US2555025A - Bus bar reversing switch - Google Patents

Description

.May 29, 195l E. E. CHEEK 2,555,025

BUS BAR REVERSING SWITCH Filed Feb. 20, 1948 5 Sheets-Sheet 1 mi p j H Q@ Em wm N n Em Ww NQ.. Q $55 llllll i -mi Q May 29, 1951 Flled Feb 2O 1948 May 29, 1951 E. E. cHEEK 2,555,025

BUS BAR REVERSING SWITCH Filed Feb. 2o, 1948 5 sheets-sheet :s

IN VEN T 0R.'

Patented May 29, 1951 BUS BAR REVERSING SWITCH Edward E. Cheek, Pittsburgh, Pa., assignor to United States Steel Company, a corporation. of

New Jersey Application February 20, 1948, Serial No. 9,793

7 Claims. 1

This invention relates to a reversing switch and, in particular, to a reversing switch adapted toA be connected in a busbar circuit carrying a heavy direct current such-as employed in electrolytic processing. l y Incertain electrolytic processes, it is desirable occasionally to reverse the polarity of the directcurrent supply. One example is the continuous electrolytic cleaning of ferrous strip. Numerous types of reversing switches are known, of course, but none of those availablev commercially is particularly suited for installations wherethe currentv load. is great, e. g., 10,000 amps., and requires a plurality of large, heavy busbars in each side of the circuit. A reversing switch for such circuits must have a current-carrying capacity at l-east as great as the circuit conducto-rs'in order to prevent over-heating., and preferably a'capacity even greater because of the unavoidable contact resistance betweenv fixed and movablel switch members and the fact that switch parts are necessarily less susceptible to cooling by atmospheric convection than the busbars themselves which are installed bare and in spaced relation. They lack of such a switch has made it necessary heretofore to unbolt the bus structure at some point, disassemble it and reassemble it with reversed polarity. Even though it is desirable to reverse polarity only infrequently, considerable time'and labor are consumed by this procedure. 5

I have invented a reversing switch particularly4 suited for connection in busbar circuits carrying heavy currents, which. makes it possible to change the polarity ofthe direct-current supply quickly and easily, as often as desired, without deenergizing the circuit for more than a few seconds. `In a preferred embodiment, the switch comprises, a generally cylindrical but slightly tapered drumV composed of two similar segments having a circumferential extent of substantially 180, disposed with their axial diametral planes adjacent but separated by insulating board. The drum is mounted on a shaft for rotation and the segments thereof have wiping contact with conducting blocks or shoes to which the circuit busbars are secured. The lateral or peripheralsurface of each segment is recessed longitudinally to accommodate an insulating segment subtending an angle of about 45. The insulating segments selectively engage the shoes on which the busbars from the load terminate. Each shoe on which a busbar from the current source terminates always has contact With the same one of the conducting segments, respectively The drum is spring-pressed longitudinally to seatv it rrnly against the shoes which have their faces tapered to conform thereto and thus afford a seat therefor. A suitable motor disengages the drum from the shoes when it is desired to effect a reversal and another motor causes a limited angular movement of the drum after which the first motor reverses and with the spring reseats the drum against the shoes. The switch may be adapted Vfor manual operation, but I prefer to employ Huid-pressure motors and I provide an automatic system of control initiated by actuation of a push-button or like starting switch, for causing operation thereof to effect the slight movements of the drum necessary tov reverse the polarity.`

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer tothe accompanying drawings illustrating the present preferred embodiment. In the drawings:

Figure l is a plan view with parts in horizontal section;

Figure 2 is a side elevation partly broken away;

Figure 3 is a transverse section taken along the plane of line III-III of Figure l;

Figure 4 is a horizontal section taken along the plane of line lV-IV of Figure 2*;

Figure 5 is a schematic diagram of the electrical control system; and

Figure 6 is a diagram showing the control means for switch-operating motors.

Referring in detail to the drawings, the reversing switch of my invention comprises a drum It mounted on a vertical shaft I I and adapted to enga-ge xed contact shoes I2, I3, I4, I5 and I 6 of copper or other suitable electrically conducting metal; The drum and shoes are generally cylindrical but are slightly tapered downwardly, the shoes forming a seat on which the drum normally rests with the lateral surface thereof engaging the shoes. The lower end of the shaft II is threaded into the piston rod of a fluid-pressure motor I'I. The cylinder of motor I? thus serves as a bearing for shaft I I, permitting longitudinal sliding movement with the piston in the cylinder, as well as rotation thereof. The upper end of the shaft is slidably and rotatably received in a guide tube or bearing I8 extending downwardly from a fixed support I9. A compression spring 2) surrounding the tube I8 and shaft II and bearing on the support I9 and drum I0, normally urges the drum against its seat. The admission of operating fluid to the motor I'I, however, serves to raise the` drum against the force of the spring preparatory to limited rotary` movement. The

3 switch is adapted for ceiling mounting by suitable hangers, not shown, in case the busbar circuits described later are suspended therefrom so as to be out of the way.

The drum I6 comprises a pair of generally semi-cylindrical conducting segments 2| and 22 of copper or the like separated from each other by insulating board 23 and from the shaft II by an insulating sleeve 24. The segments are assembled about the shaft between metal end plates 25 and 25a which are spaced therefrom by insulating discs 26. The parts of the drum are held assembled by bolts 21 extending longitudinally through holes drilled in the segments, the end plates and the insulating discs. The bolts are surrounded by insulating sleeves 28. The drum is adjustable axially of the shaft II by means of nuts Ilia threaded thereon.

The segments 2| and 22 are recessed longitudinally to accommodate insulating segments 29 and 36, respectively, spaced from the longitudinal edges of the conducting segments. As shown in Figure 4radii thro-ugh the centers of segments 29 and 36 make an angleof about 65 with the plane of insulating board 23 separating the segments 2| and 22. As a result, when the drum is in the position illustrated in solid lines in Figure 4, the shoey I4 engages the segment 2|, the shoe I6 engages the segment 22 and the shoe I5, the insulating segment 36 carl ried thereby. When the drum is turned toan angle of about 45 to its other position, indicated in chain lines in Figure 4, shoe I5 engages segment 22, shoe I6 engages segment 2| and shoe I4, the insulating segment 29 carried thereby. The shoe I2 engages the segment 2| and the shoe I3, the segment 22 in either position of the drum.

The shoes I2 and I3 have terminals 3| and 32 composed of a plurality of conducting bars extending outwardly therefrom. The terminals are held in assembled relation by bolts-33 extending through the terminals and through insulating boards 34 and 35 on opposite sides of the switch and intermediate insulating spacer blocks 36, 31 and 38. The two sides of a busbar circuit from a generator or converter, indicated at 39 and 46, each including a pair of spaced bars, are secured to the terminals 3| and 32, respectively, by bolts 4I. Conducting filler blocks 42 are disposed between the spaced busbars and between the latter and the terminals.v The bolts 33 and 4I have insulating sleeves 43 therearound. These bolts extend through longitudinal channels 44 which constitute side frames for the switch.

The shoes I4, I5 and I6 also have terminals 45, 46 and 41 extending outwardly therefrom between the insulating blocks V36 and 33, being separated from each other by insulating boards 48 and 49. The end of one side of the load busbar circuit 56 makes contact with the terminal 45. Theright-hand ends of the insulating board and block 38 are recessed to receive the end of the other side of the circuit, designated 5|, but it will be observed that the latter is insulated from the terminal 41. Jumper busbars 52 engage the ends of the busbars 5I and the terminal 46. Similar jumper busbars 53 connect the ends of the busbars 56 to the terminals 45, 46 and 41, the busbars 56, 5|, 52 and 53 and the insulating boards 48 and 46 are secured together between the outside boards 34 Y and 35 by bolts 33 and 4I in the same manner as the terminals 3| and 32 and busbars 39 and 46.v

By virtue of the construction described and particularly the jumper busbars 52, the side 5| of the load circuit is always connected to the shoe I6. The other side of the load circuit 56 is connected directly to the terminal and by the jumper busbars 53 to the terminal 41. Thus, when the drum I6 is in the position illustrated in solid lines in Figure 4, the side 56'ofthe load circuit is connected to the. side 39 of the supply circuit and the side 5I of the load circuit is connected to the side 46 of the supply circult through terminal 46 and shoe I6. When the switch drum is in the position indicated in chain lines, side 56 of the load circuit is connected to side 46 of the supply circuit through jumper busbars 53 and shoe I5. At the same time,

Y side 5| of the load circuit is connected to side 39 of the supply circuit through jumper busbars 52 and shoe I6. Shifting of the drum I6 thus effects the reversal of the polarity of the load.

For shifting the drum I6 through .the angle necessary to effect reversal, I employ a fluidpressure motor 54 mounted on any suitable support 55. A link 56 has a ball and socket connection 51 to the piston rod of the motor 54 and a similar connection 58 to a stud 59extending upwardly from the end plate 25 of the drum.

rEhe motors I1 and 54, as shown in Figure 6, are controlled by valves 60 and 6|. These are four-way valves having no neutral position and are operated by solenoids 62 and 63, respectively. The valves may be of `any suitable construction, a vrotary type being illustrated comprising a body 65 and a rotor 66 therein operated by a ratchetwheel 61. A pawl 68 pivoted to the armature of the operating solenoid causes partial rotation of the rotor on energization of the latter. Specifically, each energization of the solenoid effects aquarter-turn of the valve rotor, thus reversing the connections to the ends of the cylinders of the motors. A supply of motive iiuid is maintained under pressure at a suitable `reservoir at 64 connected to the pressure ports of the valves.

The control circuit for the solenoids 62 and' 63, as shown in Figure 5, includes a push-button or other manual switch 69. To effect a reversal of the position of the drum I6, the push button is actuated.'.The upper contact 'G9a-'of the switch closes a circuit for solenoid 62. This circuit includes an interlock 16 which is closed only when the supply circuit 39, 46 is de-ener- 'gized This prevents operation of the reversing switch under load. Energization of solenoid 62 operates the valve 6I to admit motive fluid to the' lower end of motor I1, thereby raising driun I6 against the pressure spring 26. This permits closing of a limit switch 1I normally held open by push rod 12 mounted on an arm 13 extending laterally from the shaft I below drum I6 (see Figure 2). When the push-button switch is released, its lower contact 69h completes a lcircuit including limit switch 1l, for solenoid upon opens its contact 12. On the next operation, solenoid 63 will operate valve 60 to cause the motor 54 to restore drum IIJ to the position shown in solid lines. The operation of the reversing switch is thus entirely automatic after it has been manually initiated by operation of pushbutton 69.

It will be evident that the invention provides a reversing switch particularly adapted for heavycurrent loads such as electrolytic plants requiring multiple busbar circuits for supplying current to the load. The structure of the switch is simple so it can be manufactured at relatively low cost. At the same time, it may be operated quickly and easily to eiect reversal of polarities as often as desired. The switch requires little or no maintenance. The seating spring 20 and motor l1 serve to hold the drum rmly against the xed contact shoes, except when a reversing operation is in progress. There is, however, suflicient wiping of the drum segments on the shoes as the drum seats thereon to insure good contact therebetween.

Although I have illustrated and described but a preferred embodiment of the invention, it will be recognized that changes in the details and arrangement disclosed may be made without departing from the spirit of the invention of the scope of the appended claims.

I claim:

1. A reversing switch comprising a drum mounted for rotation on its axis and composed of a pair of generally semi-cylindrical conducting segments insulated from each other, a pair of spaced contact shoes, each shoe normally engaging one of said segments, an insulating segment set in the peripheral surface of each conducting segment spaced from th'e longitudinal edges thereof, a second pair of spaced contact shoes, one of which normally engages one of said conducting segments and the other the insulating segment in the other conducting segment, and a fth Contact shoe intermediate said second pair of shoes adapted to engage one or the other of said conducting segments depending on the angular position of the drum relative thereto, said fth shoe normally engaging the conducting segment in which the insulating segment is engaged by one of said second pair of shoes.

2. The apparatus defined by claim 1 characterized by said segments being tapered and said shoes being tapered to conform to the segments.

3. The apparatus dened by claim 2 characterized by yielding means exerting pressure on the drum in the direction of its taper.

4. The apparatus dened by claim 1 characterized by terminals extending from said shoes adapted to have busbars connected thereto.

5. The apparatus defined by claim 4 characterized by a jumper busbar connecting the terminals of said second pair of shoes.

6. The apparatus defined by claim 1 characterized by said lirst-mentioned pair of shoes being disposed on one side of said drum and the other shoes on the opposite side of the drum.

'7. A switch comprising a drum and fixed contacts engageable thereby, means mounting the drum for rotation and axial movement relative to said contacts, independent motors connected to said drum for effecting axial and rotary movement thereof, respectively, means controlling said motors and solenoids for actuating said control means, a manual switch for energizing the solenoid of the axial-movement motor and a limit switch held open by the drum in its normal p0- sition for energizing the solenoid of the rotarymovement motor.

EDWARD E. CHEEK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 984,534 Brookins et al Feb. 21, 1911 1,684,650 lTuttle Sept. 18, 1928 1,721,286 Sweetman July 16, 1929 1,784,697 Martin et al Dec. 9, 1930 2,345,928 Foster Apr. 4, 1944 2,491,842 Wells Dec. 20, 1949

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