US1955287A - Switchboard construction - Google Patents

Description

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April 17, 1934.

April 17, 1934. H. c. GRAVES, JR., n Al. 1,955,287

SWITCHBOARD CONSTRUCTION Filed Feb. 6. 1931 8 Sheets-Sheet 2 INVENTORS #MM ly. gym

By www@ mL'ATToRNEY.

April 17, 1934. H. c. GRAVES, JR., Er AL 1,955,287

swITcHBoARD CONSTRUCTION Filed Feb. 6, 1931 8 Sheets-Sheet 3 FUEL* 6 INVENTORS M a4. @ab ATTORNEY.

April 17, 1934.

H. C. GRAVES, JR., E' AL SWITCHBOARD CONSTRUCTION Filed Feb. 6. 1931 8 Sheets-Sheet 4 INVENTORS ffm' ATTORNEY.

April 17, 1934. c. GRAVES, JR., Er AL 1,955,287

SWITCHBOARD CONSTRUCTION Filed Feb. 6, 1931 8 Sheets-Sheet 5 l N V EN TORS 'fb M L ATTORNEY.

April 17, 1934. H. c. GRAVES, JR., ET AL 1,955,287

SWITCHBOARD CONSTRUCTION MM' ATTORNEY.

April 17, 1934. H. c. GRAVES, JR., Er Al.

SWITCHBOARD CONSTRUCTION Filed Feb. 6, 1931 8 Sheets-Sheet 7 MZ wow Y@ ATTORNEY.

April 17, 1934.

H. c. GRAVES, JR., n AL 1,955,287

SWITCHBOARD CONSTRUCTION Filed Feb. 6, 1931 8 Sheets-Sheet 8 Fis. lZ-b Patented Apr. 17, 1934 swi'rcnBoAnn CONSTRUCTION Herbert C. Graves, Jr., Radnor, Pa., and James A. C. Krips, Haddonfield, N. J., assignors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of New Jersey Application February 6, 1931, Serial No. 513,812

1s claims.

Our invention relates to switchboards and particularly to the construction of switchboards or current distributing panels including switching ymechanisms, specifically circuit breakers, of various sizes and types.

Heretofore it has been the common practice to mount the circuit breakers, meters, etc., on the face of a switchboard panel. As the circuit breakers usually varied Widely in size and shape according to purpose, capacity, type, etc., they projected from the front of the board to widely different extents presenting an unsightly appearance and making it difficult for an operator readily to see their condition as indicated by their mechanism or suitable signal. Further, this arrangement was not only wasteful of space but was inflexible in that it did not readily permit of variation to accommodate expansion of or changes in service requirements.

In accordance with our invention, the switchboard is built up either from a plurality of sections, preferably of equal height, eachsection comprising either a framework, as of angle-iron construction, having one or more compartments, each having a door or removable panel carrying the breaker controlling mechanism, or meters, etc., all of the doors lying in the same plane to provide a flush front switchboard, or as an alternative construction, each section comprises one or more individual cells preferably of standard depth to accommodate the largest circuit breaker, and classified in different heights and widths. The height of each type cell is made equal to or a simple fraction of the switchboard height, as one-half, one-third, one-fourth, etc. 'I'hus cells of equal width may be bolted one on top of another to form sections of standard height, the doors or removable panels of the cells all lying in the same plane.

Further a number of standard height sections, which may be similar or differ as to width or number, or both, of cells, or compartments, may be assembled side by side to afford any desired arrangement of circuit breakers, measuring instruments, and other switchboard appurtenances. This assembly of sections forms a switch group, or enclosed switchboard, of uniform height and uniform depth, with the front surface lying all in one plane and with the back surface in one plane. The construction is flexible in that additional sections may readily be added or other sections substituted for those in use to accommodate an expansion of or variation in the service requirements. Other advantages are later referred to herein.

Further in accordance with our invention, the electrical connections at the back of each section are enclosed, and in some instances additional narrow sections are interposed between adjacent compartments or cells, without disturbing the bus bars.

Further in accordance with our invention, the

circuit-breaker compartments or cells are ventilated, and more particularly, ducts are provided for effecting passage of air or inert gas to and from the circuit breaker compartments, and more particularly louvers of the breaker compartmentsw communicate with narrow spaces between the breaker sections which serve as air ducts.

Our invention further resides in the features of v construction, arrangement and combination hereinafter described and claimed.

For an understanding of our invention and for illustration of some of the forms it may take, reference it to be had to the accompanying drawings in which:

Fig. 1 is a front elevational view of a switchboard assembly embodying our invention.

Fig. 2, is a horizontal cross-section taken on line 2--2 of Fig. l.

Figs. 3 and 4 are vertical section views taken on line 3--3 and line 4 4 respectively of Fig. 1.

Figs. 5 and 6 are vertical views of the right hand end of Fig. l, respectively without, and with the end cover plates.

Fig. 7 is a diagram of the electrical connections of the apparatus of Fig 1.

Fig. 8 is a perspective view of one of the compartments and contents of the assembly of Fig. 1, with panels omitted and parts broken away for clarity of showing.

Fig. 8a is a wiring diagram of the apparatus of Fig. 8.

Fig. 8b is a wiring diagram of a modification of Fig. 8.

Figs. 9 and 10 are detail views on enlarged scale of interlocking circuit-breaker removal and door-mechanism shown in Fig. 8.

Figs. 11 and 12 are detail views on enlarged scale of door-hinge construction affording a substantially unbroken panel front without interference between doors or panels.

Fig. 12a is a side elevational view in section of circuit-breakers and interlocking mechanism.

Figs. 12b and 12c are respectively plan and side elevational views of another form of interlocking mechanism between circuit breakers in adjacent compartments.

Fig. 13 is a perspective view of a cell utilized in a modified form of the invention.

Fig. 14 is a detail section view of part of a Fig. 13.

Figs. 15, 16 and 17 are front, end and plan views of a cell type switchboard.

Figs..18, 19 and 20 in front elevation, end elevation and bottom plan respectively illustrate a forced ventilation system for the composite switchboard.

Referring particularly to Figs. land 2, there is shown a typical grouping of sections to form a switchboard. Specifically, the switch group shown consists of a main circuit breaker and a distribution system of seven circuit breakers of diierent capacities to protect, for example, mo tor circuits of different current requirements. The circuit breakers are arranged in three vertical stacks which'are assembled horizontally, with other sections intermediate them to provide space for vertical bus bars.

The first of these sections, S 1, comprises, as shown most clearly in Fig. 3, two compartments,

the upper C l containing the incoming power cables I, and their connections, and transformers and other appurtenances for the meters A and A mounted upon the front panel or door D l of the compartment. The lower cell C 2 contains the main circuit breaker with protective features and special mounting hereinafter more fully described. The removable panel, or door, D 2, provides a mounting fora manually operable device for controlling the circuit breaker position, specifically, a handle H for mechanically operating the breaker.

Preferably and as shown, the section is of angle-iron construction, providing a framework whose height and depth are of a desired standard and whose width is determined by the maximum size of breaker intended to be housed therein.

The lower compartment C 2 is divided into front and rear compartments by the frame members 11, (see also Fig. 8). These compartments are isolated from each other by the base 2 of the circuit breaker, when in position, and from adjoining compartments by sheet metal plates, not shown, which are welded to the angle iron on both sides, top and bottom of compartment C 2. The top and bottom plates preferably extend entirely across the frame, while the side plates terminate at the frame members 11 to leave open the rear compartment, at least on one side, to permit the feeders F to pass to an adjacent section of the assembly. The top compartment C 1 may be completely enclosed by sheet metal. Preferably, and as hereinafter pointed out more particularly, the back of this section, as well as of the other sections, is covered by a removable or detachable panel to permit access to the circuit breaker connections which are preferably and normally entirely enclosed.

The next circuit breaker section, 8 3, is for housing three circuit breakers placed one above the other, as shown most clearly in Fig. 4, and accordingly, the framework of the section is constructed to divide it into three compartments C 3, C 4 and C 5, one above the other, preferably of equal height. The over-all height and depth of the section is preferably the same as section S1 and the width of the section is determined by the maximum sized breaker to be housed therein, usually this section is narrower than the main or receiving section S 1.

Each compartment of the section is divided into a front or circuit breaker compartment, and a rear or bus bar compartment, by the circuit breaker base 2. The circuit breaker mechanism is omitted in Fig. 4 for clearness. It will be understood that it is, in each case, mounted on the front side of the base 2, and that it is operated by the handle structure H carried by the corresponding door D 3, or equivalent.

In the particular section shown, lthe three circuit breakers are of different dimensions and accordingly the depth of the several front compartmentsvary. For example, the bottom, top and middle breakers may be of greater capacity in the order named, and the depths of the corresponding front compartments are correspondingly greater to accommodate the increasing size of the breakers. It will be understood that this standard section, as well as the others, may be manufactured in quantity in advance of orders, and assembled in accordance with the requirements of a particular installation, the connection panels being positioned in accordance with breaker sizes.

In each rear compartment, the cables and bus bars are permanently connected to stationary or xed contacts 4. By the construction shown, the circuit breakers may be individually withdrawn from their compartments at any time, through detachable front panel or door D 3, without need of access to the back of the section, or'switchboard. It has the further advantage that outgoing cables may be drawn in and connections made by electricians working through the open door space. The outgoing conduits 0 3, 0 4, 0 5, may, as shown, extend vertically, for communication with corresponding compartments where they are supported by the horizontal metal sheets. The axes of these conduit lie in a plane parallel and close to the side of the section so as not to interfere with ready access to the rear compartments. This is of particular advantage when the breaker studs are connected directly with the'bus bars, as in the third breaker section S 5, Fig. 5.

As this section is for housing four smaller circuit breakers, the horizontal frame members are disposed to divide the standard section into four compartments C 6 to C 9, one above the other, preferably of equal height. In the particular installation shown, the breakers are of similar dimensions, as depth, and accordingly their bases 2, which divide the several compartments into front and rear compartments, are secured substantially the same distance from the front of the section. The circuit breaker mechanism is not shown for clarity, but it Willbe understood that it is mounted on the front side of the base 2, and may be operated by the handle structure H mounted on the doors of detachable panels D 5.

As in section S 1, and section S 3, the compartments may be separated by horizontal plates, as of sheet metal, which extend from the front of the panel to at least the depth of the breaker compartments and preferably to the rear of the framework. Similarly, the sides of the front or circuit breaker part of each compartment is preferably covered with sheet metal to isolate the circuit breaker cells from each other and from the conductor compartment or compartments particularly when the voltages are high, as more than 400 volts.

The horizontal plates between the compartments of -the sections separate the horizontal bus bars and prevent metal objects, as tools, from beingdropped on the bars and causing short circuits; they also act as supports or guides for conduit.

Particularly, when adjacent circuit breaker sections have a different number of compartments, there may be interposed therebetween narrower sections, such as section S-2 and section S-4, for vertical bus bars. These sections are also standard depth and height, that is, they are preferably equal in height and depth to the other sections of the switchboard. Either or both the front and back panels of the sections may be removable and consist of either one piece or several pieces. This section is usually not divided into vertical compartments and leaves an unobstructed space for the vertical bus bars V.

Referring particularly to Figs. 1 and 2, the vertical bus bars V are connected to the main horizontal bars F which project through the open side of the lower compartments C2 of section S-l. The horizontal bus bars f extending to the right from the vertical bus bars V into the rear conductor compartment of C4 and C5, terminate in these compartments, while the upper bars f extend through or across the top conductor compartments of sections S-3, S-4, and S-5. Within the conductor compartment of C-3, are connections from the bars f to the fixed contacts 4 of the contact panel 3. Similarly in the top compartment of section S5, conductors extend from the bars f to the studs projecting from the circuit breaker base 2. From the vertical bus V-1, in section S4, extend bars f-l to the several conductor compartments of C-7, C-8 and C-9. If sections S-3 and S--5 are of the same number of compartments, the section S-4 may be dispensed with and the horizontal bars f continued across the back of the sections.

The bus bars entering each compartment are held rigidly in position by the complementarily notched blocks b and b', held to each other and to the section framework, as by bolts, as indicated in Fig. 4.

An important feature of this invention is that the circuit breakers of each section may be the same or different from one another, and the same or different from the circuit breakers of other sections. Obviously,.in any section, the number of compartments may be greater or less than that specifically shown and described. Further the group may consist of a single section or any convenient number of sections which may have one or more independent systems of circuit breakers and conductors.

When selected sections, preferably of equal height, are assembled to form a desired group, the front detachable panels or doors lie in the same plane so that the front of the switchboard presents an unbroken appearance, and the rear enclosing sheets lie all in one plane parallel to front.

The open sides of end sections, as S-l and S-5, are covered by detachable plate structure, which as indicated in Fig. 6 may correspond in height and width to the standard switchboard section. The top of the group, may be closed by a panel extending the length of the entire group or by individual plates for the top of each section.

With all doors and panels in position, all conductors and circuit breakers are enclosed and in addition, the circuit breaker compartments are sealed from each other and from the conductor compartment.

Each of the circuit breakers is removable through the opening afforded by the detachable panel or door of its compartment without moving the bus bar connections and additionally in sections such as S-l and S-3 this removal is possible without need of access to the rear of the switchboard. In this latter case, cables may be pulled into enclosure, as during installation, through conduits in the locations shown, by men working through the front door only. It will be understood of course, that all the sections of the switchboard may be similar to section S3, in that, for example, instead of bolting the conductors to the circuit breaker studs as in S-5, they may be connected to nd contacts on a connection panel 3.

It is possible greatly to expedite the manufacture of switchboards by fabricating them from standard sections in stock. Further, the sections, or group of sections, may be assembled, and tested in the factory with all electrical devices and internal connections. The assembly may be shipped as a unit, eliminating field assembly, wiring labor, and possibility of error in assembly, at the place of installation at which it is only necessary to connect the incoming and outgoing cables, to put the switchboard in service. It is also possible for the switchboard with all connections to be shipped, installed and connected without some or all of the circuit breakers; the breakers to be shipped and installed when completed, thereby reducing the time otherwise necessary to put the switchboard into service.

The assembled group or switchboard at the place of installation may rest upon a pair of channel irons A, supported by or embedded in the floor or foundation B, and extending the length of the group substantially flush with the front and back respectively of the framework of the sections as indicated in Fig. 5.

It is also a feature of our invention that the switchboard accommodates itself readily to expansions or variations in service. Sections in use may be replaced by other standard sections having a different number of compartments, or sizes of circuit breakers, or both, etc. Or, if desired, empty compartments, or sections, may be included in the assembly, and circuit breakers of proper capacity subsequently added as the need arises.

Referring to Fig. 8 there is shown in greater detail, the construction of the cell C-2 of section S-l, and with the circuit breaker therein disconnected from the incoming power. The circuit breaker 13 is mounted on the base 2, of insulation, which is secured, as by bolts 9 and clamps 10, to a movable frame 8 which is supported from the main frame by two pairs of pantograph links, 6, '1, one pair on each side of the base. Normally, the base 2 is in the position shown in full lines in Fig. 2, with the contacts 5 at the rear thereof in engagement with the contacts 4 of the fixed terminal panel 3. By mechanism hereinafter described, the panel 2 and the breaker mechanism thereon may be moved toward the front of the section C-2, the pantograph links maintaining the base vertical by their parallel action. 'Ihe spring fingers 5 at the back of base 2, by this movement, are withdrawn from the stationary contacts 4. As contacts 4 are in the main circuit, when the panel 2 is withdrawn, the circuit breaker is dead-and all of the circuit breakers of the group are in the same condition (see Fig. 7).

To effect this movement of the breaker for inspection, replacement, or repair, there is preferably provided a screw mechanism consisting of a nut 25 held by the plate 14 of the breaker panel frame 8 and engaging the threaded shaft having a squared end extending through the front angle of the frame, see Figs. 9 and 10, which is normally covered by the lock plate 20 which is concealed when the flanged door 18, hinged at 19, is closed. When the circuit breaker is in its normal position, with the contacts 4 and 5 in engagement, and the base 2 in the position indicated in full lines in Fig. 3, the locking bar 15 is held at one extreme position by the curved bolt 21. The toe of the locking bar 15 engages the locking flange 22 of plate 14 which projects forwardly from the circuit breaker panel frame 8. One end of the locking plate 20 guards the end of shaft 12, while the other end 16 of the plate 20 is held by spring 23 against the side of the locking bolt 21, which is pivoted as at 17, at or on the back of door 18. v

For moving the circuit breaker and its panel to the position shown in dotted lines in Fig. 3, or generally to the position shown in Fig. 8, the

door 18 is first 'opened until the notch 21a inV the end of locking bolt 2l is in line with the front angle iron at which position, the bolt is lifted by action of the spring 23 through the cam 16. 'I'he bar 15 moves to the dotted line position, Fig. 9, to uncover the squared end of shaft 12 to move out of the path of the flange 22 of plate 14, and to lock the door 18 open.

A socket wrench is then applied to the end of shaft 12 and rotated to draw the circuit breaker assembly away from the contact panel. 'Ihe initial movement draws the flange 22 out along the edge of the bar 15, locking it in the dotted line position. Consequently, the bolt 21 is held in its raised position by cam 16 with the notch 21a receiving the section frame, and so prevents the door from moving either Way during the jacking in and out of the breaker panel.

When the circuit breaker assembly is returned to its original position with the contacts 4 and 5 fully engaged, the ange 22 has been moved beyond the end of bar 15, permitting it to be moved back, (after the wrench has been removed from the end of shaft 20). The door may then be closed and held in that position by any suitable means, such as, for example, machine screws 45 which project through the door for reception by the holes 38 of the section frame. This construction insures full engagement of the contacts 4 and 5 before the door can be closed to bring the manual operating mechanism thereon into position for operating of the circuit-breaker.

Specifically, the manually operable mechanism for controlling the circuit breaker position includes two levers 34 and 35 mounted on the rear end of a shaft 32 which passes through the supporting member 33 riveted to the door. The handle H at the outer or front end of the shaft enables the operator to rotate it for operation of the circuit breaker mechanism by either of the levers 34 or 35. The circuit breaker mechanism and the construction of levers 34 and 35 per se form no part of the invention.

The construction shown in Fig. 8 also includes mechanism for preventing the circuit breaker from being in closed circuit position during the engagement or disengagement of the separable contacts 4 and 5. The lever 31 passes through a slot in the base 2 carrying the pivotal support 28 for the lever. The front end of the lever is connected to the tripping mechanism of the circuit breaker by link 29. The lower surface of the back end of the lever forms a cam 27 which rides over the stationary piece 26 secured for example to the frame member 11.

In Fig. 8 the circuit breaker panel is shown in its forward position, with the automatic trip cam clear of piece 26 which has permitted the breaker to be closed. However, upon the rst inward movement of the breaker assembly, the sloping surface of cam 27 rides up on piece 26, pulling down the link 29 to trip the circuit breaker. 'I'he cam maintains the breaker in this position until the main contacts 4, 5 are in complete engagement for which position the neck 30 of the cam is beyond the piece 26, permitting the breaker to be closed. The trip cam operates in the same manner during the disengagement of the separable contacts, tripping the breaker upon initial movement, permitting the breaker to be closed only after full separation of the contacts 4, 5.

The hinge construction of the door is such that when the circuit breaker sections are assem` bled immediately adjacent each other, or when as in the particular installation shown, the circuit breaker sections are separated by an intermediate conductor section having a flanged panel ush with the doors, the doors of dierent sections may be swung freely without interference from the door or panel of the adjacent section, and this is possible although the adjacent doors or adjacent door and panel are separated by an inappreciable distance or practically in contact, and the hinges are concealed. Briefly, this is effected by constructing the hinge so that the flanged door pivots at its outer corner.

The preferred hinge construction is shown in detail in Figs. l1 and 12, while a general arrangement is shown in Fig. 8. To the hinge blocks 19 which are secured, as by welding, to a vertical member of the section framework, are secured, as by screws, the pin supporting members 37. The clamping screw is passed through slots which 115 allow vertical adjustment of the door during assembly and after final adjustment the pin supports may be welded in position. In the inside angle of the door ange, adjacent the top and bottom of the door, are hinge pieces 38 which 120 may be welded to the door. The pin 44 passes through a hole in the upper pin support 37, through a hole in the hinge piece 38, and into a recess in the lower pin support 37. By this construction there is no need of a head for the pin 125 44. Preferably a pilot hole is provided in the lower pin support 37 for driving the pin out, with a suitable tool, as a punch. By removing the pins.

44, the door may be completely detached from the section or cell framework. 130

As clearly appears from Fig. 11, the door 18 shown in full lines, may be opened or closed independently of the adjacent door or panel indicated in dotted lines, though the rearwardly extending flange portions of the doors are practically in contact with each other, so that the front of the panel appears substantially unbroken. As previously pointed out the provision of doors permits the inspection, calibration, removal, etc., of individual circuit breakers without interfering wtih the adjacent circuit breakers or apparatus of the switchboard.

The circuit-breaker specifically illustrated in Fig. 8 may be electrically closed and opened by switches 62 and 63 (Fig. 8a) which are in circuit with the closing solenoid 58 and the tripping magnet 59 respectively. When the breaker is tripped either manually, by abnormal circuit conditions, or by remote control switch 63, switch 60 is opened to break the circuit of tripping coil 59 and switch 150 61 is closed to complete the circuit of a signal 69. The mechanical connections for operation of switches and 61 are clearly shown in Fig. 8.

As previously explained, the contacts of the circuit breaker are connected to the power or main circuit by separable contacts 4, 5 carried respectively by the stationary panel 3 and the movable base 2 of the breaker. The auxiliaries such as solenoid 58, trip 59, signal 69 etc., are similarly connected to a suitable supply circuit 64 by detachable contacts; for example, Figs. 8, 8b, the panel 57 secured to the compartment framework below panel 3, carries a pair of contact strips 53 and three contact strips 54 of greater length.

When the base 2 is in its fully retracted position, all of the contact fingers 56 projecting from the rear thereof are out of engagement with stationary contacts 53, 54. The main contacts 4 and 5 are also separated. When the base 2 is moved partly in", only the long contact strips 54 are engaged by the corresponding contacts 56 which permits testing of the remote or electrical control of the breaker. When base 2 is moved completely in all contacts including main contacts 4, 5 are engaged and the circuit-breaker is in condition to perform its usual service.

Testing of the circuit-breaker and its control circuits without removal of the breaker from the switchboard is possible also by the arrangement shown in Fig. 8b. The conductors oi the auxiliary circuits terminate in a socket 65 adapted to receive a plug 65 at an end of a multiconductor cable 66 connected to terminal block 67 mounted upon the section or compartment frame. To test, the base is moved outwardly until contacts 4 and 5 are separated. If the breaker is to be removed from the frame, the plug 65' is pulled out of the socket 65.

In Fig. 12a are shown two circuit-breakers of the type illustrated in Fig. 8, one above the other and mechanically inter-locked to ensure that when one is closed, the other is open and vice versa. Specifically, the stationary contacts in each compartment have their lower terminals connected to separate supply cables 72, 73 while the upper terminals connect to a common feeder bus f.

Assuming that the upper circuit breaker is open and the lower circuit-breaker closed, when the upper breaker is closed manually or by remote control, the lever 74, pivoted on the breaker and extending through base 2, is rotated in clockwise direction by engagement with member 74a movable with the contact-operating mechanism, to rotate lever 75, pivotally mounted on supporting member 75a secured to and extending from the section framework. Movement of lever 75 is communicated to lever 77, similarly supported by the section frame, to effect counter-clockwise movement of lever 78, extending through the base of the lower circuit breaker, which operates the tripping mechanism of the breaker.

Similarly the closing of the lower breaker effects tripping of the upper breaker through the levers and links 79-83.

The ends of levers 74, 83, 79 and 78 which extend through the circuit breaker bases 2 are provided with sloping ends to prevent interference during inward or outward movement of the circuit-breakers. Further, the circuit-breakers are interchangeable in position and may be removed or replaced without disassembling or adjusting the interlocking connections.

Another type of interlock in which the switches are mechanically interlocked by the act of placing them in their compartments is shown in Figs. 12b and 12o. The arrangement though illustrated as applied to circuit-breakers which are side by side is equally adapted for circuit-breakers disposed one over another. The opposite ends of rocker arm 84 pivoted at 85 to the switchboard framework in back of the circuit-breaker bases are respectively in the paths of movement of plungers 86 and 87 movable with the movable contacts of the circuit breakers. By this arrangement, it is necessary to trip one circuitbreaker before the open one may be closed. Each circuit breaker may be removed merely by removing bolts, screws or the like, holding its base to the framework without disturbing the interlock.

In accordance with a modification of our invention, individual circuit breaker enclosures are assembled vertically and horizontally, as shown in Figs. 13 to 17. One of the standard units is shown in Fig. 13 and comprises four metal sheets iianged and welded to, in effect, provide a compartment having an open front and back. The front edges are reinforced with angle irons 40 for supporting the door and stifening the structure. Additional angle irons 41 are welded to the side walls for supporting the circuit breaker panel, or a, connection panel. InFig. 14 one of these standard units is shown with a hinged door enclosing one type of circuit breaker. The cell is secured, as by the lower bolts 43, to the channel irons serving as a foundation for the switchboard, while the upper bolts 43 pass through the frame work of a second cell to form a vertical stack of circuit-breaker compartments, generally similar to that afforded by one of the sections of the modification of Fig. 1. The bolts 42 pass through the angle iron frame of an adjacent cell.

The standard cells will vary in dimensions according to the dimensions of the circuit breaker; within certain limits of breaker size, the depths of the cell from front to back is constant, and the distance from the front of the cell to the panel supports 51, will vary to accommodate the different sizes. The heights of the cells are equal to or a simple fraction of, the height of the switchboard, as 1/2, l/:., 1A, etc. A number of widths are standard for each cell height so that the width of the section formed by vertically disposed cells will depend on the widest breaker installed in the section.

The unit enclosures are preferably designed with a standard bolt drilling for horizontal assembly so that a section of any number of units may be attached to a section of the same or a different number of units. Figs. 15, 16 and 17 disclose a switch group built up from the unit cells which is similar to the switch group of Figs. 1 and 2, built from standard sections. In these figures, the positions of the bolts holding the cells together are indicated by a heavy line, and the unused holes by light dotted lines. Holes may be provided in the back flanges of the cells for supporting bus bar clamps and for attaching the bus bar` and cable enclosures.

In this construction also, there may be utilized hinged doors, as previously described, and when the cells are assembled all of the doors will lie in the same plane to form a fiush type switchboard. As shown in Fig. 8, the breakers may have a signal member 24 movable with their operating mechanism, the signal being visible through a window 24a in the breaker door. By

applicants flush type construction, the condition of all the circuit breakers is at once apparent to an operator glancing along the board.

With either the cell type or section construction, the doors may be provided with louvers to provide for ventilation and gas expansion. These openings are preferably protected, as most clearly shown in Fig. 8, by insulated baille plates 36.

In the arrangement shown in Figs. 18 to 20, a system of forced ventilation is utilized and the doors of the cells are without louvers, aiording more space for instruments on the doors and resulting in neater appearance. The system may consist of a motor driven blower 47 in a bus bar enclosure and a series of ducts leading fresh air to the breakers and conducting air away from the breakers.k The space between the i'loor and the bottom of the lower row of cells may be utilized as an intake manifold extending the length of the switchgroup. Between circuit breaker sections are two vertical chimneys 49, 52, one of which, 49, opens into the lower manifold 48 and conducts fresh air into each cell through the lower louvers 50, the air flowing through the breaker cell and out through louvers 51 at the upper and opposite corner of the breaker cell; that is, the air rises and diagonally crosses through the cell and is exhausted through the front duct 52 which may communicate with an outlet duct 53 extending along the top of the switchboard group.

By this arrangement all circuit breaker compartments are ventilated, and gases incident to opening of the breaker are carried off. There is practically no possibility of a flash from one breaker entering another breaker compartment as it would be necessary for the flash to travel through the duct for a distance corresponding to the breaker height and then reverse its direction of movement.

The blower system is of advantage where severe dust conditions exist,`as washed air may be used for ventilation and the cells kept under a pressure slightly above atmosphere to prevent infiltration of dust. Where `dust conditions are not serious, and appearance of smoke or gases must be prevented, a suction blower may be placed in a discharge duct to maintain a slightly subatmospheric pressure in the breaker cells.

What we claim is:

l. A dead-front switchboard comprising a plurality of contiguous compartments, the compartments forming a self-supporting structure, movable hinged panels for normally closing said compartments and lying in the same plane and with no appreciable spacing between neighboring edges of adjacent panels to form the flush front of said switchboard, switching units within said compartments each removable through an opening in the front of said switchboard afforded by movement of the corresponding panel, conductor compartments, wiring therein connecting said switching units and panels for closing said conductor compartments lying in a common plane and with no appreciable spacing between neighboring edges of adjacent panels to form the flush back of said switchboard.

2. A dead-front switchboard comprising a horizontal arrangement of sections forming a selfsupporting structure, each section having at least one switching compartment and one conductor compartment to the rear thereof, movable hinged panels normally closing said switching compartments and lying in the same plane and with no appreciable spacing between neighboring edges of adjacent panels to form the front of said switchboard, switch controlling structure carried by each of said panels, conductors extending from the conductor compartment of one section to the conductor compartment of another section, and movable panels normally closing said conductor compartments and lying in the same plane to form the back of said switchboard.

3. A dead-front switchboard comprising a selfsupporting structure having at least two sections, one of which has at least one switching compartment, and another of which has at least two switching compartments, directly above one another and a non-switching section between said switching sections enclosing vertical busses with feeders to said switching compartments.

4. A switchboard comprising a plurality of compartments for housing electrical apparatus, anged panels for closing said compartments at least some of which are movable, and means enclosed and concealed by said movable panels and pivotally supporting them adjacent their outer edges to permit them to be swung free of obstruction by adjacent panels, all of said panels lying in the same plane with their flanges directed rearwardly, and with no appreciable space therebetween.

5. A switchboard comprising a plurality of contiguous compartments, the compartments forming a self-supporting structure, removable panels for closing said compartments lying substantially in the same plane to form the flush front of said switchboard, circuit breakers in said compartments, at least one of which is provided with auxiliary electrical devices, means for supporting said breaker for movement within its 'compartment, stationary contact terminals within said compartment, circuit-breaker contact terminals movable with said breaker into and out of engagement with said stationary contact terminals, and means for maintaining connection from stationary conductors within said compartment to said auxiliary electrical devices when said circuit-breaker is in an intermediate position within its compartment with said contact terminals disengaged and permitting disconnection from said conductors to allow removal of said 'circuit-a breaker through the opening afforded by movement of the panel of its compartment.

6. A switchboard comprising a plurality of contiguous compartments, the compartments forming a self-supporting structure, removable hinged panels for closing said compartments lying substantially in the same plane to form the ilush front of said switchboard, circuit breakers in said compartments, at least one of which is provided with remotely controlled breaker-tripping and closing devices, link means for supporting said breaker for movement within its compartment, stationary contact terminals within said compartment, and co-operating contact terminals movable with said breaker for engaging all of said contacts for circuit-controlling position of the breaker and engaging only certain of said contacts for testing the remote-control devices.

7. A switchboard comprising a plurality of contiguous compartments, the compartments forming a self-supporting structure, removable panels for closing said compartments lying substantially in the same plane to form the ush front of said switchboard, circuit breakers in said compartments, at least one of which is provided with remotely controlled tripping and closing devices, means for supporting said breaker for movement within its compartment, circuit-breaker terminals movable with said breaker into and out of engagement with said stationary contact terminals, and flexible conductor to said remotely-controlled devices including a detachable connection to permit testing of said devices by movement of said breaker within its compartment to an extent effecting separation of said contacts.

8. A switchboard comprising vertical columns of separate, individual cellular compartments set one upon top of another to form a self-supporting structure, each compartment housing switchboard apparatus and having a movable panel for normally closing the front of the compartment, the said panels lying in a common plane, and the panels of adjacent compartments abutting each other and comprising the front of the switchboard.

9. A switchboard comprising vertical columns of separate, individual, cellular compartments set one upon top of another to form a self-supporting structure, each compartment housing switchboard apparatus and having a hinged door for normally closing the front of the compartment, the said doors, when closed, lying in a common plane, and the edges of the doors of adjacent compartments abutting each other, said doors comprising the front of the switchboard.

10. A switchboard comprising Vertical columns of separate, individual, cellular compartments set one upon top of another to form a self-supporting structure, each compartment housing switchboard apparatus and having a movable panel for normally closing the front of the compartment, the said panels lying in a common plane, and the panels of adjacent compartments abutting each other and comprising the front of the switchboard, said compartments having removable panels normally closing the rear of the compartments and lying in a common plane to comprise the back of the switchboard.

11. A switchboard comprising structure forming a plurality of compartments, movable panels for closing said compartments and forming the front of said switchboard, circuit-breakers removable from said compartments from the front of said switchboard through openings aorded by movement of said panels, means for operating said breakers from the front of the switchboard, and mechanical interlocking means between breakers in adjacent compartments supported by said structure.

12. A switchboard comprising structure forming a plurality of compartments, movable panels for closing said compartments and forming the front of said switchboard, circuit breakers disposed in said compartments and removable through the front of said switchboard, and interlocking means mechanically connecting the closing mechanism of a breaker disposed in one compartment to the tripping mechanism of a breaker disposed in an adjacent compartment comprising mechanism supported by said structure independently of said circuit breakers.

13. A dead front switchboard comprising an assembly of sections of uniform depth and separable along vertical planes, each section independently supported from the floor, horizontal and vertical partitions dividing each section into compartments, certain of the compartments opening to the front of the board and housing switchboard apparatus removable through the opening, other of said compartments housing bus bars connected between sections and to the switchboard apparatus, and a removable hinged panel for each of said openings, said panels being in the same plane and substantially contiguous to form the unbroken front of the board.

14. A dead front switchboard comprising an assembly of sections of uniform depth and height independently supported from the floor and separable along vertical planes, each section comprising horizontal partition structure dividing it into tiers, and vertical partitions dividing the tiers into front compartments for housing switchboard apparatus and rear compartments for housing bus bars connected to said apparatus, said front compartments opening to the front of the board, and a removable hinged panel for each of the front compartment openings, said panels being in the same plane and substantially contiguous to form the unbroken front of the board.

l5. A switchboard of the type of claim 14, characterized by the fact that the sections are of various widths, and/or the front compartments are of Various depths to accommodate Various sizes of circuit-controlling units.

16. A dead front switcboard comprising an assembly of sections of uniform depth and height and separable along vertical planes, each section comprising framework for supporting it from the floor, horizontal partition structure extending between members of the framework for dividing the section into tiers, and vertical partition structure dividing each tier into a front compartment for housing switchboard apparatus and a rear compartment for housing bus bars connected between sections and to switchboard apparatus of the respective front compartment, and a removable hinged panel for each of the front compartment openings, said panels being the same plane and substantially contiguous to form the unbroken front of the board.

HERBERT C. GRAVES, JR. JAMES A. C. KRIPS.

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