US2107902A - Supervisory control system - Google Patents

Description

Feb. 8, 1938. J. H; OLHDIER Q 2,107,902

SUPERVISORY CONTROL SYSTEM FiledSept. 12, 1933 4 Sheets-Sheet l HIGH RESISTANCE MARE/HAL CONTACTS 0N Inventori James :LjOh'v r", am

109 is Attorney.

Feb. s, 1938. I E 2,107,902

SUPERVI SORY CONTROL SYSTEM Filgl Sept. 12, 1933 4 Sheets-Sheet 2 Inventofi James H.012 er: b9

Hi' Attorney.

Feb. 8,1938. .1. H. OLIVER SUPERVISORY CONTROL SYSTEM Filed Sept. 12, 1933 4 Sheets-Sheet 3 v Invntorl James l-LOH er", 23.9. 1.. fi shA q eulog Feb. 8, 1938 J H OLIVER 2,107,902

SUPERVISOR! CONTROL SYSTEM Filed Sept. 12, 1933, 4 Sheets-Sheet 4 Inventorl James H.Oliver-;

His Ubo'r-rwegy Patented Feb. 8, 1938 UNITED STATES PATENT ori ice 2,107,902 j SUPERVISORY CONTROL SYSTEM James H. Oliver, Aidan, Pa., assignor'to General Electriccompany, a corporation of New York Application September '12, 1 32, Serial No. 689,087

11 Claims. 01. 177-353) My invention relates to supervisory control two-position control key such as CK3 and systems for supervising and controlling appa-- CK-23 which controls the operation of the corratus in a remote station from a control station, responding indicating lamps. Each group of insuch as a dispatchers ofilce. dicating lamps consists of'a red lamp such as 5 One object of my invention is to provide an R-3 and'R 23-which when lighted indicates 5 improved two-wire supervisory control system that the corresponding apparatus unit is in its whereby a desired apparatus unit in a remote staclosed position, a green lamp such as G-3 and tion may be selected by transmitting to the re- (3-23 which when lighted indicates that the -mote station a predetermined code of impulses corresponding apparatus unit is in its open poover the two-line conductors. .I'he selection may sition, a white lamp such as W-3 and W-23 l0 be checked by transmitting over the two conducwhich when lighted indicates that the position tors to the control station a predetermined check of jth eg correspinding apparatus unit does not code corresponding to the selected unit, and the correspond with the position of the associate operation of the selected unit can be effected by control key and an amber lamp such as AM3 an impulse transmitted over the two conductors I and AM-23 which when lighted indicates that 15 only if the selected unit is the proper one. the corresponding apparatus unit has been prop- Another object of my invention is to provide erly selected for operation. -Each group of keys an arrangement whereby in addition to acheck and lamps has associated therewith an individual code being transmitted to the control station indicating relay, such as IR--3 and IR-23,

after an apparatus unit has been selected, an in which determines by its position whether the asj dication of the position of the selected unit is sociated red or green lamp islighted and which 20 also transmitted over the two-line conductors becooperates with the associated control key to defore the selected unit can be operated. termine whetherthe associated white lamp is I Another object of my invention is to provide lighted. The position of each indicating relay in 25 an improved two-wire supervisory control system turn is determined by h position f e r- 25 of the above type which requires a minimum responding apparatus unit in a manner which amount of apparatus and a minimum amount of will be hereinafter described. As shown in Fig. time to eifect a desired supervisory and control 1, the indicating relays IR3 and IR23 are in operation. the position they occupy when the corresponding My invention will be better understood from apparatus units are in their open po i i ns an 30 the .following description when taken in conthe control keys CK-3 and CK-23 are also nection with the accompanying drawings and its shown in the corresponding positions so that the scope will be pointed out in the appended claims. een 1 mpS.G and (xare ted and t e Referring to the drawings which comprise other lamps are notlighted. It will be seen that 5. Figs. 1 to 4 inclusive, suflicient. apparatus a d if either controlkey should be moved to its other circuits of a supervisory control system embodyposition, the, associate White a p Would be ing my invention have been shown by means of lighted.

the usual conventional diagrams to enable my In Order that the Operation o y O e O the invention to be readily explained and understood. s t s y effect the s l on of the or- The apparatus and circuits shown in Figs. 1 and resp ndin ap a atus u a su finder and 40 2 are those located in the control or dispatchers cede Selecter ch S and a ode sender 23 are oflice while the apparatus and circuits shown in p d att dispatehe'rs Office r tra sm t- Figs g 4 are th located t th remote t ting to'the remote station over the line conductors tion which is connected to the dispatchers of-. L# and L a series of Seven r n mp l fice by only two line conductors L| and L 2 the respective polarities of which vary with the 45 v In practicing my invention I provide at the unit to be selected. The finder and code selector dispatchers voilice a group of control keys and inswitch l S and the code sender 28 preferably are dicating lamps for each apparatus unit to be selector switches of the well-known type which selected and controlled in the remote station; comprise. banks of w n y-fiv contacts, e ch In order to simplify the disclosure, only two bank having associated therewith a cooperating 50 groups of keys and lamps are shown. Each group wiper. A suitable operating magnet is provided of keys consists of a two-position select key. such for simultaneously moving all of the wipers in as SK-3 and SK-23, which is operated by the a step-byel movement Over the c n cts of dispatcher when he desires to select a c0rrethe respective banks. Any other suitable switch sponding apparatus unit for operation, and a ing means, examples of which are well known in 55 beallotted to a different apparatus unit so thatwith the arrangement shown twenty-three different apparatus units can be supervised and controlled. As shown, position 3 of the switch IS is allotted to the apparatus unit corresponding to select key SK--3 and position 23 is allotted to the apparatus unit corresponding to select key SK-23. When select key SK-3 is operated, the motor magnet M--I is arranged to be operated to efiect the movement of the switch IS from its normal position to its third position where it will stop and remain as long as the switch SK-3 is maintained in its operated position. In similar manner, when the select key SK23 is operated the operating magnet MI operates to move the switch IS to its twenty-third position Where it remains until the select key SK-23 is restored to its normal position. 7

When the switch IS stops in any one of its positions, it sets up a code individual to that position. For example, when it stops in position 3 it sets up a code individual to the select key SK-3 and similarly when it stops in position 23,

it sets up a code individual to the select key At the dispatchers ofiice asuitable start'key ST is provided which the dispatcher operates after he has operated the selcct'key of the desired apparatus unit which he desires to operate. The operation of this start key ST effects the operation of the operating magnet M2 of the code selector 2S so that this code selector moves from its normal position to its 18th position. During this operation of the code selector 2S a circuit is completed for a code transmitting relay CTR, which is a three-position polarized relay, through the wiper and contacts of the bank 2S--I when the switch 25 is in positions 3, 5, '7, 9, ll, 13, and 15. The direction of the current flow through these circuits of the code-transmitting relay CTR. depends upon the position of the; code selector switch IS. When a positive potential is connected to a contact of bank ZS-I, the code-transmitting relay CTR operates in a direction to cause a positive impulse to be transmitted over the line conductors L-'I and L-2 and when a negative potential is connected to a contact of bank 2S-'I the code-transmitting relay CT'R operates to cause a negative impulse to betransmitted over the line' conductors. In this manner a series of seven positive and negative impulses is transmitted to the remote station'to select the desired apparatus unit. 7

At the remote station this series of seven positive and negative impulses energizes a coderesponsive relay CRR" which is a three-position polarized relay. Each energization of the coderesponsive relay ORR effects the operation of a selector switch IS, comprising six banks of twenty-five contacts lSI to IS-B'inclusive and an operating magnet M-I, and the energization of one of the selective relays ZIP-33 inclusive so that in response to the code of impulses transmitted thereto the relays 2l!'33 inclusive are selectively operated to effect the selection of the desired apparatus unit.

After the selecting code of impulses has been transmitted and correctly received bythe receiving apparatus in the remote station, the operation of another selector switch 2S, comprising six banks of twenty-five contacts 2S-l to 2S-6 inclusive and an operating magnet l 1I-2,

is effected. This selector switch 2S has a sepa- As shown, positions 3 and 23 of this switch are allotted to the apparatus units AU'-3 and AU-23 respectively. These apparatus'units are shown as circuit breakers of the well-known latched-in type,"butit is obvious that each apparatus unit may be any other suitable controldevice. Each circuit breaker is provided with a suitable closing coil, such as closing coil CC'-3 for apparatus unit AU-3 and closing coil CC'-23 for apparatus unit AU"23 and with a suitable trip coil such as trip coil TC'--3 for apparatus unit AU-3 and TC-'- 23'ior apparatus unit AU'-23. Associated with each apparatus unit is a control relay, such as CR'-3 and CR- 23 for apparatus units AU3 and'AU'-E3 respectively, which selectively controls the energization of the closing and tripping coils of the correspondingapparatusfunit. As shown, these control relays are three-position polarized relays of thewell-known type whose armature re turns to its neutral position when the relay is deenergized. The circuits of the control relay windings are respectively connected. to the contacts of bank 2S'-5 allotted to the correspondcan be completed only throughthe twenty-third V off-normal contact of bank 2S-5.

In order to stop the selector switch 2S in the position corresponding to the apparatus unit selected, the relays 2S-33' are arranged to connect a potential to the contact in bank 2S-2 which is allotted to the selected unit. When the switch 2S reaches that position, the relay I is energized to open the circuit of the operating magnet M-2 so as to cause the switch 2S to 'remain in that position.

At the remote station there is also a finder and a code selector switch 3S which is similar in.

construction and operation to the finder and code selector IS in the dispatchers ofiice. The switch 3S is controlled by the operation of the switch 2S so that they always occupy corresponding positions. Therefore, when the switch 28' is moved to the position allotted to a "selected apparatus unit, the switch 38' is moved to the corresponding position and sets up the code of impulses of the selected apparatus unit. 7

As soon as both of the switches 2S and 3S have reached the, positions allotted to the selected apparatus unit, a code, sender As is operated in the remote station to transmit over the line conductors L-I and L-2 the code of im-' pulses set up by the switch 3S; This code selector 4S comprises six banks of twenty-five contacts 4S'-I to 4S'6 inclusive and an operating magnet M'-4. During the operation of this code sender from its normal position to its twenty-second position, a circuit is first coniline conductors L-! and L7 2 at the remote 10 rate position allotted to each apparatus unit; a

transmitted to the code-transmitting relay CTR" which in. turn transmits .a'cor'responding impulse over the line COIld'llCtOl'Sv At the dispatchers office theseimpulses operate'a code-responsive relay CRR, which is a three-position polarized relay. Each operation of the code-responsive relay CRR effects the op eration of a selector switch comprising four banks of twenty-five contacts 3S-l to 38-4 inclusive and an operating magnet M-3 and the selective operation of a group of selectorrelays 10 26 inclusive. After this series of impulses has been transmitted, circuits are completed by the operated control relays in" the dispatchers office for the amber lamp and the indicating relay associated with the operated select key and for a common check relay Id The lighting of the amber lamp informs the dispatcher that the selection has been properly made and the operation of the indicating relay checks the indicat- 'ing lamps and effects any change that "is necessary" in order to make them correspond with the positionyof the corresponding apparatus unit.

The energization of the check relay l4 prepares a circuit whereby the dispatchermay now operate the selected apparatus unit.

For operating a selected apparatus unit a twopos ition operate key 0K is provided at the dispatchers o'ifice. After receiving the indication that the proper apparatus unit has been selected, the dispatcher first moves the control key of the selected apparatus unit to the position corresponding to the one to' which he wants to' operate the apparatus unit and then he operates the operate key OK. A circuit is then completed for a predetermined time interval for a control relay l6 which when energized disconnects the code-receiving relay CRR from the line conductors L-I and L2 and connectsthe line conductors to the battery BAT so that a negative impulse is transmitted over the line conductors.

, As longas this operate impulse is being trans- 'mitted, an operate lampv 0L is lighted in the dispatchers oflice.

Atthe remote station this negative impulse effects the operation of the code-receiving relay CRR which in turn effects the connection of the proper polarity to the winding of the polarized control relay of the selected apparatus unit so that it in turn effects vthe desired operation of the selected apparatus unit. When the operate impulse is cut on from the line conductors L-l and L 2, the code-responsive relay CRR in the dispatchers office is reconnected across the line conductors and in the remote station the transfer relay 35f is energized for a predetermined time to disconnect the code-receiving relay CRR' from the line conductors and to connect the line conductors to the contacts of the code-transmitting relay CTR'.' The code transmitting relay CTR' is then energized in accordance with the new position of the selected apparatus unit and causes an indicating impulse corresponding to this .to the position corresponding to the new position of the selected apparatus unit. The indicating relay in turn controls the circuits of the lamps corresponding to the selected apparatus unit so that they indicate the new position thereof I. s .i 1

The dispatcher may operate the selected apparatus unit as many times as desired by successively operating the operate key before the selection is released. After each operation, the corresponding signalling lamps are operated to indicate the new position of the operated unit.

After the last operation has been performed, the dispatcher can release the selection and restorethe apparatus to normal merely by restor-- IA'23 for apparatus unit AU'-3 and AU23 respectively, which operates in response to each change in the position of the associate apparatus unit to cause the switchZS to'move to the position thereof allotted to the apparatus unit which has changed its position. Switches 38' and 48 then operate to efiect the transmission of the code of impulses corresponding to the operated apparatus unit and an impulse corresponding to the new position thereof. At the dispatchers office these impulses effect the operation of the selector switch 38 and of the relays'Ifi-ZS inclusive so that an alarm ALM is operated to inform the dispatcher that an apparatus unit has changed its position andthe indicating relay corresponding to the operated apparatus unit is operated to the position corresponding to the new position of'the apparatus unit. The indicating lamps corresponding to the operated apparatus unit are thereby lighted in accordance with the new position thereof and the associate white lamp is lighted to indicate to the'dispatcher which unit has changed its position. The dispatcher can extinguish the white lamp by moving the associate control key to the position corresponding to the new position of the unit.

The alarm ALM'is controlled by a two-position keyAK. With this key AK in oneposition, the alarm operates continuously when an apparatus unit changes its position. When the alarm key AK is in its other position, the alarm is operated for only a short time. The continuous operation of the alarm may be stopped by the op-- erator moving the alarm key to its other position.

The detailed operation'of the systemshown is as follows: With the system at rest and in an operative condition, a circuit is completed for the start lamp STL through the contacts I00 of the zero position check relay I which is energized. At the remote station'when'both of the switches ISand 48 are in their normal positions, a circuit is completed from the positive terminal of a battery BAT, through the wiper and normal contact of bank IS-4, conductor 400, winding of relay I, wiper and normal contact of bank 4S4, to the negative terminal of battery. BAT,

CRR', conductor 40I,'contacts 304 of transfer relay35, line conductorL-I, contacts IOI of relay IB conductor I02, contacts I03 of why, winding of code-receiving relay CRR, wiper and normal. contact of bank 2S-3, line conductor L2, contacts '305 of transfer relay 35', contacts 7 300 of relay If to the negative terminal oi the Since either a short circuit or open circuit on the battery BAT. The direction of current flow in this circuit is such that the contacts 402 of relay ORR and contacts I04 of relay CRR. are closed. The closing of the contacts 402 completes a cirout from the positive terminal of battery BAT", through winding of relay 3', contacts 402 of relay ORR, wiper and normal contact of bank IS'--2, conductor 465, winding of relay 36' to the negative terminal of battery BAT. By closing its contacts403, the relay 3' completes an obvious circuit for the relay 4'.

,In the dispatchers omce, the relay CRR completes a circuit from the positive terminal of the battery BAT, through the winding of relay I, conductor 200, contacts I04 of relay CRAR, con.- ductor I05, wiper and normal contact of bank 3S-I, conductor 2 0I, winding of checkrelay I, conductor I06, wiper and normal contact of bank 2S4 tothe negative terminal of the battery BAT. Contacts 202 of relay I complete an obvious circuit forrelay 0 which is of the slow-to-drop-out type. Contacts I00 of relay I complete the contacts of the start lamp STL and the contacts I01 complete a holding circuit for the alarm relay 2 through the contacts I08 of the alarm relay.

line wires would deenergize the relay ORR in the dispatchers oifice, and this relay in turn would deenergize the check relay I, it is evident that when the start lamp STL is lighted it indicates that all of the equipment is in the zero or starting position and that the line wires L-l and L-2 are in an operative condition.

In order to describe the operation of the arrangement shown, it will be assumed that the apparatus unit AU--23 is open and that the dispatcher desires to close this apparatus unit. After first observing that the start lamp STL is lighted, the dispatcher operates the select key SK-23 corresponding to the desired apparatus unit. The operation of this select key results in the opening of the contacts I09, and the closing of contacts I I0 and II I. By opening contacts I09 and closing contacts IIO, a high resistance: relay 5 is inserted between the 23rd contact of bank IS-lfi and the positive terminal of battery BAT. The closing of contacts III completes through the wiper and normal contact of IS-6 and interrupter contacts IC--I an energizing circuit for the operating magnet M--I. Magnet MI then operates in a manner well known in the art to move the selector switch IS from its zero position to position 1 and then continues to move the switch to its 23rd position since each contact of bank IS-B is normally connected to the positive terminal of battery BAT. When the 23rd position is reached, suflicient current does not flow through the relay 5 and the operating magnet M'I to efiect the operation of the operating magnet. However, relay 5 operates and by closing its contacts II2 connects the seventh off-normal contact of bank 2SI to the negative terminal of battery BAT. This relay 5 is common to a number of select keys, not shown, and is arranged so that when any one of these particular select keys is operated, the seventh off-normal contact of bank'2SI isdisconnected from the positive terminal of batteryBAT and is connected to the negative terminal thereof.

In-positions 1-23 of switch IS a circuit is completed through the wiper of bank IS5, winding of relay 4 whichis of the slow pick-up type, contacts II3 of emergency resetkey ERK, wiper and normal contact of bank 2S-- 2 to the neutral terminal of batteryBATf Since adjacent contacts of bank IS-5 are connected toopposite'terminals of battery BAT, the reversals of current which occur through the winding of relay 4 prevent the relay from picking up during the notching operation of the switch. After the switch IS stops in its '23rd,position however the relay 4 picks up and completes through its contacts I I4 a locking circuit for itself which is independent of the wiper of bank 2S2 so that the subsequent movement of switch 2S does not result in the deenergization of relay 4. By opening its contacts II5, the relay 4 disconnects the 18th off-normal contact of bank 2S -6 from the negative terminal-of battery BAT.

The -code corresponding to apparatus unitj AU -23 is now set-up by the polarities impressed on the off- normal contacts 3, 5, I, 9, I I, I3, and I5 of bank 2SI. With the p-articular arrangement shown in the drawings, the polarity of the first two impulses is fixed and so the ofi-normal contacts '3 and 5; of bank 2SI arepermanently connected to the positive terminal wipers of banks IS2, IS3, IS'-4, IS-5, re-

spectively. In the 23rd position of switch IS, the wipers IS-2 and IS'5 are connected to the positive terminal of battery BAT and the wipers IS-3 and IS-4 are connected to the negative terminals of battery BAT. Therefore, the code,

for apparatus unit AU"-23 is positive, positive, negative, positive, negative, negative, positive.

After the dispatcher operates the select key SK-23, he operates the start key ST so that contacts IIB are closed andv contacts I" are open. A circuit is then completed from the negative terminal. of battery BAT, through contacts Il6, conductor I I8, contacts II9 of relay 4, contacts I20 of. checkrelay I, conductor I2I, wiper and normal contact of bank 2SI interrupter contact IC-a'2, winding of relay 6 to neutral terminal of battery BAT. ,After a time delay relay 6 closes its contacts I2I and completes an energizing circuit for the operating magnet M2 of selector'switch 2S. Magnet M2 by opening its interrupter contactsIC-2 interrupts the abovetraced circuit for relay 6 so that relay 6 drops out and opens the energizing circuit of the operating magnet M2 "which causes the switch 2S to move from its normal position to position minal of battery BAT, relay 6 and operating magtacts 402 of relay CRR closes its contacts I2'I,

by opening net M-2 are alternately energized and deenergized to efiect the movement of switch 28 from position 1 to position 18 in which position the circuit of relay 6 is open at the contacts I I5 of relay 4. As selector switch 28 moves from position 1 to position 18, the wiper of bank 2SI engages the contacts to which the code impulse potentials are applied and completes through contacts I22 of relay 28 an energizing circuit for the operating winding of the code-transmitting relay CTR, which is a three-position polarized relay. 4

When the wiper of bank 23 engages a contact which is connected to the positive terminal of battery BAT, the code-transmitting relay CTR is operated to close its contacts I23 and I 24 so that the line conductors L-I and L-2 are con- .nected to the positive and negative terminals of battery BAT respectively, and when the wiper of bank 2S-iI engages a contact which is connected' to the negative terminal of battery BAT the relay CTR closes its contacts I25 and I26 so that the line conductors L-I and L2 are connected to the negative and positive terminals of battery BAT respectively.

When the selector switch 2S leaves its zero position, the heretofore traced zero position check circuit is interrupted by the wiper of bank 2S3 leaving its normal contact. Therefore, the relays CRR and CRR becomes deenergized and their armatures are restored to their neutral positions. In the dispatchers ofilce, the opening of the contacts I'04 of relay CRR efiects the deanergization of the relays I, I, and 8. The deenergization of the relays 1 and 8 has no eifect at this time. By opening its contacts I the check relay I extinguishes the start lamp STL and by opening its contacts I0'I it interrupts the circuit of the alarm relay2. Although the alarm relay the alarm is not operated at this time because the circuit thereof is open at the contacts 1 of the start key ST.

In theremote station, the opening of the coninterrupts the heretofore described circuit of relays 3 and 36. Relay 3 its contacts 403 and closing its contacts 404 completes an energizing circuit for the operating magnetM -I of switch IS to effect the movement of this switch'from its zero positionto position 1. This circuit is from the negative terminal of battery BAT through contacts 404 of relay 3, contacts 405 of relay 4, wiper and normal contact of bank IS6, winding of magnet MI interrupter contact ICI to the neutral terminal of battery BAT. Although the cir- I selector switch 28 in, the dispatchers ofiice reaches its third position, the selector switch IS in the remote station is in its first position. E'ach time the code-transmitting relay CTR is operated 'to transmit an impulse, a circuit is completed for the code-receiving relay CRR which is connected across the line conductors LI and L2 through contacts 304 of the transfer relays 35, conductor 40I, winding of relay CRR, conductor 303, contacts 302 of relay I2, conductor 30I, contacts 301 of relay I which is deenergized as soon as switch is leaves its normal position, conductor 308,

wiper and normal contact of bank 4S--I, conductor 309, contacts 3I0 of relay I and contacts 305 of relay 35'. When the contacts I23 and I24 of the code-transmitting relay CTR are closed, the positive impulse which is transmitted over the line conductors L-I and L-2 causes the code-receiving relay CRR to close its contacts 406 and when the contacts I25 and I 26 of the code-transmitting relay CTR are closed, the negative impulse which is transmitted over the line conductors LI and L-2 causes the code-receiving relay CRR to close its contacts 402. Therefore, when the switch 28 reaches its third position and the code-transmitting relay CTR is 0perated to transmit a positive impulse, the codereceiving relay CRR completes a circuit from the positive terminal of battery BAT through winding of relay 3, contacts 406, wiper and first contact of bank ISI, conductor 401, winding of relay 22', conductor 408, contacts 409 of relay 36 to the negative terminal of battery BAT. Relay 22 by closing its contacts 4I0 completes a locking circuit for itself to the neutral terminal of battery BAT. As soon as the switch 2S leaves its third position and the positive impulse is disconnected from the 'line conductors, relay 3 closes its contacts 404 and completes a circuit from the negative terminal of battery BAT, through contacts 404 of relay 3', conductor 4I2, contacts 4 of relay 22, conductor 4I3, wiper and first contact of bank I S6, winding of magnet M-I, interrupter contact ICI to the neutral terminal of battery BAT. Magnet MI then operates to move the switch IS .to its second position.

When the switch 28 reaches its fifth position, the code-transmitting relay CTR again operates to transmit a positive impulse over the line conductors so that the code-receiving relay CRR again closes its contacts 406. A circuit is now completed from the positive terminal of battery BAT through relay 3, contacts 406, wiper and second off-normal contact of bank IS' I, conductor 4I4, winding of relay 23, conductor 408, contacts 409 of relay 36' to the negative terminal of battery BAT. By closing its contacts M5, the relay 23 completes a locking circuit to the neutral terminal of battery BAT. When the switch 28 leaves its fifth position, the second impulse is cutoff and the code-receiving relay CRR operates to interrupt the circuit of relay 3. By closing its contacts 404, the relay 3 completes a circuit from the negative terminal of battery BAT through contacts 404, conductor 4| 2, contacts MS of relay 23', conductor 4II, wiper and. second off-normal contact of bank IS-0, magnet M-I, interrupter contact ICI to the neutral terminal of battery BAT. Magnet M-I then eifects the movement of switch IS to its third position.

When the switch 28 reaches its seventh position, the third impulse which is a negative impulse is transmitted to the code-receiving relay CRR so that this relay closes its contacts 402. A circuit is then completed from the positive terminal of battery BAT, through winding of relay 3, contacts 402 of relay CRR, wiper and third oiT-normal contact of bank IS2, conductor 4I8, winding of relay 25', conductor 4I9, contacts 420 of relay 36 to the negative terminal of battery BAT. By closing its contacts 42I, the relay 25 tive impulse is cut off and relay CRR opens itsv 6 contacts 442 so that the relay 3 is deenergized. A circuit is then completed from the negative terminal of battery BAT, through contacts 404 of relay 3, conductor 4I2, contacts 422 of relay 2%, conductor 423, wiper and third off-normal contact of bank IS6, winding of magnet M-I, interrupter contact IC-I to the neutral terminal of battery BAT. Magnet M-l then operates to move the switch IS to its fourth position.

When the switch 2S reaches its ninth position, the code-transmitting relay CTR. is operated to transmit the fourth impulse which is a positive impulse to the code-receiving relay CRR so that it closes its contacts'406. A circuit is then completed from the positive terminal of battery BAT, through winding of relay 3, contacts 446 of relay CR3, wiper and fourth off-normal contact of bank IS'I, conductor 424, Winding of relay 2%, conductor 468, contacts 469 of relay St to the negative terminal of battery BAT. By closing its contacts 425 relay 28 completes a locking circuit for itself to the negative terminal of battery BAT. As soon as switch 2S leaves its ninth position, the fourth impulse is cut off and relay CRR. opens its contacts 406 to interrupt the circuit of relay 3. A circuit is then completed from the negative terminal of battery BAT through contacts 444 of relay '3, conductor 4I2, contacts 426 of relay 26, conductor 421, wiper and fourth off-normal contact of bank IS-5, winding of magnet M'l interrupter contact ICI to the neutral terminal of battery BAT. Magnet M--l then operates to effect the movement of switch IS to its fifth position.

When the switch 2S reaches its eleventh position the code-transmitting relay CTR transmits thefifth impulse which is a negative impulse to the code-receiving relay ORR so that this relay closes its contacts 402. A circuit is'then completed from the positive terminal of battery BAT through winding of relay 3, contacts 4&2 of relay CRR, wiper and fifth oil-normal contact of bank IS-2, conductor 428, winding of magnet 29, conductor 4I9, contacts 420 of magnet '36 to the negative terminal-of battery BAT. By closing its contacts 429, relay 29 completes a locking circuit for itself to the neutral terminal of battery BAT. When the switch 2S leaves its eleventh position, the fifth impulse is out off and relay CRR, opens its contacts 402 so that the relay 3 is deenergized. A circuit is then completed from the negative terminal of battery BAT through contacts 404 of relay 3, conductor 4I2, contacts 430 of relay 29, conductor 43!, wiper and fifth off-normal contact of bank IS-6, winding of magnet M-I, interrupter contact IC'-l to the neutral terminal of battery BAT. Magnet M-I then operates to effect the movement of switch IS to its sixth position.

When the switch 2S reaches its thirteenth position the code-transmitting relay CTR is operated to transmit the sixth impulse, which is a negative impulse, to the code-receiving relay ORR so that it closes its contacts 402. A circuit is then completed from the positive terminal of battery BAT through the winding of relay 3, contacts 402 of relay CRR', wiper and sixth off-normal contact of bank IS5-2, conductor 432, winding of relay 3|, conductor 4I9, contacts 420 of relay 36 to the negative terminal of battery BAT. By closing its contacts 433, relay BI completes a locking circuit for itself to the neutral terminal of battery BAT. When switch 28 leaves its thirteenth position, the sixth impulse'is cut off and relay CRR opens its contacts 442 and interrupts the circuit of relay 3. A circuit is then completed from the negative terminal of battery BAT, through contacts 484 of relay 3, conductor 4E2, contacts 434 of relay 3!, conductor 435, wiper and sixth off-normal contact of bank IS-E, windingof magnet M'-l, interrupter contact IC'-I to the neutral terminal of battery BAT. Magnet M--i then operates to effect the movement of switch IS to its seventh position.

When switch 2S reaches its fifteenth position, the code-transmitting relay CTR is operated to transmit the seventh impulse which is a positive impulse to the code-receiving relay CRR so that it closes its contacts 406. A circuit is thencompleted from the positive terminal of battery BAT through winding of relay 3, contacts 495 of relay CRR', wiper and seventh off-normal contact of bank IS-l, conductor 436, winding of magnet 32, conductor 488, contacts 4% of relay 38 to the negative terminal'of battery BAT. By closing its contacts 431, relay 32 completes a locking circuit for itself through the neutral terminal of battery BAT. By closing its contacts 45I, relay 32 completes an obvious circuit for the control relay 20. When switch 2S leaves its fifteenth position, the seventh impulse is cut off and relay CRR opens its contacts 404 to deenergize relay 3'. A circuit is then completed from the negative terminal of battery BAT through contacts 404, conductor 4I2, contacts 438 of relay 32, conductor 439, wiper and seventh off-normal contact of bank IS'-6, winding of magnet M-I, interrupter contact IC-l to the neutral terminal of battery BAT. MagnetM-I then operates to effect the movement of switch ES to its eighth position.

Should the remote station fail to receive one or more of the code impulses, the switch IS will be in a position between its normal position and position 8 after the last impulse is transmitted. While the code impulses are being transmitted, the interval between successive impulses is not sufficiently long to allow the relay 4 to open its contacts 4B5 and close its contacts 4552. After the last impulse, however, the interval is long enough to allow relay 4 to open its contacts 465 and close its contacts 452. Therefore, if the switch is is in any position between its normal position and position 8, a circuit is completed for the slow-to-drop-out relay 5 from the negative terminal of battery BAT through contacts 484 of relay 3', contacts 452 of relay 4, wiper and contact of bank lS--5, winding of relay 5 to the neutral terminal of battery BAT. Byclosing its contacts 453, relay 5 completes a notching circuit for the magnet M-I through contacts 452 of relay 4 and contacts 404 of relay 3 to move the switch IS from whichever position it is in to position 9. Since the relay 5' is of the slow-todrop-out type, this notching circuit is maintained by the relay 5 to effect the movement of the switch IS through its position 8 although J the circuit of relay 5 is open in this position.

In positions 9 to 23 inclusive of switch IS, a notching circuit is completed through the wiper and contacts of switch IS--5 and contacts 404 and 452 to restore the switch IS to its normal position. Therefore, it will be seen that if one or more impulses of the code are not received or if an extra impulse is transmitted, the switch ES is immediately restored to its normal position after the code has been transmitted.

If the impulses are transmitted correctly, the switch iS is in its eighth position when the retacts 7 positive terminal of battery BAT" of relay 25, contacts 3S. Therefore, since the switch lay 4' closes its contacts 452 after the transmission of the last impulse of the code. A circuit is then completed from the positive terminal of battery BAT through wiper and eighth oiT-normal contact of bank IS--4, winding of relay 6, wiper and eighth ofi-normal contact of bank IS 5, contact 452 of relay 4, contact 404 of relay 3 to the negative terminal of battery BAT. By closing its contacts 454, relay completes a locking circuit for itself to the negative terminal of battery BAT. By closing its con- 440, relay 6 completes a circuit from the through contacts 440, conductor 4, contacts 3 of relay I 9', contacts 3|2 of relay 1, winding of magnet M'2, interrupter contact IC-2 to the neutral terminal of battery BAT. A notching circuit is thereby completed for the magnet M'-2 so that the switch 28' is operated until it reaches its twenty-third position which is the position allotted to the apparatus unit AU'23. A circuit is then completed from the positive terminal of battery BAT through contacts 442 of relay 6, conductor 443, winding of relay 34, conductor 3|3, contacts 444 of relay 22', contacts 445 of relay 23', contacts 446 of relay 25, contacts 441 I 448 of relay 29, contacts 449 ofrelay 3|", contacts 450 of relay 2!), conductor 454', wiper and twenty-third off-normal contact of bank 2S2, winding of relay 1 to the negative terminal of battery BAT. Relays 1 and34 are energized by the completion of this circuit. By opening its contacts 3l2, relay 1 interrupts the notching circuit of magnet M'2 so that the switch 2S stops in its twentythird position.

Since corresponding contacts of banks 3S'6 and 2S' are interconnected, the relay 8 is deenergized to completethrough its contacts 3M and the interrupter contacts IC3 a notching circuit for the operating magnet M-3 of switch 28 is operated to the position allotted to the selected apparatus unit, the switch 3S is also operatedto the corresponding position. -When both of- "these switches 28' and 38 have stopped in their twenty-third positions which are the positions allotted to the apparatus AU'-23, the relay 8' is energized through the wipers and twenty-third ofi-normal contacts of the banks 2SI and 3S6.

With the switch 38' stopped in its twenty-third position, the code of the selected apparatus unit the seventh and which is positive, positive, negative, positive, negative, negative, positive is now set up on the contacts of banks 4S-3 of code sender switch 48. Since the first two impulses are always positive, ninth off-normal contacts of bank 4S-3 are permanently connected to the positive terminal of battery BAT. The eleventh, fifteenth, and seventeenth oif-normal contacts of bank 4S3 are respectively connected by the wipers and twenty-third off-normal contacts of banks 3S--|, 3S3, and 3S'-4 to the negative terminal of battery BAT and the thirteenth and nineteenth off-normal contacts of bank -4S'3 are respectively connected by the wipers "and twenty-third oii-normalcontacts of banks 3S''2 and 3S5 to the positive terminal of the battery BAT. 1;; In order that the code-receiving selector 3S in the dispatchers office may be rendered operative 'toreceive the check code, the fifth oif-normal contact of bank 4S3 is connected to the negative terminal of battery BAT. Therefore, a

starting impulse is transmitted to effect the movement of the code selector 3S in the dispatchers oflice from its normal position before the check code is transmitted thereto.

The position of the selected unit is indicated by the potential applied to the twenty-first and twenty-second oil-normal contacts of bank 4S'-3 by-the wiper of bank 2S6. Since switch 28 is in its twenty-third position and the apparatus AU23 is open and its auxiliary contacts 32] are closed, the positive terminal of battery BAT is connected to both the twenty-first and the twenty-second ofi-normal contacts of bank 4S3. If the apparatus unit AU23 were closed, its auxiliary contacts 32! would be open and its auxiliary contacts 322 would be closed so that the negative terminal of battery BAT would be connected to the twenty-first and twenty-third ofi-normal contacts of bank 4S3.

In position 23, the wiper of bank 2S6 also connects the winding of a control selection relay CSR between the neutral terminal and either the positive or' negative terminal of battery BAT, depending upon the position of the apparatus unit AU'23. Relay CSR which is a two-position polarized relay, is arranged to close its contacts 333 and 334 when the winding thereof is connected to the positive terminal of battery BAT and to close its contacts 335 and 336 when the winding thereof is connected to the negative terminal. With the apparatus unit AU-23 in the position shown, the relay CSR operates to close its contacts 333 and 334 when the switch 28 stops in its position 23.

When both of the switches 2S and 3S have stopped in their twenty-third position and relay 8 is energized, a circuit is completed from the negative terminal of battery BAT through contacts 3| 5 of relay 8, contacts 3| 6 of relay 1, conductor 3, contacts 3l8 of relay 9, conductor 3| 9, wiper and normal contact of bank 4S--6, interrupter contact IC-4, winding of relay III to the neutral terminal of battery BAT. By closing its contacts 320, relay II) which is of the slow pick-up. type completes through the wiper and normal contact of bank 4S5 a circuit for the operating magnet M'-4 of switch 4S. By opening the interrupter contacts IC4, the magnet M4 interrupts the circuit of relay l0 which in turn efiects the deenergization of the magnet M'--4 so that the switch 48 is moved to its first position. In positions 1-6 inclusive of switch 48' the first to sixth off-normal contacts of bank 4S'6 are connected to the positive terminal of battery BAT through conductor 323, contacts 324 of relay 34, conductor 325, wiper and eighth oif-normal contact of bank lS-3 to the positive terminal of battery BAT and. in positions 7-21 inclusive the seventh to the twenty-first contacts of bank 4S-6 are connected directly to the positiveterminal of battery BAT. Therefore, as soon as the switch 35 sets up the check code, the code sender 4S moves from its normal position to its twenty-second position. I

Since only two line conductors are used, it is necessary that they be transferred from the code-receiving equipment to the code sending equipment in the remote station before the check code is transmitted to the dispatchers office. Thisresult is accomplished by relay 35' which is energized through the wiper and contacts of bank 4S-2 in positions 4-21 -inclusive of switch 48'. By opening its contacts 304 and 305, relay 35 disconnects the code-receiving relay CRR from Fit ' battery BAT. By closing its contacts 33?,re-

the relay CTR lay 35 completes a circuit from the positive terminal of battery BAT, contacts 333 of relay CSR, conductor 338, winding-of relay !1, contacts 339 of relay l3, conductor 345, contacts 331 of'relay 35, to the neutral terminal of battery BAT. By closing its contacts 34!, relay l1 completes a locking circuit for itself to the neutral terminal of battery BAT.

When the wiper of bank S-3 engages a contact whichis connected to the negative terminal of battery BAT, the code-transmitting relay CTR closes its contacts 328 line conductors L-l and L-2 are respectively connected to the negative and positive terminals of battery BAT and a negative impulse is transmitted over the line conductors. When the wiper of bank 4S-3 engages a contact which is connected to the positive terminal of battery BAT, closes its contacts 339 and 33! so that the. line conductors L! and L-2 are respectively connected to the positive and nega tive terminals of the battery BAT and a positive impulse is transmitted over the line conductor.

In the disp atchers office the impulses transmitted over the line conductors 'L-l and L--2 by the operation of the code-transmitting relay- CTR energizes the code-receiving relay 'CRR, which is. connected across the line conductors L-i and L-2 by contacts fill of relay w conductor I02, contacts I03 of relay 28, and wiper and eighteenth off-normal contact of bank 28-3. When the code-transmitting relay CTR is operated so that a negative impulse is transmitted over the line conductors, the code-receiving relay CRR closes its contacts I30 and when a positive impulse. is transmitted over the line.

conductors, the relay CRR closes its contacts I04. Therefore, when the code sender As in the remote station reaches its fifth position and the code-transmitting relay CTR is operated to transmit the starting impulse which is a negative impulse, the code-receiving relay ORR is operated to close its contacts I36 and thereby coinplete a circuit from the positive terminal of battery BAT through winding of relay 1, conductor contacts I36 of relay GER-conductor I3l,

wiper and normal contact of bank 3S-2, winding of relay i0, contacts 263 of relay 9 to the negative terminal of battery BAT. By closing its contacts 294, relay it completes a locking circuit to the neutral terminal of battery BAT. As soon as switch ts leaves its fifth position, the starting impulse is cut off from the line conductors and V relay CRR effects the deenergization of relay 1.

By closing its contacts 205, relay 1 completes a circuit from the negative terminal of battery BAT through contacts 205 of relay 1, conductor 205, contacts 281 of relay l0, conductor 208, wipers and normal contact of bank 3S-4, winding of operating magnet M3 of switch 33, interrupter contact IC-3 to the neutral terminal of battery BAT. Magnet M-3 then operates to effect the movement of switch 3S to its first position.

, When switch 4S reaches its seventh position and the code-transmitting relay CTR is operated to transmit the first impulse of the check code,

and 329 so that the to the neutral terminal of battery BAT. As soon" as the switch 4S leaves its position L'the first impulse of the check code is cut oif and relay ORR efiects the deenergization ofvrela'y' l. A

circuit is then completed from the negative terminal of battery BAT through contacts 265 of relay 1, conductor 206, contacts2|3 of relay i3, conductor 2M, wiper'and first off-normal contact of bank 36-4, winding of magnet M-S, interrupter contact 10-3 to the neutral terminal of battery BAT. Magnet M-3 ithen operates to effect the movement of switchcts to its second position.

When switch 4S reaches its ninth position and 7 relay CTR is operated to transmit the second impulse of the check code, which is a positive impulse, relay CRR again closes its contacts let and completes a circuit from the positive terminal of battery BAT through winding of relay 1, conductor 200, contacts 104 of relayrCRR, conductor Hi5, wiper and second oiT-normal contact of bank 3Sl, conductor 2l5, winding of relay [5, conductor 2l0, contacts 2 of relay 9 to the negative terminal of battery'BAT. By closing its. contacts 21%, relay l5 completes a locking circuit for itself to the'neutral terminal of battery BAT. As soon as switch 48 leaves its position 9, the second impulse of check code is cut off and relay ORR effects thedeenergization of relay i. A circuit is then completed from the'negative terminal of battery BAT through contacts295 of relay '1, conductor 206, contacts 2!! of relayzlii, conductor 2E3, wiperand second ofl'-normal contact of bank 3S- i, winding of magnet M3, interrupter contact IC-3 to the neutral terminal of battery BAT. Magnet M3 then effects the movement of switch 38 to'its third position.

When switch 48 reaches position H,'relay CTR is operated to transmit the third impulse of the check code, which is a negative impulse. Relay CRR then closes its contacts I and a circuit is completedfrom the positive terminal of battery BAT, through winding'of relay '5, contacts 22l, relay l8 completes a locking circuit for itself to the neutral terminal of battery BAT. As

soon as switch 48 leaves its eleventh position,

the third impulse of the check code is cut off and relay CRR 'eifects' the deenergiz ation of relay 1. A circuit is then completed from the negative terminal of battery BAT through contacts 2595 of relay i, conductor 286, contacts 222 of relay l8,

conductor 223, wiper and third off-normal con-'' tact of bank SSA-4, winding of vmagnet M3, interrupter contact IC-3 to the neutral terminal of battery BAT. Magnet M3 then effects the movement of switch 38 to its fourth position. When switch 43 reaches its thirteenthposition andrelay CTR. transmits the fourth impulse of the check. code, which is .a positive impulse, relay ORR closes its contacts H14 and completes a circuit from the positive terminal of. battery BAT V A-Icircuit is then th iQ h winding of relay I, conductor 200, contacts] 0,4 of relay ductor 224, winding of relay I9, conductor 2I0, contacts 2; of relay 9 to the negative terminal ofibattery BAT. By closing its contacts 225, the relay I 9:ccmpletes a -locking circuit for itself to I Assoon as switch 4 S-leaves its thirteenth position, the iourth impulseof the check code is cut off and relay-BR effects the deenergization of relay I. completed from the negative erminal of battery BAT through contacts 205 oi relay I, conductor 206, contacts 226 of relay I9,

conductor ZZl, wiper and fourth off-normal contactof :bank 35-4,, windingv of magnet M--3,

- interrupter contact IC 3 to the neutral terminal of battery- BAT. "Magnet M.3 then effects the movementtoi switch 38 to itsfifthposition. qgWhenswitch 4S reachesits fifteenth position andrelayCIR' transmits. the fifth impulse of a circuit from t which is a negative impulse, ,relaygCRR closesj its ccntacts I30 and completes e positive terminal of battery B through ,winding of relay '1, conductor 200,

CRR, conductor I05, wiper and I Y iourthoif-normal contact of bank 3S-I, coneontacts-JM of relay CRR, conductor -I3I, wiper I andqfijth oif-normal contact oibank 3S Z, con- Winding of relay22, conductor 22 0, ZNa-p re a -9,- to th a v i l tery- -BA'I. By closing its contacts 229,

eutral terminal of battery BAT. As soon as l irnpulseiof the check code iscut off and relay cRR -efiects the deenergization of relay 1. ci

A hit is thencompletedfrom the negative terof battery-BAT through contacts 205 of ;per and'iifth off-normal Conta tf ban flsr 'tr d o gnetM l interrupter contact -3 to the neutral ter- 1ininalluof battery BATU Magnet M-3 then effeetsthe movementof the switch. 38 to its sixth position.

When ,sWitchAS' reaches its seventeenth poionand the relay CTR transmits the sixth mpulse of:the;check code,which is a negative impulserelay CRRcloses its contacts l and ing itscontacts 233, relay 24 ing circuit for itself to I battery BAT. As soon completes a circuit ,from' the positive terminal *otbattery BA'Iithrough winding of relay 1, con- 'ductor; 200, contacts t 7 I30 of relay ORR, con, duster I3I, wiper and sixth oiT- normal contact ofubank 3S,2, conductor 232, winding of relay .2 conductor .220, contacts 203 of relay 9 to negativeterminal .of battery BAT. By closcompletes a lockthe neutral terminal of as switch 48' leaves its teenth position, the sixth impulse of the codeiis cut off andrelay CRR effects the d eenergization of relay 7. Acircuit is then com- .pleted'from the negative terminal of battery BAT contacts 234 of relay 24,

,,When switch 48 reaches ,sitionand relay CTR ,pulseof the check code,

" -oompletes acircuit from the positive terminal ofbatteryBAT through, winding of relay 1, conconductor 205, contacts ,230 of relay conductor 23!, 4o

therebycuts off the indication impulse.

ductor 200, contacts I04 of relay CRR, conductor I05, wiper and seventh cit-normal contact of bank 3SI conductor 236, winding of relay 2 5, conductor 2I0, contacts 2 of relay 9 to the negative terminal of battery BAT. By closing its contacts 231, relay 25 completes a locking circuit foritself to the neutral terminal of battery BAT. By closing its contacts 238 relay 25 completes an energizing circuit for the winding of relay I4. As soon as switch 48 leaves its nineteenth position, the last impulse of the check code is cut ofi and relay CRR effects the deenergization of relay 7. A circuit is then completed from the negative terminal of battery BAT through contacts 205 of relay 1, conductor 206, contacts 239 of relay 25, conductor 240, wiper and seventh cit-normal contact of bank BSFG winding of magnet M3, interrupter contact IC-3 to the neutral terminal of battery BAT. Magnet M-3 then effects the movement of switch 38 to its eighth position.

When switch 48 reaches position 2! and the code transmitting relay CTR operates to trans- -mit a positive impulsecorresponding to the open 7 BAT through winding of relay 1, conductor 200, 1 contacts I04 of relay ORR, conductor I05, wiper and eighth off-normal, contact of bank 3S-I, windingof relay II to the negative terminal of battery BAT. By closing its contacts 242, relay I! completesa circuit between the positive and neutral terminalsof. battery BAT for the master indication relay MIR so that "it closes its contacts 243. The master indication relay is a twoposition polarizedrela'y and is so designed that it remains in the position to which it is last moved whenever the winding thereof is deenergized.

Since the adjacent Off-normal contacts 2! and 22 of bank 4S-.3 are connected together, and relayCTR' is made slightly slow-to-release by having the resistor R connected in shunt to its winding, relay CTR maintains its armature in its operated position while the switch 48 is moving from itstwenty-first position to ty-second position. When the switch 4S reaches its twenty-second position an energizing circuit for relay twenty-second off-normal contact of bank 4S'4.' After the switch 48' has remained in its position 22 for a certain length of time, relay whose circuit is interrupted by the wiper of bank lS'-2 leaving its twenty-first off-normal contact opens its contacts 325 and 32? and Relay CRR then opens its contacts we and efiects the deenergization of relay I. A circuit is then com pleted from the negative terminal of battery BAT through contacts 205 of relay 1, conductor 2%, contacts 260 of relay Ii, conductor 26I, wiper and eighth off-normal contact of bank 3S 4;winding of magnet M-3, interrupter contact IC-3 to the'neutral terminal of battery BAT. Magnet M-3 then operates to effect the movement of switch 38 to its ninth position.

A predetermined time after the indication impulse iscut off by the deenergization of relay 35', relay '8, which is of the s1ow-t0-drop-out type, closesits contacts 243 This relay 8, the circuit of which is opened at contacts 202 of relayfil, is'so designed that the time interval between the diiferent impulses transmitted by the code sender 48? is not sufficiently long to allow I2 is completed by the wiper and its twenthe relay'to close its contacts 243-3. After the indication impulse is transmitted, however, the time interval is sufiicient to allow this relay to operate. When the contacts 243 close a circuit is completed from the negative terminal of battery BAT, through contacts 235 of relay 1, conductor 236, contacts 243 of relay 8, wiper and ninth off-normal contact of bank 33-3, winding of relay 21 to the neutral terminal of battery BAT. By closing its contacts 244, relay 21 completes a locking circuit for itself to the negative terminal of the battery which is independent of the contacts of the relays 1 and 8. By closing its contacts 245, relay 21 completes a circuit from the positive terminal of battery BAT through contacts 243 of relay WE, contacts 245 of relay 21, conductor 245, contacts 241 of relay I3, contacts 248 of relay I5, conductor 249, contacts 253 of relay l3, conductor I, contacts 252 of relay I9, conductor 253, contacts 254 of relay 22, conductor 255, contacts 256 of relay 24, conductor 251, contacts 258 of relay I4, conductor 253, winding of indication relay IRE-23 to the neutral terminal of battery BAT. A circuit is also. completed from conductor 259 through amber lamp AM-23, wiper and twentythird off-normal contact of bank ES,|, conduc- I tor I34, wiper and eighteenth off-normal con tact of bank 2S-5, winding of relay I4 to the neutral terminal of battery BAT. The direction of current flow in the winding of relay IR23 is such as to cause the relay to close its contacts 555 and open its contacts I56 so that the green light G-23 is lighted and the red light R-23 is extinguished. The lighting of the amber lamp AIM-23 indicates to the dispatcher that the selection has been properly made and that the selection check relay I4 is energized so that it is now possible for him to operate the selected apparatus unit. It will be observed that the amber lamp ANT-23 corresponding to the operated select key SK23 can be lighted only when the circuit established through the selection relays il -25 inclusive agrees with the contact on which the wipers of the code finding selector is at the dispatchers office have stopped.

After the amber light AWL-23 is lighted, the dispatcher moves the check key CK-23 to its opposite position thereby completing a circuit for the white light W-23. Then he operates the operate, key OK so as to close its contacts I and 533. The closing of the contacts I35 completes a circuit from the negative terminal of battery BAT through the Wiper and eighteenth off-normal contact of bank 2S4, conductor I39, contacts I38 of relay I i winding of relay I6, conductor I31, contacts 135 of key 0K to the neutral terminal of battery BAT. Relay Iii by closing its circuit from the negative terminal of battery BAT through winding of relay 32, contacts I46 of relay I5 conductor I4I, contacts H42 oi relay 33, line conductor L-2, contacts 365 of relay 35, contacts sic of relay I, conductor 339,. wind- F ing of high resistance relay I3, contacts 344 of relay I2, conductor contacts 304 of relay 35', line conductor I.r-l, contacts E43 of relay 33, conductor I44, contacts M5 of relay l6 to the positive terminal of battery BAT. Since the winding of relay I3 has a high resistance, the current in this circuit is not suificient to cause relay 32 to pick up. Relay I3, however, closes its contacts 345 and connects the winding of relay I4 and contacts 346 in a series circuit around the winding of relay I3. Relay I4 is contacts I40 and I completes aof the time delay pick-up type and is provided in the circuit so as to prevent any transient disturbance on the line from efiecting the operation of a selected apparatus unit.

By closing its contacts 341, the relay I4 connects the winding of the code receiving relay CRR across the line conductors L-I and L2. This circuit of the relay CRR is from line conductor L-I through contacts 304 of relay 35", conductor 4M, winding of relay CRR, conductor 333, contacts 341 of relay I4, contacts 346 of relay I1, conductor 309, contacts 3I0 of relay i, contacts 365 of relay 35 to line conductor L-2. The direction of current flow through the winding of relay ORR causes this relay to close the contacts 403 and'complete a circuit from the positive terminal of battery BAT through the winding of relay 3', contacts 406 of relay CRR, wiper and eighth off-normal con'-" tact of bank IS, conductor 456, contacts 352 of relay 34, conductor 353, contacts 334 of relay CSR, contacts 254 of relay I6, winding of relay I5, conductor 355, contacts 356 of relay I2 to the negative terminal of battery BAT. By 0105- ing its contacts 351, relay I5 completes a looking circuit for itself which is independent of the contacts 334 of relay CSR. By closing its contacts 358, relay I5 completes a circuit from the negative terminal of battery BAT through con tacts 353 of relay l5, conductor 359, contacts 358 of relay l4, conductor 36 I wiperand twentythird off-normal contact of bank 2S--5, winding of control relay CR-23 to the neutral terminal of battery BAT. The current in this circuit causes relay CR'-23 to close its contacts 352 and thereby complete through the auxiliary contacts 363 an energizing circuit for the closing coil CC-23 of apparatus unit AU--23.

When both of the relays I4 and CRR are connected in parallel with the high resistance relay l3 in the remote station, the current through the relay 32 in the dispatchers ofilce is sufiicient to cause this relay to pick up. By closing its contacts I46, the relay 32 completes a circuit for the operate lamp 0L so that this lamp is lighted as long as the control impulse is being transmitted to the control relay of the selected apparatus unit. By closing its contacts I51 and 53, the relay 32 completes shunt circuits around the contacts I42 and I43 of relay 33 so that the subsequent energization of relay 33 does not cut oii the control impulse. By closing its contacts 531, relay 32 completes a circuit from the positive terminal of battery BAT through contacts 535 of key OK, conductor M8, winding of relay 33, conductor I39, contacts I41 to the neutral terminal of battery BAT. By closing its contacts I53, relay 33 completes a locking circuit for itself around the contacts I41 of relay 32. Therefore, the relay 33 remains energized as long as the operate key is maintained in its .operate" position so that when the relay 32 subsequently drops out, another control impulse cannot be transmitted until after the key OK has first been returned to its normal position to effect the deenergization of relay 33.

When the apparatus unit AU-23 closes, it effects the opening of its auxiliary contacts 32I and the closing of its auxiliary contacts 322 so that the current through the windings of relays CSR, and CTR reverses. This reversal of current causes the relay CSR to open its contacts 333 and 334 and close its contacts 335 and 336 and the relay CTR, to open its contacts 330 and 33| and close its contacts 328 and 329. The opening V of the contacts 333 of relay CSR' interrupts the circuit'of relay l1 so that it opens its contacts '3 and 346. By opening its contacts 346, relay H effects the disconnection of the relays l4" and 5 CRR 'from'across the line conductorsso that the control currentis decreased below the drop out fvalue of the relay 32 m the"dispatchefs-oflice;

' Relay 32 then drops out andbyopening-Racontacts" I51 and I58 cuts'ofi'the'"controlti-mpulse l 1 10" and by closingits contacts sv transfers theiline conductors L-| and-'L- Z t'o the receiving circuit the di'spat'chers oflice-- h 7-. The operation or the apparatus unit'tAU N l'sointerrupts the lockingicircuit of, indicating "lay IA' -23;=-but as soonas" the apparatus unit enty ithi'rd Contact orbank zs' 3 conduc' a circuit from the negative terminali BAT, through the winding er-relay at e nductor 7 ontac'ts 358 501 relay l1, condu ctor36'ljcontactsf'afifi' of relay' l3; conductor*365,;wiper and 4, twenty second"off-normal'contact of bank ls' 2 l the neutral terminal of battery *BAT'.*'*- clay I at the remotestationydrops out anu 'c mplete a negative firnpulse {over the line {conductors I 1d tof'the neutral terminal of,batteryLBATf," v R lay mots 3310f relay 35"? By opening its contacts I 368,yrel ay If! interrupts the above-traced circuit rgtherelay 35' so 'thatfthe indicationfimpulse is i cutfofi and thelinejconductors11 and L"2:are

pa atu s at' the remete:, st a on; "Since-the relay I] s'of the slow-"to-pic "uptype, thein dication the line" 1 is transmittedffover battery BAT, By closing: its ay; l2freve'rses thejcurrent'through'the wind: 60 I of'relay MIR so that it'opensfit s contacts 243 V- nd f'close si its contacts 255i 5 This results 'ini'a reversal of current throughf the'indicating relay L tacts i 56" therebyextinguishing the Y green +23 and the white light w-qs and lightg f ain, desired; by mov -g the control key toth'e'opposite position and again moving "the -same as for the .jto i a ts, 35 lose?! t F a i, qhtr i p the relay [6'- to "be energized instead "of "the r 5 it's n'eivvfposition an energizing-circuit for" I the elay IA 23{is -completed throughthe' wiper When the control impulse is 'c'ut off, relay l3 4 f ybattery,

a y closing its' conta'cts' 3265115 331 ;transmits '2isince theic'q'ntacts 3281a meantime" negative terminal off ba tery, ducto'rj3 38; winding ofrelayii'; contacts 335i of v; relay I3f; conductortdo contacts 331 orr'eiay 35".

a position: a

' l 1 "by closing its contacts 34 i jc'ompl ems "a locking connected to the controlimpulse receiving v apg nductors indication I jTelaYj'CRR t0 Bl; winding of relay iZ to the negatlve tern inal i. ac 2 "solthat it opens vit'sicontactsv lii and closes The apparatusunit- Alf- 23 may be" opened operareik y to itsfcper atei position." The eneration of the apparat s in" the remote station V closing"operatioaeircept v that' the controlselect'ion relay CSR 'jnow has its =tral termina1 -o f battery'BAT,

fthen effects the 1m0verne'nt of "switch 35 to its V relay I5; In-this case relay I 6 by closing its 7 through the code transmitting'relay CTR. so that the indication impulse is a positive impulse. In

the dispatchers' oilic'e this indication impulse is received-as beforeexc'ept that relay H is ener-t gized by thepositlve'impulse to effect the operationof the indicating relay IR23 so as to extinguish there'd'lamp R-23 and to light the green lamp G23. t I 4 The apparatus unit A U-23 maybe operated as gman'y times as desired before the selection is released i To prevent the selected apparatus unit frompumping while the operate key OK is pressed, therelay l5 or I6 when energized,

contacts of the-relay CSR and opens the circuit oft-he i other felayJ Thus thefirst of those two relays to be-energlzed remains'energized until the 1 movin'gthe -select key SK 23 toits normal position; J-The closing cfthecontacts 1990f the select keyf SK- 23 connects the twenty-third off-normal contact of the bank IS6 to the positive terminal of sba'ttery'BAT so that a notching circuit is completed for the magnet M-l to move the switch glSito positionita A- notching circuit is then comjpleted"direct ly to the positive terminal or the bat tery.=,BAT:*to restore the switch iSto its normal Whenivswlt'ch IS moves" from its position 23,

' relay 4 drops "out and by closing its contacts H5 completes anotchingcircuitfor the magnet M-2 through the -vviperI-and eighteenth oif-normal contact: of bank 2S,.6; Magnet M-2 then effects the movement of the switch 28 to position -l9. Since,v the nineteenth to the twenty-fourth or! normal. contacts of bank 2S6 are connected directly to the negative terminal of the battery BAT, a notching circuit is then completed for the magnet M 2 to restore the switch 28 to its normal"position..y-

:soon' "as switch IS leaves position, the heretofore traced circuit for the relay 14 is. opened by'the Wiper of bank ISI leavingits twenty-third off-normal contact. By closing its contacts I60. relay l4 completes a circuit 1mm the "negative terminal of battery BAT-through contacts 2'll of relay 21, conduc- -tor 2 |2;:contacts1600f relay l4, conductor I6I,

winding of relay 28 to the neutral terminal of the battery BAT. Byclosing'its contacts I64,

relay 28 completes a-circuit from the positive terminal *of battery BAT through winding of relay 1; conductor200, contacts I64 of relay 28, conductor" 'l5, winding: of relay 9 to the negative terminalfof battery BAT. By opening itsconjt'acts2 03 and 2| I relay 9 opens all of the locking "circuits of the energized selection relays in the dispatchers ofiice. By closing its contacts I 62,

relay-:28 completes a'c1rcuit from the negative terminal o' f-battery BAT through I v contacts I62 of relay28 conductor 213; wiper and ninth oil- "normal. contact ofjbank 35-4, winding of magnet interrupter'contact IC 3 to the neu- The magnet M3 'tenthfpos'ition When-the switch 33 leaves posing twenty-third 20 completesa locking -circuit for itself around the tion 9 the heretofore traced locking circuit of relay 2! is interrupted so that it drops out and effects the deenergization of the relay 28 which, in turn, by. opening its contacts I64 eifects the deenergization of the relay I. After the'relay I has remained'deenergized for a sufficient length of time to allow relay 8 to close its contacts 243*, a. notching circuit is completed from the negative terminal of battery BAT through contacts 205 of relay I, contacts 243 of relay 8, wiper and ofi-normal contacts III-24 inclusive of bank 3S3, winding of magnet M-3, interrupter contact IC-3 to the neutral terminal of battery BAT. Magnet M-3 then notches the switch 38 to its normal position.

While the relay 28 is energized,.the contacts I66 thereof complete a circuit for the code transmitting relay CTR so that a negative impulse is transmitted over the line-conductors L-I and L2. In the remote station this negative impulse causes the code receiving relay, CRRto close its contacts 492 and complete a circuit from the positive terminal of battery BAT through the winding of relay 3, contacts 402 of relay,

CRR, wiper and eighth off-normal contact of bank IS2, conductor465, winding of relay 36 to the negative terminal of battery BAT. By opening its contacts 409 and 420, relay 36'.-interrupts' the locking circuits of the energized selection relays in the. remote station so that they are restored to their normal positions. By closing its contacts 466, relay 36. completesa circuit from the negative terminal of battery BAT through contacts 466 of relay v36', conductor v461, wiper and eighth off-normal contact of bank IS-6, winding of magnet M'-I, interrupter contact ICI, to the neutral terminalkof battery BAT. Magnet M-I then effects the movement of switch IS to its ninth position. In positions 9-24 inclusive of switch. IS a notching circuit is completed for the magnet M'-l through the wiper and contacts of bank IS-5, contacts 452 of relay 4 and contacts 404 of relay 3 after the release impulse is cut off from the line conductors so' that the switch IS is restored to its normal position.

When switch IS leaves its eighth position, the

circuit of relay 6 is interrupted by the wiper ;IS-4 leaving its eighth off-normal contact. By opening its contacts 440, relay 6 interrupts the heretofore traced notching circuit for magnet 28 so that the switch 2S remains in its twentythird position until another apparatus unit has been selected or an automatic operation of an apparatus unit occurs. Since the position of switch 38 is determined by the position of switch 28, switch 33 also remains in its twenty-third position.

When the selection relays 202-33 inclusive in the remote station are deenergized, the heretofore traced circuit of relay 34 is interrupted I so that this relay drops out. By closing its contacts 315, relay 34 completes a circuit-from. the positive terminal of battery BAT through contacts 375, conductor 316, wiper and twentysecond to twentyfourth oif-normal contacts of bank 4S-6, interrupter contacts IC4, winding of relay III to the neutral terminal of battery BAT. By closing its contacts 320, relay l0 completes a circuit through the Wiper and contacts of bank 4S'-5 for the slow-to-pick up relay II. RelayIl; in turn, completes a circuit for the magnet M'-4 through contacts 311. Magnet M--4 therefore. operates to restore the switch 45 to its normal position. Relay. II is connected in the notching circuit of magnet M-4 to provide slower stepping of the switch 48 from the position 22 to its normalposition. When the selector switches IS and 4S reach their normal positions, the heretofore traced check circuit is completed to effect the energization of the relay I which by closing its contacts I03 completes a circuit for the start lamp S'IL.

When the supervisory equipment is at rest and an apparatus unit changes its position, an indication is immediately transmitted to the dispatchers office. As an example, it will be assumed that the apparatus unit AU--23 is closed and opened automatically. While the apparatus 'IA'--23 to the neutral terminal of battery BAT.

When the apparatus unit AU-23 opens, the I locking circuit of.relay.IA-23 is opened so that relay IA23 drops out and closes its contacts 38I. A notching circuit is then completed for themagnet M'2 to move the'switch 28 from whatever position itmay bein to position 23 which is the position allotted to the apparatus unit AU-23. This notching circuit is from the positive terminal of battery BAT, through wiper and normal contact of bank IS-3, conductor 323, contacts 38! of relay IA-23, conductor 4, contacts 3II of relayISQContacts 3! of relay I, winding of magnet M-.-2, interrupter contact IC--'-2 to the neutral'terminal of battery BAT. When switch 28 reaches position 23, relay I is energized to open its contacts 3I2 and interrupt the above-traced notching circuit for themagnet M-2. The circuit of relay 1 isfrom the negative terminal of battery BAT through Windingof relay I, wiper and twenty-third.off-normalcontact of bank 2S-2, conductor 454, contacts 382 of relay IA'-'23, winding of relay. 9, conductor 400, wiper and normal contact of bank IS-4 tion. As soon as relay I is energized and switch 38 stops in position 23 so that relay 8 is maintainedin its energized position, a circuit is completed' from the negative terminal of battery BAT through contacts 3I5 of relay 8, contacts 3I6 of relay I, conductor 3I'I, contactso fll of relay 36, conductor 3I9, wiper and normal contact of bank 4S-5, interrupter contact IC-4, winding of relay I3 to the neutral terminalof battery BAT. Relay I0 then operates to establish a notching circuit for magnet M4 so that the code sender '43 operates to transmit the code of apparatus unit AU-23 in the manner above described to the dispatchers oflice.

As soon as switch 4S leaves its normal position, the heretofore described circuit for the zero position check relay I is opened. By opening its contacts I00, relay I extinguishes the start lamp STL, and byopening its contacts I01, relay I interrupts the locking circuit of relay 2. By closing its contacts I21, relay 2 completes, through contacts II! of start key ST, a circuit for the alarm ALM. Therefore the dispatcher is informed by the alarm and the extinguishing of the lamp STL that an automatic operation of an apparatus unit has occurred.

In the dispatchers oflice the code is received by ioode receiving relay CRR which in the normal position of switch 2Sis connectedacross the line conductors :by the wiper and normal contact of :;:bank.2s 3'.* This code efiects the energization of :selection .relaysl3, l5,- I8, I9, 22, 24, 25, and

l'in'the same'manneras described'for the check code and the relay II is energizedto effect the "operation of the relay-MIR so that its contacts 243 are closed; Therefore; when the relay 2'! is energized in response to the switch 38 reaching,

itsrininth position, indicating relay Ill-2,3 is energized so'asto close its contacts I 55 and open "litsicontacts I56 to effect the lighting of the green Fisdeenergized and therefore-the energization-of rela' l lalso completes a circuit Flor irelay '28 from the negative terminal of bat- ,qter-yBliT through contacts 27] of relay 21, coni'luctor 'flleon'tacts I60 of relay lie, conductor 6 l fwinding of relay 28, to the neutral terminal of t s Mtt'ery-ZBAT. Theenergization of'ielaylfi opens ltheilocking cirmiits of the energized select-ion relays in the dispatchers ofiice by efiectin'g the c {en'erg ization of relay ii an e fiects the movement I fofsvvitch 733 to itsnormalpositioniandoperates t stop inposition 2 2 hut contin th witch Footie transmitting cir relay CTR. so that a release impulse is transmitted over the -=1inc conductors L- IYand L-Z [in the manne previously de- In the remote Station the switch S, does 110i; lies to operate {until po ition since a notohing reaches normal connect the winding of relay 19 "across theii'ne condu tor and L-2 so that the relay I9" receives the release impulse sent out The notching of switch in positions 21-24 inclusive is slowed remains connected acrosslthe line conductors for a suflicient lengthof time to receive this release positive terminal y v auxiliary contacts 32! on apparatus unit AU'23,

contacts 386, of I relay impulse. By closing its con: completes a circuit from the of battery BAT through winding of relay IA"-=23, wiper and twenty-third I o'iI-normalcontact of bank 2S'-3,' conductor 381, Q

l9, to 'theneutral ter- 'minaloffbattery BAT; y; closing its contacts a SBOrela'y IAV-43 completesa'locking circuit for V itselfaround the contacts 386 of relay l9 so that "relay I v 7 traced zero position check circuit so that the relay ,5,

' thenx'reset for the next relay IA"23 remains energized until the apparatus unit AU23 again changes its posireaches its normal position, is energized" and completes the abovel inlthe dispatchers oifice is energized to efiect the lighting of the start lamp STL, the indication of the changed condition of; the apparatus unit AU'-23 is sent to the'dispatchers ofllce and the operation.

p aitcher extinguishers the white lamp W-23 -by turning the control key CK+23 to the position thereof which agrees with that. of theopen cirigcuit breakere *Hefcuts'ofi the alarm-by operatn i'hl alarm key AK which completes a circuit 108 completes a the dispatcher may immediately release the? I alarm key.

limited current for cult for magnet M -4 is completed through Y 'tl ie contacts 375 of the deener'gizedrclay 34 when p positions 2244 inclusive] imposition-s 2'3 and 2t cl" switch is a circuit -for. 1/ relay I8 is completed through the wiper and contacts ofib'ank '4S"--4. -l 3y closing its contacts supervisory equipment is The dis 1 3 for the alarm relay 2 either through the contacts I ll'l'or I'll depending upon the position of the check relay I. Relay 2 by closing its contacts locking circuit for itself so that While I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention. 7

What I claim as new and'desire to secure by Letters Patent of the United States is:

1. In a supervisory control system, a first station, a second station,apparatus units at said second station, two line conductors interconnecting-said stations, means including said conductors in series for selecting any of said units for operation, a, control device at said first station for controlling the operation of a selected apparatus unit, means responsive to the movement i of said device to a predetermined position for causing a limited current to flow through said conductors in series, means controlled by said effecting an increase in the current through said conductors in series and the operation of the selected apparatus unit, means responsive to the operation of the selected apparatus unit for decreasing the current t" o'ugh said conductors, and means responsive current through said conductors for preventing said control device from again effecting the flow of current through said conductors while said control device remains in said predetermined position,

I 2. In a supervisory control system, a first station, asecond station, apparatus units at said second station, two line conductors interconnecting said stations, means including said conductors in series for selecting any of said units for operation, a control device at said first stationfor controlling the operation of a selected apparatus unit, means responsive to the movement of said device to a predetermined position for causing a limited'current to flow through said conductors in series, timing means, means responsive to said limited current for effecting the operation of said timing means, means controlled by said timing means for effecting after a predetermined time interval an increase in the current through said conductors and the operation of a selected apparatus unit, means responsive to the operation of the selected apparatusunit for decreasing the current through said conductors, and means responsive to said in'c'reaseand subsequent decrease in the current through said conductors for preventing said coni trol device from again causing current to fiow through said conductors while said control device remains in said predetermined position. I

3. In a supervisory control system, a first station, a second station, apparatus units at said second station, two line conductors interconnecting said stations, means including said conductors in series for selectingany of said units for operation, a control device at said first stationfor controlling the operation of a selected apparatus unit, a relay, means responsive to the movement of said device to a predetermined poto said increase and subsequent decrease in the sition for connecting said source in series with said conductors and said relay, a time relay, means responsive to the energization of said firstmentioned relay for completing an operating circuit for said time relay through said conductors in series, a control relay, means responsive to the operation of said time relay for completing an operating circuit for said control relay through said conductors in series, means responsive to the operation of said control relay for effecting the operation of the selected apparatus unit, means responsive to the operation of the selected apparatus unit for interrupting the circuits of said time and control relays for a predetermined time interval, and means responsive to the current variations through said conductors produced by the completion and subsequent interruption of the circuits of said time and control relays for efiecting the disconnection of said source from said conductors and for maintaining them disconnected as long as said control device remains in said predetermined position.

4. In a supervisory control system, a controlling station, a controlled station, a plurality of apparatus units at said controlled station, two

line conductors interconnecting said stations, control devices at said controlling station individual to said units, signalling devices at said controlling station individual to said units, means responsive to a predetermined operation of any of said control devices for effecting the transmission through said conductors in series of a predetermined number of impulses of different character permutated individual to the operated control device, selective means at said controlled station responsive to said impulses for selecting one of said units, means responsive to the selection of a unit for effecting the transmission through said conductors in series of a predetermined number of impulses of different character permutated individual to the selected unit, selective means at said controlling station responsive to said last mentioned impulses for selecting the signalling devices individual to the selected unit, means including said conductors in series for operating the selected unit, means including said conductors in series for controlling the signalling device individual to the selected unit in accordance with the position thereof, and switching means at each station for controlling the connections to said line conductors so as to efiect said selecting, operating, and controlling operations,

5. In a supervisory control system, a controlling station, a controlled station, a plurality of apparatus units at said controlled station, two line conductors interconnecting said stations, control devices at said controlling station individual to said units, signalling devices at said controlling station individual to said units, means responsive to a predetermined operation of any of said control devices for effecting the transmission through said conductors in series of a predetermined number of impulses of opposite polarity permutated individual to the operated control device, selective means at said controlled statio-nresponsive to said impulses for selecting one of said units, means responsive to the selection of a unit for effecting the transmission through said conductors in series of a definite number of impulses of opposite polarity permutated individual to the selected unit, selective means at said controlling station responsive to said last mentioned impulses for selecting the signalling devices individual to the selected unit, means including said conductors in series for operating the selected unit, means including said conductors in series for controlling the signalling devices individual to the selected unit in accordance with the position thereof, and switching means at each station for controlling the connections to said line'conductors so asito efiect said selecting, operating, and controlling operations. 6. Ina supervisory control system, a controlling station, a controlled station, a plurality "of apparatus units at said controlled station, two line conductors interconnecting said stations, control devices at said controlling station individual to said units, signalling devices at said controlling station'individual to said units, means responsive to a predetermined operation of any of said control devices for effecting the transmission through said conductors in series'of a predetermined number of impulses of different character permutated individual to the operated control device, selective means at said controlled station responsive to said impulses for selecting one of said units, means responsive to the selection of a unit for effecting the transmission through said conductors in series of a predetermined number of impulses of different character permutated individual to the selected unit followed by an indicating impulse of g a' character dependent upon the position of the selected unit, selective means at said controlling station responsive to said last mentioned predetermined number of impulses for selecting the signalling devices individual to the selected unit, means responsive to said indicating impulse for controlling the operation of the selected signalling device, means including said conductors in series for operating the selected unit, and switching means at each station for controlling theconnections to said line conductors so as to effect said selecting, operating, and controlling operations.

'7. In a supervisory control system, a control ling station, a controlled station, a plurality of apparatus units at said controlled station, two line conductors interconnecting said stations, control devices at said controlling station individual to said units. signalling devices at said controlling station individual to said units, means responsive to a predetermined operation of any of said control devices for effecting the transmission through said conduc'tors in series of'a predetermined number of impulses of different character permutated individual to the operated control device, selective means at said controlled station responsive to said impulses for selecting one of said units, means responsive to the selection of a unit for effecting the transmission through said conductors in series of a predeter+ mined number of impulses of different character permutated individual to the selected unit followed by an indicating impulse of a character dependent upon the position of the selected unit, selective means at said controlling station responsive to said last mentioned predetermined number of impulses for selecting the signalling device individual to the selected unit, means responsive to said indicatingimpulse for controlling the operation of the selected signalling devices, means including said conductors in series for operating the selected unit from the control-' ling station only if the selected unit corresponds to t e operated control device, and switching means at each station for controlling the connections to said line conductors so as to effect said selecting, operating, and controlling operations.

8. In a supervisory control system, a controlling station, a controlled station, a plurality of apparatus units at said controlled station, two

line conductors interconnecting said stations, control devices at said controlling station individual to said units, signalling devices at said i controlling station individual to said units,

means responsive to 'a predetermined operation of any of said control devices for efiecting the transmission throughsaid conductors in series of a predetermined number of impulses of different character permutated individual to the operated control device, selective means at said controlled station responsive to said impulses for selecting one of said units, means responsive to the selection of a unit for effecting the transmission through said conductors in series of a predetermined number of impulses of different char- :acter permutated individual to the selected 'unit 'followed by an indicating impulse of a polarity dependent upon the position of the selected unit,

selective means at saidfcontrolling station responsive to saidlast'mentioned predetermined number of impulses for selecting the signalling devices individual to the selected unit, means responsive to said indicating impulse for controlling the operation of the selected signalling devices, means operative only if the selected unit corresponds to the operated'control device for transmitting through saidconducto-rs in series an operating impulse of a predetermined polarity, means at the controlled station responsive to said operating impulse for operating the selected unit, and switching means at controlling the connections to said line conduceach station for tors-so as to efiect said selecting, operating, and

. controlling operations.

9. In a supervisory control system, a controlling station, a controlled station, a plurality of apparatus units at said controlled station, two line conductors interconnecting said stations, control devices at said controlling station individual to said units, means responsive to a predetermined operation of any of said control devices for effecting the transmission through said conductors in series of a'predetermined number of impulses of diii'erent character permutated V 1 individual to the operated control device, selec tive means at said controlled station responsive to's aid impulses for selectingone of said units,

- means responsive to the selection of a unit for effecting the transmission through said conductors in series of a predetermined number of impulses of different characterpermutated individual to trolling station responsive predetermined number of the selected unit followed by an' indicating impulseof a character dependent upon theposition of theselected unit, selective means at said conto said last mentioned impulses for selecting 'g the signalling devices individual to the selected selected unit corresponds to the operated control ;unit, means responsive to said indicating impulse for controlling the operation of the selected signalling devices, meansoperative only if the device fortransmitting through said conductors r in series an operating impulse of a predetermined character, means at the controlled station responsive'to said operating impulse for operating the selected unit, means responsive to said operation of the selected unit for transmitting through said conductors infseries an indicating impulse 15 to efiect the operation of the selected signalling devices in accordance with the new position of the selected unit, and switching means at each station for controlling the connections to said line conductors so as to efiect said selecting, operating, and controlling operations.

10. In a supervisory control system, a controlling station, a controlled station, a plurality of apparatus units at said controlled station, two line conductors interconnecting said stations, control devices at said controlling station individual to said units, signalling devices at said controlling station individual to said units, means responsive toa predetermined operation of any of said control devices for effecting the transmission through said conductors in series of a predetermined number of impulses of opposite polarity permutated individual to the operated control device, selective means at said controlled station responsive to said impulses for selecting one of said units, means responsive to the selection of a unit for eiTecting the transmission through said conductors in series of a predetermined number of impulses of opposite polarity permutated individual to the selected unit followed by an indicating impulse of a polarity dependent upon the position of the selected unit, selective means at said controlling station responsive to said last mentioned predetermined number of impulses for selecting the signalling 'devices individual to the selected unit, means responsive to said indicating impulse for controlling the operation of the selected signalling devices, means operative only if the selected unit corresponds to the operated control device for transmitting through said conductors in series an operating impulse of a predetermined polarity, means at the controlled station responsive to said operating impulse for operating the selected unit, and switching means at each station for controlling the connections to said line conductors so as to efiect said selecting, operating, and controlling operations.

' 11. In a supervisory control system, a controlling station, a controlled station, a plurality of apparatus units at said controlled station, two line 7 conductors interconnecting said stations, con

trol devices at said controlling station individual to said units, signalling devicesat said controlling station individual to said units, means responsive to a predetermined operation of any of said control devices for efiecting the transmission through said conductors in series of a predetermined number of impulses of opposite polarity permutated individual to the operated control i device, selective means at said controlled station responsive to said impulses for selecting one of saidunits, means responsive to the selection of a unit for effecting the transmission through said conductors in series of a predetermined number of impulses of opposite polarity permutated individual to the selected unit followed by an indicating impulse of a polarity dependent upon the the selected signalling devices, means operative only if the selected unit corresponds to the operated control device for transmitting through said conductors in series an operating impulse of a predetermined polarity, means at the controlled station responsive to said operating impulse for operating the selected unit, means responsive to said operation of the selected unit for transmitting through said conductors in series an indicating impulse of a predetermined polarity to effect the operation of the selected signalling devices in accordance with the new position of the selected unit, and switching means at each station for controlling the connections to said line conductors so as to effect said selecting, operating,

and controlling operations.

JAMES H. OLIVER.

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