freely supported on the frame for vertical movement with said frame, means car ried by said unit for locking said unit to said frame, means on said cubicle structure simultaneously engaged by said locking means when said frame is in elevated position whereby said frame is locked to said structure, and means on said cubicle structure for preventing operation of said locking means when said unit is in intermediate vertical positions.

24. A hoisting frame for electrical switching apparatus of the class described, comprising a pair of spaced supporting members, a cross bar therebetween, a pair of parallel arms extending normal to said members and cross bar, strut members extending between the extending ends of said arms and said members, means at the extending ends of said arms and intermediate the ends of said cross bar for supporting a switch unit thereon for free vertical movement with respect to said frame and against lateral movement with respect thereto.

ELIAS S. CORNELL. CHARLES A. KOERNER. JOSEPH A. STOOS.