US2399944A - Electrical regulating apparatus - Google Patents

Description

May 7, 1946. w. c. SEALEY ELECTRICAL REGULATING APPARATUS Original Filed Nov. 13, 1942 Patented May 7, 1946 ELECTRICAL REGULATING APPARATU S William C. Sealey, Wauwatosa, Wia, asslgnor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis, a corporation of Delaware Original application November 13, 1942, Serial No. 465,425. Divided and this application August 17, 1945," Serial No. 611,053

2 Claims.

This invention relates in general to electrical regulating apparatus and relates particularly to apparatus such as may be utilized in an electrical regulator in which the use of oil as an insulating and lubricating fluid is avoided. This application is a division of parent application Serial No. 465,425, filed November 13, 1942, for Electrical regulating apparatus. a

In prior art step type voltage regulating apparatus, oil has generally been used both as an insulating and as a lubricating fluid. An apparatus of this type is shown in United States Letters Patent No. 2,177,109, L. H. Hill, granted October 24, 1939, which utilizes oil for lubricatin the operating mechanism of the tap changer, for lubricating and insulating the tap changing switch contacts and for insulating the windings oi the transformer. The problem of making electrical regulating apparatus of the above type fire proof or noninfiammable therefore involves both insulating and lubricating problems.

Transformer windings have been made fire proof by the use of air as an insulating medium or by the use of synthetic noninflammable liquids. The noninflammabie liquids suitable for such insulating purposes have undesirable properties requiring special equipment for handling, are hazardous from the standpoint of injury to personnel and are relatively expensive. Although air insulation necessitates greater insulating distances than does oil insulation, it is a good insulator but a poor lubricant. Prior art air insulated contacts have been lubricated, however, such lubrication has been detrimental to the current carrying capacity of the contacts. It is therefore an object of the present invention to provide an electrical regulating apparatus with switch contacts which are airor other gas insulated but which are at the same time lubricated. during relative motion thereof with a noninflammable lubricant.

It is a further object of the present invention to provide gas insulated, frlctionally engaged switch contacts with a noninflammable lubricant which does not impair the current carrying characteristics of the contacts.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing in which:

Fig. 1 is a diagrammatic showing of a voltage regulating system and apparatus embodying the present invention;

Fig. 2 is a detailed view of the dial switch contacts shown in Fig. 1;

Fig. 3 is a bottom detail view of the fixed contact shown in Fig. 2; and

Fig. 4 is an end-view of the contact structure shown in Fig. 2.

In Fig. 1, a tap changing switch 9 selectively connectsdiii'eringamounts of a winding 8 into a load circuit I to control the voltage thereof. The winding 8 is excited from an excitingwinding "I connected across the supply circuit 6. The voltage of load circuit 5 is maintained constant by including more or less of the winding 8 therein in response to action of a contact making voltmeter ll.

The operating apparatus for the tap changing switch 8 includes a'motor 21 connected in driving relation to a shaft 36 by a geared shaft 22 and aiso'includes the shafts 28 and 32 driven from the shaft 22 to operate the contactors i4 and I5, respectively. The sequenceof operations of the operating mechanism is such that the load circuit is made and broken at the contactors H and II, thus a change in the setting of the dial switch 8 is made only when the pertinent contactor H or I! is in open position. The contacts l2 and I3 of the dial switch 9 therefore do not make and break any current, but function to carry the heavy load current through selected portions of winding 8.

The operating mechanism may be insulated with a noninilammable gas and the various bearings thereof may be lubricated with oilless bearings of the type using graphite or some similar lapping compound. The contactors I 4 and I5 are air break switches of any type suitable for making and breaking current in air.

The windings I and 8, which are on the same core, may be insulated by a noninfiammable liquid or may be insulated by a noninflammable gas such as air. In the prior art structures, the dial switch 9 has been immersed in oil for insulation and for lubrication purposes. In order to make a noninfiammable regulating apparatus, in they present invention the dial switch 9 is insulated by air or some similar insulating gas and is lubricated in a fire proof manner that will not impair the current carrying function of the dial switch contacts. g

The dial switch 9 has fixed contact plates in circumferentially spaced for selective connection of one or a pair thereof into the load circuit by means of a plurality of pairs of movable contacts l2 and i3. Considerable contact pressure is desirable between cooperating fixed and movable contacts in order that the heavy load current may be safely carried thereby without over heat- 44 are rigidly fastened to the contacts l2 and I3 and slide in cooperating holes in the guides 43. The contact pressure against the faces of contact plate in is provided by springs (not shown) between the guides 43 and the contacts l2 and i3. When the contacts I2 or l3 are not contacting a plate It, the pins 44 hold the two parts of the contact slightly apart so that they can more easily slide over the beveled edge 40 of the next plate [0. The plates in are mounted on supporting members 42 and are held in position by'machine screws 39.

When the pairs of contacts I: and 13 are in a tap connecting position, these contacts may be positioned as shown in Fig. 2, where both pairs of contacts cooperate with the same plate It, or they may be on adjacent plates III. In either case, the contacts I2 and II are on end, noncentral or main current carrying portions of a plate It when in tap connecting position, and at least one of these contacts must sweep across the central or lubricating portion of a plate l during selective movement in arriving at a tap connecting position.

In the prior art, a dial switch such as 3 was insulated by immersion in oil and, therefore, the problem of lubrication was simple. In the present invention lubrication between the contacts l2 and i3 and the plates I0 is provided by a lapping compound such as graphite. The lubricant is positioned for effective action on both contact faces by inclusion in holes 33 drilled in the stationary contact l0.

As shown in Fig. 2 the graphite inserts are placed in the central or lubricating portion of the plate it, where the graphite inserts do not interfere with the carrying of heavy currents by the dial switch contacts when in a tap connecting position. However, by placing the graphite inserts in the central portion of the contact plates [0, one or the other of the contacts l2 or l3 will sweep across the graphite and be lubricated upon movement from one tap position to the next. Use of this type of lubrication permits air insulation to be used for the dial switch 9.

If the voltage of the circuit 5 varies from normal the contact making voltmeter l1 responds to the increased or decreased pull of the coil i3 to close contact IE or contact 20. The motor 21 is thereby energized in a proper direction and turns the shaft 22. A gear 23 on shaft 22 is provided with three pins 25, 26 and 21 which coact with the gears 30 and 33 to operate the switches l4 and I5.

In the position shown in Fig. 1 the gear 23 has been rotated in the counterclockwise direction and the pin 25 has turned the gear 30 one-third of a revolution thereby opening the switch l4. This movement of the switch i 4 was effected by turning of the shaft 23 and eccentric 28. During this movement, a second gear 34 on the shaft 22 was rotated in a counterclockwise direction to the position shown where pne of the pins 35 is meshed with the gear 31. Further counterclockwise rotation of the shaft 22 will move thedial switch in a clockwise direction so that brush I2 occupies the present position of brush l3 and brush i3 is moved to the next contact plate l0.

During this rotation of the shaft 22, the pin 26 and the gear 23 will have moved the shaft 29 a third of a revolution thus placing the switch I4 in a position to be closed upon further rotation of the shaft 22. The closing of switch I4 is accomplished by the pin 21 giving the shaft 29 a final one-third movement, closing the switch l4 after the contact l3 has reached the end portion or noncentral portion of the next contact plate iii. If a further voltage change in'the same direction is initiated by the contact making voltmeter H, a further clockwise rotation of the dial switch is obtained with the switch l5 breaking the circuit to the brush i2 and making it after the brush [2 has reached the new contact position. This is accomplished by action of the pins 25, 26 and 21 on the gear 33 to actuate the switch by means of the shaft 32 and the eccentric 3i. One-half of the auto-transformer I 6 takes the load current when the switch I4 or I5 is open.

The motor is shown as being energized from the load circuit 5, however, it may be energized from a winding on the same core as the windings 1 and 8. The switches i and I5 are connected in circuit, respectively, with the brushes l2 and I3 through the collector rings II, the brush i2 being insulated from the ring contacting the brush l3 by an insulating member 45.

Although but one embodiment of the present invention has been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a plural circuit switch, a fixed contact provided with contact faces on opposite sides thereof, said contact provided with a plurality of main current carrying portions, a lubricating portion positioned between said main current carrying portions, inserts of solid lubricating material in said lubricating portion only and extending through said contact from one of said contact faces to the other of said contact faces, and a plurality of pairs of movable contacts arranged to cooperate in rubbing engagement with opposite faces of said main current carrying portions to normally close a heavy current load circuit and arranged to cooperate in rubbing engagement with opposite faces of said lubricating portion only during movement of said movable contacts.

2. A switch comprising a fixed contact provided with a plurality of main current carrying portions, a lubricating portion positioned between said main current carrying portions, a movable contact, means for moving said movable contact in rubbing engagement with said lubricating portion only during movement of said movable contact from one to another of said main current carrying portions, and inserts of solid lubricating material in said lubricating portion and extending to the surface thereof engaged by said movable contact.

WILLIAM C. SEALEY.

Images