US3609523A - Automatic test apparatus for phase comparison protective relay systems and the like - Google Patents

Abstract

Apparatus for automatically testing protective relay system as utilized with high voltage transmission lines, the apparatus consisting of a master control unit, at a first terminal working in conjunction with one or two slave control units at adjacent terminal stations. Each of the master and slave control units are controlled through a cycle of actuation by a synchronous timer means such that a programmed series of switch closures performs a test of associated transmission and reception equipment and the respective protective relay devices to transmit starting signal, ring back, internal and external simulated faults and a selected security code. Each test control unit utilizes a time-controlled program switch which is synchronously operable to effect various test and verify operations in the control unit.

Description

United States Patent Marion D. Knox Oklahoma City, Okla. 812,770

Apr. 2, 1969 Sept. 28, 1971 Inventor Appl. No. Filed Patented Aimignee Wayne Electronic Products Company AUTOMATIC TEST APPARATUS FOR PHASE COMPARISON PROTECTIVE RELAY SYSTEMS Primary Examiner-Rudolph V. Rolinec Assistant Examiner-R. J. Corcoran Attorney-Dunlap, Laney, Hessin & Dougherty ABSTRACT: Apparatus for automatically testing protective relay system as utilized with high voltage transmission lines, the apparatus consisting of a master control unit, at a first terminal working in conjunction with one or two slave control units at adjacent terminal stations. Each of the master and slave control units are controlled through a cycle of actuation by a synchronous timer means such that a programmed series of switch closures performs a test of associated transmission and reception equipment and the respective protective relay devices to transmit starting signal, ring back, internal and extemal simulated faults and a selected security code. Each test control unit utilizes a time-controlled program switch which is synchronously operable to effect various test and verify operations in the control unit.

EXTEPNAL WEN/4L l' EX HEP/VAL 54%? MU T5 /4 26 FAULT5 12 2' pa TE-PM/A/AL TEPM/A/AL i w 42W M 20 TPAMS'M/SS/O/V EOU/PME-A/r 1 fgy i flg lgu II I GOA/740A I count I L PPOI'EC r/ we 50 56 J p leasy J a2 38 Ame/w 2W0 AUTO/144 r/c Aura/14A r/c (IE/V7641. res 7- Wot APPARATUS App/WA PATENTEU SEPZ 8 l97l SHEET 3 [1F 8 PATENTEU SEP28 IHYI SHEET '5 OF 8 INVENTOR. MAP/0M 0. KNOX ATTORNEYS PATENTEDSEP28197|SHEET 5 0F 8 QQm wmv QR hum wwn o mt w M omv awn wk wk INVENTOR. MAE/0N D. K/vox WYW' PATENTEUSEP2 8 |97| SHEET 6 BF 8 QM NM mum Qwm Sm QM R NR QR nvvmvron. MAE/ON 0. Kvox 4 T 7' OQ/VEYS PAIENTED SEP28 um I SHEET 8 BF 8 AUTOMATIC TEST APPARATUS FOR PHASE COMPARISON PROTECTIVE RELAY SYSTEMS AND THE LIKE BACKGROUND OF THEINVENTION 1. Field of the Invention The invention relates generally to high voltage transmission line protective relay equipment and, more particularly, but not by way of limitation, it relates to apparatus for automatic testing of solid-state protective relaying systems.

2. Description of the Prior Art Prior methods of testing of protective systems for high voltage transmission networks have been carried out manually by performance of prescribed operator manipulations and subsequent observations of meter readings, lamp indications, etc. In the prior types of protective relay systems, which may include either carrier-current or microwave equipment, it has been the general practice to make carrier transmission tests at specified intervals, for example, once per day. To accomplish this, it required that an operator at each terminal station send and receive specific signals, and that they thereafter log the pertinent findings as read from the respective receiver equipment, i.e. the normal, the reserve-signal or reduced power values, and whatever other standardized values as were. received in accordance with the test program.

SUMMARY OF THE INVENTION The present invention contemplates an interlinking carrier and relay testing system which can be installed at each terminal of a high voltage transmission network to carry out periodicchecks upon the protective relay system by means of a programmed, sequence of carrier transmission and reception checks as between the two or three terminal installations. In a more limited aspect, the testing system is comprised of a plurality of switching systems, each of which is controlled by a periodically actuated program switch to control the several functions of the carrier and relay equipment at each terminal. Thus, at each tenninalin the protective relay system, two or three terminals or transmission line substations being the normal situation, there is an automatic test unit consisting of a programming switch which controls a plurality of switching assemblies to efiect carrier output, verification ring back, presence or absence of simulated internal and external faults and security code, lockout of units, testing stop notice, and alarm functions in accordance with the test procedure as programmed.

Therefore, it is an object of the present invention to provide apparatus for automatically testing the carrier, the static relays and the control units in a high voltage surveillance network.

It is also an object of the invention to provide a system which enables periodic automatic testing of all functions of an electrical current transmission line protective relay system as utilized with either a carrier or microwave interconnection.

It is still a further object of the present invention to provide a phase comparison protective relay testing system which is programmable as to the sequence and type of test functions between terminals.

Finally, it is an object of the present invention to provide an automatic static relay testing system for use with either carrier or microwave systems which is compact, lightweight, and virtually trouble-free as regards maintenance problems.

Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawings which illustrate the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a block diagram of power terminal interconnection utilizing test apparatus in accordance with the present invention;

FIG. 2 is a block diagram illustrating various possible modes of application of the present invention to electrical power distribution networks;

FIG. 3 is a block diagram of one form of terminal installation utilizing the present invention;

FIG. 4 is a schematic diagram of master terminal testing circuitry;

FIG. 5 is a schematic diagram of one form of interconnection circuitry as utilized in one form of the invention;

FIG. 6 is a partially schematic illustration of a program switch as utilized in the present invention;

FIG. 7 is a schematic diagram of a remote testing terminal constructed in accordance with the invention;

FIG. 8 is a program diagram which may be utilized in a two terminal testing system;

FIG. 9 is a program diagram which may be utilized in a three terminal testing system; and

FIG. 10 is a block diagram illustratingthe use of the present invention for testing an alternative form of relay interconnecting system.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates a typical form of electrical power transmis sion line with transmission proceeding from asource 10 to apower terminal 12 andpower terminal 14 to aconsumer 16. Control surveillance of the transmission system includes electronic transmission equipments l8 and 20 interconnected at therespective power terminals 12 and 14 and in communication via alinkage 22, e.g. wireless, coaxial cable, microwave transmission, pilotwire, etc. As regards the power tenninals l2 and 14, powerline faults occurring'between stations in thearea 24 would be designated internal faults, while line failures occurring in either ofareas 26 or 28 would be termed external faults. It should be understood too that the terminal configuration may be variously interconnected as shown in FIG. 2, as will be described.

Thetransmission equipment 18 functions withpower terminal 12 in response to acontrol unit 30 which is interactively operable with anautomatic test apparatus 32 and aprotective relay 34 to effect the required safety cautions through line switching by control of terminal circuit breakers (not shown). Similarly, thetransmission equipment 20 atpower terminal 14 is controlled by acontrol unit 36 functioning with anautomatic test apparatus 38 andprotective relay 40. Fault indications are derived from line voltage or current sensing atrespective power terminals 12 and 14 vialines 42 and 44' for application tocontrol units 30 and 36, respectively. One terminal may be designated as central and it will then include an alarm andcentral control 46 for regulating the automatic test system as is carried out by theautomatic test apparatus 32 andY 38, to be further described.

the type and number of interconnections is practically unlimited. Thus, apower generator 50 supplies electrical power vialine 52 toterminal 54 which performs various functions in different interconnections as regards its automatic test capabilities. Thus,terminals 54, 56 and 58 constitute a three terminal power network whereinterminal 54 is the master or A terminal whileterminals 56 and 58 are slave, or respective B and C terminal automatic testing stations. A two terminal network is formed byterminals 54 and 60 withterminal 54 still being the master or A terminal whileterminal 60 is a B terminal testing station. A similar two terminal automatic testing network is formed bytenninal 58 as master A terminal andaterminal 62 as a remote or slaved B terminal.

Interconnection of still another power generator orsource 64 gives rise to further integration of the power grid. Thus, aterminal 66 may be a master terminal for both ofterminals 68 and 70. Each of theterminals 68 and 70 is then a slaved remote terminal responding to automatic test control functions as initiated from theA terminal 66. In similar manner, terminals. grid interconnection betweenterminals 66 and 54 might findterminal 54 slaving to automatic test function output from theA terminal 66. Any number of terminals through various interconnections are possible with but minor alterations in test programs as will be further described in detail.

While the present invention can be utilized to test various forms of carrier and microwave equipment utilizing any of several types of protective relay line control, the invention is particularly described herein with respect to a phasecomparison relay system 80 as employed at abreaker 82 along high voltage power transmission lines 84, 86 and 88. The phase-comparison relay system 80 is a standard protective equipment such as is commercially available from the Westinghouse Electric Corp. of Newark, N. J. The phase-comparison relay system 80 may consist of acontrol unit 90 and arelay unit 92 functioning with acarrier equipment 94, i.e. atransmitter 96 and receiver 98 operating through aselected transmission line 100.

Therelay unit 92 consists of a sequence network 102 which is connected to sense currents in the respective power transmission lines 84, 86 and 88 to derive a matrix output for application to a high-low fault detector 104. Fault detector 104 then provides a high-set output 106 and a low-set output 108 for control purposes as will be further described. A trip coil 1 10 controls tripping of the powerline circuit breaker 82.

Thecontrol unit 90 receives control output from sequence network 102 viainput 110, a sixty cycle half-wave voltage, which is supplied through a low pass filter 112 to a terminal 114. Voltage atterminal 114 is then applied on aline 116 to modulate thecarrier transmitter 96 when applied in coincidence with a low-set output onlead 108 from fault detector 104. Keying of thecarrier transmitter 96 then provides carrier output viatransmission line 100.

The voltage fromjunction 114 is also applied through a local amplifier 118 which includes phase delay with input to aphase comparison circuit 120. Sixty cycle half-wave pulses from a remote tenninal are received viatransmission line 100 to carrier receiver 98 whereupon its output is conducted through aremote amplifier 122 for application to phasecomparison circuit 120. The output ofphase comparison 120 is effectively a comparison of the local voltage online 124 and a remote voltage online 126 to derive a trip voltage online 128. If thephase comparison 120 indicates in-phase voltages onleads 124 and 126, an internal fault is existent, and output onlead 128 is applied through atime delay 130 to a flip-flop 132 which actuates atrip amplifier 134. The high-set output from fault detector 104 onlead 106 is applied to enable the flip-flop 132. Output fromtrip amplifier 134 is them applied online 136 to the trippingrelay 138.

An automatic test apparatus 140, the subject of the present invention as will be further described, is interactively connected with each of thecarrier transmitter 96 and carrier receiver 98, as well as sequence network 102 and the trippingrelay 138. The automatic test apparatus 140 functions with anauxiliary relay 142, periodically, to check selected terminals of the relay carrier system including such as the associatedcontrol unit 90,relay unit 92 and carrier set 94. While the structure of FIG. 3 represents equipment at a single terminal of a power transmission line, it should be understood that similar apparatus will be located at each terminal, and that the automatic testing system will function between terminals in selected combinations of two or three.

Referring now to FIG. 4, anautomatic test unit 150, a master of A terminal tester, is interconnectable by means ofterminal boards 152 and 154 into an associated relay system. The interconnection diagram of FIG. illustrates such interconnection connection from respectiveterminal boards 152 and 154 to the specific components of the control unit, relay unit, and carrier set. Aninterconnection circuit 156, as shown in FIG. 5, receives llS-volt AC line input vialeads 158 and 160 for application in parallel toterminals 162 and 164 ofterminal board 154, as well as to aprimary coil 166 of atest transformer 168.

With further reference toterminal board 154, a terminal 170 is connected to a lead 172 which is connected to telephone hand setunit 174 with return to a negative l25-volt DC lead 176. The negative l25-volt DC lead 176 leads up tovoltage input terminal 178 as well as to a terminal 180 onterminal board 152. Positive voltage of volts DC is applied at .terminal 181 for distribution throughout interconnectingunit 156 viavoltage lead 182, thelead 182 also connected to aterminal 184 ofterminal board 152. Atenninal 186 ofterminal board 154 is connected through aconductor 188 to analarm bell 190, and thealarm bell 190 is energized by means of carrier receiverelay contacts 192 which connect to the plusDC voltage lead 182. Therelay contacts 192 are energized closed upon energization of carrier receiverelay 94 which is connected for actuation betweencarrier receiver 196 and the minusDC voltage lead 176. The plus DC side of thealarm bell 190 is connected by means of a lead 198 to a terminal 200, the carrier receive terminal, ofterminal board 152.

Returning again toterminal board 154, atenninal 202 is connected to a lead 204 in series with a normally closed automatic test disable switch 206 which leads back toterminal 208. Atenninal 210 connects to a lead 212 in series with a secondary 214test transformer 168 with return vialead 216 back to aterminal 218 ofterminal board 154.Terminals 220 222 are each connected torespective leads 224 and 226 which are connected to the primary of asaturation transformer 228.Saturation transformer 228 includes a phased array of control transformers in inductive relationship to the power transmission line and it serves to pick up and present any fault currents during fault conditions.

Terminals 230 and 232 provide connection to analarm output 234 for efiecting a suitable form of alarm actuation.Terminals 236 and 238 provide flip-flop reset energization asterminal 236 is connected through a reset switch 240 and it normally open fault detector contact 242 to a reset contact 244 which is located on the control unit flip-flop circuit (e.g. flipflop 132 of FIG. 3). The remainingterminal 138 is connected by means of a lead 246 to a flip-flop power supply 248.

Referring again to secondaryterminal board 152, a terminal 250 is connected through aconductor 252 to a pair of normally open contacts of theauxiliary relay 142.Terminal 256 is connected directly to one side ofrelay coil 258 ofauxiliary relay 142 with return to the negativeDC voltage lead 176. The nonnally closed contacts ofauxiliary relay 142 are connected in parallel to a lead 260 which leads to the trip coil 110 (FIG. 3) which is returned through negativeDC voltage lead 176, and thelead 260 is also applied through abackup relay 264 to the positiveDC voltage lead 182. A lead 266 from the parallel-wiper contacts ofauxiliary relay 142 is connected in series through asuitable trip indicator 268 andalarm relay contact 270 with return to thepositive voltage lead 182. The remainingterminals 274 and 276 of secondaryterminal board 152 are connected to atransmitter keying circuit 278 which effects control of the carrier or such transmitter equipment which is associated with the particular terminal installation.

Returning again to FIG. 4, the master or A terminal test unit is energized by AC line input attenninals 162 and 164, and energization is enabled by a start switch 289 which applies the AC line voltage across asynchronous timing motor 282. Thesynchronous timing motor 282 may by any of various commercial types which include an associated gear box (not specifically shown) for reducing output rotation to a low rate of angular advancement. Thus, in one form of the invention, it is found desirable to employ aprogrammable timer motor 282 which effects closure of atimer switch 284 periodically. This timing or the frequency of closure oftimer switch 284, can be varied in accordance with the exigencies of particular equipment applications.

Thestart switch 280 applies the AC line voltage through a lead 288 to testboard terminal 208 for circuit through the automatic test disable switch 206 (FIG. 5) for return throughterminal 202 and a lead 290 to anAC energizing lead 292. When thetimer switch 284 is closed, the AC energizing voltage fromlead 292 is applied through an energizingcoil 294 oftime delay 296 with return to the other side of the AC line, a lead 298 toterminal 164. AC voltage fromjunction point 300 is conducted through timedelay switch contacts 302 for a period of about 10 seconds and through a lead 304 to one side of aprogramming motor 306. AC initiation to lead 304 is also I conducted through a suitable form ofcounter 308 with return through the remainingAC lead 298 to provide a testing tally.

Theprogramming motor 306 effects program control of a plurality of program switches 310, 312, 314, 316, 318, 320, 322, 324, and 326. Theprogram switch 310, the test cycle program switch, will be held in the open position (opposite that shown) when thetest unit 150 is in its standby or quiescent state. Starting of rotation ofprogram motor 306 upon closure oftimer switch 284 will then allow closure of the testcycle program switch 310 to supply energizing AC voltage fromlead 292 through alead 328 and 330 to maintain cnergization of theprogram motor 306. It may also be noted that amanual test switch 332 is provided to enable an operator to initiate a test cycle at other than times dictated bytimer motor 282 andtimer switch 284. Depression ofpushbutton switch 332 will apply AC voltage fromlead 292 ontolead 304 to energize theprogram motor 306.

FIG. 6 illustrates one form ofprogram motor 306 as it may be associated with suitable programming structure. Amotordriven program switch 334 is similar to structure which is fully disclosed in 11.8. Pat. No. 3,414,773, also assigned to the present assignee. Theprogram switch 334 embodies a unique design which enables easy variation of the switch program. That is, aprogram drum 336 is divided into sixty equal, arcuate segments arrayed about its circumference, there being agroove 338 between each segment such that plastic placers or inserts 340 can he slid into thegrooves 338 and aligned with particular ones of the leaf switch actuators (switches 310 through 326) thereby to construct a desired relief or switch actuating structure. Thus, any program desired may be set into the program switch simply by adding or removing theplastic spacers 340 at the given program positions, i.e. a circumferential path in alignment with a particular one of theswitches 310 through 326. In the prototype equipment, thetest units 150employ motor 306 and gearing (not specifically shown) which generate one revolution per minute such that each segment of the program drum 118 is equal to I second in time.

Each of the program switches 310 through 326 performs a specific function through each 1 minute test cycle or revolution of the program drum as provided byprogram motor 306. Thus, the testcycle program switch 310, a normally closed switch is allowed to remain in its closed position, (as shown to provide holding energization to theprogram motor 306 through its entire 1 minute cycle. At the end of the cycle, asingle program spacer 340 is engaged to open theswitch 310 and stop the revolution of theprogram motor 306. Aprogram switch 312, the open alarm bell switch, is normally closed to provide a connection betweenleads 342 and 344 toterminals 170 and 186 ofterminal board 154. When actuated,program switch 312 connects thelead 342 to lead 346 which provides energizing connection to arelay 348 when certain additional enabling conditions are met, as will be further described. Program switches 314 and 316 are designated change polarity" switches as they serve to reverse the polarity of voltage attest transformer contacts 210, 220, 222 and 218. Theterminals 220 and 222 are connected vialeads 350 and 352 to the respective wiper contacts ofswitches 314 and 316. Switch connections are then alternated betweenleads 354 and 356 which, whenrelay 348 is actuated to closecontacts 358 and 360, are connected torespective leads 362 and 364 leading toterminals 210 and 218.

The open trip circuit"program switch 318 is in a normally open position withwiper lead 366 leading to the auxiliary relay"terminal 256 ofterminal board 152; a parallel branch oflead 366 also provides connection to the.relay coil 348. Upon actuation,program switch 318 is closed for connection to a lead 368 through arelay contact 370 and lead 372 to the plus l25-volt DC source orterminal 184 ofterminal board 152. Thenest program switch 320 serves a verify local alarm and trip function and it is normally open but actuated closed to connect theAC voltage lead 292 to alead 374.

Agreen lamp 380 is energized bylead 328 fromprogram switch 310, i.e. in parallel withprogram motor 306, such that it indicates the test cycle on that time whenprogram motor 306 is running. Ablue indicator bulb 382 is connected for energization between one of therelay trip terminals 250 and the negativeDC voltage terminal 180 ofterminal board 152, and thisblue indicator 382 is energized in response to a trip condition switched through the auxiliary relay coil 258 (FIG. 5), as connected via lead 383 toterminal 250. Ared indicator lamp 384, the alarm indicator, is energized to indicate the alarm condition as will be further described below. Thelamps 380 and 384 may be standard AC indicator bulbs while the blue lamp 383 is a DC lamp having a suitable resistance value.

Aterminal trip relay 386 is connected in parallel with theblue indicator 382 and it is energized during the trip" condition to control therelay contact 388 such that lead 374 fromprogram switch 320 is removed from connection to a lead 390 which provides energization to the red alarm"indicator lamp 384. This removable of connection betweenlead 374 and lead 374 and lead 390 also disables the posibility of energization of analarm relay 392 under control of the verify local alarm and trip"program switch 320.Alarm relay 392 controls a plurality ofcontacts 370, 394 and 396.Contacts 394 are normally open as between thealarm output terminals 230 and 232 ofterminal board 154; andrelay contacts 396 are normally open between the voltage source lead 390 and a lead 398 in series with a normally closed reset"switch 400 i.e., conventional pushbutton type of switch which is returned to theAC lead 292.

A carrier receiverelay 402, connected between thenegative voltage terminal 180 and the carrierreceiver terminal board 200 ofterminal board 152, is energized in response to closure ofrelay contacts 192 of carrier receive relay 194 (FIG. 5). The carrier receiverelay 402controls relay contact 404, a normally closed contact, to open up electrical contact betweenlead 374 fromprogram switch 320 and a lead 406 connected to the normally open contact ofrelay contact 388 of therelay 386. A parallel connection oflead 406 is also applied to the wiper contact of the verify remotealarm program switch 322.

Alarm output attenninals 230 and 232 ofterminal board 154 is provided fromrelay contacts 394 byrespective leads 408 and 410. The alarm output would be in the fonn of a switch closure atrelay contact 394. The test reset output atterminals 236 and 238 is provided from the "reset"program switch 324 vialeads 412 and 414, respectively. Closure of the carrier start"program switch 326 provides switch actuation throughterminals 274 and 276 ofterminal board 152 to the transmitter keying circuit 278 (FIG. 5).

FIG. 7 illustrates a B or C terminal, or a remote test unit which functions in coaction with themaster test unit 150 to carry out the system test. Theremote test unit 420 is generally similar to themaster test unit 150, but it is characterized by absence of some master control components. Thus, primary and secondaryterminal boards 422 and 424 provide all interconnection contacts. Theterminal board 422 provides volt AC line voltage input atterminals 426 and 428, and theterminals 430, 432 and 434 provide respective connections for hand set," alarm bell," and test disable." The test transformer connections, four in all, are applied atcontacts 436, 438, 440 and 442, and a second test disable" connection is made atcontact 444. Further,contacts 446 and 448 receive alarm output" connection while a pair ofcontacts 450 and 452 provide the necessary test reset interconnection.

The secondaryterminal board 424 receives positive and negative DC voltage supply atrespective terminals 454 and 456, with carrier receive," trip input and auxiliary relay,"

connections being made at the respectiveterminal contacts 458, 460 and 462. In general then, the input connectionsfor theremote test unit 420 are similar to those for themaster test unit 150, and a similar type of interconnection circuitry, such as is shown in FIG. 5, is employed as the interface structure.

Also, a similar type of program switch is utilized in theremote test unit 420, i.e. aprogram motor 464 providing output motion viadashline 466 to provide periodic actuation of the respective program switches 468, 470, 472, 474, 478, 480, 482 and 484. The program assembly consisting ofprogram motor 464 and the plurality of switches 468-484 is preferably a drum-type utilizing the plurality of switches as described in FIG. 6, and as fully set forth in the prior issued US. Pat. No. 3,414,773 which is the property of the common assignee.

The AC energizing voltage is applied through astart switch 486 through alead 488 andtenninal 434 to an external circuit interrupter, e.g. test disable switch 206 of the FIG.interconnection unit 156. The energizing voltage is then returned viaterminal 444 and a lead 490 to ajunction 492 which provides energizing voltage distribution via parallel leads 490 to fulfill several start-up functions. First, since theremote test unit 420 is started upon receipt of carrier energy from the master unit, a carrier receiverelay 494 is connected vialeads 496 and 498 betweenterminals 456 and 458, respectively, ofterminal board 424, and it is energized to provide actuation ofrespective relay contacts 500, 502, 504 and 506. Therelay contact 506 is then closed to connect AC energizing voltage fromlead 490 through arelay coil 508 oftime delay relay 510 to close relay contact 512 for a time delayed interval, e.g. seconds, such that energizing voltage is available onlead 514. However,relay contact 504 will also have been opened so that AC energization must proceed fromvoltage junction 492 oflead 390 through the testcycle program switch 468, which will have been moved to its closed or normal position (as shown), to provide AC energization alonglead 516. The AC onlead 516 energizesprogram motor 464 to begin its constant, programming revolution to control the respective program switches 468 through 484. The other side ofprogram motor 464 is returned by alead 518 and a lead 520 to the other side of the AC input atterminal 428. Agreen indicator lamp 522 is connected between the energizinglead 516 and theAC lead 520 to provide lamp energization during the test cycle.

Program switch 470, the lockout switch, is actuated to make connection between theAC energizing lead 516 and a lead 524 to the normally closed position ofrelay contact 502 of the carrier receiverelay 494. The wiper connection ofrelay contacts 502 is connected to alead 526 and alarm indicator 528, a red lamp, with return to AC lead 520. The test key"program switch 472 provides the functions of opening the alarm bell circuit and keying the test source. The wiper position is connected to a lead 530 leading toterminal 430, the handset terminal ofterminal board 422. The normally closed contact is connected by a lead 532 to thealarm bell terminal 432 of theterminal board 422, and the normally open contact connects by a lead 534 to relay 536 which is returned by means of a lead 538 to therelay trip terminal 462 of secondaryterminal board 424.

The program switches 474 and 476 combine to carry out the "change of polarity function with respect to the test voltage. Thus, a test voltage present atterminals 436 and 442 vialeads 552 and 554 is supplied throughrelay 536, Le.contacts 548 and 550, to the respective program switches 474 and 476. The wiper input positions ofcontacts 548 and 550 are then connected toleads 552 and 554 which are connected to the respectivetest transformer terminals 436 and 442.

Theprogram switch 478 functions to open the trip circuit and it is nonnally open with one contact connected to alead 556 and the wiper contact connected to thelead 538 which is connected toauxiliary relay terminal 462.Lead 556 is connected through arelay contact 558 which is normally closed to receive positive DC voltage vialead 560 fromterminal 454. The verify local alarm and trip"switch 480 is normally open but actuated closed to connect AC voltage fromenergization lead 516 through a lead 562 which is connected in parallel to normally closedrelay contact 500 as well as to acontact 564 of arelay 566.Relay 566 is connected vialeads 568 and 570 betweenterminals 456 andtrip input terminal 560. Ablue indicator lamp 572, a DC lamp, is connected in parallel with the coil ofrelay 566 to indicate the trip" condition whenrelay 566 is energized.

Theprogram switch 482 functions to verify remote alarm with no trip condition, and it is normally open but actuatable to connect theAC energizing lead 516 to a lead 574. Lead 574 connects to the common or wiper position ofrelay contact 500 as well as to the normally open position ofrelay contact 564 of therelay 566. Finally, theprogram switch 484 carries out the reset function as it is normally closed to provide short circuiting betweenleads 576 and 578 which are connected thetest reset terminals 450 and 452 ofterminal board 422.

Analarm relay 580 is connected betweenlead 526 and theAC lead 520 and it is energized to provide several control functions. Thecontact 558, which is normally closed to conduct positive DC voltage fromterminal 454 and lead 560, is opened to prevent energization ofrelay 536 or DC output to the auxiliary relay 142 (FIG. 5) via 462. A normallyopen relay contact 582 may be energized to complete the alarm circuit betweenleads 584 and ,586 to thealarm output terminals 446 and 448 ofterminal board 422. The remainingrelay contact 588 is normally open and energized closed to connect theAC energizing lead 516 to the intermediate energizinglead 526 which includes holding energization of the alarm" indicator lamp 528 andrelay 580.

OPERATION The operation description is set forth with respect to a two terminal testing system, Le. a master A terminal and a remote B terminal. FIG. 8 illustrates a two tenninal program diagram for both the A and B terminals. Thus, FIG. 8 represents the circumferential field of program drum 336 (FIG. 6) which has 60 segments per complete revolution, and the plurality of horizontal black lines indicate the position of plastic spacers 340 (FIG. 6) disposed thereon for actuation of each of the respective A terminal program switches 310 through 326 and B terminal program switches 468 through 484.

It is generally the procedure to begin testing operation with the transmitters adjusted to generate some designated percentage of normal or full output, i.e. a reduced power output. This then enables what is effectively a reduced power test between the particular terminals, with full power tests and verifications effected thereafter.

Program test is initiated at the A terminal (FIG. 4) astimer motor 282 closes switch 284 to apply AC energization throughtime delay relay 296 to initiate rotation ofprogram motor 306. In the off position,program motor 306 will be held deenergized by a program spacer 602 (FIG. 8) which terminates and holds off energization of the test apparatus after each test cycle. Initial energization ofprogram motor 306 through timedelay relay contact 302 is sufficient to move the program drum so thatprogram spacer 602 no longer holdsprogram switch 310 open, and in its closed position it maintains energization for the following 59 segments of program drum rotation. Theprogram spacer 604 is arranged to actuateprogram switch 326, the carrier test circuit, from positions two through 19 such thatprogram switch 326 keys the carrier on for 18 seconds. At position three,program switch 322 responds to a program spacer 606 to verify reception of a local alarm, absence of verification serving to stop the test in progress. Theprogram switch 312 is actuated by program spacer 608 to hold open the local alarm bell circuit until position 19.

Meanwhile, at terminal B, carrier received indications will cause actuation of arelay 494 to closerelay contact 506 such that thetime delay relay 510 is energized with current conduction through thecoil 508. When therelay 494 ceases conduction, after receiving at least 15 seconds of carrier on" indication, theremote program motor 464 is energized thrucontact 504 andremote program switch 468 is moved out of contact with program spacer 610 such that program motor 464 (ter minal B) remains energized for the next 59 seconds of the duration of its respective test cycle. At this occurrence, the respective master andremote test units 150 and 420 are running and they are in synchronization.

It may be noted that telephone conversations, telemetering transmissions or other supervisory control transmissionsin addition to fault conditions might cause energization of a long pulse of carrier which could start the remote terminals. However,time delay relay 296 protects such that carrier transmission of less than 15 seconds is not able to start the running and synchronization of program motors at remote terminals. After starting, the remote terminal must still verify a security code before proceeding with the remainder of the test cycle.

Thus, atposition 20, a master terminal program spacer 612 actuatesprogram switch 318 to energize the related auxiliary relay 142 (FIG. Actuation of theauxiliary relay 142 opens the energizing circuit vialead 260 to the actualequipment trip coil 1 to remove effects of actuation of thealarm relay 270. Thus, conduction during simulated fault condition is fromlead 266 throughauxiliary relay 142 to lead 252 and terminal 250 (FIG. 5) to energize the terminal trip"relay 386 of FIG. 4. This also energizes theblue lamp 382 to indicate the trip condition.

Simultaneously, positive DC voltage is supplied fromprogram switch 318 to the test enablerelay 348. Then, whenprogram switch 312 is keyed byprogram spacer 614 frompositions 22 through 24 of FIG. 8, it serves to open the alarm bell circuit while energizingrelay 348 to actuatecontacts 358 and 360 closed so that they connect the test source potential to the static relay, i.e. the protective relay undergoing test at the particular terminal installation. In the present application, test source potential will be available onleads 350 and 352 to theterminals 220 and 222 (FIG. 4) for conduction via leads 224 and 226 (FIG. 5) to the primary ofsaturation transformer 228.

In the case of a phase comparison protective relay system, as is primarily disclosed in respective FIGS. 4 through 8, the low-set fault detector should operate to effect transmission of half cycle pulses from therespective carrier transmitter 96 FIG. 3), while the high-set fault detector serves to generate the local trip condition in conventional manner. The trip condition will be indicated by illumination of theblue trip lamp 382 withrelay 386 energized. At the B terminal, half cycle pulses must be received at therespective carrier receiver 196 with indication to thetest unit 420 whenprogram switch 470 closes for 1 second in response toprogram spacer 616 at position 23, contact 502 must be actuated open or the system will alarm. The proper receipt serves to verify or effect a second portion of the security code, which, in turn, serves to keep the terminals unlocked and ready for testing.

Absence of the signal, i.e. when no half cycle pulses are received at the B terminal carrier receiver, thetest unit 420 will alarm and lock out since failure to apply a carrier receive input atterminal 458 ofterminal board 424 fails to energize carrier receiverelay 494 to open thecontact 502; and, any closure ofprogram switch 470 will then effect the alarm condition by illuminating red lamp 528 andactuating alarm relay 580. Also in position 23, a terminalA program spacer 618 effects closure ofprogram switch 320 to verify thetrip relay 386, i.e. AC energizing voltage as applied from 292 throughlead 374 andrelay contact 388 to actuate thered alarm lamp 384 and thealarm relay 392. If test security is true, closure ofprogram switch 320 serves to verify thattrip relay 386 is energized and thatcarrier relay 402 is energized.

At the B tenninal,position 25,program spacer 620 actuatesprogram switch 478 to effect closure of that auxiliary relay 142 (FIG. 5) which is associated with the 8 terminal. Energization of the auxiliary relay 142 (B terminal installation) opens the energizing circuit for therespective trip coil 110 to apply trip energizing power vialead 252 to the terminal 250 (FIG. 5). This, in turn, provides connection acrossterminal 460 ofinput terminal board 424 of Bterminal test unit 420 such that a trip energizes the blue trip"lamp 572 and thetrip relay 566. Simultaneously, as the trip is opened, the positive DC voltage is supplied to relay 536 such that, upon keying ofremote program switch 472 at positions 26-28 byprogram spacer 622, the alarm bell circuit is opened andrelay 536 is energized to connect the test source potential to the primary of the respective saturation transformer.

The remote terminal static relay then must also operate to transmit half cycle pulses of carrier and trip. Tripping will be indicated by the illumination of theblue trip lamp 572. At position 27,program switch 480 is actuated in response toprogram spacer 624 and this serves to verify thetrip relay 566 as carrier receiverelay 494 is energized. At the master A terminal,program switch 322 is closed in response toprogram spacer 626 at position 27 and this verifies reception of carrier from the remote terminal, but without local tripping as respects the master terminal equipment.

Program spacers 636 and 638 (remote) control respective program switches 318 and 478 which operate to open the respective trip circuits by energizing the relatedauxiliary relays 142 at each of the master and remote terminals.

An internal fault is simulated whenmaster program switch 312 is keyed byprogram spacer 628 at positions 33 to 35, andremote program switch 472 is keyed byprogram spacer 630 at the same position, respective local trips being keyed thereby. Theauxiliary relay 142 at each terminal passes the trip torelays 386 and 566 for verification atposition 34, i.e. aplastic spacer 632 effectingprogram switch 320 and, at the remote terminal, a plastic spacer 634aifecting program switch 480. Actuation of the respective program switches 320 and 480 serves to apply the AC energizing voltage to the contacts of the respective trip relays 386 and 566 thereby to verify their switch setting.

The master and remote terminals can change the phase of their respective test source potentials by keying of program switches 314 and 316 at the master terminal, and program switches 474 and 476 at the remote terminal. Thus,program spacers 640 and 642 actuate program switches 314 and 316 such that the A terminal test voltage phase is reversed attest transformer terminals 220 and 222. Output is not realized until DC is supplied to relay 348 in response to closure ofprogram switch 318 under control of program spacer 644. Presence ofprogram spacer 646 to actuateprogram switch 312 completes the low side energization ofrelay 348 which applies the test transformer output in the proper reversed phase.Program spacer 648 then closes programs switch 324 to effect test reset and, 2 seconds later, program spacer 650 effects closure ofprogram switch 322 to verify the test condition.

Proper coordination with the A terminal carrier transmission is then made at the B terminal through switch closure by theprogram spacers 652 and 658. Comparisons of local and received signals are made at the terminals to verify the reception of alarms, but without the tripping conditions. These indications again must be verified or each tenninal will alarm and lockout, and the test will be stopped with alarms being reported to and stored at the masterterminal test unit 150.

The B terminal program atposition 45 then reverses the phase of its test source potential by keying program switches 474 and 476 by means of theprogram spacers 656 and 658. At this time all test potentials are again in phase. The simultaneous comparisons of local tripping conditions are made when the masterremote switch 312 is keyed by the master Aterminal program spacer 660, verification coming with closure ofprogram switch 320 in response to program spacer 662. At the same time theremote program switch 472 is keyed in response to program spacer 664 with a verification by actuation of theprogram switch 480 in response tospacer 666. If at any time the units fail to obtain the proper starting signal, ring back, presence or absence of simulated faults along with the proper security codes; all units will alarm, lockout, stop testing and the proper alarm indications will be reported to the master terminal. The alarm indications, which may be repeated at some designated control center, must be personally ackowledged by an attendant and manually reset at the master terminal.

It should be fully understood that a test system constructed in accordance with the present invention is applied to selected test terminals or stations. Thus, a two or three tenninals automatic testing system can be installed for coactive operation at two or three terminals. Theprogram 670 of FIG. 9 illustrates a three terminal program with proper program spacer arrays for each of tenninals A, B and C. Terminal A is the master terminal maintaining the control central and alarm functions while both of terminals B and C are made to slave to the master tenninal A.

FIG. 10 illustrates another form of commercially available transmission line surveillance network which can be tested with the automatic testing system of the invention. It should be understood too that various surveillance networks using different subcombinations of commercially available type are compatible with the present invention. In FIG. 10, thesurveillance network 680 is a microwave transmission link shown installed between two terminals, includingcircuit breakers 682 and 684, along apowerline 686.

Atcircuit breaker 684, acontrol transformer 688 is located in sampling proximity to thepowerline 686 to provide a sequence network output viaconnection 690 to astatic relay 692. Thestatic relay 692 would include atrip amplifier 694 and aconnection 696 for breaking the circuit. Thestatic relay 692 may take any of the various forms; however, the present application is directed mainly to the phase comparison type of relay. Thus, asuitable test source 698 may be energized by akey input 700 to provide a suitable test signal input tostatic relay 692, whichstatic relay 692 is in coacting interconnection with acontrol unit 702 of conventional type. A low-set output fromstatic relay 692 is utilized to key atone transmitter 704 which, in turn, modulates a microwave transmitter/receiver 706, and also to supply an input control signal to controlunit 702.

The microwave transmitter/receiver is a conventional UI-IF or SI-IF transmitter as utilized for telemetric purposes. Suitable microwave telemetric transmitter/receiver equipment is, for example, commercially available from the Leukurt Electric Co. of San Carlos, Calif. Energy received by the microwave transmitter-receiver 706 is applied to atone receiver 708 which demodulates and applies its output to thecontrol unit 702 to complete the control function. Suitable forms of tone receivers and transmitters, as may be employed fortone receiver 708 andtone transmitter 704, are Model MC22 which are commercially available from the Motorola Company of Chicago, Ill.

Theother terminal 682 includes similar equipment. That is, a microwave transmitter/receiver 710 functions in coaction with atone transmitter 712 and atone receiver 714, each being interconnected to acontrol unit 716. An output fromcontrol unit 716 is applied to atrip amplifier 718 which is an integral component of astatic relay 720. Thestatic relay 720 is connected by means of theconnection 722 to acontrol transformer 724 while maintaining a mechanical disablingconnection 726 with thecircuit breaker 682. Thekey input 728 andtest source 730, similar to that at the other terminal or proximate thecircuit breaker 684, are included with input interconnection tostatic relay 720.

Interconnection of the test equipment to carry out the various test, verify, alarm, etc. functions is easily carried out, interconnection being similar to that previously described in FIG. 5. Inputs and outputs relating to the prior carrier functions would be applied to the like components of the microwave transmitter/receiver system, and the control interconnection relating to the static relay, control unit and trip amplifiers would remain the same.

The foregoing discloses a novel automatic testing system for use in maintaining high voltage electrical transmission networks. The test system is capable of interconnection for coactive testing operation automatically and between any two or three terminal stations in a power distribution grid. In addition, the automatic test can be utilized with various forms of communication equipment, i.e. carrier equipment, microwave equipment, telephone hookup, etc. Testing may be effected in coaction with various types of the conventional protective relays such as directional, phase comparison, impedance directional comparison, conductance directional comparison, and combination whether solid-state or hard tube types.

While it is intended that circuit components utilized in the present invention may be of the time-proven types capable of heavy duty, long time operation with little or no maintenance, it is also contemplated that the entire system can be constructed from the more recently developed solid-state components. Such choices as to components and overall types of construction may be dictated by the exigencies of each particular application.

Changes may be made in the combination and arrangement of elements as heretofore set forth in the specification and shown in the drawings; it being understood that changes may be made in the embodiments disclosed without departing from the spirit and scope of the invention.

What is claimed is:

1. Apparatus for testing a plural terminal powerline protective relay system which includes a transmitter and receiver interconnected with a control unit and protective relay connected to control a line circuit breaker assembly at each terminal, each of the transmitter and receivers being in mutual communication, the apparatus comprising:

first programming switch means located at a first terminal and being actuatable to function for a predetermined duration;

first control means which is actuated by said first programming switch means to energize the first terminal transmitter to transmit carrier energy;

second programming switch means located at a second terminal and being actuatable to function for a predetermined duration;

second control means which is actuated by the second terminal receiver upon receiving the transmitted carrier energy from said first terminal to actuate said second programming switch means to function for said predetermined duration;

first and second auxiliary relay means located at respective first and second terminals and being energizable to remove said circuit breaker assembly from control con nection to said control unit and protective relay; and

first and second switching means controlled by respective first and second programming switch means to energize respective first and second auxiliary relay means during predetermined intervals of said predetermined duration.

2. Apparatus for testing a plural terminal powerline protective relays system as set forth inclaim 1 which is further characterized to include:

third programming switch means located at a third tenninal and being actuatable to function for a predetermined duration;

third control means which is actuated by the third terminal receiver upon receiving transmitted carrier energy from said first terminal to actuate said third programming means to function for said predetermined duration;

third auxiliary relay means located at said third terminal and being energizable to remove the circuit breaker assembly from control connection to said third terminal control unit and protective relay; and

third switching means controlled by the third programming switch means to energize a respective third auxiliary relay means during predetermined intervals of said predetermined duration.

3. Relay system testing apparatus for use with electrical transmission lines having plural terminals each of which includes an interconnected transmitter and receiver, ad a phase comparison protective relay and control unit, which control unit includes means for keying a respective transmitter with alternating, discontinuous fault voltages in response to a fault condition at the respective terminal, the test apparatus compnsrng:

first means at a first local terminal for generating a first fault voltage which simulates a first trip condition;

second means at a second remote terminal for generating a second fault voltage which simulates a second trip condition;

verification means receiving each of said first and second fault voltages to determine phase relationship thereby to indicate a predetermined fault condition relative to said first and second tenninals; and

first and second program switch means automatically energized in synchronous relationship to actuate the respective first and second means simultaneously.

4. Testing apparatus as set forth in claim 3 which is further characterized to include:

first switch means actuated by said first program switch means to reverse the phase of said first fault voltage such that said verification means indicates a second predetermined fault condition.

5. Testing apparatus as set forth in claim 4 which is further characterized to include:

second switch means actuated by said second program switch means to reverse the phase of said second fault voltage such that said verification means indicates a different fault condition.

6. Test apparatus for use in testing a protective relay system functioning with an electrical transmission line wherein each of local and remote terminals interconnecting sald transmission line include a circuit breaker with trip circuitry to operate said circuit breaker upon reset fault indication, a transmission and receiver equipment, and a protective relay including control circuitry for keying said transmitter in response to locally detected fault indication signals and for comparing the phase of fault indication signal received from remote transmitters with the phase of fault indication signals generated at the local transmitter to determine if the fault is internal or external of the interconnecting transmission line, the test apparatus comprising:

program control means located at said local terminal and actuatable to efiect selected operation of a plurality of program switches at differing intervals through a predetennined time sequence, each of said switches being connected to provide a program control output actuation; starting means for actuating said program control means;

an electrical power supply;

auxiliary relay means connected to said circuit breaker trip circuitry to apply electrical power to said trip circuitry when said auxiliary relay means is deenergized such that the trip circuitry will operate said circuit breaker upon preset fault indication;

circuit means connecting a first program control output actuation of one of said plurality of program switches to energize said auxiliary relay means thereby to remove said electrical voltage to said trip circuitry to disable operation of said circuit breaker for the duration of said fist program control output actuation; and

fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said protective relay and control circuitry to key said transmitter and provide trip indication.

7. Test apparatus as set forth in claim 6 wherein said fault simulation means comprises:

transformer means connected to simulate a fault current indication as an AC electrical voltage; and

first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry. 8. Test apparatus as set forth in claim 7 which is further characterized in that:

fourth and fifth program control output actuations of said plurality of program switches are periodically actuated to reverse the phase of the output AC fault indication voltalge from said first rela means. 9. est apparatus as set orth in claim 6 wherein said remote terminal also includes test apparatus comprising:

remote program control means located at said remote terminal and being actuatable to effect selected operation of a plurality of program switches at difiering intervals through a predetermined time sequence, each of said switches being connected to provide a program control output actuation; carrier relay means responsive to transmission from said transmitter at the local terminal to start actuation of said remote program control means; a remote electrical power supply; remote auxiliary relay means connected to said remote circuit breaker trip circuitry to apply electrical power to said remote trip circuitry when said remote auxiliary relay means is deenergized such that the remote trip circuitry will operate said remote circuit breaker upon preset fault indication; remote circuit means at the remote station connecting a first program control output actuation of one of said plurality of program switches of the remote program control means to energize said remote auxiliary relay means thereby to remove said electrical voltage to said remote trip circuitry and to disable operation of said remote circuit breaker for the duration of said first program control output actuation; and remote fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said remote protective relay and control circuitry to key said remote transmitter and provide a remote trip indication. 10. Test apparatus as set forth inclaim 9 wherein said remote fault simulation means comprises:

transformer means connected to simulate a fault current indication as an AC electrical voltage; and first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry. 11. Test apparatus as set forth inclaim 10 which is further characterized to include:

fourth and fifth program control output actuations of said plurality of program switches are periodically each actuated to reverse the phase of the output AC fault indication voltage from said first relay means. 12. Test apparatus as set forth in claim 6 wherein said starting means comprises:

synchronous motor means mechanically coupled with an electrical switch means, said motor means functioning to close said switch means at periodic intervals. 13. Test apparatus as set forth inclaim 9 which is further characterized in that:

said starting means at the local terminal consists of an electrical switch closed at periodic intervals by a synchronous timing motor, and said remote terminal starting means is a relay means energized in response to receipt of carrier from the local transmitter to start a cycle of test operation at the remote terminal.

Claims (13)

1. Apparatus for testing a plural terminal powerline protective relay system which includes a transmitter and receiver interconnected with a control unit and protective relay connected to control a line circuit breaker assembly at each terminal, each of the transmitter and receivers being in mutual communication, the apparatus comprising: first programming switch means located at a first terminal and being actuatable to function for a predetermined duration; first control means which is actuated by said first programming switch means to energize the first terminal transmitter to transmit carrier energy; second programming switch means located at a second terminal and being actuatable to function for a predetermined duration; second control means which is actuated by the second terminal receiver upon receiving the transmitted carrier energy from said first terminal to actuate said second programming switch means to function for said predetermined duration; first and second auxiliary relay means located at respective first and second terminals and being energizable to remove said circuit breaker assembly from control connection to said control unit and protective relay; and first and second switching means controlled by respective first and second programming switch means to energize respective first and second auxiliary relay means during predetermined intervals of said predetermined duration.

2. Apparatus for testing a plural terminal powerline protective relays system as set forth in claim 1 which is further characterized to include: third programming switch means located at a third terminal and being actuatable to function for a predetermined duration; third control means which is actuated by the third terminal receiver upon receiving transmitted carrier energy from said first terminal to actuate said third programming means to function for said predetermined duration; third auxiliary relay means located at said third terminal and being energizable to remove the circuit breaker assembly from control connection to said third terminal control unit and protective relay; and third switching means controlled by the third programming switch means to energize a respective third auxiliary relay means during predetermined intervals of said predetermined duration.

3. Relay system testing apparatus for use with electrical transmission lines having plural terminals each of which includes an interconnected transmitter and receiver, ad a phase comparison protective relay and control unit, which control unit includes means for keying a respEctive transmitter with alternating, discontinuous fault voltages in response to a fault condition at the respective terminal, the test apparatus comprising: first means at a first local terminal for generating a first fault voltage which simulates a first trip condition; second means at a second remote terminal for generating a second fault voltage which simulates a second trip condition; verification means receiving each of said first and second fault voltages to determine phase relationship thereby to indicate a predetermined fault condition relative to said first and second terminals; and first and second program switch means automatically energized in synchronous relationship to actuate the respective first and second means simultaneously.

4. Testing apparatus as set forth in claim 3 which is further characterized to include: first switch means actuated by said first program switch means to reverse the phase of said first fault voltage such that said verification means indicates a second predetermined fault condition.

5. Testing apparatus as set forth in claim 4 which is further characterized to include: second switch means actuated by said second program switch means to reverse the phase of said second fault voltage such that said verification means indicates a different fault condition.

6. Test apparatus for use in testing a protective relay system functioning with an electrical transmission line wherein each of local and remote terminals interconnecting said transmission line include a circuit breaker with trip circuitry to operate said circuit breaker upon reset fault indication, a transmitter and receiver equipment, and a protective relay including control circuitry for keying said transmitter in response to locally detected fault indication signals and for comparing the phase of fault indication signal received from remote transmitters with the phase of fault indication signals generated at the local transmitter to determine if the fault is internal or external of the interconnecting transmission line, the test apparatus comprising: program control means located at said local terminal and actuatable to effect selected operation of a plurality of program switches at differing intervals through a predetermined time sequence, each of said switches being connected to provide a program control output actuation; starting means for actuating said program control means; an electrical power supply; auxiliary relay means connected to said circuit breaker trip circuitry to apply electrical power to said trip circuitry when said auxiliary relay means is deenergized such that the trip circuitry will operate said circuit breaker upon preset fault indication; circuit means connecting a first program control output actuation of one of said plurality of program switches to energize said auxiliary relay means thereby to remove said electrical voltage to said trip circuitry to disable operation of said circuit breaker for the duration of said first program control output actuation; and fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said protective relay and control circuitry to key said transmitter and provide trip indication.

7. Test apparatus as set forth in claim 6 wherein said fault simulation means comprises: transformer means connected to simulate a fault current indication as an AC electrical voltage; and first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry.

8. Test apparatus as set forth in claim 7 which is further characterized in that: fourth and fifth program control output actuations of said plurality of program switches are periodically actuated to reverse the phase of the output AC fault indication voltage from saId first relay means.

9. Test apparatus as set forth in claim 6 wherein said remote terminal also includes test apparatus comprising: remote program control means located at said remote terminal and being actuatable to effect selected operation of a plurality of program switches at differing intervals through a predetermined time sequence, each of said switches being connected to provide a program control output actuation; carrier relay means responsive to transmission from said transmitter at the local terminal to start actuation of said remote program control means; a remote electrical power supply; remote auxiliary relay means connected to said remote circuit breaker trip circuitry to apply electrical power to said remote trip circuitry when said remote auxiliary relay means is deenergized such that the remote trip circuitry will operate said remote circuit breaker upon preset fault indication; remote circuit means at the remote station connecting a first program control output actuation of one of said plurality of program switches of the remote program control means to energize said remote auxiliary relay means thereby to remove said electrical voltage to said remote trip circuitry and to disable operation of said remote circuit breaker for the duration of said first program control output actuation; and remote fault simulation means energized by a second program control output actuation during said first program control output actuation thereby to energize said remote protective relay and control circuitry to key said remote transmitter and provide a remote trip indication.

10. Test apparatus as set forth in claim 9 wherein said remote fault simulation means comprises: transformer means connected to simulate a fault current indication as an AC electrical voltage; and first relay means energized by a third program control output actuation of one of said plurality of program switches to apply said AC electrical voltage fault indication to said protective relay and control circuitry.

11. Test apparatus as set forth in claim 10 which is further characterized to include: fourth and fifth program control output actuations of said plurality of program switches are periodically each actuated to reverse the phase of the output AC fault indication voltage from said first relay means.

12. Test apparatus as set forth in claim 6 wherein said starting means comprises: synchronous motor means mechanically coupled with an electrical switch means, said motor means functioning to close said switch means at periodic intervals.

13. Test apparatus as set forth in claim 9 which is further characterized in that: said starting means at the local terminal consists of an electrical switch closed at periodic intervals by a synchronous timing motor, and said remote terminal starting means is a relay means energized in response to receipt of carrier from the local transmitter to start a cycle of test operation at the remote terminal.

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