US2399943A - Electrical regulating apparatus - Google Patents

Description

S U T A. R A N May 7, 1946.

Filed NOV. 13, 1942 Patented May 7, 1946 ELECTRICAL REGULATIN G APPARATUS y William C. Sealey, Wauwatosa, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation oi' Delaware Application November 13, 1942, Serial No. 465,425

(Cl. Ill-119) 6 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 l and lubricating fluid is avoided.

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 lubricating the operating mechanism of the tap changer,

' for lubricating and insulating the tap changing switch contacts and for insulating the windings of the transformer. The problem of making such a regulating apparatus fire proof or noninilammable therefore involves both insulating and lubricating problems;

Transformer windings have been made re proof by the use of air as an insulating medium or by the use of synthetic noninflammable liquids. The noninflamniable liquids suitable for such' insulating purposes have undesirable properties requiring special equipmentvfor 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.

It is therefore an object of the present invention to provide an. electrical regulating apparatus with transformer windings having a noninilammable fluid insulation and with switch contacts which are air or other gas insulated but which are at the same time lubricated during relative motion thereof with a noninammable lubricant.

It is a further object of the present invention to provide an electrical regulating apparatus with gas insulated, frictionally engaged switch contacts with a noninammable 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:

' inflammable regulating apparatus, in the present Fig. l is a diagrammatic showing of a voltage In Fig. 1, a tap changing switch 9 selectively connects differing amounts of a winding 8 into a load circuit 5 to control the voltage thereof. The winding 8 is excited from an exciting winding '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 ltherein in response to action of a contact making voltmeter l1.

The operating apparatus for the tap changing switch 9 includes a motor 2l connected in driving relation Ato a shaft by a geared shaft 22 and also includes the shafts 29 and 32 driven from the shaft 22 to operate the contactors il and i5,

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 compoun'd. Thecontactors I4 and I5 are air break switches of any type suitable for making and breaking current in air.

The windings 1 and 8, which are on the same core, may be insulated by a'noninflammable liquid or may be insulated by a'noninammable gas such as air. In the prior art structures, the dial switch invention the dial switch l is insulated Vby 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.

The dial switch 9 hasy fixed contact plates i0/ 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 I2 and i3. Considerable contact pressure is desirable between cooperating flxed and movable contacts in order that the heavy load current may be safely carried therebywithout over heating. The pairs of contacts I2 and i3 are each made in two ,parts which, as shown in Fig. 4, cooperate in rubbing engagement with opposite faces of the stationary contact plates Iii. Both parts of each contact assembly are carried by guide members 43 rotatable by the shaft 35. Pins Il are rigidly fastened to the contacts I2 and I3 and slide in cooperating holes in the guides 43. The contact prsure against the faces of contact plate I3 is provided by springs (not shown) between the guides 43 and the contacts I2 and I3.

When the contacts I2 or I3 are not contacting a plate III, the pins Il hold the two parts of the contact slightly apart sov that they can more easily slide over the beveled edge 40 of the next plate III. The plates III are mounted on supporting members 42 and are held in position by machine screws 33.

When the pairs of contacts I2 and I3 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 I0, or they may be on adjacent plates III. In either case, the contacts I2 and I3 are on end, noncentral or main current carrying portions of a plate III when in tap connecting position, and at least one of these contacts must sweep across the central or lubricating portion of a plate I3 during selective movement in arriving at a tap connecting position.

In the prior art, a dial switch such as 9 was insulated by immersion in oil and, therefore, the problem of lubrication was simple. In the present invention lubrication between the contacts I2 and I3 and the plates III is provided by a lapping compound such as graphite. The lubricant is positioned for effective action on both contact faces by inclusion in-holes 3l drilled in the stationary contact III.

As shown in Fig. 2, the graphite inserts are placed in the central or lubricating portion of the plate I0, 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 I0, one or the other of the contacts I2 or I3 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 3.

If the voltage of the circuit 5 varies from normal the contact making voltmeter I1 responds to the increased or decreased pull of the coil I8 to close contact I9 or contact 20. The motor 2l is thereby energized in a proper direction and turns the shaft 22. A gear 23 on shaft 22 is provided with three pins 25, 25 and 21 which coact with the gears and 33 to operate the switches I4 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 I4. This movement of the switch Il was effected by turning of the shaft 29 and eccentric 23. During this movement, a second gear 3l on the shaft 22 was rotated in a counterclockwise direction to the position shown where one of the pins is meshed with the gear 31. Further counterclockwise rotation of the shaft 22 will move the dial switch in a clockwise direction so that brush I2 occupies the present position oi' brush I3 and brush I3 is moved to the next contact plate III.

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 Il is accomplished by the 23 a final one-third movement, :losing the switch Il after the contact I3 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 I1, a further clockwise rotation of the dial switch is obtained with the switch I5 breaking the circuit to the brush I2- and making it after the brush I2 has reached the new contact position. This is accomplished by action of.' the pins 25, 25 and 21 on the gear 33 to actuate the switch by means of the shaft 32 and the eccentric SI. One-half of the auto-transformer I3 takes the load current when the switch I4 or Il 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 3. 'I'he switches I4 and I5 are connected in circuit, respectively, with the brushes I2 and I3 through' the collector rings Il, the brush I2 being insulated from the ring contacting the brush I3 by an insulating member Il.

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 an apparatus for changing transformer taps normally carrying heavy load currents, transformer windings immersed in noninfiammable fluid insulation, a plurality of fixed switch contacts immersed in gaseous insulation and connected to taps on one' of said windings, a movablecontactA cooperating with certain of said fixed contacts in frictional sliding engagement therewith to connect and disconnect certain portions of said tapped winding in and from an electric circuit to control a characteristic thereof, and means for lubricating said contacts during relative movement thereof comprising solid lubricant positioned in a portion of one of said contacts not carrying said heavy load current.

2. In an apparatus for changing transformer taps normally carrying heavy load currents, transformer windings immersed in noninflammable fluid insulation, a plurality of fixed switch contacts immersed in gaseous insulation and connected to taps on one of said windings, a'movable contact cooperating with certain of said fixed contacts in frictional sliding engagement therewith to connect and disconnect certain portions of said tapped winding in and from an electric circuit to control a characteristic thereof, and means comprising inserts of solid lubricant positioned in one of said contacts and operatively effective only during a tap changing operation, for lubricating said contacts.

3. In an apparatus for changing transformer taps normally carrying heavy load currents, transformer windings immersed in noninflammable fluid insulation, a plurality of fixed switch contacts immersed in gaseous insulation and connected to taps on one of said windings, a movable contact cooperating with certain of said fixed contacts in frictional sliding engagement therewith to connect and disconnect certain portions of said tapped winding in and from an electric circuit to control a characteristic thereof, and inserts of solid lubricant in one of said cooperatpin 21 giving the shaft 75 ing contacts positioned out of contact with the other of said cooperating contacts when said tap changer is at rest.

4. In an apparatus for changing transformer taps normally carrying heavy load currents, transformer windings immersed in noninflammable fluid insulation, a plurality of adjacently positioned fixed switch contacts provided with a central portion and a noncentral portion, inserts of solid lubricant in said central portion, a pair of movable contacts cooperable with said noncentral portion to connect certain portions of said tapped winding in an electric circuit to con trol a characteristic thereof, one :of said pair of movable contacts cooperable with said central portion of one of said fixed contacts and the other of said pair of movable contacts cooperable with an adjacent fixed contact during a tap changing operation.

5. In an apparatus for changing transformer taps normally carrying heavy load currents,-

winding in an electric circuit to control a characteristic thereof, one of said pair of movable contacts cooperable with said lubricating portion of one of said fixed contacts and the other of said pair of movable contacts cooperable with an adjacent fixed contact during a tap changing operation.

6. In an apparatus for changing transformer taps normally carrying heavy load currents, transformer windings immersed in noninflammable fluid insulation, a plurality of fixed switch contacts immersed in gaseous insulation and connected to taps on one of said windings, a movable contact cooperating with certain of said fixed contacts in frictional sliding engagement therewith to connect and disconnect certain portions of said tapped winding in and from an electric t circuit to control a characteristic thereof, means l said movable contact and immersed in gaseous insulation and provided with nonliquid oilless bearings for lubricating the relatively movable elements of said mechanism.

WIILIAM C. SEALEY.

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