US2051901A - Electrical switch gear - Google Patents

Description

g. 25, 1936. A. M ROSSMAN 2,051,901

ELECTRICAL SWITCH GEAR Filed Feb. 5, 1934 4 Sheets-Sheet l m/ -lx NNN IL \W\ mxMH|- m FTQ w www m tw w sh A Aug. 25, 1936.4 A' M, ROSSMAN 2,051,901

ELECTRICAL SWITCH GEAR Filed Feb. 5, 1954 4 Sheets-Sheet 2 j Ng WAI/IWWWWMM Aug. 25, 1936. A M ROSSMAN i n 2,051,901 I ELECTRICAL SWITCH GEAR Filed Feb. 5, 1934 4 Sheets-Sheet 3 l? FQ; f O l I O am my Aug. 25, 1936. A. M. RossMAN ELECTRICAL SWITCH GEAR Filed Feb. 5, 1954 4 Sheets-Sheet 4 QQQ Patented ug'. 25, 1936 UNITED STATES PATENT OFFICE Application February 5, 1934, Serial No. 709,761

18 Claims.

This invention relates in its broad aspects to electrical switchgear applicable to power stations, substations, and switching stations, and is particularly concerned with novel and improved arrangements for switching. units of the type in which the circuit breaker is portable and easily removable from the remainder of the structure.

The leading aims underlying the invention are to simplify both the method of and the means formoving the circuitbreaker into and out of its operating position in the housing structure and the method of and means for connecting the circuit breaker to and disconnecting it from the portions of the electrical circuits which are stationary in the housing structure.

In prior designs of switchgear having easily removable oil circuit breakers, three methods are used' for connecting the circuit breaker to the stationary structure.

In the first method the circuit breakerV is mounted on a pair of horizontal rails. The movable circuit contacts, which are a rigid part of the circuit breaker assembly, are lined up very accurately with the stationary contacts and the circuit breaker is pushed horizontally into its normal operatingposition by means of a gear and rack or some other equivalent device, dependence being placed on accuracy of alignment to insureproper contacting of the current carrying parts.

In Vthe second method, the circuit breaker is pushed horizontally into the stationary housing and -is then elevated to its operating positionby means of a screw device. or some other equivalent mechanism. With this method of handling, the rigid upward extending contacts on the circuit breaker must be lined up accurately with the stationary contacts and suitable guiding devices must be provided to insure that the current carryingparts register properly.

kIn vthe third method, the circuit breaker is pushed horizontally into the stationary housing whereby the rear terminals of the circuit breaker are moved into register with their corresponding stationary terminals 4by the movement of the circuit breaker into its operatingposition, while the connections to the front Aterminals of the circuit breaker are Vmade subsequently by closing disconnecting switches.

AAll three methods havethe objection that they require a high degree of Vaccuracy in design, fabrication, and assembly to insure a proper registrationof contacting parts. -Misalignment will cause trouble which can range from overheating of contacts to damaged parts due to the jamming or" the heavycircuit breaker` against the comparatively 4light .circuit terminals.

AMethod three has the further objection' -that it leaves livefparts exposed, accidental contact with (Cl. F75- 298) which'can cause damage,`injury, oreven fatalities.

One object of my invention is to separate the double function of pushing the circuit breaker into its 'operating position and closing the circuit"contacts,'into two independent, non-simultaneous yfunctions.

Afsecond object is to eliminate theA necessity for close alignment ofthe circuit breaker in the structure which'has heretofore'been necessary to "insure accurate registration of the circuit contacts.

Athird object is to'insure that allhigh voltage partsl are adequately insulated while the circuit breaker is-in service.

-A fourth Objectis toprovide interlocking means to prevent accidental arcing at the circuit disconnecting contacts.

A fth object relates to providing a new design of switching unitfwhich is lighter, simpler, and less expensive thanhas heretoforebeen available.

Other objects-'will be'apparent from the disclosure.

iwill now describe methods of constructing a switching-unit embodying the principles vof the present invention, reference being made to the following drawings:

Figure l isa sectional elevation ofV a switching unit taken along the line -l-I inl Figure 2.

Figure2 is a sectional planof the switching unit' assembled in a row of units taken along the line n2--2 in Figure 1.

Figure 3 is a front elevation showing the a-rrangement of contact arms.

Figure-44s a detail in partialsection of one of the contact arms shownin front elevation.

Figure5 is a detail of another type of contact arm,v shown-in side elevation.

Figure 6 is a sectional elevation of a switching unit designed with a double bus.

Figure 7 is a detail of a stick for operating'the movable contacts.

Figure 8 isa sectional elevation ofa switching unit similar to Figure l but' havingadifferent forni of bus and bus housing.

-Figure 9 is a plan-of arow of units of the type shownin Figure 8.

Figure: 10 is a detail=of analternate type of movable contact member infengagement'with its co-operating stationary contact member, the latter shown section.

Figure 11 is a-'frontelevation of the-contact members of Figure 10.

'Figure 12 is a-detailpartly -in section' ofv the contact-member of Figure 5`shown inv co-operation with its respective stationary contact.

In' Figure l is shown a sectional elevation taken along line l'-|A of'Figure 2 of a switching unit embodying the principlesof the present'vinvention, In general; Ethe switching unit-'is of -the'class described in my earlier disclosures, Patent No. 1,830,409, dated November 3, 1931, and application Serial No. 440,606, led March 31, 1930. In common with these disclosures, thepresent invention consists of a vertically disposed fabricated metal enclosingl structure, comprising a structural framework A, supporting sheet metal walls B, thus forming several compartments, one compartment 2 housing a circuit breaker I bus bars 3 disposed within a separate compartment 4 above the circuit breaker, and a third compartment 6 in which terminates a feeder cable 5. The switching unit is designed to be placed in line with a number of similar units in such a manner that the bus bars 3 extend continuously through the line of switching units, the bus bar compartments 4, which rit together to form one continuous tubular housing, in the manner disclosed in the above mentioned documents.

Unlike the earlier disclosures, however, the circuit breaker I is not raised into the operating position, but is merely rolled into place withinV the enclosure by means of a small individual truck l mounted on wheels 8. Instead of an individual truck, the breaker can be moved into the compartment by means of an industrial type truck and set down on the iioor, after which the truck can be removed. In either case, the breaker I rests on the floor, thereby relieving the frame Vstructure A of the duty of supporting its weight.

The necessity of extreme accuracy in guiding the breaker into operating position is also obviated in the present design by provisions which will be described later. These features of lightness of structure and the elimination of the necessity for accurate guides, etc., result in a simpler, lighter, and less expensive switching unit.

A switching station of this type is made up by assembling a group of switching units, setting them in alignment, and connecting their respective bus sections 3 in series to form a continuous bus. One set of circuit breaker terminals in each switching unit are adapted for connection with the bus conductors 3 while the opposite terminals are adapted to connect to an external circuit which feeds power to or is fed from the bus bars. The external circuit terminates in the terminal chamber 5 in the form of cables 5.

Connection is made between the front row of terminals I5 on the rcircuit breaker and the bus bars, after the circuit breaker has been set in operating position by means of hinged disconnect arms 9, each of which is provided with a Contact head II. The latter member is adapted for cooperating with stationary contact member I3, comprising a connector which will be described later disposed within a hollow insulating bushing which is fixed to the frame structure. The bus bars are connected respectively by means of conductors It to the terminals IQI on the rear end of the stationary contact members I3. The terminals are connected conductively to the connectors within the hollow insulating bushings.

A plan of the contact members showing their relative positions within the structure is shown in Figure 2 which is a section taken along a line 2-2 in Figure 1. This drawing also illustrates the position of the switching unit relative to the other units in line, the circuit breaker compartment 2 being shown between two adjacent compartments 2A, 2B.

Figure V3 is a front elevation of the circuit breaker I, disconnect arms 9, and stationary contact bushings I3. Although a three-phase unit is illustrated, as evidenced bythe three circuit 1 panel into the bus bar compartment 4.

breaker terminals in line and corresponding arms,

contact members, and bus bars, circuits of other numbers of phases can be designed for by applying the same principles of construction.

The stationary members I3 are mounted on a panel 84 and extend through apertures in the This panel is supported on the structural frame of the unit and forms part of a partition between the circuit breaker compartment 2 and the lower extension of the bus bar compartment 4.

The rear row of circuit breaker terminals 2@ is connected with the cables e by a row of disconnect Aarms I0 similar to those 0 in the front row but shorter. A contact head I2 on the end of each arm co-operates with a stationary contact member I4.

Y The three lower stationary contact members I4 yare mounted in alignment on a panel 85 which is supported on the framework A and forms part of a partition 23 between the circuit breaker compartment and the cable terminalY compartment t. Each stationary contact member I4 extends through an aperture in the panel 85 into the terminal compartment 6. A current transformer 24 is connected to each terminal IUI on the rear end of each of the contact members I4. The incoming cables 5 are connected to the other terminals of the current transfo-riners so that one transformer is connected in series between each cable and its corresponding stationary contact member I4. In some installations current transformers are connected in only one or two of the phases.

The cables enter the terminal chamber 6 through a .conduit 25 at the bottom of the chamber. If it is more convenient for the cables to enter from above, the compartment 6 can be located as shown in broken lines in whichV case the current transformer 24 would be mounted above the Contact bushing I4.

The use of the current transformers for operating meters and overload relays, etc. is well known.

The contact bushingsY I3, I4 can be spaced farther apart horizontally than the circuitY breaker terminals I 5 to provide greater clearances as shown in Figure 3. The two outer disconnect arms of each ro-w are bent outward so that the connectors II register with the hollow bushing I3.

The disconnect arm 9 consists of a rigid insulated conductor connected by hinged joints to the Contact headV II at the top and to the circuit breaker terminal I5 at the lower end.

The joints in the arm are protected against accidental contact by means of insulating sleeves I8, I9.

Each of the short disconnect arms I@ is connected in -a similar manner to one of the circuit breaker terminals 20 in the rear row by means of a flexible joint which is insulated by a sleeve 2l.' The upper joint between the arm I0 and connector head I2 is also insulated by a sieeve 22.

Referring now to Figures 4 and 5, which show the front and side elevations of embodiments of the jointed disconnect arm, the rigid conductor S is connected to the head II by means of a hinged joint 25. This joint consists of a lug 2l' on the head member II disposed between two ears 28, 29 on the arm S and abolt 30 inserted through registering holes in the lug and ears. Clearances in the lug 2l aroundthe bolt 36 and between the ears and the lug allow considerable play in the joint. Y This permitsY a limited amount 75 of -motion of the head to allow for in-accuracies in aligning the circuit breaker. Flexible conductors, such as braided strips 3I, are connected across the joint 26 to insurergood conduction. As shown, the braids are held to the head by a ring 33 which is soldered, brazed, or otherwise fastened to the braidand to the conductor, and the braids are fastened to the arm by screws or bolts 32. There are .obviously Vmany possible variations in the design details of this joint.

The head I i comprises an insulated rod 35 bent at right angles just above the joint 2E, on the end of which is located the contact member 34. The contact member consists of a plurality of flexible fingers 52 fastened to the end of the conductor 35 by bolts or rivets 53 or otherwise fastened in a, suitable manner. The fingers 52 are arranged around the conductor so that they enclose a tubular space into which slips the plug type contact with which the member 34 cooperates. The fingers are corrugated or waved as shown in order to insure several points of contact on each finger with the co-operating Contact member. To provide sufficient contact pressure, garter type coil springs 54, 55 are provided encircling the group of fingers.

There are several known Variations of this contact; for instance, in one known type the lingers are formed of a comparatively large number of metal wires, each wire being bent into a number of curves or waves to increase the number of points of contact. Of course the locations of the plug and socket members can be reversed; that is, the fingers 52, forming the socket 54, can be disposed within the stationary hollow bushing member I3 while the plug is disposed on the contact head II. This is a less desirable arrangement, however, as maintenance is simplified by locating the more complicated socket portion of the contact on the movable member II, which can be more easily disconnected from the energized portions of the circuit for repair and repl-acement.

Referring to Figure 12, showing the contact members in co-operation with each other. This drawing shows the hollow insulating bushing 91 in section, having a flange IID having holes through which bolts III fasten the bushing to the panel 84. The bushing extends through a hole I I2 in the panel.

Within the bushing 91 is disposed the plug contact 99, which has a flange portion II3 fixed upon it. This flange bears upon the rear end wall II4 of the bushing. The shank II5 of the plug extends through a hole in the end II4 of the bushing and is threaded to accommodate a nut II6, which is screwed up firmly against the bushing to hold the plug rigidly. The threaded end IOI of the contact plug is used as a termi nal for making connection with the bus bars or other parts of the circuit. The rod 35 is sho-Wn broken away ahead of the hinged joint 26. This drawing shows an additional protection against accidental contact with live parts as furnished by an annular flanged member II1, preferably composed of insulating material. This flange is fastened to the movable contact head II and extends outwardly to cover the opening in the hollow bushing 91 when the contacts are in cooperation. The flange is shown made in two halves which are clamped over the insulated rod 35 by means of bolts II8.

Referring again to Figures 4 and 5, the operation of connecting and disconnecting is accomf plished by means of an attachment 36 that fits tightly on` thevvertical portion of the head Il. Extending out on each side of the head are two projections or lugs 31, 38 in which are holes 39, 40 respectively. This attachment is engaged by a forked operating stick, which will be described in more detail later. This stick has projections which are inserted through the holes 39, 4D, thereby allowing the connector to be controlled.

Around the bottom of the attachment 33 is a raised annular portion 4I over which a flexible insulating sleeve I8 of rubber or the like is drawn and held in position to prevent accidental contact with the bare joint. The sleeve I8 and the braid 3l arel broken away to show the details of the joint.

The lower joint 42 between the contact arm 9 and the circuit breaker terminal I5 comprises a lug 43 on the terminal I5 which interleaves between two ears 44, 45 on the arm 9 and is joined to the ears by a bolt 46 which completes the hinge. Excess play is allowed in this joint as well as in the upper joint to provide flexibility. Conduction is insured by flexible jumpers 41 for conducting current across the loose joint. These jumpers are riveted or soldered to the arm and are secured to the terminal by the bolts 48. The insulating sleeve I9, shown in section, consists of a cylinder of insulating material having a closed upper end in which is a hole through which the arm 9 extends. This sleeve rests on a ring or clamp I9 which is fastened on the arm 9. The sleeve extends around the joint down below the terminal on the circuit breaker bushing I5. The diameter of the sleeve is larger than that of the bushing to allow a limited angular motion of the arm.

Although the upper joint 26 is shown with a flexible sleeve I8 and the lower joint 42 is shown with a comparatively rigid insulating sleeve, either type of sleeve can be used on either upper or lower joint.

In Figure 5.an additional slip joint 50 is shown in the arm which is not shown in Figure 4. In some cases it is desirable to provide for more flexibility than can be obtained by adding play in the hinge joints. With this type of slip joint, it is possible to provide for several inches of vertical movement of the head by raising or lowering the arm. This type of joint also allows a rotary movement of the arm around the vertical axis of the terminal I5. It also allows the arm to be easily removed from the circuit breaker and another arm slipped on. The utility of this feature will be discussed in connection with a later embodiment.

The joint 50 comprises a plug member 5I, which is disposed above the lower hinged joint 42 and a socket member similar to the contact 34 on the head II, consisting of a number of flexible fingers 52 fastened to the arm 9 by rivets 53 or other suitable means. The fingers are bent into a number of waves or corrugations to insure several points of good Contact with the plug member 5I and pressure is maintained by garter type springs 54', 55' around the socket member over the points of contact. The sleeve I9EL is made long enough to cover both the hingedv 4. It is possibleV to omit the control cable conduit and simply lay the control cable in the cable compartment. The control wires for each unit terminate in a junction box 63 located in the control cable compartmentof the switching unit.

From the junction box 6 3 the control cable 55 extends through the bottom of the compartment 62 into a control box 64 located on a hinged panel 66 directly in front of the jointed disconnect arms. The panel 65 is hinged at one side so that it may be swung away horizontally from in front of theV circuit breaker. In or on the front of this control box are located the necessary relays, meters and junction boxes which are required fcr the operation of the circuit breaker. As this equipment is well known to those skilled in the art, the details of connections will not be described herein, but the control equipment is indicated as rectangles shown in broken 1in-es in the control box 6&3. To establish connection with the operating mechanism 6l of the breaker, a short length of multi-conductor control cable B8 is shown leaving the operating mechanism lil and terminating in a multiple circuit plug 69 which plugs into a co-operating socket l0 located in the floor of the control box 64.

rThe system of interlccks for insuring that the circuit breaker cannot be connected or disconnected from the bus and feeder circuit cables 5 unless it is in the open position is inherently very simple. An interlock rod ll extends from the tripping latch in the circuit breaker operating mechanism to a plvoted arm l2 on the circuit breaker case. The other end of the arm "i2 is connected to a rod 'i3 which issupported on a lug l'i.

As the latch for tripping a circuit breaker is well known in the art, for the sake of simplicity the details of the tripping mechanism and the connection with the interlocking rod ll are not included in the drawings. Suflice it to say that the common type of circuit breaker is closed by means of a motor or solenoid against a strong spring and is held closed by a latch. This latch can be opened either mechanically or by means ci a solenoid which is controlled from the remote control position, thereby causing the spring to rapidly open the circuit breaker contacts. It is therefore obvious that the interlock rod 'll can easily be arranged in relation to the trip latch in such a manner that when the panel G6 is swung into the closed position as shown in Figure l., the control box 655 engages the rod i3 and pushes it back into the position shown, thereby moving the interlocking rod 'ii forward into the operating mechanism 6l. When the rod is in this position, it does not engage the tripping latch. However, when the panel is opened, as illustrated Figure 5, the rod i3 is pulled forward by the spring l5, drawing the interlock rod il back and causing it to actuate the tripping latch. In this manner the circuit breaker is tripped open when the front panel is opened. The control cable t8 is brought out of the operating mechanism 8l on the side away from the panel hinges so that as this length of cable is made appropriately short the control cable 68 must be disconnected by removing the plug te from its socket le in the control box, thereby preventing operation of the circuit breaker from a remote control station, before the front panel can opened.

After the panel is open, the'next step in re- Y moving the circuit breaker is to pull out the connectors Il, I2.

It is usually desirable to disconnect a circuit breaker from the bus first and from the feeder circuit last. This order of disconnecting is compelled by interlock spacing members l. These members consist of sticks, preferably of insulating material, Vclamped on each of the longer connection arms 9 substantially at right angles to the arm. This member projects from the arm 9 to the head l2 of the rear contact member iii and from the arm to the control box 6ft. The length of each projection is made such that it prevents the front panel S5 from closing unless all contact plugs are pushed well into their respective contact bushings.

There are several obvious variations in the mechanical interlock 76, such as a bar extending out from the back of the control panel whichV would interfere with the front connecting arms 9 unless they were in connected position, while a short spacing member between the front and rear arm could be fastened to the head l2 of the rear arm i@ instead of the front arm 9. Any variation of this device would obtain the result of spacing both front and rear arms within the enclosure so that with the front panel closed the contacts must necessarily all be in operating position.

It is obvious that a hinged'or removable bar or other type of barrier can be substituted for the hinged panel to achieve the same ultimate result of a safety interlock. One of the essential features is a barrier which must be removed bebore the breaker is removed, the removal of the barrier being interlock-ed to cause the circuit breaker to trip open; the other feature is that the barrier must be closed before the circuit breaker can be closed, but the barrier is prevented from being closed unless the disconnect contacts are iirst closed.

This interlock 76 also pre-vents the rear contacts from Vbeing opened before the front contacts with the main bus are opened. After all contacts have been opened, the circuit breaker can be remove-d from the compartment.

The'spacing members also perform another function, that of locking the arms in the connected position and preventing them from being forced out of contact in case of a heavy surgey of current through the breaker due to a short circuit. Y

When replacing the circuitV breaker, it is desirable that the connection with the bus. be made after the feeder circuit connections are in place. The correctl order of this operation is insured by the interlock 76 which requires the rear plug l2V will interfere with the closing of the panel. With the closing of Vthe panel, the interlock rod i3 is pushed back, thereby disengaging the tripping mechanism of the circuit breaker. The last operation is the plugging in of the control circuits, again establishing connection with the remote control station.

Access to the control box is obtained through a door Tl in the front panel titi. The door is opened by means of a handle 78. The front panel is opened by means of a second handle i9.

Access to the control cable compartment 62 is obtained through an opening in the front wall which is covered by a cover plate 8B. The main bus compartment 4 is made accessible by removing a cover plate 8| in the top, or another cover 82 in the rear wall. A cover plate 83 covers an opening in the rear Wall of the terminal compartment 6.

Figure 6 is a modification of Figure l showing a double bus design. In this drawing the Vcontacts are shown in the open position. The method of opening the contacts is also illustrated. The operating stick 86 is shown engaged with the attachment 36 on one of the rear disconnect arms |0. The operating stick is also shown in plan View in Figure 7. It comprises a handle tl and a pair of arms 88, 89 onthe end of winch are prongs 90, 9|. The arms 88, 89 are spaced apart so that when engaged with a rear contact member as shown, one arm extends on each side of the corresponding front disconnect arm 9. The prongs are spaced apart a dist-ance equal to the distance between the holes 39, 40 in the attachment 36. As the prongs t reasonably close in the holes, contact head |2 can be aimed and con* trolled by means of the operating stick.

In Figure 6 a second set of bus bars 92 are disposed within a rear bus compartment 93. Access to this compartment is had through openings in the top and rear Wall which are closed by covers 94, 95 respectively. The bus bars 92 are connected to the stationary contacts i3 by conductors 96. The bus bars 3 are connected by conductors |6 to an upper row of stationary contact members 99 above the contact members I3.

The circuit breaker as shown is prepared to connect the feeder cables 5 with the rear bus 92. When it is desired to connect to the front bus 3, the front row of hinged arms 9 are removed from the circuit breaker and longer ones 98 are attached as shown in dotted lines. This can be accomplished in several ways. The entire length of arm can be replaced by unbolting at the lower joint 42, the head I can be removed at the upper joint 20, and a second head on an extension can be bolted in its place, or the arms can be provided with a slip joint as shown in Figure 5, in which case the substitution is easily made by slipping ohone set of contact arms and replacing with a set of the longer ones.

Figures 8 and 9 show an elevation and plan of a third embodiment cf the present invention. Figure 8 is a section taken along line 8 8 in Figure 9 In this case the bus bars 3 are vomitted and insulated cables |02 are substituted. The bus compartment |03 extends alone the row of switching units behind the stationary contact members forming a continuous bus housing, and the cables are laid in the housing. The bus housing in this case is shown to extend beyond the circuit breaker compartment 2 and is joined to the adjacent unit by bolting together the iianges |0'l`around the bus housing openings. In this arrangement no splicing is necessary, as can be seen in the plan view shown in Figure 9. The terminals |00 of the three contact members |20 of the center unit are connected to the respective terminals |84 on the Contact members |2| in the adjacent unit on one side by three short insulated cables |02, while three other cables |05 connect the terminals |80 to those 05 on the members |22 in the adjacent unit on the other side. A new unit can be easily added to a group by placing it in line and connecting its contact terminals with the respective terminals of the adjacent unit by a set of short insulated cables. The bus, therefore, is composed of a series of jumper connections from each switching unit to the next adjacent unit.

In Figures 8 and 9 the unit is shown with disconnect arms and contact members of another design. The details of this design are shown in Figures l0 and l1. This design is alternative to the design shown in Figures 4 and 5 and can be substituted in Figures 1, 2, 3 and 6. Likewise, the type described heretofore can be substituted in Figures 8 and 9.

Figure l0 is a side elevation of the alternative design showing the insulating bushing |23 of the stationary member |29 in section. Figure ll is a front elevation of the assembly.

The disconnect arm |25 consists of a iiat bar of conducting metal, the upper end being bent edgewise at substantially right angles to form the contact blade. The contact portion |26 is adapted to co-operate with a stationary contact |2 of the conventional knife switch type, having a number of ilexible fingers |28 to receive the blade |26. These ling-ers |28 are mounted on a base |29 which bears on the bottom of the hollow portion of the insulating bushing |23. A stud |30, fastened to the base |29 of the switch contact, extends through a hole in the shank |3| of the bushing and is threaded at the end to receive a nut |32 which is drawn up to hold the contact |27 rmly in the bushing. A terminal member |00, adapted for receiving cables as shown in Figures 8 and 9, can be screwed on the threaded end of the stud |30 or thecable terminals can be slipped directly over the stud and held by another nut in a well known manner.

A ange |33 is provided on the insulating bushing |23 for fastening the bushing on the panel |36 by means of bolts |345, the shank |3| of the bushing extending through a hole 35 in the panel |36.

As can be seen in Figure ll, the insulating bushing is oval shaped rather thancircular. This allows somewhat closer spacing of the stationary contact members, thereby requiring less angularity of the contact arms, as was explained in connection with Figure 3.

The arm |25 is insulated its entire length except on the contact blade 23 and on the lower end |37 at the joint |30. On the circuit breaker stud 5 is mounted a double pronged lug |39. Between the prongs |63, |45 the end ll of the arm |25 is inserted and a bolt 32 is inserted through registering holes in the prongsand the armi. The arm thus hinges cn the lug |39 and sufficient play is allowed the joint to provide flexibility. A vertical misalignment between the movable |26 and stationary |27 contacts is permissible in this type of contact, due to the absence of mechanical obstruction to relative vertical movement between the two contact members.

Flexible conductors |43, it!! are fastened to the arm |31 by rivets |45 or the like, and are bolted to the lug |39 to insure good conduction around the joint. A flexible insulating sleeve MS is shown in this embodiment although the rigid insulating sleeve shown Figure e can be substituted.

At attachment |47 for operating the disconnect arm is clamped to the upper end of the arm. This attachment, which is constructed preferably of non-conducting material, is made in two parts |48, |49 which clamp together over the head of the arm by bolts |58. Registering holes |54 are provided in the attachment |41 to accommodate an operating hook such as is used on conventional types of disconnect switches.

Flanges |5|, |52, provided in the attachment,

are adapted to cover the opening in `the front of the insulating bushing while the switches are closed.

While the drawings show a stationary structure fabricated from steel, it is quite evident that the stationary structure can be made of concrete, a combination of concrete and steel, or even an open framework of pipe or structural members, but still retaining the advantages oi the method of connecting the circuit breaker to the bus and feeder, the method of interlocking, and the arrangement of busses shown and described herein.V

I do not intend to be limited to the details disclosed in these specications and drawings. What I claim and wish to protect by Letters Patent is set forth in the following claims:

l. In a switching unit of the class described, a set of bus bars, stationary contact members connected to said bus bars, a second set of bus bars, stationary contact members connected to said second set of bus bars, a portable circuit breaker, and means associated with said circuit breaker for making connection selectively with either set of bus bars, said means comprising two interchangeable sets of hinged contact arms cooperable respectively with said stationary contact members of each set of bus bars, said contact arms having slip joints for interchangeably connecting them to said circuit breaker.

2, In a switching station of the class described, a portable circuit breaker having a terminal post, a stationary contact member, means attached to said circuit breaker comprising an assembly of insulated conducting links joined together by a plurality of independently iiexible joints for connecting said terminal post to said stationary contact, insulating sleeves covering said joints, and operating lugs projecting from opposite sides of one of said links, whereby said conducting links can be guided into connection with said stationary contact member.

3. In an electric system, a plurality of metal clad switchgear units, each unit having iieXibly jointed disconnecting contacts and a metal bus compartment, said compartment having apertures in a Wall thereof, and openings at opposite ends thereof, and insulating shields supporting xed disconnecting contacts adapted to cooperate with said flexibly jointed disconnecting contacts, said shields being mounted in and eX- tending through said apertures, the respective switchgear units being in alignment, the end openings of the bus compartments of adjacent units being in communication, and buses comprising short lengths of insulated cables extending from the fixed disconnecting contacts in each compartment through said openings to respective xed disconnecting contacts in the adjacent compartment.

4. In a switching structure of the class described, the combination of a stationary conductor, a portable circuit breaker, and means mounted on said circuit breaker for connecting the circuit breaker to the stationary conductor, said means comprising an insulated conducting blade hinged at the circuit breaker connection, the free end of said blade being bent substantially at right angles, contact means at the end oi said blade, and a stationary contact adapted to co-operate with said contact means, said stationary contact being mounted Within a hollow insulating bushing and connected to said stationary conductor.

5. In combination, a horizontally disposed hollow insulating shield, a stationary switch contact disposed therein, a terminal post movable with respect to said stationary Contact and normally disposed below said contact, a switch arm supported on said post by a flexible joint, said arm comprising an insulated blade, the free end of said blade having a substantially right-angle bend, and a contact portion at the end of said blade co-operable with said stationary contact, whereby movement of said arm on said joint provides for the insertion of said free end of the blade into said hollow shield and the contacting of said co-operable contacts.

6. In combination, a plug contact member, a socket contact member, a horizontally disposed hollow insulating supporting shield for one of said members, said last mentioned contact member being disposed horizontally Within said hollow shield, an elongated insulated contact head for supporting the other of said members, an insulated conducting arm, a flexible joint connecting said head to one end of said arm, a terminal post, a second flexible joint connecting the other end oi said arm to said terminal post, whereby motion of said arm on the last mentioned joint provides for bringing said contact head up in approximate alignment with said hollow shield, and motion of said head on the first said joint provides for aligning the Contact member supported thereon with said horizontally disposed contact member. Y

'7. In combination, a row of front terminal lugs, a row oi rear terminal lugs substantially in alignment therewith, a conducting arm hinged to each of said lugs, a movable contact on each of said arms, corresponding stationary contacts co-operable with said movable contacts respectively, insulating supports for said stationary contacts, a movable barrier normally disposed in front of the front row of arms, and spacing members attached to certain of said arms for spanning from the arms in the front row to said barrier and from the last mentioned arms to the arms in the rear row when contacts are in co-operation and said barrier is in normal position.

8. In combination, a stationary Contact, an insulating support therefor, a terminal post normally disposed below said contact and movable therefrom, a conducting arm movably jointed to said terminal post, an elongated contact member movably jointed to said arm, the movement of said member with respect to said arm being independent of the movement of said arm with respect to said post, said contact member being co-operable with said stationary contact, operating lugs projecting on opposite sides of said contact member, said lugs being engageable by a double pronged operating stick for guiding said member into contact with said stationary contact.

9. In combination, a circuit breaker, a front terminal post, a rear terminal post, a switch arm movably jointed to each of said terminal posts, stationary contacts mounted on insulating supports, said contacts being cooperable respectively with said switch arms, operating lugs projecting from opposite sides of each of said switch arms, and a double pronged operating stick adapted to engage said lugs, whereby to engage the switch ,arm on said rear terminal post, said operating stick straddles the switch arm on said front terminal post.

10. In combination, a stationary contact mounted within a horizontally disposed hollow insulating bushing, a movable contact cio-operable with said stationary contact, said movable contact being connected to one end of a contact head comprising an elongated conducting member having an insulating covering, said head being adapted for insertion into said insulating bushing for establishing contact between said movable and contacts, a rigid insulated conducting arm, said contact head being supported at one end or" said arm by a movable joint, an insulating covering for said joint, a terminal lug, an insulating support therefor, said lug being connected to the other end of said arm by a second movable joint, and an insulating covering for said second joint.

11. In combination, a circuit breaker having a row of front terminals and a row of rear terminals, a pair of electric circuits adapted to be interconnected by said circuit breaker, a rst row oi stationary contacts connected to one of said circ* its, insulating supports therefor disposed above said circuit breaker, a second row of stationary contacts connected to the other of said circuits, insulating supports therefor, said second row of contacts being disposed below said first row of contacts, a two-jointed connecting arm movably jointed to each of said front terminals, contact heads bearing contact members co-operable respectively with said rst row oi stationary contacts, one of said heads being movably jointed to each of said connecting arms, and a two-jointed connecting arm movably jointed to each oi said rear terminals, contact heads bearing contact members co-operable respectively with said second row of stationary contacts, one of said heads icing movably jointed to each of the last mentioned arms.

12. In combination, a stationary contact mounted within a horizontally disposed hollow insulating bushing, a terminal lug, a supporting bushing therefor disposed below said hollow bushing, an upwardly extending insulated conducting arm connected to said lug by a hinged joint, a horizontally disposed contact head connected to the end of said arm by a second hinged joint, insulating sleeves covering each of said hinged joints, a contact member disposed on said contact head, said member being co-operable with said stationary contact, and means for guiding said head and contact member into said hollow bushing and into co-operation with said stationary contact.

13. In combination, a stationary contact, an insulated support therefor, a terminal post movable with respect to said stationary contact, a conducting hinged to said post, a Contact head hinged to the free end of said arm, a contact member carried on said contact head, said member being co-operable with said stationary contact, and additional means for compensating for lim misalignment oi said terminal post with respect to said stationary contact.

11i. A switching station of the class described, comprising in combination, a set of bus bars, an electric circuit adapted i r connection thereto, stationary contact members mounted Within horizontally disposed hollow insulating bushings and connected to said bus bars and said circuit respectively, a portable circuit breaker having terminal posts, a rigid insulated conducting arm hinged to each or said terminal posts, an insulated contact hinged to each ci said arms, said hinged connections permitting movement of said Contact heads with respect to said arms, independent of the movement of said arms with respect to said posts, a contact member carried on each oi said contact heads, and means for manually guiding said contact heads into said bushings and for establishing connection with said stationary contact members.

15. In a switching station of the class described, a portable circuit breaker, a terminal post on said breaker, a stationary contact member, and means attached to said breaker for selectively connecting said terminal post to said stationary contact, said means comprising a plurality of conducting links serially joined together and to said post by flexible joints, said joints being operable independent of each other.

16. In combination, a stationary contact member mounted Within a horizontally disposed hollow insulating shield, a movable contact head having a contact member co-operable with said stationary contact member, a terminal post, means for connecting said post to said contact head, said means providing a rigid supporting arm for said Contact head, said means including conducting means and including also insulating means surrounding the conducting means, a ilexible joint for connecting one end of said arm to said head, and a second flexible joint for connecting the other end of said arm to said terminal post, said exible joints permitting movement of said head with respect to said arm independent oi movement oi said arm with respect to said post.

i7. In combination, a portable circuit breaker having a terminal, a stationary contact member mounted within a horizontally disposed hollow insulating shield, a contact head having a contact member co-operable with said stationary contact member, and means connecting said circuit breaker terminal and said contact head, said means providing a rigid arm supported on said circuit breaker on aI cXible joint and including also insulating means surrounding the arm, said head being jointed to the free end oi said arm, said iieXibie Iioints permitting movement of said head with respect to said arm independent of movement of said arm with respect to said circuit areaker.

l8. A switching station of the class described, comprising in combination a set of bus bars, an electric circuit adapted for connection thereto, stationary contact members mounted within horizontally disposed hollow insulating bushings and connected to said bus bars and to said circuit respectively, a portable circuit breaker for connecting said bus bars and said circuit, said breaker having a terminal corresponding each of said stationary contact members respectively, a movable contact member co-operable with each or" said stationary Contact members respectively, each of said movable contact members being supported on an insulated head, means for connecting each of said movable contact members to said circuit breaker terminals respectively, said means providing supporting arms for said contact heads and including also insulating means surrounding the respective arms, each of said heads being mounted on one end of one of said arms respectively with a limited amount oi movement with respect thereto, and means for supporting the other end of each of said arms on said circuit breaker, said supporting means permitting motion or said arms relative to said circuit breaker independent oi the motion of said contact heads relative to said arms.

ALLEN M. ROSSMAN.

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