7 Oct. 22, 1946. W.‘A. DERR ETAL 2,409,840 CONTROL SYSTEM _ Filed July 7, 1-944 4 Sheets-Sheet 1 /9 Maj/(final Jag‘ INVENTORS Maurie e ?feayaf? andh/i‘lard Ii?er/I 'ArroR ' Oct. 22,1946." w. A. DERR EI‘AL ' - - 2,409,840. CONTROL ‘SYSTEM Filed Juiy 7, 1944 4 Sheets-Sheet 2 Leyenaf @ D/recf /D05/7/'Ve Cannec?bn ‘ @ Pas/Wire Comedian fbrazyb arma/‘ure Z 25’ 22.9 23 4 218 24? 2.98 235 |NVENTOR5 - Z. , - Maurice fla’aja'n and h/lYl/ara/ 1796/72 ATTORN ‘ ‘ ' Oct.‘ 22,1946. ‘ w. A. DERR ETAL 2,409,840 CONTROL SYSTEM Filed July 7, 1944 4 Sheets-Sheet a To 1'na’rkaz‘f/ly 1 amps ‘Raw WITNESSES: é 4W 0 d: . “W, 2M , Oct. 22, 1946. ~ ' ' w. A. DERR ETAL ' 2,409,840 I‘ CONTROL ' SYSTEM Filed July '7, 1944 ' ’4 Sheets-Sheet 4 0 454 WITNESSES: _ 'ITORNE ‘ Patented 0a. 22, 1946 2,409,840 UNITED. STATES PATENT ‘OFFICE ; CONTROL SYSTEM Willard A. Derr and Maurice E'. Reagan, Wilkins-v burg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application‘ July 7, 1944, Serial N0. 543,837 13 Claims. (Cl. 1'77—--353)v 1 Our invention relates,rgenerally, to control sys terns and it has reference in particular‘to super visory systems for supervisory control systems; Generally‘stated, it is an object of our invention 2 by a‘ supervisory relay which isnormally. con trolled by the ground detection relay and e?ects operation of a supervisory point relay to cause a fault code to be sent over the supervisory system. False operations of the supervisory relay due to operation of the impulse relays which connect the channel to and disconnect it from the remote and control station batteries, are ‘prevented by to provide a supervisory‘ system for‘ detecting faults on supervisory control systems, which is simple and inexpensive to manufacture and is easy to operate. More speci?cally, it is an object of ‘our invention v means of an auxiliary supervisory relay which to provide for detecting grounds and short or open 10 operates Whenever the supervisory control chan circuits on a supervisory control channel, as well nel is pulsing to remove the supervisory relay from as grounds on other portions of the system, and ' the control of the ground detection relay. low voltage on either the remote or control station For a more. complete. understanding of the battery, and to provide for indicating these condi nature and the scope of our invention, reference tions at the control station. 7 may be made to the following detailed description It is also an important object of our invention in connection with the accompanying drawings, in to provide for normally maintaining supervision which: of a supervisory control-channel by means of a Figure 1 is a diagrammatic view of the indivi relatively small supervision current when the dual equipment and selecting relays at the control channel is not in use, and for preventing false 20 indications of fault conditions while the channel Fig.‘ 2 is a diagrammatic view of the common. is being used for pulsing. equipment at thecontrol station; Another object of our invention is to provide for Fig. 3 is a diagrammatic view of the individual detecting and indicating grounds on the supervi equipment. and selecting relays ‘at the remote station; , . . sory control channel or on the remote station bat station; and tery, and preventing changes in such indications Fig. 4 is a diagrammatic view of the common equipment at the remote station. whenever the channel may be disconnected mo mentarily from the remote station equipment dur ing a pulsing operation. _ r The above-described figures are disposed to be arranged in a similar manner to Figs. 1 through Yet another object of our invention is to provide 30 4 of the Boswau Patent No. 2,091,301, which issued for detecting and indicating grounds on both the on August .31, 1937. -When thus arranged they remote and control ‘station batteries and to pro represent a supervisorylcontrol system which is vide‘ for preventing a ground on the control‘ sta basically the same as the system described in de tion battery from being indicated by the‘ remote tail in the BoswauPatent." For the purpose of station equipment during a pulsing operation. 35 simpli?cation,‘ some of the, circuit conductors‘ Still another object of our invention is to pro have been rearranged from the positions‘ shown‘ vide for indicating ground conditions on the sup in the Boswau Patent, but the’ general arrange-i ervisory control channel or the remote station bate ment of the supervisory control equipment and‘ the tery and preventing repeated reporting of the manner of operation‘ thereof ‘remains substantially ground condition owing to‘operations of the line 40 the same. Most ‘of the elements of the system of control relays during pulsing operations. ' A further object of, our invention is to provide for detecting and indicating low battery voltage conditions‘upon a relatively small change in the voltage‘ thereof. the present‘ application in‘ the same cooperative relation as in the Boswau patent, and they‘bear the same‘ reference characters as in the drawing 45 of the Boswau ‘Patent. ‘ Other objects will in part be obvious, and will in part, appear hereinafter. the‘Boswau patent are shown‘in the drawings-of ‘ In accordance with our invention, a recti?er de vice having one terminal grounded is used to operate a ground detection relay whenever the battery or the supervisory control channel, or any of the supervisory control circuits connected to the battery or channel become grounded. Indi cation of a ground condition at the remote station or‘ on the supervisory control channel is eiiected Certain relays of the Boswau Patent have been modi?edjslightly and other‘ relays have been added in order»? to perform 4' functions di?erent from those of the apparatus of the Boswau Patent. Entirely new elements have been designed by reference characters not found in the Boswau Patentpwhereas other ele ments which have been changed‘ only slightly have been- designated by means of prime numbers cor responding ‘to the designation-in the Boswau Patent in order‘ to more readily identify them. 4 3, be provided which may be normally energized and releasable upon operation of the line supervision Referring particularly to Figs. 2 and 4 of the drawings, it Will be seen that the line circuit or supervisory control channel connections have been changed from the series impulsing circuit of the Boswau patent to provide instead a par allel line impulsing circuit which is the type of relay I2. Circuit means may be provided in con nection with armatures 22, 23, 24 and 25 of the restoration start relay 2M, selection coding start relay 21E, relay 2H, and a supervisory alarm re layv I21 of the- control station equipment, respec circuit ridw mostgenerally usedsince it provides tively, to provide holding 1 circuits for the auxil iary supervisory relay 2|, which may be inter connecting the operating coils of the line relays 10 .posed between the control relay [6 and the alarm relay. is to prevent energization or deenergiza 268 and 400 of the control and remote stations tion of the alarm relay due to operation of the by means of a supervisory control channel com a continuous circuit which may be used for re mote metering, etc. In other words, instead of impulse relays. Relays l6 and ill may be of the prising the conductors H9 and .223 inseries cir- . ‘time delay type so as to insure the completion of relays 20! and 4M, respectively, as in the Boswau 15 the auxiliary holding circuits should the line su pervision relay l2 become deenergized due to op-. patent, the line relays 2G0’ and 40%!’ are herein cuit relation with contact members of the impulse eration of .the impulse relays. shown connected in parallel circuit relation. The Supervision of the supervisory control channel and thejiremote station equipment to detect and impulse relays 2M’ and Alli’ which connect the 20 indicate grounds may be’ provided by means of ground (detection apparatus shown .in Fig.3,and supervisory control conductors 2L9 and 223 to the, denoted generally by thenumeral 276.; For exam: positive and negative terminals of the control and ple, a ground relay 2'l_ may be provided in con‘-v remote station batteries, respectively. Control of the impulse relays 29!’ and dill’ may be effected ' junction with a suitable source of control poten inexactly the same manner as described in de 25 tial'hsuch as the recti?er bridge circuit 128, for line relays 200’ and 400’ are normally deener- ' gized, and may be energized by operation of the connection between the positive terminalof the tailqin the Boswau patentfor the impulse relays remote station battery and ground. Means such as the supervisory relay 30 may be ‘provided for In order to maintain supervision of the super-, visory control channel, means may be provided . normally operating under the control of the for normally applying a line supervision poten 30 ground detection relay 2'! for energizing the point‘ relay 3H1, whichmay operatev in connection with tial to the control channelconductors, having a point 4 of the supervisory control system. polarity opposite to that normally used during Since operation of the impulse relays ‘2t!’ and,‘ pulsing operations.‘ For example, as shown in dill’ connects the supervisory control channel to Fig. 4, auxiliary means such as the control re sistor Ii], which may be of a relatively high ohmic 3-5 and disconnects it from the control station and remote station batteries, false indications of value so as to normally prevent operation of the ground conditions might result therefrom. For line relays, may be provided for connecting the example, in the case of a ground onv the control conductor 223 to the positive terminal of the re channel itself, operation of the impulse relay 401,’ motestation battery through armature 42?'and back contacts, and the operating coil of the line 40 periodically disconnects the ground from the re‘ mote station equipment, causing periodical deen relaydu?', while the, conductor Zlilmay be, con ergization of the ground detection relay-27;- On nected to the negative terminal through armature the other hand, in the case of a groundron the M9 of thelimpulse relay 49!.’ and a back contact control station battery or equipment, operation of. thereof to the negative terminal of theremote 2i)! and 4M“, 1‘ station battery. . . , Means such as the line super the impulse relay 20L’ periodically connects the 45 ‘ground to the remote station, equipment thus vision relay I2 shown in Fig. 2 may be provided at the control station end of the supervisory con causing periodic operation of the ground detec trol channel and disposed, to be normally ener tion relay 21. pervisory control channel his. at rest andin' a 50. normal condition. Unidirectional current devices [3, i4 and I5 may be provided in connection with. the line supervision relay and the control chan nel for making the line‘ supervisionrelay respon-v. sive ‘only to the line supervisioncurrent. ,y . , For the purpose of preventing such false indiev gized by the supervision potential when the su , - . cations, means such as the auxiliary supervisory relay 32 may be provided. 'The auxiliaryjrelay 32 may be interposed between the ground detec-v tion relay 2'! and the supervisory relay ally and provided with energizing circuits in connection; with armature 42! and back contacts and armae.1 c A control relay 16 may be provided for operat-. " tures 33, 34‘and front contacts of the remote ing under the control of the line supervision relay l2 ‘in the event. it becomes deenergized to light a pilot lamp 19 at the control station as shown in Fig. l, which indicates to the dispatcherthat the equipment is not normal._ Means such as the su station, release relay 402, relay M8‘ and the re. mote'station start relay 4H, respectively._ Relay, ‘ pervisoryor alarm relay [8 may be provided for, 30 may be normally energized through bacl; con 60 tactssof relay $2 vand front contacts of relay 2.7. An auxiliary circuits'ma‘y be provided through, front contacts of relay‘ 32. normally operating in response‘to operation of . Accordingly, if‘v the supervisory‘controlchan? thelinesupervision relay I 2 to control the opera nel Tis pulsing, the auxiliary supervisory relay 33 operates to prevent the release of the control of the supervisory relay 39 and thus prevents tion of an alarm I05 and a line supervision lamp I] also shown in_Fig. l. A’reset relay‘ 20 may be provided for operating-under the control of the , the point relay 3 [3 from being energized to trans-; ' re1ease;key Hi3 andinterrupting the operating mit the ground signalc'ode. ' Relays Ziuand 3:2 may be of the slowv release type so as to insure providing for proper operation. In ‘order to prevent false indications vdue to momentary deenergization of theline-supervision ’ Indication of low battery voltage at the remote, circuit ofthe alarm bell.’ , . , H _ . V _ relay; [2 when the‘ impulse relay Mil’ at the re station may be providedby means of‘ a voltage, responsive relay 3! which controls a supervisory mote station is energizedor when the impulse re relay 35 to effect operation of the point relay lay Zlllfat the control station is energized, means such as the auxiliary supervisory relay 2| may} 75, 3M. By normally energizingthe voltage relay 2,409,234.05 3| through‘ aicontrol resistor 36~of ‘one. value“ andrprovidingfa reenergizing‘ circuit through an originated l at the ‘remote auxiliary control resistor of ,a.different. value.) when‘ the voltage relay dropsdue to reduced volt.-v age; the*'relay may be made to pickup when the: 5 batteryvoltagejncreases only a relativelyslighté amount. The voltage. relay may thus .be:‘made to indicate very slight ‘variations in the. battery: voltage in order to report accurately. the. condi—‘ tion of the battery, 10 station; andthrough";.=~ either‘ armature 24 1of ‘relay 2 I‘! ‘or, armaturewzz‘é of therestoration- start'lrelay- 2 I‘ tilt :‘the systems is th‘roughlv regulanpulsing and-‘inthewresetllstage.E Should- ashortlcircuitior an'open‘circuit occur-‘I on» the supervisorywcontrollchannel, the?“ line- ' supervision relay- l2l'will b'e- deenergized-i'andiJan-l obvious energizing ‘circuit-.- will!" be’ provided; for: the“ control relayl i 6 ‘through ‘armature 62¢? and‘! backlcontact ‘of the linealsupervision- lrelayl- I21} At-w the same time the relay I2 interrupts the en‘era Grounds‘ on, the control station‘ equipment may‘ beindicated' by means ofca‘groundv relay liciin gizingcircuit for» the’ auxiliary “supervisory-relay conjunction. with suitable source of direct-cure 2 I . Relay 16 operates to energize-the~pilot1lamp- \ rentipotentialsuch as the recti?er bridge circuit i9 ‘through- armature “52 l and *fr’ont “contactsjl. Ill which maybe connected between ground and 15 energizing circuit‘ is providedfor thealarm'relay' the .negative terminal of the control station bat is through the back contacts and arn1ature~53~ tery. In order to provide for preventing. the of- supervisory control relay 2|. Thai-relay: IBM ground. detection relay 40 ‘ from. indicating a operates“ and" provides an energizinge circuit ifor' - groundion the remote station equipment ‘when impulsingris ‘being done from the controlstation; 20 control relaysl43 and 44 may be provided incon junctionxwith a‘supervisoryrelay 45. The con-‘ trolrelay 44 may be of the pendulum. time delay type ‘having. a vibrating; armature 45 which periodically engages front contacts for a prede 251 the supervision ‘lamp 1‘! through:-armature-‘5d? termined‘ time after it is deenergized so that when‘ the ground detection relay '46 operates and com and an energizing circuit for the-alarm-bell F505‘? through its armature 55 and armature-"5S v‘oftlfew reset relay -2 D, By operating the release key-H13, an energizing" circuit is provided for'the resetrelayezlli‘wlriohil locks in through its armature-3'!‘ and =front1con tact, in multiple with the alarm'relay-‘lB through-* 13min‘ turn provides a circuit for energizing the the armature 53 \of ‘thesupervisorypontrol irela-y'i 2i. The alarm bell? circuit is interrupted-bye armature 56 of the reset relay. supervisory relay'll? for apredetermined time. The'relay G5, in turn, provides an energizing cir visory control channel or“ the remote stat-ions pletesla circuit for the‘control relay M, the relayv Should a ground occur ‘ on either‘ the super cuit for relay 43 LWhich remains in the energized position for a relatively‘long time interval or detection relay 2‘! picks upyinterruptingthe nor-“ from two to‘. approximately eight seconds, de pending, upon the adjustment of the timedelay ' relay 30‘at armature ‘51' and back‘contacts.‘ Ree relay M; and prevents operation of an alarm él; The.time interval is su?iciently long that an alarm 'is prevented. from being given, due to any equipment while the system is at rest; th'eground mal energizingcircuit‘ for the supervisory control‘ lay 39' drops after ‘a time interval and provides" an energizing circuit 'for-the point control relay 3 14 through armature 58 and back contacts.‘ The“ condition whichmay occur during. impulsing, supervisory control system then‘ operatesi‘in the" since the time interval required for impulsing is, much shorter than the time delay period‘of the and select'point'll relay“ at the" control station: relay '44; usual manner to send out four control impulses" The selection'is checked'inithe usual manner'and " Low battery voltage at the control station may relay I30 operates so that lamp I23 lights toin be indicated by means of 'a voltage relay 48 and dicate aground on the remote station equipment an auxiliary relay 49, in conjunction with a, 4 1‘? or on the supervisory control channel. control resistorill and an auxiliary control re- ‘ Should the impulse‘relay 40!’ ‘operate while a sistorsli! in “a similar manner to that described in connection with the voltage relay 34 ‘at the remote station. Under normal conditions with the system at rest, the line supervision‘relay I 2 is energized from 'the'remote station battery‘throughv a'cir cuitwhich may be‘ traced :from: direct‘ positive through armature 4200f the line relay 489’ and.‘ backcontact, control‘resistor i5, operating coil‘ of the .linerelay 409", conductor 223, operating co-ilqof line relay 209’, recti?er device‘ ill, operat- ‘ ground exists on the supervisory control channel, . the ground detection ‘relay 21 would be momene ‘tarily released owing to the disconnection‘of'the ' "remote station‘ from the channel. 'I‘h'e‘supere‘ visory relay‘ 30 is- prevented from‘ periodically" picking up and releasing'the ‘point relay 3M‘ to indicate removal of the fault, by providing-for interrupting the energizing circuitof the super 7-visory relay 3!] through armature 59 and‘ back contacts of the auxiliary‘supervisory relay 32. The auxiliary supervisory relay‘32 is energized ing coil of line supervision relay i2,‘ back contact each time the channel pulses through the arma and armature 42 of impulse relay 2G2’, conductor tures of one or another of the relays 402, 411 and ‘M9,. armature elguand lback'contact of impulse 601 Accordingly, the energizing circuit of the relay. 4M’. 1 supervisory relay 3!] will be broken by the aux Should either of the impulse relays operate iliary supervisory relay 32 each time the channel‘ such as during a pulsing operation, the line super is disconnected from the remote station equip vision relay [2 will be momentarily deenergized. ment, thus preventing the supervisory relay 30' Operation of the impulse relays 2M’ and '40!’ :_from picking up and giving a false indication. momentarily drops the line supervision relay, In the event that a ground occurs on the con causing .the control relay iii to pick up. The trolistation battery or equipment, a false indica auxiliary‘ supervisory relay 2i is not dropped tion thereof by the remote station is likewise pr however, since an auxiliary holdingK circuit therevented whenever the impulse relay 20!’ connects for. is provided from negative through the op 70 “ the supervisory control channel to the control erating coil ofrelay 2!, armature 6i) and front station equipment; The auxiliary supervisory contacts, conductor 6!, and through armature relay 32 is energized through one or another of 23 :or selection start relay ZIG if the pulsing was the armatures, 34 of the substation start relay started from the ‘control station‘; through arma 4", 33 of the relay 4l8'or‘42l of the-release relay‘ ture 125“. ofw' the» alarm ‘ ‘ relay- I21‘!- if < thee pulsing» v5402; depending‘onwhet-her the pulsing originates “ 2,409,840 ‘ 8 7 tions operable .over a single supervisory and con trol channel therebetween comprising, means whether it is in the reset stage at the end of a pulsing operation. A holding circuit is thereby at one of the stations including a ground relay provided for the supervisory relay 30 through ar and a source of operating potential connected mature 59 and front contacts of, relay 32, and 5 between ground and one terminal of the battery armature 58 and front contacts of relay 30 which at said station to be responsive to a ground fault remains in the energizing position for a predeter condition on the supervisory control equipment mined time even though its energizing circuit at said one station and the channel and associ at the remote station, the control station, ‘or was momentarily interrupted by armature 59 moving from the back contacts to the front con ated circuits, supervisory means controlled by 10 said means operable to indicate the fault condi tacts. tion at the control station, and circuit means including relay means controlled in accordance with operations of the impulse relays from either of the stations to prevent operation of the im In the case that a ground occurs during a puls ing operation, the release of supervisory relay 30 does not take place until the auxiliary supervisory relay 32 releases after the impulsing is over. 15 pulse relays from a?ecting the fault-responsive When relay 3!] once releases, it cannot be picked up again until both relays 32 and 21 are released. Relay 32 seals in through front contacts of ground detection relay 21, its own front contacts, and a back contact of supervisory relay 30. Re lay 32 is thus prevented from releasing due to the means when a ground fault occurs on the channel. 3. For use in a supervisory control system having supervisory and control equipment includ 20 ing a line relay at each of a remote and a con trol station operably connected in parallel cir-, release of relay 2'! during pulsing. The super cuit relation by a single supervisory control line visory relay 30 is, therefore, prevented from be disposed to be selectively connected to sources ing energized again until ground detection relay of the same polarity at each of the stations by 2'! drops out for a long enough time to indicate 25 impulsing relays, means responsive to‘ a fault that the ground no longer exists. Repeated re condition of the line or equipment including a porting of the ground is thus prevented, and the supervision relay at the control station and uni visual indication at the control station is held directional current means at the control and. re until the ground is removed. From the above description and the accom panying drawings, it will be apparent that we have provided, in a simple and effective manner, for providing complete supervision of the station equipment and supervisory ‘channel against mote stations connected to provide a series cir 30 cuit with the line relays over the control line only for a supervision potential of an opposite polarity, supervisory means normally responsive to operation of the fault-responsive means, and means including control means operable in ac-‘ grounds, and have. provided for accurately indi 35 cordance with the operating condition of the cating the relative location of such ground. In addition, provision has been made for maintain supervisory control line to prevent connection of the line to and disconnection thereof from the ing continuous supervision of the supervisory supervisory and control equipment during oper control channel against short or open circuits ation of the line relays from affecting operation without any interference by reason of impulsing 40 of the supervisory means. operations over the channel. Separate indica 4. For use with a supervisory control system tions are also provided of low battery conditions’ having supervisory control equipment at remote at the remote and control stations. and control stations controllable over a super Since certain changes may be made in the con visory control channel which is normally con struction of the above-described apparatus and 45 nected to a source at one of the stations by different embodiments of the invention may be impulse relays, means including a recti?er bridge made without departing from the spirit and scope circuit connected between ground. and the posi thereof, it is intended that all the matter con tive terminal of the source to which the channel tained in the above description and shown in the is normally connected and a ground relay re accompanying drawings shall be considered as 50 sponsive to a ground condition on the super illustrative and not in a limiting sense. ' visory control channel or the equipment associ We claim as our invention: ated with said one source, supervisory means 1. In a'supervisory control system having re normally responsive to operation of the ground mote and control stations with a single super responsive means to provide indication of a visory and control channel extending therebe 55 ground on said equipment or the channel, and tween and supervisory and control equipment at circuit means including control means responsive each station including normally deenergized to predetermined operations of the supervisory supervisory control relays for controlling the . control equipment for preventing changes in the energization of the supervisory and control chan connections between the supervisory control nel, control means responsive to‘ a faulty condi ,60 channel and the said- equipment from affecting tion of the channel or an associated circuit, cir cuit means including a back contact ‘of a ‘nor mally deenergized supervisor control relay nor- 7 the operation .of the supervisory means when a ground occurs on the channel. . 5. For use in a supervisory control vsystem mally connecting the channel to 'a source at having remote and control stations connected by the remote station, means responsive ‘to oper 65 a supervisory control channel connecting line ation of the control means for indicating the relays at the stations in parallel relation and faulty condition at the control station,’ and controlled by supervisory, control equipment ine means responsive to energization and deenergi eluding normally deenergized supervisory con zation of the supervisory and control channel trol relays at each station, means for normally for preventing false indications due to operation 70 applying a supervisory potential to the super-. of the supervisory control relays. , 2. A ground detection system for a supervisory visory control channel through contacts of a supervisory control relay, trol station connected to at a remote station normally deenergized and means at the con the channel by a nor control system having supervision and control apparatus including an impulse relay and a sta tion battery ateach of remote and control sta 75 mally deenergized supervisory control relay‘ to be r l controlled byrfsaid potential for‘ operationain response to a fault condition on'lthechannel.‘ $16.".F0r‘ usein supervising the supervisory‘and control channel iconnecting supervisory “:control equipment including normally de'energized line : :relays at remote‘ and‘ control ‘stations, 'means normally vconnecting ‘the’ channel to a source ‘at the remote station/for supplyinga supervision potentia'lto the channel without operating the line relays‘when the system is at rest which'is i opposite m‘- polarity to. the operating‘ potential of the ‘channel, supervisory meansoperable in response to the supervision potential to indicate 10 means associatedlwith the remote station impulse ‘relay ‘for energizing the channel'with an opposite polarity. when‘ the-channel is‘ not in operation, supervisory‘means including av relay associated with the channel. and operable ‘only in‘ response to ‘said opposite polarity, a time delay relay. oper able in response to release of the supervisory - means, a normally energized auxiliary time delay ‘relay controllediby said time delay relay, signal means fnormally operable when the auxiliary time delay relay‘ releases, and circuit means as sociated with one of the‘ supervisory control re lays for providing aiholding circuit for the aux an open circuit or short‘cir‘cuit on the ‘channel, iliary time supervision means including a ground ‘relay con 5:15 operates. nected between the source and ground operable to indicate a ground on the remote station equip ment or channel, and means eiiective ‘to prevent operation of the supervisory control equipment from affecting operation of the ground relay to indicate a faulty channel condition while the channel is operating. . 7. In a supervision system‘for a supervisory delay relay when the'impulse relay ‘ 10. A ground detection system for ajsuper-Q visory control system having supervisory-control ‘equipment with separate .source‘srat remote and control stations connected by a single supervisory control channel under the control of impulse re lays at each ofthe stations comprising, ground detection means connected to the source of the remote station operable in response to a ground control system having a supervisory control condition, supervisory means normally controlled channel connecting the equipment at remote and 25 by the ground detection means for providing an control stations disposed to be energized with a predetermined polarity during operation by im pulse relays at the remote and control stations, channel supervision means, unidirectional current means connected between the channel super vision means and the channel for preventing op eration thereof only on a polarity opposite to the operating polarity, means associated with the remote station for applying a supervision indication at the control station of a ground condition, and means associated with the super visory means for preventing the ground detec tion means from effecting operation of the super visory means in response to a ground condition at the other station while the channel operatively connects the equipment at both stations. 11. A ground detection system for a super visory control system having supervisory control potential to the channel opposite in polarity to 35 equipment at remote and control stations with the operating potential of the channel when the a plurality of points and a Supervisory control channel is not in operation, auxiliary means un channel connecting normally deenergized line der the control of the channel supervision means relays controlled by impulse relays for connecting for indicating a loss of supervision potential at the control station, and means including relay means operable when the channel is operating to prevent the auxiliary means from indicating the channel to control sources at each station for predetermined intervals during operation comprising circuit means connecting the chan nel to the source at the remote station when the a loss of potential when the channel is operating. impulse relays are deenergized, a ground detec 8. In a supervision system for a supervisory tion relay, circuit means including a recti?er and control channel connecting supervisory and 45 device for providing a unidirectional ground de control equipment at remote and control stations tection potential connecting the ground detec including supervisory control relays at the con_ tion relay between the remote station source trol station operable under different conditions and ground, time delay supervisory means oper of channel operation and impulse relays at the able under the control of the ground detection remote and control stations operable to connect 50 relay to send a fault code signal from a pre ‘the channel to a source of one polarity, a line supervision relay, circuit means including a uni determined point, and an auxiliary time delay relay operable during connection of the chan nel to the control sources to prevent any change directional current device connecting the line supervision relay to the supervisory control in the condition of the supervisory means. channel, means associated with the remote sta 55 12. In a supervisory system for a supervisory tion line control relay for applying a supervision control system having supervisory control equip potential to the channel when the channel is ment including line relays at remote and control not in operation for operating the line super; stations with sources of control voltage at each vision relay, indicating means normally respon station and a supervisory control channel ex sive to operation of the line supervision relay to 60 tending between the stations connecting the line the inoperative position .to indicate a faulty chan relays in parallel relation and disposed to be ‘ nel condition, and control means controlling connected to the sources by impulse relays for operation of the indicating means, said control providing one polarity while operating and the means being responsive to operation of one of opposite when not operating, a point relay at the supervisory control relays to prevent oper 65 the remote station operable to provide a prede ation of the indicating means during operation termined signal code for indicating at the con of the supervisory control channel. trol station, means including a separate source 9. In a supervision system for a supervisory control channel connecting supervisory control equipment at remote and control stations includ ing impulse relays operable to energize the chan and a ground relay responsive to a ground con_ dition on the channel or at the remote station 70 for normally effecting operation of the point relay to signal said condition, normally ener nel with a predetermined polarity and a plurality gized relay means operable after a time delay of supervisory control relays operable to effect to the deenergized position to e?ect operation of operation of the impulse relays in selecting, the point relay, normally-deenergized relay checking operating and supervisory operations, 75 means responsive to operation of the ground re 2,409,840 v12 ‘ 11 1ay normally operable to effect operation of the normally energized relay means, and control means operable in accordance with the operating condition of the channel for e?ecting energization of the normally ‘deenergized relay means while the channel is operating to transmit a‘ code signal. ' > ' 13. In a supervisory system for a supervisory nel to prevent operation of the line relays from ' affecting the operating condition of the super visory means, line supervision means including a line supervision relay connected to the channel by the control station line-control relay in the’ inoperative condition, means associated with the remote station impulse relayfor applying a super vision potential to the channel when said im ‘control system having supervisory control equip pulse relay is in the inoperative position for tion, supervisory‘means normally responsive to operation of the ground‘ responsive means for channel for preventing operation'of the‘ impulse relays from affecting the operating position of e?ecting operation of the remote station im pulserelay to signal a fault condition, control means at the remote station operable in accord 20 ance with the operating condition of the chan the supervisory means. ment with associated sources of control voltage 10 effecting operation of the line supervision-relay, supervisory means at the control'station operable at remote and control stations and a supervisory under the control of the line supervision relay control channel extending therebetween disposed for indicating a short’ or open circuit condition to be connected to said ‘sources by impulse relays of the channel, and control means operable. in under the control of said equipment, means at the remote station responsive to a, ground condi 15 accordance with the operating conditionof the > WILLARD A. DERR. MAURICE E. REAGAN.