US2237367A

US2237367A - Switchboard

Info

Publication number: US2237367A
Application number: US251500A
Authority: US
Inventors: Jr William M Scott
Original assignee: ITE Circuit Breaker Co
Current assignee: ITE Circuit Breaker Co
Priority date: 1938-08-27
Filing date: 1939-01-18
Publication date: 1941-04-08
Anticipated expiration: 1958-04-08

Description

April 8, 1941. w, SCOTT, JR 2,237,367

SWITCHBOARD Omiginal Filed Aug. 27, 1958 5 Sheets-Sheet 1 izw'awg W zm w A TTORNE Y.

April 8 1941. w. M. sco'rT, JR

SWITCHBOARD Original Filed Aug. 2'7, 1938 5 Sheets-Sheet 5 INVENTOR. BY Lag- A. (My

ATTORNEY.

April 8, 1941. w M SCOTT, JR 2,237,367

' swmcnsomo Original Fi led Aug. 27, 1938 5 Sheets-Sheet 4 I I 1 WEEK mmmum F ,9. Y INVENTOR.

ATTORNEY.

April 8, 1941.

W.-M. SCOTT, JR

SWITCHBOARD Ofiiginal Filed Aug. 27, 1938 5 Sheets-Sheet 5 INVENTOR. fizz-W1 M ATTORNEY.

trative pilthe relat Patented Apr. s, 1941 UNITE-D ISTATES PATENT OFFICE s'wrrcrmoann William Scott, In Mawr, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia,

Pa.., av corporation of New Jersey s I Original application August 27, 1938,1Serial No.' I

227,089. Divided amlqthisapplication January 18,1939, Serial-No. 251,500 I reclaims. (Cl. 175-298) My lnventioni elates to switchboards, particularly switchboards ot the'type comprising circuit-con'trolling apparatus such'as switches, circuit breakers, and thelike, removable as units from the switchboard.

In accordance with my lnvention,-'a-removable. circuit-breaker unit includes racking gear which.

is interlocked with tripping means of the circuit breaker to prevent withdrawal of the circuitbreaker unit from service"--position until the.

circuit breaker istripped, to determine a test" switchboard units when their disconnect contacts are engaged-Fig. 6, and disengaged-Fig. 7;

Figs 8 and9 are rear and front perspective views or thetruck unit of Fig. 4;

Fig. 10,in perspective, illustrates the essential elements of the circuit-breaker operating mechanism and tile-truck racking gear;

- -Figs.- Ila-11d illustrate different positions of elements of- Fig. '10 referredflto in explanation position. to prevent closure of the circuit-breaker when the unit ,is intermediateits' "service" and test"-positions,' and to ensure tripping oi the.

circuit breaker during movement or the unit from test to service position.

This application isa division of my copending application Serial No.' 227,os9, filed August 27, v

vInaccordance with another aspect of my invention, the withdrawal:circuit-breaker unit also includes racking gear which is interlocked with means for manually tripping oi the circuit breaker to prevent withdrawal of the unit; from service position until the circuit breaker is tripped,

, to determine a test" position, to prevent closure of the'clrcuitbreaker when the unit is intermediate-its service and test positions, and to insure 'trippingot the-circuit breaker during movement of-the' unit from test"-to servicd position.

My invention further resides in the features of construction, combination and arrangement hereinafte'r described andclaimed.

'For an understanding of my invention, reference is to be had to the accompanying drawinns in which:

Fig. l is a front perspective view of a switchboard with a plurality of truck type circuit breakers in service position:

Fig. 2 is a perspective'view of the rear of the switchboard 'of Fig. 1 with'some of its panels removed; 7

Fig. 3 is a perspective of part of the switchboard of-Fig. l with the truck units completely 5 Fig. 5 is..a perspectiveview on enlarged scale and with. parts broken-away ciadisconnect arrangement, shown in Elml;

Figs, 6-and-;.-7 .are plan-vie ,inlsection illusp itions-of the truck and of the ,interlockingrelations between the rack- .ing gear and the tripping mechanism of the circuit breaker. 1

-Referring to Fig. l, the switchboard SB is a rectangular..metal clad structure containing bus bars, cable connections,.and one or more truck or. withdrawal ty e circuit breakers ISL-B6.

The-stationary. structure S, Figs. 2 and 3, of the switchboard comprises units Si-SB, corresponding in number withthe circuit breakers, suitably mounted-in alignment-with each other.

The ends of the switchboard are suitecfiy reinforced steel panels attached to the end units SI, SB and are substantially wider than the side panels of the units. Each of the units S |.S5 consists of three compartments vertically aligned, individually covered with removable steel panels, and separated or sealed by horizontal steel bar-. riers. Since all units are, or may be similar in construction, only one of them need be described. Referring .to Fig. 4, the uppermost compartments l and 1c, of aunit S, exemplary of any of units Si-SB, are .sealed from the next lower com- .partment 2 by the horizontal steel barrier 3;

the upper wall 4 of the compartments I, la is' a steel plate forming thetop of the unit; the rear wall of the compartment I is the removable steel cover plate 5; and the sides of the-compartment I are formed by side plates B extending from top to bottom of the unit.-. The steel partition 1;.iso lates the two compartments i and la from .each

other. v Iv The upper compartments I, lafcontain auxiliary apparatus such as potentiaftranstormers PT, relays, and wiring from control and signal contacts 8 which are. suitably mounted on the under side of that portion of the bottom of compartment or ductia which projects beyond the front wall of compartment 2, Other auxiliary apparatus as metersM, control switches and the like, may be mounted upon therear Iace (Fig. 4) of panel 5 for observation or operationfrom the rearof the switchboard.

Within the. compartment 2 are supported the three

bus conductors

9, 9a, 9b each wrapped in phenolic insulation, molded and cured in posiof insulating material and in which there are three staggered slots ii for permitting contacts I'I extending from the rear of the circuit-breaker unit 18 to pass through the panel into the similarly staggered disconnect housings I8. Thus, when the unit B is withdrawn, it is impossible for an attendant accidentally to touch any uninsulated parts at high potential.

v The bottom compartment l8 of the unit S, whose rear face is closed by the removable steel panel l8, contains cable disconnect contacts, suitably encased in insulating housings 20, current transformers CT, and the outgoing cable-connections' therefrom. The housings 20 are supported, asby insulators 2| from the cross brace 22, in alignmentto receive the contacts 23 whi h pass through slots 24 in the lower part of panel I! from the rear of the breaker unit B. The duct.

25 along the front face of compartment i8 may CT to a protective relay or electromagnet hereinafter identified. Access to the interior of duct.

28 may be had by removal of the steel panel 25a. Extending from the front of each unit (SI-S6) are the rails 28 for guiding the wheels 21 of its associated circuit breaker unit (BL-B6 a pair of lugs 28 whose purpose will hereinafter be described, and a dust shield member 28 for the auxiliary. contacts 8. The rails, extend upwardly from the steel base 80 from which also extends the tripping cam 31 whose purpose will hereinafter appear. a

The steel base 30, comprising plates and structural members, extends the length of the switchboard and forms a foundation to which the units are secured.

Reverting to the arrangement providing for, disengageable connection of the bus conductors with disconnect contacts I! of the circuit-breaker unit B, the support II for the bus disconnect contacts l2 comprises two members II a, iib (Fig. of metal which are clamped by bolts 32 directly to the bus conductor 9. From the front of member il b extend the brackets 33 for supporting the pins 34, 35 upon which the upper and lower contacts i2 are respectively pivotally mounted. The upperand lower contacts 12 of -each' of the several groups shown in Fig. 5 are biased toward each other by a spring 38 which encircles a bar 31 through which loosely extend two yoke members. I

The upper equalizing yoke 38 presses downwardly on the upper face of two adjacent upper contacts i2; a similar yoke (not shown) bears against the underfacesof the corresponding pair of lower contacts l2. 'The pin 39 .passes loosely through forward ends of all of the upper contacts 12 and similarly pin 40 passes loosely through. the forward ends of all of the lower contacts i2. This contact construction, more fully described in United States Letters Patent #2,029,028 to Kneass et al., insures equal distribution of the contact pressure between contacts l2 and I1 notwithstanding their appreciable misalignment,

The housing H which is assembled about the bus disconnect structure after the latter has been clamped to the bus conductor comprises two separable parts held together as by screws 4 I. Across 5 the open front end of the housing extend two pivotally mounted shutters 42 of insulating material biased toward engagement with each other by springs 43. The gap between the forward edges of the shutters is in alignment with the corresponding slot i6, Fig. 4, in the panel l5. When the circuit-breaker unit 3 is pushed into ters its corresponding slot l6, separates a pair of shutters 42, and slides between the upper and lower disconnect contacts l2. When the unit B is completely withdrawn, the

shutters

42, 42 within each housing I3 close the corresponding panel slot l6 and preclude accidental contact with the disconnect contacts l2.

As more apparent from Fig. 2, the bus conductors and live parts connected thereto are completely insulated and efiectively isolated from each other. The bus conductors, as previously stated, are encased in insulation except within theinsulating housings l3,'and each disconnect contact assembly is within its individual housing I3 of insulation. When panel i4 is opened, there is, therefore, no possibility of accidental contact with any of the live parts within compartment 2. Moreover, as shown in Figs. 6 and 7, the sides be used to encase the wires from the

transformers

6, 6 of the unit S so far overlap the sides of the circuit-breaker unit B that it is not possible for an, attendant to touch the contacts il until after the unit B has been so far withdrawn from the switchboard that contacts Hare out of engagement with the live disconnect contacts I2.

Each of the truck units Bi-B6, exemplified by unit B, Figs. 4, 8 and 9, is a substantially rectangular structure formed by angle iron and sheet steel suitably joined as by welding. The door 44 which permits access to the circuit-breaker mechanism hereinafter described is provided near the top with a louvered opening 45 to permit escape of gases incident to circuit interruption and al- 45 low circulation of air for cooling. In the particular construction shown in Figs. 4, 8 and 9, the

top of the truck structure is closed by a sheet metal wall 46.

The circuit breaker and its operating mechanism is removable as a unit from the rear of the truck structure. The framework 5! of the unit comprises a sheet-steel and angle iron structure having a vertical wall 41 and a horizontal wall 48 connected and braced by gusset plates 49 having therein holes 50 to receive crane hooks.

Holes 50 are approximately in line with the center of the center of the gravity of the unit to facilitate its manipulation while suspended from a crane.

When the unitis in position, its wall 41 serves as the lower part of the rear wall of the upper or circuit-breaker compartment of the truck;

the upper part of the rear wall of the truck comiis slidable along and supported ns" '52 extending across the sides ela in position'by bolts 53 a g, through the angle pieces 54 projecting rearwardly from the rear wall 41 of the'fr ame.5'i rackets 55 serve to guide racking links he matter described.

-. The upper face bflthe-horizontal panel 48 and the front face of the vertical wall 41 are covered or lined with the panels 51, 58 of insulating maposition, each of the disconnect contacts ll enterial. The strips 58 of insulating material projecting upwardly from panel 51, and similar strips 60. extending forwardly from panel form slots for receiving the bottom and rear edges of the panels ii of an interpole barrier unit. The rear wall of the truck is internally faced with a panel 58a of insulation which is, in efiect, a .continuation of panel 58 and from it project the strips 60a of insulation which are, in effect, con-.

tinuations of the strips 60. The topof the unit The uppermain contact assembly, Fig. 4, comprises the main contact member 81, the auxiliary contact member 88, the arcing horn 89, the arcing tip it, and blowout coil ii.

The lower main contact assembly ll, Fig. 4, comprises the stationary frame member 86 within which is pivotally mounted the movable frame 62 is closed by panel 63 which, like panels I,

is of insulating materiaL- The front of the interpole barrier unit is closed by panel 04 of insulating material from the bottom thereof to a level somewhat below that, of louver 48 (Fig. 4)

leaving the upper, forward parts of. the isolated compartments formed by the'panels ii, 84, I1 and 58 open for discharge of arc'gases. Preferably, short horizontal ledgesilb project inwardly of the compartments from or adjacent the upper edge of panel 54 to prevent the arc gases from flowing downwardly and adjacent the parts of the circuit breakenand within each compartment above the ledge 64b is fastened the arc gas deflector plate a, also of insulation.

The interpole barrier unit is removable from the front of truck structure'B by opening door 44 and pulling the barrier unit forward in the slots provided by guides 59. Handles Nc'may be provided to facilitate the withdrawal.

The'circuit breaker shown herein is a three-- member it! connected bypigtail to the stationary frame -rnember and to the bridging contact member I" loosely pivotally mounted in.the movable frame member .103.

To the upper end of movable frame member I is attached the arcing contact H5 which, when the circuit breaker. is closed, engages both the auxiliary or shunt contact 88 and the movable arcing horn tip Iii. Preferably contacts ll, ,8! and ID are or Elkoni or similar arcresistant materiaL- When the circuit breaker is tripped the contact Hi, inmoving to its fully open position, separates from the auxiliary contact 8| thus to include the blowout coil 8| in circuit. Shortly after separation of contact 5 'from the horn tip N,- the arc extends fromthe horn 8! .toarcing tip N6 of the movable arc contact lit until the'itip H6 moves sumcientiy close to'ithetip ill of a second,-stationary arc- .ing'hornilll connected to the frame it and at the same potential as tip Hi. When the arc transfers-"from the tip ii! to the upper arcing horn ill, a second blowout coil I20 is included in circuit further to force thearc upwardly in the are chute hereinafter described and further to separate the terminals of the arc.

The side panels I38 and end panels I43 of the are chute are of suitable insulating material; for example, the sides It! may be of sheet asbestos and the ends I43 of fibre or the like.

Within the are chute above the arcing horns are sleeves 13, ll of insulating-material. By tightening nut 16, the sleeves", It are clamped to opposite sides of the rear vertical wall of the frame ii.

The disconnect contacts ll, 23- are held to the

studs

68, 12 by the nuts 11, II, respectively.- The upper end of each of the disconnect contacts I! is braced by an insulator 19, Fig. 8, to resist bending during insertion and withdrawal of the circuit-breaker unit B from the switchboard. The insulators 19 are secured to and project horizontally from the rear-face of the upper part of the steel wall 41 of frame Ii.

Preferably, the portion of wall "which supports insulators lies in a plane farther to the rearthan the plane of that portion of the wall from which the studs l8, 11 extend. The upper'most portion of wall 41 is provided with a series of holes through which pass' screws ll, Fig. 4, for securing it to. the' rear face'of the truck. These screws, as well as screws 53, are removed for withdrawal of the frame ii on which all of the contact structure and operating mechanism therefor is mounted. 'Ihe main contact assemblies 65 and II ar mechanicallyinterconnected by the insulator It which resists forces, due-to flow of heavy currents, tending to move the assemblies awayfrom each other. The insulator t5 mechanically connected-to'the frame member 86 of assembly II and to the base plate 8 of the'unit frame 5| stiifens or supports the assembly ll against forces or shocks incident to the opening and closing movements of the parts of the circuit breaker.

four groups of spaced plates I of insulating material, for example fibre, which serve to split the arc lengthwise as it rises .in the chute and as a source of arc-quenching or deionizing gases. The plates of each group are suitably separated as by spacers and held' in position by bolts Ila.

If the arc rises above plates I, it is lengthened and split into a large number of arcs in series by the series of copper plates 1 spaced and insulated from each other in the top of thearc chute. These plates serve to quench. muffle, and

chill the gases of, the arc. Their construction and arrangement is similar to that disclosed "and claimed 'in United States Letters Patent #2930582 to Graves.

To facilitate withdrawal of the arc chutes from the truck, each of them. is provided with a pair of plates ll! held 'to the sides I39 of the chute and having holes 9 in their upper ends to receive theends of an inverted U-shaped link I suspended from and slidable along guide bars ISI suitably attached to the under face of the top wall 48 of the truck structure. When the interpole barrier assembly is in place, the links i" rest upon the top wall 83 of the barrier assembly (Fig. 4); but when the barrier assembly is removed, the links I50 swing downwardly each above its associated arc chute I so that the lower ends thereof maybe hooked into the holes I of the plates 8 of, the are chute.

To assist in alignment of the arc-chutes I36, the rear upper endof each of them is received by a notch in the plates N3 of insulation (Fig. 4)- which project forwardly from the front face of the vertical wall 41 of the supporting frame for the contact structure of the circuit breaker.

All of the operating mechanism. for the circuit o'ommii breaker is supported from the under face of the horizontal wall 49 of the frame II and the only connections between the movable contact -structures and their operating mechanism =are the rods I94 which are oi insulation; the upper end of each .r'od I 94 is received by a coupling member I99 pivotaliy connected to the movable frame I99 hr the movable contact structure ofone pole .of the circuit breaker and the lower end of each 'od I94 isreceived by. a coupling member I59 ivotally connectedg to. an operating arm I51 (Figs. 4 and '10)'.-"@All cfithe operating arms I51 aresecured to shaft Isa-supported intermediate its ends by a pair-of split b'carings, one.on each of'the side plates"l92.- I

The coil I99 which maybe energized to effect closure of the circuit breaker iswithin a housing J IIiI (Fig. 4) having two sides formed by steel 7 plates I62 which are attached. toi'and depend from the wall 49 of frame SI and'two sides-fanned by steel plates I99 which extend-between; and-sein addition to serving as sidesfof-v'thscoil" housing andbearing'plates' forshaftsoftheoperating I mechanism, alsoaprovldef feet upon which the "circuit-breakerunit ma rest-when:witlidravvn fromthe truck; The rear wall'o which througnpla'tef- I194 "threadablyr'to 'en- Sage blocksjifii welded-to the'ginnermar corners of the housing. .--The. iront wail-o! thecoilhQus-F ing comprises steel plate I 91iwelded'in'place and provided with s cpenihgto receive the-guide housing. The stop Il'Iforlimiting the forward movement ofthe' core-5| 99 comprises a plate welded at its opposi endstothe'plates I92 beyond the front wall of the coil housing. The core I69 is biased by spring 'I9 9a (1 ig.- 10) to'its forward position.

The link II2pivoted at its rear end' to the front end of core I99 is provided with an elongated slo't I19 which slidably'receives the pivot pin I'I4 of: the toggle links I19, I19. The upper end of toggle link I19 is pivotallyconnectedzby pin III to that one of the arms I91 which is 'atta'chedto the central portion of shaft I99 between the plates I92 which supp rt most of the circuit breaker operating mechanism. The lower end of toggle link I19 is pivotally connected by pi'n\II9 to a bell-crank lever I19 whose pivot pin I99\provides a fixed axis for angularmovement' of lever H9. The ends of pin I99 are supported 1- plates I92.

The arm "I of lever I19 is engageablenearits. A

free end by the latching member I92 'secured\to shalt I99 and biased to its, latching position by spring I94. Whencoil'l of'the'tripping ma readily be assembled and tested as a completely operative-unitprior to mounting in the truck.

Preferably the kinetic energy of the moving operating parts is absorbed by a friction brake B simi- 5 lar to that disclosedand claimed in United States jLettrsPatent No. 2,137,001.

The circuit breaker may be tripped manually by depressing the forward or handle end of lever I99. which is pivotally mounted within a housing 10 or bracket I9I secured to the front end of the .frametI- The handle of lever I99, as shown in Figs. 1 ,-4 and 9, projects through a slot I9I|a in the door 44 of the truck. When the handle is depressed theextension I92 of lever I99 engages the eirtensionl93-of latch I92 to affect its release from arm-inland so permitsprings I99 to open the circuit breaker.-

-by,inserting a bar I94 through an opening I 95 20 (Figs. 1 and 9) in the truck door and into the slot I96 of a disk I9'I loosely mounted, between the .sides of .bracket I9I, on the shaft I98 (Fig. 10). A A link I99 connects the disk I91 to the toggle pin I14. After the bar I94 is so inserted, it is swung downwardly through "an arc of about 90 and so moves pin I14 to the left thus to rock the shaft- I99 in clockwisedirection to lift the rods 'movablecontacts' of the circuit breaker. If an $0 overload exists, the circuit-breaker cannot beheld closedby:bar;I94 because when the latch- I82 is released; the toggle collapses and springs I99 are :iree'-- openithe circuit breaker regardless of the positi n 'o f"disk"i9'l. -The construction and operation ofthe operating-mechanism is similar to thati.disclosed' and claimed in Reissue-Patent No. v 2 9,753:toHQC. Grave's.

. visible through opening --I95 in the truck door 44 is colored. or otherwise marked to indicate whether the circuit breaker is in open or closed circuit positions: The'disk l 91 is biased by spring 299 to the-fope'n circuit position 'so that it will move to that position when bar I94 is removed orreleased after vtripping of the breakerduring manual I9I to its latching position after tripping of the circuit breaker in readiness for the subsequent re settingof the toggle incident to automatic or man 1 reclosure of the circuit breaker.

Fro the tripping lever I90 is suspended the rod 19K which extends through the base of the cruel;- iihline with the cam 3| on the base so of theswitch board to trip the circuit breaker, if it 5 be closed, as the truck is pushed into the switch- .board. 1 The bar-292 pivotally-sus'pended from arm I5Ia on the operating shaft I58 of the circuit breaker is utilized to operate the auxiliary switches 203 60 mounted upon the panel 204 suitably mountedin thefiblower' compartment ofthe truck. These switches'may be used-to operate signal lights or net I99 is sumciently energ as 1 O c fi perform other control functions in accordance rence of an overload, the movement of its armsture I91 through arm I99 rocks shaft I93 in counterclockwise direction to release the latch I92, whereupon powerful springs I99 \(one oi" which is shown) rocks the shaft I99 to open'the'; circuit breaker.

All of the stresses incident to opening .and closure of the circuit breakerare confined to the. frame BI and are not transmitted from one-operating part to another through the truck-frame.

Moreover, since the operating mechanismin its entirety is part of the circuit-breaker unit, it may ably slopedso that if it is ldownlwhen thetruck ispushed into the switchboard the engagement of the sloping end with pin 206 causes the bar to lift anddrop over the pin. The other end of each" Th'ecircuit breaker may be reclosed manually I94 and so effect circuit-closing'movement oi the Preferably. fthejed'ge 'ofldisk I91, which is fclosure thereof. Spring200 also restores the arm' the truck is to such extent from the switchboard unit 8 that all circuit connections'between them are broken, the shaft I88 is rotated a half revolution from the position shown in Figs. 10 and 11a.

To effect this movement, a bar or rod I880. is inserted by the operator in the notch 208A of disk 208 substantially in-alignment with the stop I8ia defined by the lower edge of housing I! and then swung upwardly. through an arc of about 90, until arrested by stop I8Ib defined by the upper edge of housing "I; the bar I88a is then removed and reinserted in notch 208!) of disk 208 and again moved upwardly throughan arc of somewhat less than 90. Throughout substantially all of the resultant movement of cranks 201 effected by the two-step rackingmovement of bar Isla, the rear ends of the bars 208 remain in engagement vwith and press against the abutments'28 so that the counterclockwise rotation of the cranks 201 from the position shown in Figs. 11a to the 180 displaced position shown in Fig. 11d effects a forward movement of the truck B. Somewhat before completion of the 180 movement of cranks 201,

the bars 208 rest intermediate their ends upon* the abutments 208 so that further movement of the cranks in the same (counterclockwise) direc- -tion causes the bars 205 to pivot about the abutments 209 and so lift their hooked ends free of the pins 208.

When the circuit-breaker unit B is in its normal or service position shown in Fig. 4, the disk 208 is in the position shown in Fig. lid with its notch 2080 receiving the upper end of the vertically slidable pin 2I0 which is pivotally mounted upon the manual tripping lever I90 biased to nontripping position by spring 2| I. The notch 208a and notch 208d for the pin 2 I 0 are out of the plane of the notches 208a, 2081) so that, except when the pin 2| 0 is received by one or the other of

notches

2080 or 208d, it is impossible toclose the circuit breaker. Before the circuit-breaker truck can be moved from the position shown in Fig. 4, and before disk 208 can be moved from the position-shown in Fig. 11a to the 90 displaced position shown in Fig. 11b, the handle I90 must be depressed-thus to insure the circuit breaker is open before the disconnect contacts II of the truck B separate from the disconnect contacts I2 of the switchboard.

To provide a test position in which the circuit breaker, while its main contacts are out'of circuit with the bus conductors, can be operatedsby control circuits through the contacts 8, the disk 208 is provided with a flattened cam notch 208d into which the pin 2I0 of the trip lever I80 rides (Fig. 110) as the disk 208 approaches the end of its aforesaid second 90 movement. Engagement of .the pin 2I0 with the shoulder 2I2 can'be felt by the operator who is thus informed the truck has reached the test" position. In this position the circuit breaker can be opened and closed either automatically or manually, and operation of its parts observed without danger to the operator and without need completely to withdraw the truck from the switchboard.

With the circuit breaker truck in test" position and the circuit breaker closed, the breaker can further be raised to complete the second 90 movement of the disk 208 (from the position shown in Fig. 11b to the position of Fig. lid).

The disclosed construction of disk 208 and its relation to pin 2 I0 also prevents the circuit breaker from being closed when the truck is moved from v "test" position toward the switchboard to restore the circuit breaker to its service position and thus precludes completion of the bus to cable circuit when the disconnect contacts I1 and 23 of the truck engage the disconnect contacts of the switchboard. More particularly, when disk 208 is rotated in clockwise direction from Fig. 11c, "test" position, to Fig. 11a, "service" position the cam-face of slot 208d moves pin ,2I0' downwardly and so effects tripping movement 'of lever I80.

To summarize, the interlock between the racking andtripping mechanisms preventsclosure of the circuit breaker for truck positions intermediate the fservice" and. "test" positions, determines the test position during withdrawal of the truck from the switchboard, prevents accidental withdrawal of the truck from "test" position, and efiects tripping of the circuit breaker, if closed, as the truck is moved from test toward service" positions. p I

Features herein described but not claimed are claimed in aforesaid application Serial No. 227,089 Q Q and in divisional applications Serial Nos. 331,507 and 331,697, filed, respectively, April 25, 1940 and engagement to a position in which said disconnect contacts are disengaged, and means for locking said racking means including amember movable to unlock said racking means whether said switch be in open or closed circuit position and concurrently to actuate said tripping means to effect disablement of said switch operating means.

2. A circuit-controlling arrangement comprising a fixed unit, amovable unit adapted to be withdrawn therefrom, complementary disconnect contacts mounted on said units, a switch mounted on said movable unit and connected to the disconnect contacts thereof, operating means for closing said switch and releasably retaining it in closed circuit position, tripping means for releasing said switch and for effectively decoupling it from its said operating means, manually operable racking means for moving said movable unit from service position in which the disconnect contacts of said units are in engagement to a test position in which said disconnect contacts are disengaged, and means for locking said racking means including a member vQich, with respect to both test and service positions of said movable unit, is movable to lock and unlock said racking means for open and closed circuit positions of said switch, which actuates said tripping means when moved to unlock said racking means, and which for all positions of said movable unit between its service and test must be tripped manually before the lever IBM Positions coacts with said pp g means to maintain said operating means decoupled from the switch. b f

3. A circuit-controlling arrangement comprising a fixed unit, a movable unit adapted to be withdrawn therefrom, complementary disconnect contacts mounted on said units, a switch mounted on said movable unit and connected to the disconnect contacts thereof, operating means for closing said switch and releasably retainingit in closed circuit position, tripping means torreleasing said switch, andffor efiectively decoupling it from said operating. rnea.ns.-manually operable racking means for moving said movable unit from service positioniin which the disconnect contacts of said units arein en- ,gagement'to a'test position in'whi'ch said disconnectcontactsare' disengaged, and means for looking said-racking means comprising two interlocking members both carried by, said movable unit, one of which ismovable in unison withsaid racking means, and the other of which, withrespect to both the test and service positions of said movable unit, may be moved into or out of interlocking relation to said one of said members to restrain or permit operation of saidgracking means, and which when out of interlocking relation coacts ,with said; tripping means for-all positionsof said movable unit to maintain-saidoperating means efiectively decoupledfrom"theswitch.

4. A circuit-controlling arrangement comprising a fixed unit, a movable unit "adapted to be withdrawn therefrom, compler'nentary disconnect contacts mounted on'said units, a switch mounted on said movable unit andconnectedto the disconnect contacts thereof, "operating means for closing said switch including a toggle for releasably retainingit in closed circuit position, tripping means operable to break the toggle to release said switch and to prevent reclosure thereof by actuation of said operatingmeans, manually operable racking meansfor moving said movable unit from service position in which the'disconnect contacts of said units are in engagement to a second position in which said disconnect contacts are disengaged, and interlocking means between said tripping means and said racking means includinga member operable to actuate said tripping means and concurrently to release said rackto effect operation of said tripping means by initial movement of said movable unit from test toward service position comprising two interlockingmembers carried by said movable unit, one of which is operable to actuate said tripp means for all positions of said movable unit, and the other of which is-moved with respect to said one of said members by said racking means.

6. A circuit-controlling arrangement comprising a fixed unit having power circuit disconnect contacts and auxiliary circuit contacts, a truck on which is mounted circuit-breaker disconnect contacts for engaging said power circuit contacts and other contacts for engaging said auxiliary circuit contacts, racking gear for moving said truck from service position in which all of said contacts are in engagement to a 'test position in which only said disconnect contacts are out of 'in test position, and to prevent closureof the circuit breaker for positions of the truck between test and service positions. v

'7. Racking gear for a circuit breaker comprising a shaft supported from the circuit. breaker 'irame,-an operating bar, a disk secured to saidshaft and havingnotches therein to receive said operating bar, a crank arm secured to said shaft, a stationary pin, a racking link having a hooked end to embrace said pin and connected at its other end to said crank. and an abutment fixed with respect to said frame and engaged by said link during movement of said frame by said bar to eflect release of the hooked end of said link from said pin.

ing means for actuation to move said movable. unit from either of said positions to the "other, and which for all positions of. said unit intermediate its second and service positions coacts with said tripping means to prevent resetting of' said toggle.

.5. A circuit-controlling arrangement comprising a fixed unit, a movable unit adapted to be withdrawn therefrom, complementary disconnect contacts mountedon said units, a switch mounted on said movable unit and connected to the disconnect contacts thereof, operating means for 'closing said switch and releasably retaining it in closed circuit position, tripping means for releasing said switch and for disabling said operating means, manually operable racking-- means for moving said movable unit from service position in which the disconnect contacts of said units are in engagement to a position in which said disconnect contacts are disengaged, and interlocking means between said tripping means and said racking means to prevent movement of said movable unit from service position while said switch is closed, to prevent closure of said switch during movement in either direction of said movable unitbetween service and test positions, to determine the test position, to prevent accidental movement of 'said unit beyond test position, and

*8. A circuit-controlling arrangement comprising a fixed unit including power circuit disconnect contacts, and a circuit breaker unitffwithdrawable frcnr-"sairi fixed unit comprising disoonnectcom tacts: and a circuit breaker having contact structure electrically connected thereto, a stationary pin on saidfixed unit, racking gear for effecting 5 j -"-withdrawal of said circuit-breaker unit comprising a link having a hooked end for embracing said pin, means for operating said link including an actuating bar, a disk having a notch for receiving said actuating bar and a shaft to which said disk is secured, means for tripping the circuit breaker including an interlocking member 'receivedby a notch in said disk, and means for closing the circuit breaker including a disk loosely mounted on said shaft and notched to receive an operating bar 9. A circuit-controlling system comprising a fixed unit, a movable circuit breakerunit adapted to be withdrawn therefrom, complementary disconnect contacts mounted on said units, racking means operable to move said movable unit toward and from service position inwhich said contacts are in engagement, a member movable to one position to lock said racking meansand-to'a' sec-,

ond position to unlock said racking means and trip the circuit breaker, -Jmeansfor f closing said circuit breaker including a" disengageable" me.

chanical connection br'okensolong as said member is in its said second position, and-structure preventing movement of said member to its locks eamer and trip the circuit breaker, means for closing said circuit breaker including a disengageable mechanical connection broken so long as said member is in its said second position, and structure permitting movement of said member to its locking position, for both the service position and the test position of said movable unit, and. maintaining said member in its said second position for positions of said movable unit other than its 10 said service and test positions.

WILLIAM M. SCOTT, JR.