US1714938A - Automatic switching equipment - Google Patents

Description

May 28, 1929. R. E. BEAR 1,714,938

AUTOMATIC SWITCHING EQUIPMENT Filed April 28, 1928 Inventor: Ralston E.Bear, WWW

Hus Attorney Patented May 28, 1929.

UNITED STATES PATENT OFFICE.

'RALSTON E. BEAR, or LOS ANGELES, CALIFORNIA, AssIGNoR T GENERAL ELECTRIC I comm, 1 conreorm'rron or raw YORK.

AU.!'OIA TIC SWITCHING EQUIPMENT.

Application filed April 28,1928. serial to. 273,780.

My invention relates to automatic switching equipments and particularly to automatic switching equipments for controlling the connection between a plurality ofsources of current and a plurality of load circuits so that under light load conditions all of the load circuits are supplied bL' the same source and under heavy load con itions certain of the circuits are independently supplied by different sources and one object of my inven- 'tion is to provide an improved control varrangement for accomplishing this result.

In accordance with my invention I pro vide an arrangement whereby a plurality of load circuits are normally supplied by a preferred source of current and an auxiliary source which is arranged to supply certain of the load circuits when the preierred source if overloaded is normally inoperative. WVhen the load on the preferred source reaches a predetermined Value which indicates that the load is approaching a valueat which it is dc.- sirable to place the auxiliary source in serv ice, the auxiliary source is startedand placed 7 in an operative condition to supply current.

\Vhen the load on the preferredsource 'exceeds another predetermined value certain of the load circuits are disconnected from the preferred source and are connected toithe auxiliary source. Suitable switching means is provided whereby either source may be made the preferred source and the other the auxiliary source.

My invention will be better understood from the following description taken in connection with the accompanying drawing which diagrammatically shows a-control system for controlling the connection between two load circuits and two sources of current and the scope of my invention will be pointed out in the appended claims.

In the accompanying drawing 1 and 2 are two load circuits which are arranged to be connected to a main bus 3 by switches 4 and 5. The load circuit 1 is also arranged to be connected to an auxiliarybus 6 by aswitch 7. The switches 4, 5 and .7 may be of any suitable type examples of which are well known in the art. JFor supplying current to the mainbus 3 and the auxiliary bus '6 I provide two sources ofcurrentwhichmiry be of any suitable type. As shown these sources are the generators 8 "circuit 14. The motors 12 and 13 are pro vided with suitable automatic switching means respectively whereby the starting of each motor generator set is vefi'ected by the completion of a starting circuit associated therewith. Since such automatic switching systems are-old and well known in theart and the details thereof constitute no part of my present invention, I have deemed it unnecessary to complicate the drawing by showing these switching means in detail.

The automatic switching means 15 .(not

shown in detail) for the motor 12 is arranged to be operated to effect the starting of the motor 12 whenever a starting circuit 16assoelated therewith is completed. The auto matic switching means 17 (not shown in detail) associated with the motor 13 is similarly arranged tobe operated to effect the Starting of the motor 13 whenever a starting circuit 18 associated therewith is completed. Manually controlled switches 19 and 20 are shown as one particular arrangemcnt'for ef- 'fect-ing at will the completion of thestarting circuits 16 and 18 respectively. Any other suitable control means, however, examples of which are'wellknown in'the art may beprO- vided for accomplishing this result;

For exciting the generators 8 and 9 I providethe exciters '22 and 23 which are directly connected to the motors 12 and 13 respectively and which are arranged to be connected to the field windings of the generators 8 and 9 respectively by suitable field switches 2i and 25. These switches 24 and 25 may be controlled either automatically or manually in any suitable manner examples of which are well known in the art.

In order that either generator may be made the preferred source and the other the auxiliary source I provide a transfer switch 27 which is arranged when in one position to connect the generator 8 to the main bus 3 and the generator '9 to the auxiliary bus 6 and which is arranged when in another position to connect the generator 9 to the main bus 3 and the genera-tor 8 to the auxiliary bus 6.

Under light load conditions both of the switches 4 and 5 are closed sov that the load '1 loadedi.

source is connected thereto.

circuits 1 and 2 are connected to the main bus sponsiveto the voltage of the bus .3 anda voltage relay 29 which is'connecte'd to the load c-1rcu1t'2 so as to be responsive to the voltage thereof. hen them-am bus 3 is energized and the load circuit 2 is deenergized and enerlliary source. In order that this relay. may

gi'zing circuit is completed through the contacts of the relays 28 and 29 for acontrol relay30 across a suitable-source of control current 31. In the arrangement shown in the drawing the control circuits 31 is arranged to be connected by. means of a manually controlled switch 32 to the' secondary ofa potential transformer 83, the primary of which is connected to the supply circuit 1 1. {The con.- trol relay 3O whenienergized completes acir-v cuit fol-the closing coil 34,01? the: switch across the control circuit 31 so that the switch pletesi a locking circuit for. the control relay so. that the opening orthe contacts of the voltage relay 29 due to the energization of the load circuit 2. does not effect {the 'deenergization of thecontrol relay 30. 1 Y

i The closingof the switch 4; between the mainibus. 3 d ad circuit 1 is-conttollfid by the-Voltage y s which is responsive to'fthe voltage of the bus 3 and also by a voltage 1Gl&yf86\Vl1lCl1:lS connected across the load circuit 1 so that it'is responsive to the voltage thereoffl When the main, bus 3 is energized andtheload circuit 1: is deenergized a circuit is completed "for the control .relay'37through'the contacts of the relays 28' and 36. l/Vhen the relay 37 is "energized lit completes a circuitfor the closing c'oil 38of the switch 41 if'the switch 7 is openand either of the ficldiswitches 24: or 25 is -open indicating that :both generators are not'excited or the current output :ofthesource connected to themain bus 3 is below'a predetermined value,

thereby indicating that the sourceis notover- In accordance with onefeature of iny invent-loathe auxiliary motor. generator set s normally shut down so that it is man 1noperative condition to supply current to the aux.-

iliary bus andis arranged who started automatically and to be placed in an operative condition to supply current to the auxiliary ;,bus' when the current output ofth'e source connected to the mainbus-reaches a predeftermin'ed Nalue. lVhenjthje current outputot the source connected to .themainubus reaches is; accom' lished} in 1 the followin =manner.

Tworelays 40 and} -11 are connected to the Thee nergiZatiOn of therelay '5 is'closed. 1 The switch 5 when closed COIl'I-i main bus 3 in any suitable manner so that they are energized in accordance with the current output of the source connected (to the main bus. When the" current output of the source connected to the main bus reaches a predetermined Value the may ato opcrates and completes the. circuit 01 a control relay 4&2 associated therewith. This control relay in turncomp-letes the startingcircuit or the automatic. switching means associated with whichever motor generator set .is, the auxcomplete the'proper starting circuit'the transfer switch 27 is providcd with suitable I contacts 7 sojthatin each operative position of the switch the/"contacts of the-relay 42 are connected across the startingcircuitj of'which-' ever source isthe auxiliary source.

If the output of the source conneeted'to'the main-bus exceeds a' greater predetermined value: the ;relay "4:l completes the circuit of an auxiliary f relay 43 associated therewithopening or the switch 4; so as to'd'isconne ct the load circuit 1 from the mainb'us The energization of the relay ialso' completes acira predetermined a'lu'efso that the voltage relay lfi, which isconnected'across the aun I iliary bus 6, is energized a predetermined effects the 2 amount. As soon as the control relay'ee becomes energized and the switch 4 is opened a circuitis completed for the-closing coil 46 of the switch 7to close the switch 7 and connect the load circuit '1 to the auxiliary bus 6. r The circuit of the closing'coil 16 includes the manually controlled S'Wlt't'h' lj? whichjis provlded so thatthe switch 7 maybe opened to effect thcdisconnection ot the loadcircu-it V l'from' the auxiliary bus 6 and itsueconnecs on the two load'circuits is such that it :may

(the operation 1 ;tion' to Ithe main bus "3' when the total load 1 s 1 J '110 the arrangement shown in theaccompanyingdrawing is as follows: E

Let-it: be assumed-that the switches 24-, 25,

32 and'lL'TQ-are closed and that the transfer switch 27 is in itsleft h'andposition so that the generator 9 is connected :to the auxlhary bush and the generator Sis connected to the mainbus 3. hen it .is dcsired to supply.

currentito the load circuitsl and 2 from the main source 8 themanually controlled switch 19 is closed so as to "effectthe completion of the starting circuit 16 1 and the operation. of the automaticfswitch ng meansfle associated with the motor-12 to' start the motor genera 1 'tor'set 10. As soon as the voltage of the 'erator' 8 builds up to a'predetermmedwalue" the voltage relay 2S1operates-t0; closeits contacts 51- o frthe voltagerelay, 29 willbe closed tactsfit). If at this time'the load circuit 2 is i not; energizedby some ,other-soiirceth'e =con- Y 7 V by closing itscontacts 53 connects the closing coil34 of the switch 5 acrossthe control circuit 31 so that theload circuit 2 is connected to the main bus 3. By closing its auxiliary contacts 54 the circuit breaker 5 completes r a locking circuit for therelay 30 so that this relay is not deenergized by the opening of thecontacts 51 of the relay 29 when the load circuit-2 energized, v

If the load circuit 1 is not, energized by lsomerot her source at the time the relay 28 closes its contacts 50 a circuitis completed for the control relay 37, This circuit is from one side of the control circuit .31 through the coil of relay 37, r esistor 55, contacts 5.6 of relay 36, contacts 50 ofrelay 28 to the other side of the control-circuit. Relay 37'byclosing its Contacts 57 completes a circuit for the closingcoil 38 0f the switch 4. This circuit is from -.one side of the control circuit 81 through swit cli 47, closing coil 38 of switch 4, the parallel connected contacts 58 59 and 60 of relay .43and field switches 24 and respectively, contacts 57 of relay 87, auxiliary contacts'fil on switch 7 to the other side of .31 throughswitch 47 a n; "creativeL onid the control circuit. The energization of the closing coil38 closes the switch 4 so that the load circuit 1 is connected to the main bus 3.

contacts 62 of relayj'40 to the other side of the control circuit 31'; The relay 42 by closing its contacts 673 completes a circuit in parallel around thecontacts 62 of relay 40 so that the relay 42 remains energized in case the relay 40 subsequently opens its contacts .42, Relay 42 by closing its contacts 64wl1iclrare con: nected in the starting circuitby the means of V the transfer switch 27' effects the operation of the automatic switchingv means 17- assoelated with the motor 13 of the motor generatorset ll/ The automatic switching means 17 thenefliects the starting of the motor gen,- lator S '1fiefl ha thf g nera r i pl c 1 I on to supply current it l when the switch is sub} to 1 'ad ci' cu seduentlyclosed.

v QWhen the current output ofthe source 8 exce s r ate Pre e l rfi aed Y h e th current relay 41 closes its contacts 65 and thereby completes a circuit for the control relay 43. This circuit is from one side of the control circuit 31 through the switch 47 the coil of relay 43, contacts 65 of relay 41 to the other side of the control circuit 31. Relay 43 by closing its contacts 66 completes a circuit in parallel around the contacts 65 of relay 41 so that the relay 43 remains energized in case the relay 41 should subsequently open its contacts 65. The relay 43 by opening its contacts 58 effects the deenergization of the closing coil 38 of the switch 4 it both of the field switches 24 and 25 are .closcd'at this time. The vdeenergization of the closing coil 38 of the switch 4'causes the switch 4 to open and disconnect the load circuitl from the main bus 3. If the voltage across the auxiliary bus 6 is above a predetermined. value so that the contacts 67 of the voltage relay 45 are ,1

age relay 45 to the other side of the control circuit 31, As soon as the switch 4 opens and the relay'44isenerg1zed a circuit is com.-

pleted through the contacts 70 of the relay 44 for the closing coil 46 of the switch 7. This circuit is from one side of the control circuit 31 through the switch 47 closing coil 46 of switchi, contacts 70 ofjrelay 44, auxiliary contacts 71 of switch 41to the-other side of the control circuit31 The energiza- ,t-ion ofthe closing coil 46 effects the closing of .theswitch 7 so that the load circuit 1 is connected to the auxiliary bus 6. Each. of the load circuits is nowindependently energized by aseparate source of current.

Switch 7 by closing its auxiliary contacts 72 completes a locking circuit for the control relay 44 which is independent of contacts 68 of relay43 and contacts 67 015 relay 45.;

i If at any time. the source connected to the main bus 3 becomes deenergized so that the voltagerelay 28 opens its contacts 50 and closes its contacts 74, shunt-circuits are completedjaround the coils ofthe control relays 3O and37 othat the openingofthe switches 4 and 5 is effected. The shunt circuit around the coil 30 includes the contacts 74 of the relay 28 and the auxiliary contacts 75 of the switch 5, The shunt circuit around the coil of the relay includes the contacts 7404? the relay28 andthe: auxiliary contacts 75 on the switch 4; Therefore, whenever the source connected tether rnainbus fails both of the load circuits are disconnected from the main bus v; In a similar manner it the source connectedtothe auxiliary bus 6 fails while the switch. 7 is closed the opening of the switch 7 is efiectedso as to disconnect the load c'ir: ei irelm t e au i us hi result rent output of whicheversource is connected to said one of said buses and the excitation of the generators of both motor generator sets for effecting the disconnection of certain of said load circuits from said one of said buses, and means dependent upon predetermined energization of said other bus and the disconnection of said certain of said load circuits from said one of said buses for effecting the connection of said certain of 1 said load circuits to said other bus.

In Witness whereof I have hereunto set my hand this 23rd day of April, 1928.

RALSTON E. BEAR.

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