US2073579A - Tap changing mechanism - Google Patents

Description

Patented Mar. 9, 1937v UNITED STATES anni;

PATENT ortica TAP CHANGING MECHANISM Application August 25,

' 9 claims.

This invention relates in general to electrical apparatus of the type having an operating mechanism and provided with a housing having a portion removable for the purpose of inspection, ad-

justment, repair or replacement of parts of the apparatus.

In electrical apparatus of the above type the removing and replacing of such portions of the housing has become more and more diiiicult as the size and theweight of the apparatus has increased. It is therefore an object of the present invention to provide a means for utilizing the operating mechanism of such electrical apparatus for the removing 1 and replacing of the l5 removable portion ofthe housing. v

It is also an object of the present invention to provide a means whereby the control apparatus for the operating mechanism of an electrical apparatus is also utilized to control the removal and replacement of the removable portion of the housing.

It is a further object of my invention to provide interlocking means for the control of an, operating mechanism for electrical apparatus of the above type so that the control Will function eiliciently both for controlling the operating mechanism and for controlling the removing and replacing of the removable portion of the housing.

It is also an object of the present invention to provide, in electrical apparatus of the above type,

a means for manually actuating the operating y mechanism to either operate the apparatus or to remove or replace a portion of the housing and also to provide means forpreventingl electrical control during such manual operation.

These and other objects and advantages are obtained by this invention, the various novel features of which will be apparent from the drawing and description herein and will be more particularly pointed out in the claims.

An illustrated example of an application of this invention is shown in the accompanying drawing in which the single figure is a diagrammatic showing of a transformer tap changer under load embodying the present invention.

Referring to the drawing by characters of -reference, ill is a tapped transformer winding which is connected into a load circuit, notshown, at

any one of a number of taps in the conventional manner by tap changing switches I2 and i3 and circuit breakers i4 and I5 through the midtapped reactor I8. The tap changing system is shown for single phase operation, it being understcod that for multiphase operation addi- 1934, Serial No. 741,417

tional transformer windings, tap changing switches and circuit breakers are used. The tap chang-- ing switch I2 and circuit breaker I5 are in series and likewise thetap changing switch I3 and circuit breaker i4 are in series. These switches and circuit breakers are operated in a certain sequence by means of the intermittent gear i6 and the circuit breaker operating cam il in a manner so that the circuit breakers always break the load circuit and hence no arcing occurs at the tap changingswitch contacts. I

The circuit breakers i4 and i5 are encased in -a housing I9 usually containing an arc extinguishing liquid. The housing I9 has a portion 20 removable for inspection, adjustment, repair or replacement of the circuit breaker contacts or other parts, the portion 20 normally being fastened to the housingi in a suitable oil tight manner. Mounted on each of two sides of the housing i9 and 20 are anged pulleys 23 over which cables 22 are led from fasteningr means 2l on the housing i9 to a Winding drum'24. As the drum 24- is unwound the cables allow the tank portion 20 of the housing tobe lowered by the force of gravity, the pulleys 23 being so placed on the housing that a balance is maintained.

\.As the cable is wound on the drum 25 the tank portion 20 is raised to the position shown.

The operating mechanism for the tap changing switches and the circuit breakers includes a reversibleV motor 3i) which drives a stub shaft 33 through a worm and wheel. The stub shaft 33 is arranged'to drive the tap changing mechanism shaft 38 by means of clutch members 34 and 35 when in engagement. The motor 3u is driven in one direction or the other by energizing its raise or lower eld 3l or 32 through raise or lower control switches d2 or d3. To raise or lower the transformer voltage, control switch :l2 or 43 is actuated by solenoid 44 or I5 Acontrolled through the raise or lower push button switch 48 or M.

To raise the voltage across the transformer terminals, the handle oi the clutch operating inember 55 is moved downwardly, as viewed in the drawing, thereby closing switch 5i and also moving clutch member 35i into engagement with clutch member 35. Closing of the push button switch closes an energizing circuit for the solenoid M as follows: line 2, conductor push button switch 23S, switch t, conductor i?, solenoid 54, conductor l, raise limit switch 33, conductor S, switch 553 to line 3. Energization of coil Iii closes a circuit for the motor Sthrough switch i2 and field winding Si. The motor drives the shaft 38 to operate the tap changing switches and circuit breakers to include more of the transformer winding in the circuit thereby raising the voltage. The operation for lowering the voltage is similar exceptthat the motor 30 is runv in the opposite direction.

In the present tap changing system a showing of the automatic control regulated by the line voltage and also remote control from a switchboard and the various necessary electrical interlocks have been omitted for the sake of simplicity and clarity in illustrating this embodiment of the invention.

A position indicator 5| indicates the tap position occupied by the tap changing switches lI2 and I3 and also operates limit switches 48 or 49 when in either extreme position, thus deenergizing the appropriate energizing circuit.

3 solenoid 44 so that upon the tank 20 being raisedA To raise or lower the portion 20 of the circuit breaker housing the same operating mechanism and control features are utilized. When the clutch member 34 is moved to its lower position so that it engages the cooperating clutch meniber 36, the shaft 33 drives a shaft 39 which is geared to the winding drum 24, thus by energizing either the raise or lower solenoid 44 or 45 the winding drum is rotated in one direction or the other to raise or lower the tank 20. A limit switch 52 is provided in the circuit of the raise A'to theposition shown, the arm 53 will open the circuit and deenergize the motor. In order to provide for disabling the control of the switch 52 so that the tap changer may be operated to raise the voltage while the tank is in the position shown, a switch 54 is provided short circuiting the switch 52 and is operated to short circuiting position when the clutch operating member 55 is in tap changing position.

Manual operation of either the tap changing equipment or the tank raising and lowering mechanism is obtained by means of a crank 56 which may be utilized to rotate the motor shaft by being fitted on to an extension 51 thereon. Normally the crank 56 as shown holds a switch 50 in closed position so that when manual operation is desired and the crank is removed, the switch 50 opens thereby deenergizing all electrical control. This safety control is especially necessary where remote and automatic control are utilized. Y

Although only one embodiment of the present invention has been illustrated and described, it is to be understood that modications and changes therein may be made by those skilled in...the art,without.,departing from the spirit of the invention or from the scope of the following claims. 1

It is claimed and desired to secure by Letter Patent:

1. A tap changing mechanism comprising a transformer'winding provided with taps, switches connected to said taps, a housing for said mechanism provided with a removable portion, means for operating saidswitches and means for utilizing said operating means to raise or lower said removable portion from said housing said last said means including an interlocking means preventing operation of said switches during raising or lowering of said removable portion.

2. In an electrical apparatus, the combination of a load circuit, a transformer winding pro' vided with taps, tap changing switches for connectingcertainofsaidtapsinsaid circuit,a

housing for said apparatus having a removable portion, means for operating said switches to raise or lower the voltage across said load, nieansv including a control circuit for controlling said operating means, means for utilizing said operating means and said controlling means toremove or replace said removable portion of said housing, switch means controlled by said removina and said oil circuit breakers to raise or lower the f voltage across said transformer winding, and means for utilizing said actuating means to raise or lower said removable portion of said housing said last said means includingmeans preventing operation thereof during operation of said tap changing switches and' said oil circuit breakers.

4. In combination, a transformer winding provided with taps, tap changing apparatus comprising tap changing switches connected to said taps, means for operating said tap changing switches to raise or lower the voltage across said transformer winding, means for electrically controlling said operating means, means for manually controlling said operating means and means whereby utilization of said manual means provides disabling of said electrical control means. y 5. In combination, a transformer provided with taps, tap changing switches therefor, circuit breakers cooperating with said tap changing switches, a housing for said circuit breakers having a removable lower portion, means for actuating said tap changing switches and. said circuit breakers to raise or lower the voltage of said ,transformer winding,vmeans for electrically conating means, and means for' selectively connecting said operating means either to operate said switch or to operate to., remove and replace said portion of said housing said last said means including means for preventing one of said operations during the other of said operations.

7. A. tap changing apparatus comprising 'a transformer winding provided with taps, tap changing switches connected to said winding taps, circuit breakers associated with said apparatus housing for said circuit breakers provided with a removable portion, operating means, and means for selectively connecting said operating means either to operate said switches and said circuit -breakers or to operate to remove and replace said removable portion of said housing said last said means including means for preventing either of said operations during the other of said operations. A

and connected in -circuit with `said switches, a o5 A S. A tap changing apparatus comprising a transformer winding provided with taps, tap changing switches connected to said winding taps, circuit breakers associated with said apparatus and connected in circuit with said switches, a housing for said circuit breakers provided with a removable portion, operating means, means including a control circuit for selectively connecting said operating means either to operate said switches and said circuit breakers or to remove or replace said removable portion.I of said housing, and a switch in said control circuit operative in response to movement of said portion of said housing.

9. In a tap changer under load apparatus, the

combination of a transformer winding having taps, tap changing switches therefor, circuit breakers cooperating with said switches to break the load` circuit, a housing for said circuit breakers having a removable portion, actuating means, control means, and means for selectively utilizing said actuating means and said control means either to operate said switches and circuit breakers to raise or lower the voltage of said transformer winding or to raise or lower said removable portion of said housing, said selective means including means preventing operation of said switches and circuit breakers during raising or lower of said housing.

ziiliLAND H. HILL.

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