US1745039A - Telephone system - Google Patents

Description

'Jan. 28, 1930. L. M. SIMPSON 7 9 TELEPHONE SYSTEM Filed Jan. 9. 1928 12 Sheets-Sheet l I?mm L ancslFl' mm? Sim sun Jan. 28, 1930. L. M. SIMPSON 1,745,039

TELEPHONE SYSTEM Filed Jan. 9, 1928 12 Shee'ts-Sheet 2 1% I Landfill 7m Sim sun Jan. 28, 1930. I SI 1,745,039

TELEPHONE SYSTEM Filed Jan. 9. 1928 12 Sheets-Sheet 3 Im LancelETP'TFHfi 51m sun L. M. SIMPSON TELEPHONE SYSTEM Jan. 28, 1930.

Filed Jan. 9. 1928 12 Sheets-Sheet 4 Jan. 28, 1930. L, M. SIMPSON 1,745,039

TELEPHONE SYSTEM Filed Jan. 9; 1928 12 Sheets-Shget 5 Lam: FYI Tm 51m sun I Jan. 28, 1930. T M, SIMPSON 1,745,039

TELEPHONE SYSTEM Filed Jan. 9. 1928 12 Sheds-Sheet 6 Lan 5131mm mm 5011 F "Jan 28, 1930. v L. MpSIMPSON 1,745,039

TELEPHONE SYSTEM Filed Jan. 9, 1928 12 Sheets-Sheet 7 5K 31111-11113 11 111 I CK JJ M (111,111 1 K SHK SEK

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TELEPHONE SYSTEM Filed Jan. 9, 1928' 12 Sheets-She'et 8 73 87! a "*ll;

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. .zTELEPHONE SYSTEM Filed Jan. 9, 1928 12 Sheets-Sheet 9 ImlE-"- LancelFl Mm 51m sun Jan. 28, 1930. I M. SIMPSON 1,745,039

TELEPHONE SYSTEM Filed Jan. 9,- 1928 12 Sheets-Sheet 10 Jax' .28, 1930. L. M SI'MPSON I 1,745,039

TELEPHONE SYSTEM Filed Jan. 9. 192a 12 Shets-Sheei 11 L ancsl'n'l'mm 51m sun Jan. 28, 1930; M. SIMPSON 1,745,039

TELEPHONE SYSTEM Filed Jan. 9,- 1928 12 Sheets$het 12 H 2%. l2. H425 H253 H238 r Patented Jan. 28, 1930 r LANCELO'I. 'MARTiIN srMPsoN, or ggnonnnn; nnan Iinnns, ENGLAnniAssIGno'R To ASSOCIATED TELEPHONE nn TELEGRAPH coMPANm-onKAnsAs CITY, MISSOURI.

A GORFORATION OE l r 7 ii, 'i'rELEBHOLTE 5mm 7 Application fiieaaan z 9,1928, ser al no. 245,343, at; injGreat Britain January 13, 1927.

i The present (invention relates telephone systems and: is more,particularly.concerned with apparatus for: use. inesuch systems: for

/ performing routinegtests. lts is generally recognized nowadays that it is desirable that apparatus of the-complexityot that employed in an automatic telephone exchangeas hould be subjected to certaintests at stated intervals so that faultsmay be discovered before they occur in an actual connection. Certain ofthe features of the present invention are-applica ble to'routin-ing apparatus in general but the invention more particularlyiconcerns and has beenievolved in connection'with apparatus for testing register translators -which are ar? ranged. to" register. the; digits dialled 'by a I, 4

together with certain ,of the control relays calling party andsendout translated i111. pulses in accordanceitherewithaq According to enefeatureof the'invention the apparatus to be routinedis; arranged in groups and a switching device associated witheach group is provided on the operation particular group only.

of which the routining equipment isadapted autoniaticallyto. connectf with and tes't that According toanother feature of invention the apparatustobe; routined is arranged in groups and arrangements areigprovided whereby a single setting ofthe control keys of the routining equipment will secure the application of a series of teststhe naturelof which varies in accordance with; the group which isbeingfte'sted; w i i 1 I 1-- ,A further featuregof theinvention' is' that' in a testing arrangement for the routine test ing of apparatus as used intelephone systems the routining equipment :is adapted towsend in trains of impulses to the-apparatus under test and to receive trains of impulses therefrom, a portion-of thesending operation beingdependent upon a ing operation." 1 j, hesefeatures and others not specifically. mentioned at this point will be more-fully understood from the 1 following I description satisfactoryfreceiv of one method of carrying the invention into eifect which should be taken in conjunction with the accompanyingdrawings. It will be understood howevert-hat the specific, applicationof the invention shown and describedis OFFICE;

ivinb'y, wayofexample only an tha v Y ous modifications to the circuit details could be madeby those skilled in'theart without exceeding the scopeofcthe inventionu a v Reterringnow to. the drawingscomprising Figs. 1 to'12,Figs. 1 1 1, whenproperlyfitted together show suflicient of the circuits of a routiner suitable for use in. testing register translators of the type described in thecopending application .of xJohn Ostline,

Serial Number, 755,3741filed-ion 12th Decemk her, 1924, to enable the invention to be prop erly understood, while Fig. 12 showsja partot the; circuits which are not .fully' included in theot-her figures inorder to avoid confusion. Fig. 1. shows the group routine key GRK through. the operation ofwhich the sender of the test. mechanism is controlled. Fig.2 shows additional control relays, through the operation ofwhich the digitsto ,be trans-:

sender mechanism. lfhe relays shown in i Fig. .4 control the signal lamps responsive tothe receipt of certain digits from the registeritranslator then under test. Fig.6 shows the group distributor GD'and'the register distributor: RBI, and also one loank 360 of another register distributor. "Through the operation of thelzgroup distributorthe group of register translators to. be tested is determined,'and the register distributor RDl is Qperatedto select a particular translator in thatgroup. Fig. 6v shows thesendingswitch SS andthe Brelaytiming switch'BS through the operation of 'which certain functions of the translator-is tested. Fig; 7 shows theicontrol keys of the test mechanism through the operation ofwhich 'theitest' mechanism is ar-' ranged to perform particular :testsoni -the selected-register translator; Figs. 8 and 9' show the digit control switches, relays and signalylampsg and in the upper right hand corner of Fig. 9 ,is-,shownthe control switch through the 'opertaion of which the sending mechanism of the testing device is controlled. Figs. 10 and 11 show the remainder of the control relays of the sending device and in Fig. 11 the pulse test switch PT together with suitable signal ,lamps for supervising the operation of this portion of the test.

As may be seen from the above mentioned application, it is usual to arrange the register translators in a number of groups having different translating facilities and to select the proper group in response to the first digit dialled by a calling party. Two. further digits representing the remainder of the exchange code are then sent to a register translator in the proper group and are suitably translated, while the remaining four numerical digits are transmitted without translation. Accordingly, if the apparatus according to the present invention is to be arranged to test the register translators in all the groups without alteration, it will be necessary to have a special test code which can be common to all groups, since it will be understood that in general the same two digits sent into the register translators in different groups will produce different translations. The routining apparatus is connected to the particular register translator under test by way of a grou distributor and an appropriate number 0 register distributors, in the case considered, 14, a sufiicient number of register distributors being assigned to each particular group of register translators according to the size of the group. The register translator is taken into use ahead of the one which is actually being tested so as to ensure that all shall be routined during the test without undue delay, and in case a register translator is busy when seized for testing, an alarm is given if it does not become idle within a definite time. Sets of keys are also provided on which the input test number is set up together with the expected output, and in case the output received at any time does not agree with the setting'of the output keys the test is stopped and an alarm is given. The number received is also displayed on a suitable lamp panel whether correct or incorrect, so that if some fault should occur the incorrect number may be some indication to the attendant of the nature of the fault. The test number is preferably transmitted to the register translator twice under conditions representing the extreme upper and lower working limits of operation of the switches. Special arrangements are also necessary in dealing with register translators in the tenth or 0 group since the normal operation is that when such register translators are required, for instance in completing calls to operators, the single letter O is dialled but no other digits. Some special provision is also necessary to deal with the case in which the subscriber has been instructed to dial three letters only, for instance INF for information,

and these arrangements will be fully described in due course.

Considering now the detailed operation of the apparatus shown, it will be assumed that a general routine test is to be conducted, that is to say a test on the register translators in all ten groups. In order to initiate this test the attendant operates first the general routine key GRK and then the start key SK. lVhen the start key is thrown, at its lower contacts it completes a circuit over normally closed contacts of the continuous routine key CK, lead 104, back contact and armature 19, armature 25, and its back contact, lead 114, winding of magnet 359 to battery, over lead 315, through relay 261, and at its upper contacts it com letes a circuit over lead 98, armature 26' a its back contact, winding of relay 17 to battery. Relay 17 thereupon operates after a slight interval and at armature 18 prepares a homing circuit for the various register distributors, at armature 19 opens the circuit just traced formagnet 359 of the group distributor GD whereupon this switch advances one step, at armature 20 completes a circuit over lead 714, for relay 48, a parallel circuit for this rela being also completed over lead 128 and tl ie operated contacts of the key, SK, at armature 21 prepares a circuit for relay 1, and at armature 22 connects earth to motor start lead 23. Earth connected to lead 23 causes the operation of the motor employed to drive the interrupters which supply the various types of impulses used throughout the testing operations. Earth is also connected to this lead at different stages of the operation by armatures 46, 60, 65 and 69 so as to ensure that the motor for driving the various interrupters shall be maintained in operation as long as the routiner is in use. Relay 48 at its armatures 49 and 50 completes circuits for relays 59 and 61 and 52 respectively, at its armature 51 opens a point in the locking circuit extending over lead 94 of relay 585 and at its remaining armatures closes points in the circuits of the indicating lamps connected to the normal positions of the various register distributors. Relays 52, 59 and 61 all operate at this time and perform similar functions, the necessity for a plurality of relays being that the number of contacts required is greater than the capacity of a single relay. At armatures 53 and 62 points are opened in the circuits of the relays 63 and 66 one of which is energized when the group distributor has connected up one of the register distributors. When the-switch GD advances one step as above described, a circuit is completed for relay 30 as follows: battery, winding of relay 30, lead 107, wiper 351 and the secondcontact in its bank, lead 101, operated left-hand contacts of the general routine key GRK, lead 708, front contact and armature 50 to earth. Relay 30upon operating, at armature 31 locks itself up over the left-hand contacts of the key GRK, at armature'32 completesthe circuit of relay 1, at armature-33 prepares the test circuit for the first register translator,

and at armature 34 opens a point inthe homing circuit ofthe switch GD. Relay 1 upon operating, at armature2 opens a point in the circuit of relay 37, at armature 3 completes circuits for relays 10 and 28 both of which are slow to pull up, at armature 4 prepares a circuit over lead 108 for relay 6 from test lead 373 of the first register translator, and at armature 5 prepares a circuit for relay 26 from the-test lead of the next register translator over lead 102. Over wiper 366 of the register translator the circuit fcr the indicating lamp 370 is completedas follows: battery, lamp 370, conductor 122,'armature 57 and its front contact, conductor 125, firstcontact in the bank of wiper 366 and said Wiper, lead 116, winding of relay 63, lead 118, second contact in the bank of wiper 357 and said wiper to earth. Lamp 370 is accordingly lighted to indicate which register translator is undertest and relay 63 is operated, thereupon atarmature 64 preparing a stepping circuit over lead for the magnet 367 of the switchRDl. r 1

Assuming that the register translator which is now connected with, is busy at this time, there will bean earth on thetest conductor 37 3 which will be extended over wipers 363, 354, lead 108, armature 33 and its front contact, armature 4 and its front contact, armature 12 and its back contact, winding of relay 6 to battery. Relay 6 upon operating at this time, atarmature 7 opens the circuit of relay 10 and at armatures 8 and 9 prepares circuits over leads 88 and 124 for the purpose of giving an alarm if this condition persists unduly long as will be more fully explained subsequently. Similarly if the next register translatorisbusy at this time, relay 26 will now be operated and at armature 27 will open the circuit of relay 28. When this register translator becomes free, relay 26 falls away and relay 28 operates, thereupon applying earth from operated contacts of the start key over lead 109 to the test lead so as to prevent seizure by a subscriber at this time. Assuming that the register translator seized for test shortly becomes idle the circuit for relay 6 is opened and it deenergizes, thereupon at armature 7 completing a circuit for relay 10 and at armatures 8 and 9 opening the alarm circuits. Relay 10 is now energized over armature 7 and at armature 11 completes a circuit from earth, armature 3 and its front contact, front contact and armature 11, lead 705, armature 72 and its back contact, lead 78, windingof relay 249 to battery. Moreover at armature 12 a circuit is prepared extending over lead 88 for relay 576 and at armatures 13 and 14 the in coming pulse leads from the register translay 261.- Magnet 460 accordingly advances the wipers 461'464 one step, whereupon a circuit iscompleted from earth at armature 250, lead 309, wiper 462 and the second contact in its bank, lead 379, normally closed contacts of the forced release cancelkey FRK,

lead 289, windingof relay 151 to battery. Relay 249 also at armature 251 prepares a circuit over leads 311 and 312 for the relay .604, the purpose of which .will beappreciated indue course. r p

Whenthe register translator is definitely taken into use for the test, earth is fed back 7 over the/test lead 373, and is then extended over wiper 363, wiper 35 4, lead 108, armature 33 anditsfrontcontact, armature4 and its I front contact, armature 12 and its front contact, lead 88," normally closed sprlngs controlled lcya-rmature 581, winding of relay 576 to battery. Relay 57 6 operates and at arma ture 577 prepares a circuit for advancing the control switch, at armature 57 8 completes a holding circuit for the switching relays associated with the digit recording switches over lead 418,150 the normally closed contacts of the release key :RK, at armature 580 prepares a circuit overlead 99-for relay 193, at armature 579 opens apoint in the circuit for subsequently advancing the control switch CS, at armature v581 locks itself up to earth on lead88,.at armature 582 prepares a circuit 'for.relay60 1,'at armature 583 opens'a point in an alternative locking circuit for relay 624, and at armature 584 opens a point in the energizing circuit of this relay. Relay 151 on en ergizing in response to the completion of its circuit, at armature 152 connects relay 253 over leads 720 and 80 to the pulse lead 374 of the register translator under test, at; armature 153 completes a circuit over lead 722 for the forced release test lamp 266 and preparesa circuit for'the'forced release test failure lamp 267, at armature 154 prepares a locking circuit over lead 703 for relay 255, at armature 159 connects earth pulses at 65-second intervals over leads 281 and 739 to the lower winding of relay 255, at armature 155 opens a point inlthe circuit of relay 601, at armature 156.

closes a point in the circuit of relay 173, and at armature 158 closes another point in the circuit for advancing the control switch CS.

The circuits remain in this condition while g after its seizure. This operation is brought about by the connection of low resistance battery to the pulse lead. Accordingly when this battery connection is made in due course, relay 253 is operated over lead 720, and at armature 254 a circuit is completed from earth at armature 577, lead 280, front contact and armature 158, lead 735, front contact and armature 254, lead 305, winding of magnet 460 to battery through relay 261. The battery connection in the register translator is only momentary so that relay 253 de-energizes after a short interval and opens the above circuit at armature 254, whereupon magnet 460 releases and advances the wipers 461464 one step. The circuit of relay 151 is now opened and it (lo-energizes, thereupon completing a circuit for relay 601 which extends as follows: battery, winding of relay 601, armature 600 and its back contact, lead 766, front contact and armature 582, lead 767, lead 300, armature 155 and its back contact to earth. Upon the operation of relay 601, at armature 602 a point is opened in the circuit of relay 598 and at armature 603 earth impulses at the rate of 20 per second are connected over armature 606 and its back contact, lead 311, front contact and armature 251, lead 312, lower winding of relay 604 to battery. Belay 604 is a two-step relay and at the end of the first impulse operates to transfer the pulse lead at armature 606 over lead 410 to the winding of magnet 404 and thence over lead 315 to battery through the supervisory relay 261. The B relay timing switch BS is accordingly set stepping and continues to do so until the above traced circuit is opened 011 the de-energization of relay 601. This will be effected when relay 576 de-energizes due to the removal of earth from the test conductor of the register translator. Upon the de-energization of relay 601 a circuit is completed from earth on armature 602, front contact and armature 608, for relay 598, and this relay at armature 600 opens another point in the circuit of relay 601 to prevent it re-energizing subsequently, and at armature 599 connects earth over lead 411 to wiper 405 of the switch BS so as to light the appropriate lamp to indicate the release time of the B relay. It will be understood that after the register translator has been released due to the forced release feature, the circuit for the B, or release relay, will be opened and it will de-energize after a short interval. lVhen it finally falls away earth will be removed from the test conductor and consequently the position in which the switch BS is brought to rest is a measure of this time interval. In case the B relay releases too quickly, wiper 405 will be engaging either the second, third, or fourth contact in its bank and a circuit will be completed for the fast lamp 407 over lead 744, lead 288 and through the alarm relay 171 to battery. If the B relay is releasing properly the lamp 408 will be lighted to indicate this fact while if it has held up for too long lamp 409 will be lighted the circuit of this lamp also extending to battery through relay 171. Upon the release of relay 576 a circuit is completed from earth, front contact and armature 250, lead 309, wiper 462 and the third contact in its bank, lead 456, back contact and armature 579, lead 451, interrupter contacts and winding of magnet 460 over leads 741 and 315, to battery through relay 261. Consequently the control switch CS is advanced a further step and in the position which it now occupies a circuit is completed from earth, front contact and armature 250, lead 309, wiper 462 and the fourth contact in its bank, lead 378, normally closed springs of the series test cancel key SEK, normally closed springs of the key CHK, lead 293, upper winding of relay 160 to battery. Relay 160 is accordingly operated and at armature 161 completes a circuit from earth, back contact and armature 199, lead 729, resistance 270, back contact and armature 244, lead 721, armature 161 and its front contact, lead 80, wiper 356, wiper 365 to pulse lead 374 thus again seizing the register translator. Moreover at armature 162 relay 160 completes a locking circuit for itself, at armature 163 lights the series test lamp 263, at armature 164 again completes a circuit'for relay 576, and at armature 165 completes a circuit extending over lead 284 for relay 193. The routiner will now send in to the register translator under test a certain test number which has previously been set up on the input keys the corresponding output being set up on the appropriate output keys. Since this is to be a general routine test, the exchange code portion of the test number will need to be one which produces similar translation in all the groups of register translators. The test now to be considered is made with the resistance 270 in series with the pulse lead, this resistance conveniently having a value of 750 ohms.

Returning now to the detailed operations, relay 193 operates when its circuit is completed and at armature 194 opens a point in the homing circuit of the sending switch SS, at armature 195 prepares a locking circuit for the two-step relay 190, and at armature 196 connects up pulses over lead 732 at the rate of 7 per second from springs 278, back contact and armature 248, lead 732, armature 196 and its front contact, armature 191 and its back contact, back contact and armature 204, lower winding of relay 190 to battery. Relay 190 only operates its light spring 192 on the first pulse and, when the pulse ends, transfers the pulsing circuit at armature 191 over lead 292 to the magnet 403 of the sending switch. This accordingly advances the wipers 401 and 402 one step, whereupon a circuit is completed from earth on the multipled contacts in the bank of wiper 401 and said wiper, lead without saw:- at the present time. Impulses are accordingly sentin: over pulse lead 374 to the register translator and the sending switch SS is advanced one stepifor each pulse; *This stepping continues until a circuit is completed for relay 201 as follows; earth, wiper 461 and the fourth contact in its bank lead 380, springs of the operated first'code input key, asso;

.ciated contact in the b anli'rjof wiper 402and said Wiper, lead 316, lower winding ofrelay 201 to battery. 7 Relay 201 upongoperating,

at armature 202 completes a restoring circuit for the switch SS wherebythe wipers 401 and 402 are returned automatically to normahat armature 203 completes a lockingcircuit for itself and opens the circuit of magnet 460 whereupon the wipersof the control'switch are advanced one step, at armaturei204'opens the circuit of relay 190 so that this relay deenergizes, at armature 205 short-circuits springs 276 to preventlaiiyv further'impulses being sent into theregister translators, at

' armature 206 short-circuits springs I277 though this operationis without eifect'fat this time, and at armature 207 prepares a holding circuit for itself which "will not comeinto use" at the present time; 7 When the switch SS has reached its normal position, the circuit of relay 197 is opened and it de fenergize s; thereby opening the lockingcircuit for relay 201, This de-energizes in its turn after a slightins terval and conditionsare then set up for send; ing the second code input digit,the only difi'erence being. that since the control switch CS has been advancedlone step the second digit is underthe control of the secondfset of code input keys instead of the first set. The second code digit istherefore sent in to the register translator and the control switch is advanced one step as before, Sincethecom plete exchange code has now been set. the register translator should commenceto send the corresponding, exchange output and it is arranged that the sending of, any further digits is delayed until one digit hasbeen received back from the register. translator, This delay is effected because afterthev second input digit has been sent a locking circuitis completed for the relayi20l as follows battery, upper winding of relay 201, front.

contact and armature 207 armature, 189 and its back contact, lead 294, lead '382,lsiXthcon-j tact in the bank .of,wiper and said wiper to earth. Relay 593 isa1so operated at this time everits lower winding and at armature 594,.prepares a lamp signaloyer lead 79in case no pulses are receiVed,-, at armature 595 alters the circuit of relay193, andat armaturesl-596 and 597 prepares circuits'for operatingrelay 255 to give an alarm; I I

Cons dering how the receipt jot impulses attheroutiner, itm'ay be pointedout that upon the operation of vrel ay".' 76 a circuit completedfor' relay 4 asffollows'z. battery,

lower .windingfof relay 465, lead 97, normally closedfsprings controlled by armature 215,

lead 92,. armature 14 and its front contact,

lead 103, wiper 352, wiper 361, lead 371,[send-" ing loop in the register translator,,lead'f 372,

wiper 362,.wi'per v353, lead 106, front contact and armature 13, lead 8 9, normally closed springs controlled by armature 214,1ea'df96,

upper .windingoi relay 465, lead 83, back'contact and armature'474,lead 455, armature 578,21I1d its front contact, lead 7 63, lead 418, normally closed contacts o'fthe key to earth. "Relay 465 is energized in this circuit and completes a circuit extending from earth, back contact and armature 155, armature 17 6 and its back contact, lead 290, armature4 66 and its front contact, winding. fofrela'y 467 tobattery. Relay 467 upon energizing, at

armature 468 prepares a p ointin thecii'cuit of seriesrelay 470 andat armature 469 opens a point, in the circuitot relay 173,. extending over lead 87.v WVhen impulses are transmitted from the, register translator, relay 465 re spends and upon each de energization com pletes a; circuit through the winding of relay 470, armature 47 9 andits back contact, winding of rotary magnet-481 to'battery. f Magne't 481 accordingly operates intermittently and adyances thewipers 482- 484 anumber of steps corresponding "to the "digit 'sentfout. Relay 470. operates in series with the magnet and at armature 471 completes acircuit for relay. 472 which is slow to release. When relay 470, de-energizes at theend'of the series of impulses, a c rcu t is momentarily coinpleted fronijeart-h, armature 471 and itsj'back;

contact,'-armature 473 and its front contact, armature 478 and its back contact, lower windingfofrelay 475 tobat'teryi Relay 475 now operates its light armature477 and when relay 472'falls away. operates fully, thereuponat armature 476 preparing a circuit for the. succeeding switching relay 486, at arma-' ture 478 transferring its'initial energizing I circuit to this relay, at armature 479 preparing the circuit of the rotary magnetic-f the nextminor switch, and at armature 480 completing a circuit over wiperf483 .for the corresponding indicating. lan' p, this circuiteX- I tending to battery over the operated cona tacts of the corresponding out-put key. A circuit is. also now completed 4 from; an inter:

ing, operated contacts of'the' corresponding rst eedaeitr tker lsalt ream 3? rupterfproyiding earth impulses second, wiper 482 and the contactjwhich it 1sengag and its back contact, lower winding of relay 182 to battery. Relay 182 which is a two-step relay now prepares a locking circuit over its light armature 184 and at the end of the first pulse pulls up fully and thereupon at armature 183 removes earth from lead 297 extending to the bank of wiper 554 of the pause timing switch PT, at armature 186 transfers the pulse lead over armature 181 and its back contact, lead 296 and wiper 553 to the magnet'555 of the switch PT, at armatures 185 and 187 prepares locking and energizing circuitsfor relay 177, at armature 188 completes a marking circuit for the first numerical input digit in the bank of wiper 402, and at armature 189 opens the locking circuit of relay 201 so as to permit sending to continue from the routiner. Magnet 555 now operates from the pulses to advance the wipers 551-554 over their respective banks, while after the usual pause the second code digit is sent out from the register translator under test. As soon as the first impulse of-the next series is received, relay 465 de-energizes and a circuit is thencompleted from earth, back contact and armature 155, armature 176 and its back contact, lead 290, armature 466 and its back contact, armature 468 and its front contact, lead 283, front contact and armature 187, lead 299, wiper 551, lead 291, armature 179 and its back contact, upper winding of relay 177 tobattery. Relay 177 accordingly operates and at armature 178 applies earth over lead 317 and wiper 552 for lighting the corres onding fault lamps in case the pause should be incorrect. For instance, if the pause should be too short, wiper 552 will not at this time have passed clear of its 13th contact, and a circuit will be completed for the short pause lamp 558 to battery through the upper winding of relay 612 which thereupon operates to give an alarm in a manner which will be more fully described subsequently. Similarly if the pause is excessive so that wiper 552 has reached its 24th contact a circuit will be completed for the long ause lamp 559 through relay 612 as before. llelay 177, moreover, at armature 179 opens its initial energizing circuit and prepares a circuit extending over lead 726 for the relay 228, at armature 180 looks itself up over its lower winding to earth on armature 186, and at armature 181 opens the pulsing circuit to the magnet 555 of the switch PT so as to bring this switch to rest. In case, however, the pause between the first and second code digits lies within the permissible limits, no circuit is completed over wiper .552 and the test roceeds without interruption.

W en the second code digit has been 'received from the register translator, relay 486 is operated to rform similar functions to relay 475 inclu ing the lighting of the lamp correspondin to the digit received. Moreover, upon the operation of armature 487 4 a circuit is completed from earth, armature 487 and its front contact, lead 123, lead 702, operated contacts of the key GRK, lead 701,

lead 86, back contact and armature 169, lead 734, back contact and armature 231, winding of relay 208 to battery. Relay 208 thereupon operates and at armature 209 a circuit is completed over leads 126, 76 and 111 for the loop reversed lam 556, at armature 210 another point is close in the circuit of relay 222, atarmature 211 earth pulses at 2-second intervals are connected up to the two-step relay 258, and at armatures 212, 213, and 216 circuits are prepared which only become effective during tests on the 10th group of register translators. Moreover, at armatures 214 and 215 the connections of relay 465 to the sending loop extending to the register translator are reversed. Reference to the aforementioned application will show that the eifect of this is to cause the operation of a polarized relay in the register translator which thereupon holds up a further sending until it-is released. Two-step relay 258 operates fully in due course and at armature 260 transfers the pulsing lead over lead 736 to relay 166 so that after a further interval this relay operates fully and at armature 168 opens its own energizing circuit and at armature 169 opens the circuit of relay 208 whereupon this de-energizes and reverses the sending loop back to normal. Consequently the sending of the remaining digits from the register translator is now resumed and takes place in the usual manner. When the full six digits set up on the input keys have been sent into the register translator the control switch CS will have advanced to its 10th position whereupon a circuit is completed over wiper 461 and lead 452 for the up er winding of relay 593, whereupon this re ay again operates with the results previously described except that no circuit is now completed for maintaining relay 193. The effect of the de-energization of relay 193 is to open the pulsing circuit for the magnet 403 of the sender switch SS so that no more imlses are sent in to the register translator.

oreover at wiper 462 the initial energizin circuit of relay 160 is o ened and this re ay is now held energized e endent upon armature 474 of relay 500. In tlie meanwhile the register translator continues its sending operation and the two-step relays similar to relays 475 and 486 are operated in turn at the end of each digit to transfer the various control circuits to the relay and minor switch corresponding to the next digit. As each two-stepswitching relay is operated, the ap ropriate lamp of the set associated with t e minor switch will be lighted, the circuit for each lamp extending through the operated contacts of the corresponding output key. When the last numerical digit has been received, relay 500 operates and at armature 501 prepares [circuit forfrelay 567'over leads 453 and454, 'a'tarmature 502 locks itself up,-and 'at"armature 503 Opens its initial energizing ci'rcuit. Moreoverat armature 504 the'circuit oi the-associated rotary magnet is-opened-to prevent-any fur ther operation of this magnet and at arma ture 474 'thelockingcircuit of relayf160' is opened, so that it de-en'ergizes and'at arma-" ture' 161 removes earth-from the pulse lead 374e'xtending to the register translator under test thereby -eflectingthe release of this register. Moreover owing to the fact that the circuit of the last indicating lamp extends to'battery through the winding of relay-616 instead of direct, this relay is operated at this time. Thereupon, at armature 619 it prepares a lockingcircuit for relay. 629, at armature618 connects up earth pulses at'4- second intervals to this relay, at armature 617 Opens a point in thecircuitior advane,

1 ing the control switch CS, at armature 620 release magnets. Moreover,-at armature 626 it looks itself up to earth over'armature 619 and at armature 625 prepares a pointin' the circuit for stepping the control switch. The various minor switches are nowreleased by their associated magnets and relay 621 operates in series therewith and at 'armature622 completes a holding circuit forrelay616 an'd at armature 623 lights the minor-switch release alarm lamp 561. Relay 621'is energized as long as any of the switches areoff-normal and since relay 616 is slow'torelease it is maintained for a shortinterval after relay 621de-energizes." Since relay 624 is locked up'dependent upon relay 616and-is'also slow.

to release-,when 'relay 616 fallsawa'y a circuit is momentarily completed as follows: earth, operated-contacts of the start key SK, normal contacts of the release key, RK, lead 416, armature 625 andits'front'oontact, back contact and armature 617, lead304, armature 213 and its-back contact, bac'k contact and armature'225', armature 220janditsback contact,'lead 305, winding of magnet 460 of a control switch CS over leads 741 and 313 to battery throughjrelay261'as usual. I Magnet 460 therefore operates to a dvance'wipers 461- 464 inclusive afurther step. 'Iiithisposition 01": the control switch a circuitisicom pleted from earth, frontcontactand "armaj lead 309, wiper 462 and the llth contact inits'hank, lead'37 7 normallyclosed springs of the liey SHK, normally closed springs of the key CEK', lead 308, winding of relay 242 to battery. Relay 242 now operates and at armature 243,0pens the circuit extending over lead 727 1 of theseries test lamp 263' andlights the shunt test lamp 274, at armature 244 disconnects the pulsing fsprings 276, and'at armature 245 connects up instead springs 277 which are operated at the rateof 14 pulses per second.- Moreover, at armature 246 aleak resistance 271 which may have a 'Value of 50,000 ohms is connected up, at armature 247 a locking circuit is completed for relay 242, and at arinature 243 a circuit is also completed over lead 728 for the lowerwinding of relay 160 and.

thisoperates with substantially the same re- 'sults 'as previouslydescribed; Owing to the connection of earth over back contactand armaturet200 lead721 and lead to the,

pulse lead 37 4, the register translator isagain seizedand prepared for operation. I

' The same input code and numerical digits are now sent into it but as already pointed out impulses are now at a faster rate, for'instance 14 impulses per seconch and a shunt resistance is employed lIlStGEtCl of the series resistance 270 as 1n the previous test.

On the completion of the transmission of each lnput digit, thecontrol switch is advanced one step as previously described and; when all the digits have been sent'it is advanced o its 11th posltion in which a ClIClllu 1S co1npleted iorrelay 593 as before. The switch waits inthis position until all thetranslated digits have been sent out frointhe register translator under test, whereupon relay 616 is operated and thejcircuit previously traced formagnet 460 of the controlswitch is again completed when the minor switches have re leased. lVhen the control switch isadvanced- I to 18th position, a circuit is completed from earthov'er wiper 4611and the 18th contactin its :bank, lead'105, lower winding o'lslow relay 15 to battery. Relay 15 accordingly operates and at armature 16 opens the circuit for relay 1 wh ch therefore de-energizes. Thereupon at armature 3 the circuit of relay 10a'nd of relay 249'extending over'leads 705 and 78 is opened, at armature4 the test lead is dlsconnected, andat armature 5 the circuit overthe auxiliary test wiper is opened. A- branch of the circuit for energizing relay 15 alsofextends overthe normally closed contacts of the continuous routine key CK, lead 112, armature 56 and itsiront contact,:front contact and armature 64, lead 115 ,windin g of magnet 367 over leads7 40 and'315' to battery through relay 261 as usual. This circuit is opened when the control switch CS reaches normal-position after its homing movement was started by the de-energization of'relay" 249, Accordingly the switch RDl is advanced one step to connect the r'outiner through to the next register translator which has previously been seized and held bus'y while the test just described was taking place. This register. translator is then subjected to the same tests as have just been described and when they have all been successfully completed relay 15 is again operated and the switch RDl is advanced a further step.

This continues until the switch RDl advances to its 25th set of contacts to test the register translator accessible from that position, whereupon a circuit is completed as follows: earth, wiper 357 and the second contact in its bank, lead 118, winding of relay 63, lead 116, wiper 366 and the 25th contact in its bank, indicating lamp 369, lead 82, armature 228 and its back contact, lead 77, winding of relay 35 to battery. Owing to the operation of relay 35, when the circuit for relay 15 previously traced is completed at the end of the test of this particular register translator a branch of the circuit extends from lead 105, normally closed contacts of the continuous routine key CK, lead 112, front contact and armature 36, lead 114:, winding of magnet 359, lead 315 to battery through relay 261. The wipers 351358 of the group distributor GD are therefore advanced one step to connect with the register distributor RD2 (not shown) whereupon the same tests are carried out on the register translators accessible from the banks of this switch. In the arrangement shown, since two register distributors are assumed to be necessary for the first or ABC group of register translators the register translators reached from the switch RD2 will be in the same group as those which have been considered.

Since as already pointed out, in a general routine test the test code employed is one which will be translated similarly by the register translators of all groups, the operation is precisely the same when other groups are reached, hence no detailed description will be given of the actual testing operations which proceed in precisely the manner described until the tenth or 0 group is reached. The register translators of this group difler from those which have just been considered in that since they are taken into use in response to the dialling of the digit 0 not followed by any further digits they must be arranged to start their sending operation as soon as they are taken into use. Consequently in this case the routiner need not be arranged to send in any particular digits to the register translator but only to simulate the conditions corresponding to its seizure which is done by reversing the leads of the pulsing loop. Actually there are no separate register translators forming the tenth group but certain of the register translators accessible from other levels are multipled also to the tenth level but with the outgoing pulse leads reversed. .Hence the testing of the socalled tenth group of register translators is strictly the testing of special functions of register translators which have already been tested as regards their ordinary functions; for this reason the forced release test is omitted at this time. These register translators which start sending as soon as they are seized are not all precisely similar but are divided into two groups, which may be termed 0 level regular register translators and 0 level barred register translators. These latter are only accessible from particular substations, for instance pay stations, which are not entitled to set up long distance calls for which the assistance of an operator is obtained by dialling the digit 0. Consequently if a subscriber at one of these stations endeavours to obtain access to the toll operator by dialling the single digit 0, the call is routed instead to a monitoring operator who explains that the subscriber is not entitled to make long distance calls. The par ticular codes which are necessary for routing a call either to the regular toll operator or to the monitoring operator will necessaril be different from the normal translation 0 the general test code, but in order that the general routine test may include the tenth grou without further attention from the atten ant, it is arranged that a test is made of the correct reception of these codes irrespective of the position of the output keys so that these may be left in the position correspondin to the output number of the general test. his is shown more clearly in Fig. 7.

The 0 level register translators are accessible from a separate register distributor RD14 of which only wiper 360 corresponding to wiper 366 of switch RDl is shown, the circuits over the other wipers being precisel similar to those of the switch RDl. Vhen the group distributor GD operates its wipers into engagement with this special register distributor a circuit is completed from earth, wiper 357 and the 15th contact in its bank, lead 119, winding of relay 66, lead 130, wiper 360 and the first contact in its bank through contacts of relay 59 and the corresponding indicating lamp to battery. Relay 66 upon operating, at armature 67 prepares a circuit for the stepping magnet 368 of the register distributor RDH, at armature 68 completes a circuit for relay 71, at armature 69 ap lies an additional earth to the motor start ead 23, and at armature 70 connects earth pulses at 25-second intervals to the relay 255 for a purpose which will be described subsequently. Relay 71 now energizes and at armature 72 opens a point in the circuit of relay 249 so as to prevent the routiner sending in any impulses, at armature 73 prepares a circuit for relay 208, at armature 7 4 completes a circuit for relay 226, and at armature 75 completes a circuit for relay 233 and also for the 0 level regular lamp 272. Relay 71 moreover oper-

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