US1705725A

US1705725A - Tap-changing system

Info

Publication number: US1705725A
Application number: US171900A
Authority: US
Inventors: William R Farley
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1927-03-01
Filing date: 1927-03-01
Publication date: 1929-03-19
Anticipated expiration: 1946-03-19

Description

March 19, 1929, W R, FARLEY 1,705,725

TAP CHANGING SYSTEM Filed March 1927 5 Sheets-Sheet l WITNESSES: INVENTOR Will/am Rfhr/ey I I ATTORNEY a Mamh 119 1929 w FARLEY L705J25 TAP CHANGING SYSTEM Filed Mar 1927 5 Sheets-Sheet 2 tad/if WITNESSES:

Z/Sh INVENTOR Wf/Ham ff. Far/62y March 19, 1929. FARLEY 1,705,725

TAP CHANGING 'SYSTEM Filed March 1, 1927 5 Sheets-Sheet 3 F/ya.

lio

WITNESSES: INVENTOR M VV/flmm E I ZV/dy/ M, W BY ATTORNEY WILLIAM It. FARLEY, OF WILKINS B'URG,

.- v 1,705,125 PATENT OFFICE.

PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY,.A CORPORATION OF PENNSYL VANIA.

TAP-CHANGING SYSTEM.

Application filed March 1, 1927. Serial No. 171,900.

My invention relates to transformer tap changing devices and particularly to the control circuits and apparatus therefor.

' One object of my invention is to provide a transformer tap-changing system that shall operate in accordance with the variations of the potential of a connected electrical circult.

Another object of my invention is to provide a transformer tap-changing system that shall be responsive to the fluctuations in the potential of a connected electrical circuit for simultaneously controlling a plurality of transformer banks.

Another object of my invention is to provide a transformer tap-changing system that shall be responsive to fluctuations in the potential of a connected electrical circuit in all of the tap-changing positions of one or more transformer banks that are under control.

Another object of my invention is'to provide a system ofcontrol for a plurality of transformer banks that are connected to the same electrical circuit that shall cause the operation of the transformer banks e1ther 1ndividually or in unison.

Another object of my invention is tov provide a tap-changing system for one or more transformer banks supplying current to an electrical circuit that shall he operable either manually or in response to the fluctuations in potential of the electrical circuit.

Another object of my invention is to provide a tap-changing system for one or more transformer banks supplying-current to an electrical circuit that shall be operable either manually or in response to the fluctuations in potential of the electrical circuit and in which the means for controlling the system in response to fluctuations in potential is rendered inoperative whenever faulty operation of predetermined parts of the-system occurs.

Another object of my invention is to pro- 1 vide a tap-changing system, the operation of which shall be so controlled that at least a minimum period of time shall have elapsed since a previous initiation of the tap-changing operation before a subsequent tap-changing operation may occur.

Another object of my invention is to pro vide a top changing system that shall be responsive to conditions of voltage fluctuations in an electrical circuit and that shall be controlled by the'duration of the voltage fluctua tions. 0

Another object of my invention is to provide a transformer tap-changing system that shall have provision for both manual and electrical operation, and in which the electrical operating devices are rendered inoperative whenever the transformer tap connections are being adjusted manually.

Another object of my invention is to provide a tap-changing system for controlling a plurality of transformer banks, each of which shall be normally responsive to a relay unit, and in which provision is made for so interconnecting the relay units that they may be controlled in unison from a single relay unit.

- Another object of my invention is to provide a tap-changing system for controlling a plurality of transformer banks, each of which shall be normally responsive to a relay unit, and in which provision is made for a so interconnecting the relay units that they may be controlled in unison from any one of the relay units.

Another object of my invention is to provide a tap-changing'system for controlling a plurality of transformer banks, each of which shall be Dnormally responsive to a relay unit, and in which provision is made for so interconnecting the relay units that they may be controlled in unison from any one of the relay units, and in which the subsidiary relay units are rendered inoperable from any source other than the master relay unit then in service.

Another object of my invention is to provide a transformer tap-changing system with indicating means that shall indicate whenever any one of the component transformer units is out-of-step with the other transformer units, and that shall also indicate whenever an electrical controlling system is rendered inoperative.

A-further object of my invention is to provide a tap-changing system for a plurality of transformers that shall normally be controlled by electrical conditions in a circuit supplied by the' transformers, but which shall be inoperative whenever there is no voltage upon the transformers.

In transformer tap-changing systems, as heretofore employed, it has been a customary practice to initiate the control for varying the tap connections of a plurality of transformers by switches requlring the close attention of an operator. When ta -changing transformer systems are utilized For supplying electrical energy to distributing systems the duties of an operator when present are usually multifarious and the necessity for constantly watching the voltage of a trans former bank may be thus avoided. Also the need for tap-changing transformer equipment is often found at points of interconnection between high voltage transmission lines, which points of interconnection being remote ly disposed with respect to central stations, it is frequently inconvenient to maintain the service of an operator at such places.

1 According to my invention, I provide a transformer tap-changing system that is normally responsive to fluctuations in the potential' of the controlled transmission or power circuit but which is also adapted for manual control in addition to automatic actuation, when desired. In carrying out the foregoing objects of my invention, I have provided a plurality of relay units the number of which corresponds to the number of transformer banks under control and in which provision is made for controlling all of the relay units from a single relay unit, and for rendering the relay units inoperative under predetermined or abnormal operating conditions.

In the accompanying drawings,

Fig. 1 is a diagrammatic view of a plurality of transformer banks and motors for changing their tap connections, together with portions of the control circuits therefor,

Fig. 2 is a similar view of circuits and apparatus constituting one of the interconnected relay units for controlling the apparatus shown in Fig. 1,

Fig. 3 is a view, similar to Fig. 2, showing another relay unit constituting a portion of my invention.

When Figs. 1, 2 and 3 are placed in side-byside relation, reading from left to right, a composite view of the entire invention is had.

My invention comprises, in general, a pri mary electrical circuit 1 that supplies energy to a secondary circuit 2 through a plurality of transformer banks 3 and 4, each of the individual transformers 5 in the respective banks 3 and 4 being provided with a motor 6 and a set of contactors 7 for controlling its direction of rotation and a supply circuit 8 for energizing the motors 6 and relay controlling system 9 that is divided into two relay units 11 (Fig. 2) and 12 (Fig. 3). 7

Each of the relay units 11 and 12 comprises a pair of parallel connected contact-

making voltage relays

14 and 15, respectively. The

relays

14 and 15 are connected in parallel circuit to ensure a wider range of voltage. control by having the contacts of the relays connected in series relation and each relay adjusted for a different voltage range. The re- I lays 14and 15, and all relays hereafter referred to, are shown in an electrically de-energized condition.

Referring to Fig. 1, the"e1ectrical circuits 1 and 2 are heretofore referred to as primary and secondary circuits, respectively, as is the case Where the transformer banks 3 and 4 are connected in a distributlng circuit, or they may represent power lines of different voltage ratings that are interconnected by the transformer banks 3 and 4. In the latter case, the transformer bank 4 might be connected to a third power line 16. The individual transformers 5 may be-of any preferred type that are equipped with a plurality of contactors or switches, connected to winding taps at various points, and driving mechanism including shafts 17. Such mechanisms are shown and described in the applications for Letters Patent of Dann, Hill, Thompson, and Knotts, SerialNo. 101,246, filed April 12, 1926, both of which are assigned to the \Vestinghouse Electric and Manufacturing Company. The details of the contactors and driving mechanisms constitute no part of the present invention, and, accordingly, and also in order to simplify the case, they have been omitted.

The motors 6 fhay be of any suitable type. Referring to Figs. 1, 2 and 3, each of the setsof contactors 7 comprises groups of

contactors

21, 22 and 23 for completing the circuits between the motor 6 and the circuit 8, to raise the voltage ratio of the associate transformer 5, and contacts 24, 25 and 26 for completing circuits between the motor 6 and the circuit 8 so that it turns to lower the voltage ratio of the associated transformer 5. The

contactors

21, 22 and 23 for each motor 6, constituting the transformer bank 3, are controlled by three windings 27 in the relay unit 11, and the same contactors for the transformer bank 4 are controlled by windings 28 in the relay unit 12. Likewise, the

contactors

24, 25 and 26 for transformer banks 3 and 4 are controlled by

windings

29 and 30 in relay units 11 and 12, respectively. The

contactors

21 and 24, for each motor 6 are in parallel circuit in one phase conductor of the circuit 8, while the

contactors

22 and 26 serve to reverse the connection of a second phase conductor to the motor 6, and the

contactors

23 and 25 serve to reverse the connection of the third phase conductor to the, motor 6. By reason of the reversal of the connections between each motor 6 and two of the supply conductors, it may be reversed. Referring to Fig. 1, the

voltage relays

14 and 15 are energized from the circuit 2 by a potential transformer 29A. Each of the

relays

14 and 15 comprises an electromagnet 31 that opposes a spring 32 and a pair of contact members 33 for completing a circuit 'when the potential of the circuit 2 falls below a predetermined value, and a pair of contact members 34 for completing a circuit when the potential ofthe circuit 2 becomes too high. As has previously been explained, the

relays

14 and 15 are employed in pairs to afford a wider range of potential or voltage fluctuafor the sake of clearness.

In Fig. 2, is shown a control switch TS,

having ten groups of. contacts therein, numbered TS1 to TS-,10 inclusive. Contacts TS8 and TS9 for the relay unit 11 have a closed position when the switch occupies either its off or its on position. The contact TS1O is a back contact. The contacts TS8 and TS-9 of relay unit. 12 are simple front contacts. Connections to the contacts TS-l to TS-10will be explained in connection with the detailed discussion of the operation of the relay unit 11. The closing of the switches TS is a necessary operation before the tap-chan ing mechanism of transformer bank 3 or transformer bank 4 may be energized.

A'control switch RS, having groups of contacts RS-l to RS11, is provided with a removable handle 41 that may be removed only when the switch BS is in its off position. The handle 41 is adapted to control a similar switch BS in the relay unit 12, so that, by pro- Viding only a single handle 41 for the entire control system 9, it is possible to cause either the relay unit 11 or the relay unit 12 to control the operation of both banks of transformers 3 and 4, provided the control switches TS associated with each bank of transformers are closed. The function of the switches BS is to determine which of the relay units'11 and 12 is to be used at any one time, as both of the relay units 11 and 12 cannot be employed in its entirety at any one time. The elements of the relay units 11 and 12 that may operate simultaneously will hereinafter be discussed,

and include the windings 27 to 30, inclusive. The contacts RS 10 and RS11 are back contacts. The connections to the contacts RS1 to RS11, inclusive, will hereinafter be discussed in more detail.

The relay unit 11 is provided with secondary relays R and Lfor' relieving the currentcarrying parts of the relays.14 from heavy currents. Each of the relays R and L is provided with two groups of contacts numbered R1, R2, and L-l, L2, respectively. The relay R is controlled by the contacts 33 for raising the voltage-ratio of the connected transformer banks 3 or 4 or both 3 and 4, while the relay L is controlled by the contacts 34 for lowering the voltage-ratio of the transformer banks 3. or 4 or both 3 and 4. Relay unit 12 is also provided with relays R and L,

' but the relays R and L of the relay unitsll and 12 cannot operate simultaneously by rea- SOl of their connection to the control switches Each of the relay units ll and .12 is provided with a pair of tertiary relays MR and ML for the purpose of proyiding the neeessary control and interlock circuits for the operation of the motors 420i the GR timing relays and the various other elements of the control system 9. Each of the relays MR and ML is provided with five contacts MR1 to MR5 and ML1- and ML5, respectively, MR4, MR5, ML4 and ML5 being back contacts.

Each motor 42 is provided with a winding 43 for causing it to drive the associated GR relay in a forward direction and a winding 44 to drive it in a reverse direction.

Each GR relay comprises a shaft 45 for connecting it to a motor 42 and a'drurn 46 upon which are mounted

contact plates

47, 48 and 49. The contact plate 47 is rectangular in shape and co-operates with

stationary contact fingers

51, 52 and 53. The contact plate 48 engages with

contact fingers

53 and 54. The main portion of contact plate 49 engages with a contact finger 55, and projections 56 and 57, thereof engage

contact fingers

58 and 59, respectively." The relays GR of the relay units 11 and 12 are not arranged for simulta neous operation.

Each of the relay units 11 and 12 is DI'O- Vided with a lockout relay J L having a pair of contacts JL-l and JL2, JL-1 being a back contact. The function of the JL re lays is to deenergize both of the relay units 11 and 12 under predetermined operating conditions of the GR, MR and ML relays.

Each of the relay units 11 and 12 is provided with an operating relay MC, having six contacts MC1 to MC-'6, inclusive. The MC relays of the relay units 11 and 12 are adapted to work simultaneously, either under the contr'olofthe

potential relays

14 and 15 or under the control of a manual control switch CS.

Each of the relay units 11 and 12 is provided with. three auxiliary relays AR and AL, having two contacts each for controlling the energization of the main contactor control-

Windings

27 and 28 and 29 and 30, respectively. Each AR relay is connected in series with a forward limit switch 61 that is actuated. from a shaft 17 of one of the ,motors 6 in the corresponding transformer bank 3 or 4. Likewise, each AL relay is connected in'series with a reverse limit switch 62.

The AR and AL relaysfor controlling each transformer 5 are in series circuit with a manually operated switch (33 in order that. should any transformer 5 become out of step with the other transformers 5 in the same transformer bank 3 or 4, it may be independently operated by the manipulation of the associated switches 63 and CS.

Each relay AR'and AL utilizes one of its contacts for completing its own holding circuit and the other contact for completing the circuit of the associated

contactor windings

27 or 28 and 29 or 30, respectively.

Associated with eachgroup of cont-

actors

21, 22 and 23 and in series relation to their winding 27 is a back contactor 67 that is the latter are closed. Likewise, each winding 29 is interlocked with the related group of

contactors

21, 22 and 23 by a back contactor' 68. In the transformer bank 4, the

contactors

21, 22 and 23 and their winding 28 are as sociated with a back contactor 69 that is operated in unison with the

contactors

24, 25 and 26. The windings 30 are in series connection with back contactors 71 that are actuated with the

contactors

21, 22 and 23. Accordingly, the sets of

contactors

21, 22 and 23, and 24, 25 and 26 for each motor 6 are interlocked so that both sets of contactors may not be closed at the same time and thereby shortcircuit the supply circuit 8. 4

One under-potential relay HM, having two front contacts HM1 and HM2 and one back contact HM3, is employed for the purposes of deenergizing both of the relay units 11 and 12 in the event of subnormal potential of the control circuit 8 when the tap, changer is traveling in a direction which will raise the potential in the circuit 2 anddeenergize both relay units 11 and 12 upon the end of travel being reached by the transformer tapchanging mechanism when travelingin the direction which will affect an increase in the potential of the power circuit 2.

Another under-potential relay 75, having two front contacts 76 and 77 and one back contact 78 is intended to deenergize both of the relay units 11 and 12 in the event of subnormal potential of the control circuit 8 at the time the tap-changing mechanism is traveling in a direction to decrease the potential of the power circuit 2.

Relays HM and are shown as being disposed with relay unit 11, although they might be disposed with relay unit 12 without effecting their functions. Likewise, an alarm bell 7 9 and a battery 81 are shown in relay unit 11.

Each of relay units 11 and 12 is provided with a three-positionmanual-control switch CS, each having five contacts CS1 to CS5, inclusive. The switches CS permit the operation of the control mechanism 9 when the

potential relays

14 and 15 are inoperative. The switches CS must be in a neutral position in. order that the neutral contacts shall be closed to impress a potential upon the associated

potential relays

14 and 15. Contacts CS2 control the energization of the relays MC. Contacts CS3 make contact whenever the switches CS are moved, to raise or lower the potential of the transformer banks 3 and/or 4, to complete the circuit for the relays MC. Contacts CS4 are closed for raising the potential of the distributing cir cuit 2 and contacts CS-5 are closed to lower the potential.

The shaft 17 of each motor .6 drives a plurality of cam switches 119, 120, 121, 122 and 123, in addition to the limit switches 61 and 62. The cam switches 119 control the holding circuit of the several relays AR; the cam switches 120 control the holding circuits of the

windings

27 and 28; the cam switches 121 control the holding circuits of the relays Ali; cam switches 122 control the holding circuits of the windings 29 and 30'; and the cam switches123 are closed during the tap-changing operations to complete circuits controlling the relays R and L in the relay unit 11 or 12 then in operation. Accordingly, the failure of any one transformer 5 to properly complete a tap-changer operation deenergizes the entire control system 9.

Referring to Figs. 2 and 3 and reading downwardly of the sheets, whichcorrespond roughly to the sequence of operation of the relay units 11 and 12, the conductors and apparatus are connected in the following circuits.

The supply circuit 8 is conected to two vertically extending

bus bars

204 and 205 in

relay unit

11, and 304 and 305 in relay unit 12. The bus bar 204 is provided with

terminals

206, 207, 208 and 209, and the bus bar 304 is provided with

terminals

306, 307, 308

and 309. The bus bar 205 is provided with

terminals

211, 212, 213 and 214, and the bus bar 305 is provided with

terminals

311, 312, 313 and 314.

A lockout circuit for both the relay units 11 and 12, that is controlled by the relays J L, extends from the terminal 206 through a conductor 215, the back contact J L-1 of the relay JL of the relay unit 11, a conductor 216, the back contact JL1 of the relay unit 12, a conductor 315, a conductor 317, the neutral contact CS1 of the relay unit 11, conductor 217, the contact RS1 of relay unit 11 (shown in open position), and a conductor 218 to an auxiliary bus bar 219. Accordingly, the auxiliary bus bar 219 is not energized unless both of the relays J L are deenergized, and the switch RS of relay unit 11 is closed. The bus bar 219 controls the automatic portions of the relay unit 11and is provided with

terminals

221, 222, 223, 224, 225, and 226. i

Referring to Fig. 3, the back contact L1 of relay J L is connected, through a conductor 318, the contact RS1 (shown in the open position), and the neutral contact CS1, to

.a bus bar 319 that corresponds to the bus bar 219 of relay unit 11. The bus bar 319 is provided with

terminals

321, 322, 323, 324, 325 and 326 corresponding to the terminals 221 to 226, inclusive, in relay unit 11, respectively.

Accordingly, neither of the bus bars 219 and 319 can be energized unless both relays JL are in their deenergized positions and unless the co-operating switch BS is closed, and the associated contact CS1 is in its neu- .tral position. Since butone switch RS may be closed at one time, as hereinbefore eX- plained, but one of the bus bars 219 and 319 may be energized at any time, since the contacts CS-1 are not in their closed positions when the control system 9 is under manual operation.

From the terminal 221 on the bus bar 219, a circuit extends through a conductor 227 and the contact Its-2 (shown in its open position) to a terminal 228. From the terminal 228, two circuits extend in parallelism to an auxiliary bus bar 229 for automatically causing the voltage ratio of the transformers 5 to be raised and lowered. The circuit for raising the voltage ratio extends from the terminal 228, through-a conductor 231, the contacts 33 of one of the potential relays 14, a conductor 232, a terminal 233, a conductor 234, a terminal 235, a conductor 236, the contact 33 of the other potential relay 14, a terminal 237, the coil of the secondary relay It, and the contact HM1, and a conductor 238, to the bus bar 229. The bus bar 229 is con nected, through a resistor 239, terminal 241 and contact IRS-3, to the terminal 211 on the bus bar 205. The circuitfor automatically lowering the voltage ratio of the transformers 5 extends from the terminal 228, through a conductor 242, the contact 34 of one of the potential relays 14, terminal 235, conductor 234, terminal 233, contact 34 of the other potential relay 14, terminal 243, the windingof the relay L, the contacts 76 of relay 75 and a conductor 244, to a terminal 245 on the bus bar 229. The automatic raising and lowering circuits just described in connection with the relay unit 11 are duplicated in connection with the relay unit 12. The parts designated by the numerals 227 to 245, inclusive, in relay unit 11, are identical with the parts designated by the numerals 327 to 345, inclusive, respectively. The only exception of the foregoing statement is that the contact HM-2 in relay unit 12 is on the same relay as the contact HM-1 in relay unit 11, and, likewise, the contacts 76 and 77 are on the same relay, since the relays HM and 75 are undervoltage relays common to both of the relay units 11 and 12.

From the foregoing description, it is apparent that, in order to have either of the relay units 11 or 12 operate in accordance with the potential of the circuit 2, or automatically, it is necessary thatone switch RS shall be closed, that the lockout relays JL shall be deenergized, that the switch CS associated with the closed switch RS shall be in a neutral position, and that the relays HM and 75 shall be energized. The relays HM and 75 will not be energized until one of the switches TS is closed, as is hereafter 'explained.

Extending from the terminal 222 on the bus bar 219 is a circuit for energizing the relay MR and it includes the terminal 222, a

conductor."246, the contactAR-lof the relax R, a conductor 247, a terminal 248, a conductor 249, the winding of the relay MR, a conductor 251, a terminal 252 on a conductor 253, and the conductor 253, to the terminal 241. A similar circuit for the relay ML of relay unit 11 extends from the terminal 223 on the bus bar 219 through a conductor 254, the contact Ir-1 of the relay L, a conductor 255, a terminal 256, a conductor 257, the winding of the relay ML, and a conductor 258 to a terminal 259 on the conductor 253. The circuits for controlling the relays MR and ML in the relay unit 12 are identical with those in relay unit 11 except that the reference numerals bear the prefix 2 in relay unit 11 and the prefix 3 in relay unit 12.

Accordingly, the relay MR and ML are operative only under the conditions prescribed for the relays R andL and with the additional condition that the associated relays R and L are energized.

For energizing the motor 42, a circuit extends from the terminal 224, through a conductor 2611, contact MR-1,' a conductor 262, a terminal 263, a conductor 264, the motor windingv 43, a conductor 265, a terminal 266 on the conductor 265, a conductor 267, the armature of the motor 42, and a conductor 268, to a terminal 269 on the conductor 253. The foregoing circuit is paralleled between the

terminals

224 and 263 by a circuit extending from terminal 225 on the bus bar 219, through a conductor 271, the contact ML1, and a conductor 272, to the terminal 263. The terminal 273 is connected to the contact finger 59 by a conductor 274. The foregoing 44 of the motor 42, and the latter is connected directly to the conductor 265. The contact finger 54 is connected to the bus bar 205 through the contacts RS-6, a conductor 283, a terminal 284, the contacts ML-3 and MR3, in parallel circuit, a terminal 285, and the winding of the lookout relay JL, to the terminal 212 on the bus bar 205.

Accordingly, should either the MB or the ML relay of either of relay units 11 and 12 be held closed a sufficient length of time to permit the associated relay GR to complete the circuit between the

contact fingers

53 and 54 through the plate '48, the lookout relay J L operates to disconnect the bus bars 219 and 319 from the supply 8 and thereby render the entire automatic portion of the relay systems 11 and 12 inoperative.

The contact fingers 53 are connected to the bus bar 204 at

terminals

207 and 208 through the contacts MR2 and MIr-2, respectively, in parallel circuit. The contact finger 52 is connected through a conductor 286, the contact RS5, a conductor 287 and the contact L-2 to the terminal 243 or the contact R2 to terminal 237, the contacts R2 and L-2 being in a branched circuit that is in series connection to the conductor 287. The

conductors

287 and 387 arc-connected by a conductor 288. The contact finger 51 controls the energization of the relay MC, and. a bus bar 289 to which the relays AR and AL are connected by a circuit that extends from the contact fin 'er 51 through a conductor 291, the contact R 9, and a conductor 292 to a terminal 293. From the terminal 293, a circuit extends, through the neutral contact CS2, a conductor 294, a terminal 295, the winding of the relay MC, and a conductor 296, to the terminal 213 on the bus bar 205. From the terminal 295, a conductor 297 extends to the common terminals of the switch CS.

Accordingly, the relays MC are controllable either from the

potential relays

14 and 15 or from the manual switch CS. Hence, all the circuits that are controlled through the relays MC' are adapted to operate whenever the motors 6 are to be energized. By a conductor 298 extending from the terminal 293 to the terminal 393, both of the relays MC are simultaneously energized from either of the

potential relays

14 and 15, provided the switches OS are in their neutral positions.

From the terminal 293, a circuit extends through the conductor 292 and the contact TS4 to the bus bar 289. Accordingly, the bus bars 289 and 389 are energized in accordance with the operation of the timing relays G181 and the position of the switches TS and R From the terminal 248, a conductor 2101 extends downwardly to the contact RS8, and the latter is connected by a conductor 2102 on which a terminal 2103 is mounted, through the contact TS3 to a bus bar 2104 that energizes all the windings of the relays AR when the relay MC is closed. The terminal 2103 is connected to the switch contact CS-4 by a conductor 2105, and from the contact -CS'4 of relay unit 11 to the contact GS4 of relay unit 12 by a conductor 2106. The foregoing circuits permit the energization of the

bus bars

2104 and 3104 upon the closure of either of the switch contacts CS4, for raising the potential of the circuit 2.

The circuits of the several relays AR are similar for the relay units 11 and 12 and, accordingl the circuit for a single relay AR only is ere traced from the bus bar 2104 through a conductor 2107, a contact of the relav MC, a terminal, the winding of the relay AR, a conductor 2109, the forward limit switch 61, a terminal 2111, the switch 63, and

the contact TS-5 to the bus bar 205. From the terminal 2108, a holding circuit for the relay AR extends through a contact AR-1, and the cam switch 119 to the bus bar 289. The relays AR are originally energized from the

bus bars

2104 and 3104 that are connected to the bus bars 219 and 319 or the switches CS. However, the energization of the bus bars 219, and 319 lasts only for a short period of time, which is shorter than the time required for a tap-changing operation. Hence, the holding circuits are connected to the bus bars 289 and 389 that are energized through the timing relay GR. i

The relays AL are connected to bus bar 2112 through conductors 2113, contacts of the relay MC, a terminal 2114, the winding of the relay AL, a conductor 2115, the reverse limit switch 62 and the terminal 2111 and the switch 63. The holding circuit extends from the bus bar 289 through the cam switch 121 and the contacts AL, to the bus bar 2112. Since both the raising or relay AR, and the lowering or relay AL circuits for any transformer 5 include. the same manual switch 63, it follows that any tap-changing mechanism may be removed from the control of the control system 9 by opening the proper switch 63.

The bus bar 2112 is connected through the contact TS2 to a terminal 2116, that is connected through the contact RS7 and a conductor 2117 to the terminal 256 and by a conductor 2118 to the contact CS-5 of the switch CS. The contacts CS-5 of the relay units 11 and 12 are connected by a conductor 2119.

The voltage raising and lowering

windings

27, 29 of the

relay unit

11 and 28, 30 of the relay unit 12 are connected between

bus bars

2121 and 2122, and 3121 and 3122, respective ly. The bus bars 2121 and 3121 are connected through the contacts TS-6 of their respective co-operating switches TS to the bus bars 204 and 304, respectively. Hence the bus bars 2121 and 3121 are connected directly to the circuit 8 upon the closing of their associated switch TS. Likewise, the

bus bars

2122 and 3122 are connected through the contacts TS5 to the bus bars 205 and 305, respectively, to the circuit 8.

Each winding 27 and 28 is controlled by a contact AR2 of its associated relay AR and by an interlocked

contact

67 and 69, respectively. The contacts AR-2 are paralleled by holding circuits including position switches 120 and

contacts

27A and 28A, controlled by the

windings

27 and 28, respectively. Likewise, windings 29 and 30- are controlled by a contact AL2, of its associated relay AR and by an interlocked

contact

68 and 71, respectively. The contacts AL2 are paralleled by holding circuits including position switches 122 and

contacts

29A and 30A, respectively.

The relays HM and 75 of the relay unit 11 are both connected through the contact TS7 to the bus bar 2121. The HM relay is connected through the two-position contact.

TS8 by a conductor 2123 to one of the relay windings AR or by a conductor 2124 and the contact TS9 of relay unit 12 and a conductor 3123 to a winding of a relay AB in the relay unit 12. 7

Likewise, the relay 75 is connected through the two-postion contact TS9 and a conductor 2126 to a winding AL or through a conductor 2127 and the contact TS8 of relay unit 12 to a winding of a relay AL. A conductor 2128 connects the common terminal of the relays Hll/Land 75, to the right of the contact TS7, to the contact T S7 of relay unit 12 and the bus bar 3121. Accordingly, the relay windings HM and 75 are connected through a contact TS7 to either the bus bar 2121 or 3121 whenever either of the relay units 11 and 12, or both, are utilized.

The relay windings HM and 7 5 are, therefore, energized whenever 'one of the switches TS is closed, the circuit 8 is energized and the windings AR and AL to which the relays are respectively connected are not open circuited by their associated

limit switches

61 and 62, respectively.

In the event that the relay windings HM and? 5 remain deenergized,their back contacts HM 3 and 78, respectively, complete a circuit through one of the contacts TS, that are connected in parallel circuit by the

conductors

2131 and 2132, and the battery 81 for ringing the alarm bell. 79. The energization of the lockout relay JL also completes a bell-ringin g circuit through the contacts JL2.

The common terminals of the switches CS are connected by a conductor 2133. For manunits 5, the bus bars 229 and 329 are connectback contact TS10 ed by a conductor 2136 in which are placed the contacts RS4 of both relay units. Between the contacts RS4, a terminal 2137 is secured to the conductor 2136 to which the contact switches 123 of transformer bank 3 are connected in parallel circuit with a back cont-act TS10 of relay unit 11, and by a conductor 2138 in series relation to the contact switches 123 of the transformer bank 4, the latter being parallel circuited by the back contact TS-lO of relay unit 12, to the conductor 288. Whenever a switch TS is manipulated to operate either of transformer banks 3 and 4, the corresponding switches 123 are placed in circuit by the opening of the The closure of the proper contact switches 123 shunt-circuits the relays R and L of relay unit 11 between the

terminals

237 and 243, respectively, and the bus bar 229, and between the bus bar 329 and the

terminals

337 and 343 of the relay unit 12. If the operating relays R and L are not short-circuited and thereby kept inoperative after the tap operation has commenced, there is danger of the

potential relays

14 and 15"initiatinga second operation immediately upon the completion of the first operation.

The resistor 239 of relay unit 11 is employed for the purpose of limiting the current to a normal value during the period that the windings of relays R and L are shortcircuited by the circuit extending from the

terminals

237 and 243, through the conduc-'

tors

2141, 2142 and the contacts R-2 and L-2, respectively, to the common conductor 287, thence, through the conductor 288, conductor 3126, the alternate circuits through the back cont-act TS-10 of relay unit 12 or the contact switches 123, the conductor 2138, the alternate circuits through the back contact TS10 of the relay unit 11 or the contact switches 123 of the relay unit 11, terminal 2137, contact RS-4 of relay unit 11, conductor 2144, terminal 2143, the terminal 245, and the conductors 238 and 244'the contacts HM and 76, and the windings R and L to the

terminals

237 and 243, respectively.

Assuming that it is desired to operate the tap-changers on transformer bank 3 from the relay unit 11, the operator first closes the switch TS of the relay unit 11. In case the operator desires to control both of the transformer banks 3 and 4 from the relay unit 11, both of the switches TS are closed and, if it is desired to control the transformer bank 4 only, the switch TS of relay unit 12 is closed and the switch TS of relay unit 11 is left open.

Having closed the desired switch or switches TS for indicating upon which transformer bank 3 and /or 4 the tap-changers are to be operated, the operator takes the handle 41 and places it in the switch RS for relay unit 11. Where the operator desires utilizing the relay unit 12 instead of the relay unit 11, the handle 41 would be placed in -the switch RS of the relay unit 12. The selected switch BS is then closed which places a potential on the bus bar 219, provided the lockout relays JL are deenergized and the switch OS of relay unit 11 is in its neutral position. The circuit for energizing the bus bar 219 has already been traced. I

After the energization of the bus bar 219, potential is placed on one of the

contact mem bers

33 and 34 of the relays 14. If the relays 14 are caused to fluctuate by reason of variations in the potential of the circuit 2,

to raise the voltage of the latter, thecontacts 33 are closed, which energizes the relay R, provided there is potential on the supply circuit 8 to energize the relay HM and thereby close its contact HM1. The energization of the relay R closes its contact R-l which then energizes relaylMR, and the latter closes its contact MR1 to energize the winding 43 and the armature of the motor 42.

The ener 'ization of the motor 42 starts the relay G to turning and by further turning of the relay GR, a circuit is completed between the

contact fingers

55 and 58 through the contact plate 49, provided the contacts MR4 and ML4 are closed, the reverse winding ,44 of the .motor 42 is energized to reverse the motor and return the relay GR to its initial position. But, since the contacts MR4 and ML4 are open-circuited so long as the relay MR isenergized, the motor 42 will continue to turn in its forward direction unless the voltage fluctuation that initially caused energization of the relay MR was of such a transitory character as to have subsided before the contact plate 49 engages I the contact finger 58. Accordingly, the relay GR resets itself when set in motion by a transitory fluctuation of the potential of the circuit 2.

Assuming, however, that the fluctuation of potential of the circuit 2 is sufliciently stable to have caused the contacts MR4 and ML4 to remain in open position, the relay GR continues to turn. until movement of the contact plate 49 causes it to engage with the contact finger 55 and to become electrically energized from the bus bar 219 and the contact plate 47 engages the

contact fingers

53, 52 and 51. The closing of a circuit between the contact members 53 and 51, through the contact plate 47, completes the circuit for the relay MC. The closing. of the relay MC connects the several windings of the relay AR to the bus bar 2104, which, in turn, connects them through their holding circuits to the bus bar, 289. The closing of the relays AR completes the circuit through the windings 27 between the

bus bars

2121 and 2122, as has heretofore been described. The energization of the windings 27 causes the

contacts

21, 22 and 23 of the motor 6 of the transformer bank 3 to be closed.

In the event that the switch TS,shoWn in relay unit '12 and associated with the transformer bank 4,.has been closed, the relay MC of the unit 12 is likewise energized, with the result that the contacts .21, 22 and 23 of the motor 6 in the transformer bank 4 are also closed. Both relays MC are energized simulthe contact plate 47 of the rela GR, and after the contact switches 123 have een closed by a partial operation of the selected transformer tap-changer units, 5, the relay R is short-circuitcd by the circuitv heretofore described. The completion of the circuit between the

contact fingers

55 and 59 insures that the relay MR will beshort-circuited until the relay GR. has been re-set preparatory to another complete operation.

Continued rotation of the relay GR completes the circuit through the contact plate 48 between the

contact fingers

53 and 54, for energizing the lockout relay J L, provided the relay M-R has not already been deenergized. The energization of the'relay JL results in the disconnection of the bus bar 219 from the supply circuit 8. I The structural features of the relay JL are such thatit requires a manual reset, and, accordingly, the operator must satisfy himself as to the cause of the energization of the relay J L before resetting it.

The foregoing operations described in connection with the relay unit 11 are duplicated in the relay unit 12 whenever the switches RS and TS are closed to put the relay unit 12 into service. At the end of each step of the operation of the motor 6, the circuits of the switches RS and TS are broken by the operation of the associated cam switches 119 and 120.

In the event that the'relays 14 operate to close their contacts 34 for energizing the relay L to lower the potential of the circuit 2, the relay ML and the motor winding 43 are energized, as has previously been explained in connection with the operation of raising the potential of the circuit 2. However, the bus bar 2112 is energized instead of the bus bar 2104 that is energized when the potential is being raised. The energization of the bus bar 2112 results in the energization of the relays AL rather than the relays AR, with the consequent energization of the

windings

29 and 30, if both switches TS are closed to control the

contacts

24, 25 and 26 of the several motors 6.

The selection'of the bus bar 2112 in lieu of the bus bar 2104, is controlled through the switches TS and RS from the contacts L1 rand R-1 of the relays R and L at the

terminals

232 and 256, respectively.

If any one or more of the transformer units 5 gets out of step with the other transformercunits, they may be put back in step by any one of three methods. The first is to continue to operate the tap-changing system until all of the limit switches 61 and 62, as the case may be, are open. The second method is to disconnect the correct transformers 5 from the control system 9 and to rely upon the relays 14 initiating the proper operation of the control system 9 to bring the connected transformers 5 back into step. The

third method is to disconnect the correct transformers 5 and to operate the manual control switch CS until the connected transformers 5 are back in step. The individual transformer tap-changing units may also be put in step by a suitable manually operative mechanism (not shown).

Assuming that it is desired to control one or more of the transformer units 5 by the hand switch CS, the latter is moved to close its contact (S-4 or its contact CS5, as desired. The movement of the switch CS disconnects the bus bar 219 from the circuit 8,

at the neutral contact CS 1, with the result that the automatic relay control system centering about the potential relays 14 is rendered inoperative. Before the switch CS is manipulated, the switch RS, previously in service, should be opened. The common terminal of both of the switches CS is then connected by a conductor 3135 and the bus bar 304 to one of the conductors of the supply circuit 8 and also through the back contacts RS11, the conductor 2135 and the conductor 2134 in series relation. Accordingly, the switches CS are energized independently 'of the lockout relays JL and the switches TS. However, before the contact (IS-4 may become effective to energize the

bus bars

2104 or 3104, the proper switch T$ must be closed, and, likewise, the same switch TS must be closed before the contact CS-5 can energize the

bus bars

2112 and 3112. At such times,

the relay MO is connected to the common terminal of the switch TS by the conductor 297 and to the bus bar 205. Accordingly, the relay MO is continuously energized when the relay unit 11 is under manual control.

In the event that the'potential of the supply circuit 8 fails, or in the event that the lockout relay JL is energized, the bell 79 gives the operator an indication of the condition. This is important for the reason that the apparatus connected to the motor 6 may be at a considerable distance from the location of the relay units 11 and 12.

Accordingly, I have devised a system of control for the plurality of banks of transformers equipped with tap-changing apparatus in which the operation of the tapchanging equipment is automatically controlled in accordance with the voltage fluctuation of the circuit to which the transformers are connected. Provision is also made for operating the control system from a manually actuated switch and for disconnecting one or more of the transformer units from the control system when desired. The con-' trol system is also provided with numerous interlocking and alarm features for indicating the faulty operation of'any one of the -.transformer units and also for determining whether the. fluctuation that initiated the automatic operation of the control system period.

was of a transitory or stable character. By-

suitably adjusting the speed at which the timin relay operates, it is possible to insure that t e control system will operate only a given number of times in a predetermined It 15 to beunderst ood that such changes may be made in the arrangement, number and character of the component parts of my invention as shall fall withinthe scope of the appended claims.

I claim as my invention:

1. In a transformer tap-changing system, a plurality of transformer tap-changing units arranged in groups, a control system therefor comprising a plurality of units, and

meansjwhereby any unit of the control system may selectively control one or more groups of tap-changing units.

bination of the groups of tap-changing units and the separate tap-changing units in each group.

4. The combination with a plurality of tap-changing units, of a control system for the tap-changing units comprising a plurality of relay units and selecting switches for determining the operative combination of tap-changing and relay units at any time.

5. In a tap-changing system, a control system comprising a plurality of relay units each of which comprises an automatic relay section and a contactor-controll-ing section, and means for so interconnecting the relay units that the automatic relay section of one unit controls the contact-controlling sections of a plurality of units' 6. In a tap-changing system, a control sy stem oomprlsmga pluralityof relay units each of which comprises an automatic relay section and a contractor-controlling. section, and

a relay actuatable by the automatic relay section and controlling the actuation of the contact-controlling section, and means for so interconnecting the relay units that the automatic relay section of one unit controls the controlling relays for a plurality of units.

7 In a tap-chan ing system, a control system comprising a p urality of relay units each of which comprises an automatic relay section and a contactor-oontrolling section, and a relay actuatable by the-automatic relay section and controlling the actuation of the contact-controlling section, and means for so intel-connecting the relay units that the automatic relay section of one unit controls the controlling relays for a plurality of units and selective switches associated with each relay unit for determining when the contact controlling section of any relay unit is to become energized from the associated controlling relay.

8. In a control system, a relay unit comprising an automatic section, a controlled section, a control relay energized from the automatic section and controlling the operation of the controlled section and manually controlled means for controlling the control relay and rendering the automatic section inoperative.

9. In a control system, a relay unit comprising an automatic section, a contact-controlling section, normally operated by the automatic section, and manually controlled means for operating the contact-controlling section to the exclusion of the automatic section.

10. In a control system, a relay unit responsive to conditions of voltage fluctuation in an external circuit and comprising a motordriven timing relay, the directionof movement of the timin relay being governed by the frequency of t e voltage fluctuations.

11. In a control system, a relay unit responsive to conditions of voltage fluctuation in an external circuit and comprising a motordriven timing relay and means for controlling the direction of moveme t of the timing relay in accordance with the f equency of the voltage fluctuations.

12. In a control system, a relay unit responsive to conditions of voltage fluctuation in an external circuit and comprising a motordriven timing relay and means for controlling the direction of movement of the timing relay in accordance with the frequency of the volt- .age fluctuations and means for permitting a complete operation of the timing relay regardless of recurring voltage fluctuations.

13. In a tap-changing device, a plurality of tap-changing units, means for-simultaneously and automatically controlling the opsupply circuit and the bus bars of the relay units comprising the back contacts of the lockout relays in series relation.

15. In a control system, a supply circuit, a plurality of similar relay units comprising lockout relays having back contact members and a bus bar and a connection between the supply circuit and the bus bars of the relay units comprising the back contacts of the lockout relays in series relation and selective switch contacts constituting portions of the relay units.

16. In a control system a circuit, a plurality of potential responsive relays energized from the circuit and each having a different range of operation, each relay comprising a pair of contact members that are closed under predetermined conditions of potential drop and a pair of contact members that are closed under predetermined conditions of voltage rise, like pairs of contact members of each pair of relays being connected in series relation, whereby the range of operation of the plurality of relays is greater than the range of operation of'either relay.

17 In a control system, a circuit, a tapchanging mechanism for controlling the potential of the circuit and a relay system for controlling the tap-changing mechanism comprising a plurality of potential responsive relays energized from the circuit and each having a different range of operation, each relay comprising a pair of contact members that are closed under predetermined conditions of potential drop and a pair of contact members that are closed under predetermined conditions of voltage rise, like pairs of contact members of-each relay being connected in series relation, whereby the range of operation of the plurality of relays is greater than the range of operation of either relay.

In testimony whereof, I have hereunto subscri lped my name this 21st day of February, 192

WILLIAM R. FARLEY.