US1777709A - Telephone system - Google Patents

Description

F. APPELIUS TELEPHONE SYSTEM Original Filed Jan. 21, 1928 2 Sheets-Sheet 1 avg In1.rafi CIT-- Ffili E alius Oct. 7, 1930. F. APPELIUS 1,777,709

TELEPHONE SYSTEM Original Filed Jan. 21, 1928 2 Sheets-Sheet 2 PETE 5152211115 Patented -Oct. 7, 1930 PATENT: OFF-ICE Q FRITZ ,Arrnmus, or BEnmmcHARLoTTnNB- ne; enn vmnYgAssienoa To m mo rl arraaar-r anm g n. BERLIN, Gum Lann- "rnnnrnonn SYSTEM 1 1 Application filed, January '21, 1928, serialno. 248,342, a a m Ger an January 22, 1927.1 Renewed February 28,1930Qzm1;

"ni telephone systems withautornatic work- 7 ingit known to so connectseveral subQeX- changes to a line outgoing from. a main ex change that intl ieir diflierent positions the I switches, 1 which 1 are: connected up 1 in every sub-exchange, take into usethe further circuits for connectingup the subscribers lines, see for example the German Patent 360,610., Now the inventionirelates to small sulJ-e;:-

changes and it Fconsists in that one andthe same switch, when is, positionedfor the {first positioning in the wantedm ld-exchange,

connects up the otherconnecting up, circuits,

and after its release during the succeeding train of impulses it hunts for the; wanted line. The invention alsoenahlesthis switch to be used for finding and if required for disconnecting the faulty: lines. i i

The use ,ofthe sameswitch for several purposes'enables the; sub-exchanges to be most economically installed, g This advantage is i of particular importance for sub-exchanges At t /2 is close and gltO/fi are opened.

with the relaysystein. V

In the drawings Figs. 1 and 1A when placed endto end with Fig. LA at the right of Fig. 1 there is shown oneniainexchange line AL, which connects a manual niain exchange (field 1) with several sub-exchanges,

of these is shown the one taken into use with the numbers (-19.).

Semi-automatic work ng is shown by way of example, but the lnventlon 1s not limited ,to this type of working.

The drawing is divided into eight fields and in the description for example 8 II meansthewinding I1 efrelay Sp in field 8. The designation 4!?) 11/3 means the third contactof relay Y 1 and shown in field 4t."

i Outgoing call 7 n 1. The subscriber numher lO takes down hisreceiy'er. The relay T Q(zer o)i is oper' ated over; earth, back eontact {l c 1/3, 1 ab 3, 4 cl 3, {l t (1/1, suhscrihers loepof the station i 10, back contact 1 t 9/3, relay TO indings I IlLandI, battery, earth.

T Ofs operatedr Its contact h re ay l beforethe con cts 4 0/1 The'relay D is operated oyer zi earth,

ng clrcu t. H

ttery', winding front contact l T 0/2, back contacts ld2 and I 1 @6 1, relay 4 D,back contact tch 2, earth. V

The contact l (Z t again earths the c-lead,

while the contact 1- d 2 opens the short circuit V across the rela y'AZ) winding Lhence the latter is operated.

The contacts {id and 3 open the s tart 2. The" feed earth, battery, relay 2 R, back contact 2 f 3,

b-leaol, frontcontact'c t (l/6, suhscribers loop of the station 10, front contact 4 t 0/5,;a-lead, hack contact 2 1, choking coil Drwinding I, earth. i 1 I i so, that it cannot f'all hack,

7 3. At the front contact 2 circuit is established; earth, back centact 2 p 2, relay 2 A'winding I, front contact 2 1" 1,

back contact 2 7r; 1, a,-lead to the inain exchange, back contact lac, relay lwAR, bat- ,tery, earth.

ing relay 21B is operated over; 9

t at i The front. contact 4 1" 3 is closed and again earths the c lead thereby the short circuit 7 (4; (L64, 4 l) is again opened for the Dfrclay,

r 1 the following 79 A and AR are operated (has v I an connects the call indicator ASZ to the 80 b-lead: earth, battery,call indicator 1 AS Z,

front contact 1 ar, hack contact 1 are; 2/2, b-lead (to the I relays in the sub-exchanges), relay 2 I 1, resistance 210i 6, earth.

In all the sub exchanges the back contact 99 j v 4 o l/3 opens the starting circuit for imark- .ing engaged all sub-exchanges for outgoing calls. Thefront contact 4111/4 again earths the cflead for the rightsucces'sion during the the sub-exchanges) over: earth, front contact'S n 1/1, hack contactS 8p 3, relay 2,

5 In all the sub-exchanges therelays I i "are operated. i #At the contacts 2'. 2the relay V1 is enerreleas e taking place later on. The front con- 2 tajct 8 '21 1/1 energizes the relayK 2 (in all impulse circuit, while the front contact 7 '0 2/3 prepares the switch relays and the back contact el- 7. 1/ 3 opens the starting circuit.

6. The operator in the main exchange inserts an answering plug into the jack VK 1. A front jack spring applies battery over the AB relay to the b-lead, in order thus to further lock the relays 1' in all the subexchangcs. The contact 1 ab 1 energizes a slow acting relay 1 AV 1 and this over the contact 1 0w 1 energizes a second relay 1 AV 2 for the purposes of the release.

Over the bush of the jack, the relay AC is energized and the engaged potential (battery on the bush) is applied. The relay AC disconnects the relay AR, thus tie-energizing the call indicator ASZ.

7. The operator answers the call in the usual manner and sets up the call with the calling plug in the main exchange. By throwing the answering key, she opens the direct current circuit for the relay A in the group centre. The relay A is released.

8. The switching through relay K is operated over: earth, battery, relay 8 K winding II, front contact 8 d 1, back contacts 8 0 /2 and 8 11/5, front cont-act 8 7) 1/1, earth.

In the group centre are energized the relays T O, D, Ab, R, I, V1, V 2, K.

The front contacts 2 7c 2 and 2 7a 3 switch through the speaking leads in the calling subexchangc. This switching through does not take place in the other sub-exchanges, because there the relays D have not been energized.

9. Release of the group centre 10-19. The subscriber 1O hangs up his receiver. The relay R falls back. The back contact 4 r 4 short circuits the relay D, which also falls back. The back contact 2 r 2 closes the following circuit: earth, back contact 2 p 2, relay 2A winding I, back contacts 2 r 2 and 2 f 2, front contact 2 7s 2, (Head, clearing signal in the cord circuit, relay AB winding I, battery, earth.

In response to this clearing signal the operator withdraws the plug from the ack.

10. In the main exchange the relay AB at its contact 1 a7) 1 opens the circuit for energizing the relay AV 1. The latter after considerable delay opens at contact 1 (w 1 the circuit for energizing the relay AV 2, which likewise after considerable delay closes the circuit of the call indicator ASZ. The two delays of the relays AV 1 and AV 2 take longer than all the release delays in the group centres, so that all the group centres ha e reliably released before another seizure can take place. The contact 1 (m) 2/1 likewise keeps the busy potential on the jack bush until the release has taken place at all the group centres.

11. In the group centre 1019 the relay I falls back when the operator withdraws the plug. The circuit changes hereafter described are due to the fact that a falling back of the relay 1. is equivalent to one number 11npulse. Hence there is first a number impulse and then the release. The relay U is operated tacts 2 p 1 and 7 eh 2, front contact 7 2) 2/3,

earth. The relay E 1 looks itself over: earth, front contact 7'0 2/3, back contact 7 2h 2, front contact 2 6 1/2, relay 2 E 1 winding II, back contact 6 g 3, relay 6 P, battery, earth. The relay P is operated and likewise relay IC; earth, front contact 77) 2/3, back contact 7 2h 2, relay 2 IC, front contact 2 u 2, resistance 2 9, battery, earthj Contact 8 a 5 opens the circuit of the relay K, which falls back.

The following relays are energized: T 0,

Ab, V 1, V 2, U, E 1, P and IC. 12. After some delay relay V 1 falls back. Contact 8 '0 1/1 opens the circuit for energizing the relay V 2 and the contact 4 11 1/3 opens the locking circuit of the relay T 0. After some delay the relay V 2 falls back. At its contact 7 '0 2/3 it opens the locking circuit of the relays E 1, IC, and P, which fall back. Relay IC takes a long time to fall back.

The contact 8 c 2/1 disconnects the relay U. The relay 8 Ab is the last to fall back after some delay; it has been held to the last by the contact 8 2'0 3. The group centre can now be taken into use again for outgoing calls. As the relay 'V 2 falls back before the relay IC, no) circuit is closed at the contact 7 2'0 2 (see 36 13. Release of the group centres from which no call was made. Condition during conversation (see 5). On withdrawing the plug, the relay I. falls back. The contact: 8 v1 1 energizes relay U and contact 2 u 2 energizes the relays E 1, TC and P. The contact 8 7'0 3 energizes the relay AZ) over winding II. This condition is maintained until the relay V 1. falls back.

The contact 8 '21 1/1 opens the circuit of the relay V 2, which then falls back after a little while.

The opening of the locking circuits causes the following relays to fall back: relays E, IC and P over contact 7 7! 2/3, relay U over contact 8 c 2/1 and relay A?) over contact 8 7'0 3.

14. The relay AZ) is the last relay to fall back. The starting circuit and the contacts 41 (Z 3. 4 ab 3 and 1 7) .1/3 therefore are not closed until all have fallen back. In the main exchange the relays AB, AV 1 and AV 2 fall I back when the plug is withdrawn. The call indicator ASZ cannot be energized again until the relay AV 2 has fallen back. But in the means time all relays have fallen back in all the group centres.

iii)

Y Call to subscriber 1 in grbup'centre N0. 1

20. The operator tests, fora free line vy ith the tip oftheseleelting plug W812. If itlhe free, she-inserts the selecting plug into the selector jack Wli 11. Over the lead the relay AC is energized and the hnsypotentialis applied to the bush' contact 1 do disconn ects thevcalling relay AR; Over the a-sprin g of the jack the .relay AT is energized, Which connects the E-jletdto the selectorjack.

In all the subexchanges the'relayl is 5 e'rated over i earth ,resistance 2 wt 6, relay'2 1 selecto jad el cting plug ,5 VVSt, number Si ry,earth; 1

21; In all the sub-exehanges the relay s vl areoperated: earth, front contact8i2,relay 8 V1,,battery,-earth. vThereupon relayV 2 is also operated over: earth, front contact 8 01/1, hack contact 8' 8p 3, relay 8, V2, bat- In all thesub-ezrchangesthe back contact 4:

411/ 3opens the starting circuit for prevent Tens selection,

"ing the{sub-exchangesmaking calls to the mainexchange, y p 1 it First current inter- -uptlon. Relayl falls baclcand relay U s energizedover; ,ea rth, hack contact 8 z 1,

frontc0ntactf8 0 2/1, baclrcontact 8 st 1 relay 8 U, battery,earth.- ,f'ilhe relayslG and 1 y are, operated oy er ear h; front contact ,7 112/3, backcontact 7 zit 2, and 2 p 1, relay 2E 1 Winding I, front contact 2a 3 resist A Windingll.

gance 2 g,]battery, earth, and parallelther:

to relay 2 1G, front contact 2 10 2, resistance 2 battery, earth, Being slow acting,the relay 1C reinains energized during theuni- 111GIflCZll S 6leCi31Q11. i

Over the contact 8 therelay AZ) inding IIishperated v i l i The, relay E 1 locks itself over: earth, front contact 7 'u 2 3 haclncontact 7' 2h 2 front coi'itact 2 01/2, relay 2 E 1 Winding Ill, back contact 6 g 3, relayG P,-hattery,earth. V

'llh erelay l? is operated and at its Contact 2 p 1 1t d sconnectsthe relay E 1 wind ng 1 and over Contact 2 p 31tcon'nectsup therelayIG thereforefalls back, because its ener-v gizing circuit is opened "at contact 2 a 1 w i. the group centre 10-19 thefrelay Z is operatedo'yer: earth, front" Contact? 2/3 front contact 7 relay battery, earth.

7 c 2/3, relays 7 ZH and 7 Z winding 11, front "0' contact (210, 1'es1sta11ce e,,hatte1,y,-earth.

e 1/4,relay 7 winding 1, It .locksitself over: front con-tact 1 Therehythe relay ZH is also operated: E l

The back cont'act7 eh 2 opens, the locking circuit ofthe relays E 1 and, St and P, which l Relay VVvVis operated over eartlnbattery, relay 7 NVV, front contact 7 .4111, back con menu; 6, front contact? '0 2/3 earth. 1 .7 a

The relay VVVVlocks itself over its contact 7 cow Relays I, V 1 V 2,;1Z, ZH, 1V are energized. 7

26. Inthe group zcentre"20 29 thecontact 7 e 2/.-1 is connectedto the winding I of the 7' Z, While the Winding 1 of {the relay 7 -S is connected to the contact7 6 1/ 1 and 63/ 1 to e 9/&. If two: impulses had been i sent 'during the tens selection, the relay Z of the group centre 20-29 Wouldhave been ener gized. But as thetensylselectiononly coin prised one impulse',the relay Sp is operated atthe group centre20 29 after the tens selecttion: leartln'hatteiy, relay: 7-Spi'iyihding I, i

front contactz7 6/1/ 1, back contactsT wwi and 7: i0 2,: front contacts :7 p 5 and 7 1) 2/3, -earth. i i The contact8sp ergizinglthe relayj l 2, which falls back and 8 8' 2closes theloc king ci rcuitforthe relay resistance 8 8p, rela'yQSJSp Winding II, hat tery,earthp m I r The front Contact? "U 2/3 opensthe locking circuit of the back; 1 V i y 27. At the group centre 30-39 the contact i'elaysE 1, and St, \i hich fall 7 c 3/4 is connected to the. relay 7 Z, While the contacts-e 1/41, 02/4,. 6 1/4; toe 9 4, are connectedto the rela 7 Sp. Therefore after the tens selection 1 in the group centre 30-39 also the relay Sp is operated (as in and in the group centre 3039 the following relays are energizedzrelays LV 1, Sp.

28. Unlts selection 0. 171F813 1111111811021 USP/180M011 by open ng thecircuit at the number Ifalls back and relay U operated over: earth, back contact 8 @1, front eon tact 8 q) 2/1,back;contact 8st 1, relay 8U, battery,earth."-

The relays IC, and rib Winding fare operated over: earthyfrontcontact 7 c 2/3,

front contact 7 wow 4, front contact 7 2h 3, relay 2 1G,;front contact 2 102, resistance 2 g, batteryyearth:earth, front contacts 7 c 2/3, 7 @0404 and 7- eh 3, hack contact 2 p 1, relay 2 E1 WindingI, front contact 2a 3, resistance 2 g,'battery, earth earth,frontcontact8id3,

relay 8 Ab Winding II, battery, earth.

3 opens the circuit for en- Sp: earth, front contacts8 01/1 and 8,819 2,

The relay-E 1 looks itself over: earth, front contacts 7 422/3, 7 ww l, -7 2h- 3 and 2' e 1/2,

I again (because 8 2' 1 is open).

relay 2 E 1 winding II, back contact 6 g 3, relay 6 P, battery, earth.

The relay P is operated.

29. First circuit closure at the number dial.

The relay I is again operated and the relay U falls back. The relay IC remains energized, because it is slow acting.

The relay S15 is operated as follows: earth, battery, relay 2 St winding I, back contacts 2 g 1 and u 1, front contacts 2 79 4, 7 eh 3, 7 7010 4 and 7 c 2/3, earth. The following relays are energized: I, V 1, V 2, ZH, WW (IC), E 1, P, St.

30. Second current interruption. Relay I falls back. The relay St windingII is held and the relay G is energized over: earth, back contact 8 z' 1, front contacts 8 '0 2/ 1, 8 st 2, relay 8 St winding II, relay 8 G winding I, battery, earth.

The latter is locked over: earth, battery, relay 2 G winding II, front contact 2 g 2, back contact 2 u 1, front contacts 2 p 4, 7 2h 3, 7 tow 4 and 7 '1) 2/3, earth.

The relay E 2 is operated: earth, battery resistance 2 9, front contacts 2 g 4 and 2 st 4, relay 2- E 2 winding 1, front contacts 2 6 1/3 7 sh 3, 7 am; 4 and 7 5 2/3, earth.

The relay E 2 locks itself over: earth, battery, relay 6 P, front contact 6 g 5, relay 2 E 2 winding II, front contacts 2 c .2/2, 7 eh 3, 7 row 4 and 7 a 2/3, earth.

31. Second circuit closure. The relay I is again operated and the relay St falls back, because the winding I of the relay 2 St is open at contact 2 g 1 and the winding II of the relay 8 St is open at contact 8 i 1. V The relay E 1 falls back, because the locking circuit for the relay E windingII is opened at contacts 6 g 3 and 6 at 6.

The following relays are energized I, V 1, V 2, Z. 7111, 1V (IC), P, G and E 2.

32. Third interruption. The relay I falls back again and relay U is operated: earth,

-. back contact 8 i 1, front contact 8 1) 2/1, back Contact 8 at 1, relay 8 U, battery, earth.

Its contact 2 u 1 opens the locking circuit of the relay 2 G winding II, hence it falls back.

The relay E 3 is operated over: earth, battery, resistance 2 g, front contact 2 u 3, relay 6 E 3 winding I, front contacts 2 c 2/3, 7 2h 3, 7 ww 4 and 7 o 2/3, earth.

The relay E 3 locks itself over: earth, front 1 contacts 7 c 2/3, 7 ww 4, 7 2h 3, 6 0 3/2, relay 6 E 3 winding II, back contact 6 g 3, relay 6 P, battery, earth.

33. Third circuit closure. The relay I is again operated and the relay U falls back Relay St is operated over: earth, battery, relay 2 St winding I, back contacts 2 g 1 and 2 u 1, front contacts 2 p 4, 7 eh 3, 71010 4, 7 4) 2/3, earth. a l V The relay E 2 falls back, because the contact 6 g 5 is opened and 6 st 6 is closed and thus the locking circuit has been opened for the relay E 2 winding II.

The following relays are energized: I, V 1, V z, ZH, ww (Io), P, St, E 3.

This is exactly the same condition as at the first circuit closure (see 29, except that the relay E is energized instead of the relay E 1.

34. At the succeeding number impulses when'the circuit is closed after odd numbers the condition is the same (end of 33) except that E 5, E 7, E 9 is energized instead of E 3 and when the circuit is closed after even numbers the condition (end of 31) sets in with the difference that the relay E 4, E 6, E 8, E 0 is energized instead of the relay E 2. At the tenth circuit closure the following relays are energized: relays I, V 1, V 2, Z, ZH, VWW (IO) P, G, E 10.

35. The unit selection does not take place at the other sub-exchanges. Although the relays I oscillate, the selecting relays are dis connected (at 8 'v 2/1 and 7 7) 2/3) because the relay V 2 has fallen back (see end of 26).

36. Coupling up the subscribers line 10.

The relay I remains energized and thus the relay U is operated no more, hence the relay IC falls back after the time taken for it to fall back has elapsed. The relay K is operated: earth, battery, resistance 7 z 1, front contact 7 e 2, relay 7 K winding I, front contact 7 ww 2, back contact 7 2'0 2, front contacts 7 p 5 and 7 '0 2/3, earth.

The relay K locks itself over: earth, battery, relay 8 K winding II, front contact 8 7a 4, back contact 8 u 5, front contact 8 '1) 1/1, earth.

The front contacts 2 k 2 and 2 7c 3 switch through the speaking leads. At contact 4 5 is closed the circuit for energizing the line relay 4 T 0 earth, battery, relay 4 T 0 winding I, front contacts 4 a 10/1, 4 ' ww 5, 4 7a 5, 4 '21 2/2, earth.

The relay T 0 is operated. Its contacts 4 t 0/5 and 4 t 0/6 connect the subscribers loop to the common speaking leads.

37. Release of the switches. As soon as the relay K is operated, the relay Sp receives cur rent over: earth, battery, relay 8 Sp winding II, front contacts 8 2 4 and 8 7c 4, back contact 8 u 5, front contact 8 o 1 1, earth.

The contact 8 8p 3 opens the circuit for en ergizing the relay V 2, which after a little while releases its armature. The contact 4 a 2/2 disconnects earth and the following circuit functions: earth, battery, relay 4 T 0 winding I, front contact 4 t 0/2, back contacts 4 ( Z 2 and 4 ab 1, relay 4 D, front contact 4 a 1/4, earth.

The relay D is operated. Its contact 4 d 2 opens the short circuit across the relay 4 Ab winding I, which is likewise operated if it has fallen back after the release of IC.. The contact 7 c 2/3 opens the locking circuit of i which then fallsback.

H 1 The alternating current energizesthe relay the relays 2,. ZH, WW; r; E 10 and- G. The contact 4-1164 short circuits the relayD,

After the switch has been disconnected, the

1 following relays are energized: I, V 1, K, TO,

Ab, Sp.

. 38. Ringing. change inserts the callingplug into the speaking-jack VK 1. Therefore thebattery re-j 10..

inains connected over .therelay AB to the" I)- lead. She then withdraws the selecting plug; The interchange ofthe plugs; has no effect on the sub eXchangea The operatornow trans Inits alternating current by throwing the ringing key. The relays I must not bede energized by the alternating current.

W at the group centre 10-19 where the relay K is energized. The contact 2 W energizes theyringing relay F,.which atcontacts 2f 2 and2 f1 opens the branches to .relay A and choking coil D7", and at the contacts2 f 4 and 2f it short circuitsithe condensers C 1 and C 2 hence ringing current flows from the main exchange direct to the bell of thesubscriber s station so long as the operatorv keeps the ringing key in the operatedposis tion. {During-the ringing pauses the contact 2 f 3 connects thefeeding relay R to the subscribers line and the contact 2 f 1 connects the choking coil"Drwinding I to that line. 39. The Subscriber at station .10 answers the call. Duringa ringing pause the relay R.

is operated over: earth, battery, relay 2 R, back contact 2 f 3,6-lead, subsoriber s' loop [Z-lQiLCl, back contact 2; 1, choking coil Dr winding I, earth..

The closing of the contact 2 r 1' disconnects the relay A iroinithe a-lead, hence the .earth disappears from this lead. This circuit changerenders the supervisory signal in the cord circuit at the main exchange ole-energized, thus notifying the operator that the call has been answered. The back contact l 1* 1 removes the short circuit fromthe relay D, which isagain operatethwithout, hoW- ever, nowcausing.any'circuit,changes. Q. i

During the speaking condition, the follow ingrelays are energizedwz I, V 1, K,.T 05D,

Sp,A7),R. m V. y

10. Clearing slgnal to the main exchange. The subscriber hangs up his receiv'eri The relay" R falls: back. Its backlcontact 4t 9" a short circuits the relay {1 D, which falls back without having any further effect. The back contact 2 2 closes-the following circuit: earth,backcontact2 3912, relay 2A winding I, back contacts 2 a" 2, 2f 2, front contact 2 i1", 2,

. cap-lead, clearing signal at the main exchange,

b -lead, relay 1' AB winding l, battery, earth. Therelay Aand theclearing signal are spurred. Tlieyrelay l AB is energized over thexb-lead; the, relay 2 I1.

The operator at the main eii-l plug. This, causes circuit changes at the main exchange that have been desoribed under ma At the group centre 10-19 therelay I falls i back. Its contact 8 12 opensv the energizing circuit o'f the relays VAL Thelrelay 1 releases its armature afte'r allittle delay, thereby opening at its contact 8 a .1/1 the locking circuits cit-he relays K and At contact 4: a) l/tis openedthe locking circuit of the rea lays 41 T 0 and 4 Ab. Relayi TO fa'llsback quickly, whilethe relay 4A6 onlyreleasesits V armature after a little While has elapsed.

The contactt aby3'again closes the'starting v circuit. a

I. Reoertine"call'jto tlie oapag ro itp centre subscriber12 isassuniedllto wantlthe subscriber 17 42. The subscriber12 i ceiver. The circuit changesfarethe; same as those desoribed in 1-t0 8.jffllhereforeqduring i the answering of the call the following relays are energized in the" group centre 10-19: I, V 1, V2, IQR, 112,1), Ab,

that a revertiye call is Wanted onthe line, but

she does not know from Whichgroup centre the call originates.

13. The operator requests subscriber to hang up his receiver. lVhenthis has been done, the relayR falls back. Its

back contact 4 774: short circuits the relay D, this havingno eti'ectat present. ;;The contact to disturb the bridge .located behind the contacts-2 70 2 and27s 3. a 1.

Over the contacts 2a 2 and 2a 3 therelays The demand for. .17 notiiies the operator 1. At the breakiinfront contact 8 1;2/1, back contact 8 st 1, relay 8 U, battery, earth. 1 i

. ItSZCOHtZLCt B u 5 opens the locking-circuit got the relay K, Whichfalls back, in order not i "l and 16 are operatedzearth, battery, re-w sistance 2 9, front contact 2M3, 1 winding I, back contacts 2 and 7 ch 2,

front [contact 7 '0 2/3, earth, and parallel thereto relay 2 IC, frontcontact sistance 2 16 battcry,earth.

The relay E 1 looks itself over :earth, front contact 7 a) 2/ 8, back contact? 2702, front contact 2 e 1/2,'relay 2 E 1 Winding II, back con tact 6g 3, relay 6 P, battery, earth.

The latter is operated.

At the succeeding circuit lnakeat the number dial, the relayI is operated again. Relay U falls back and the relay IC also falls back, because the circuit is closed for'some time.

The tens relay Z is operated earth,battery, relay 7 Z winding I, front contact 7 c 1/4, back contacts 7 1070 1 and 7 7'0 2, front con tacts 7 p 5 and 7 '0 2/3, earth.

The relay Z locks itself over: earth, battery, resistance 7 2, front contact 7 2 3, relay 7 Z winding II, relay 7 ZH, front contact 7 2/3, earth.

i The contact 7 272. 2 opens the locking circuit of the relays E 1 and P, which fall back. The relay VVIV is operated: earth, battery, relay 7 IVIV, front contact 7 2h 1, back contact 7 p 6, front contact 7 7; 2/3, earth.

This locks itself over the front contact 7 IVVV 3; After the tens selection the following relays are energized: I, V 1,T 12, AZ), Z, ZI-I, IVIV.

45. Units selection. This condition is the same as at the beginning 28, except that the relays T 12 and A5 are energized. These relayshave no effect on the succeeding units selection. The seventh circuit closure creates the condition (see end of 33 and 34).

46. Coupling up the line 17. After a little while the relay IC falls back. The relays K and T 7 are operated as described in 37. The release of the switch takes place as described under 37. y

At the succeeding ringing, the two subscribers are called. When one of them answers, the operator asks for the number. If the calling party has answered, the operator asks him to hang up again and she continues to ring.

47. The release is initiated when both subscribers have hung up their receivers, because relay R then falls back.

I V. Revert ice call to another group centre The subscriber No. 10 wants the subscriber No. 23.

48. The subscriber No. 10 calls the ex change and hangs in the call he is requested to hang up his receiver.

In the group centre 10-19 the following relays are energized: I, V 1., V 2, K, T A?) (condition see 8).

In the group centre 20-29 the relays I, V 1, V 2 are energized (condition see 49. The tens selection 2 in the calling group centre 10-19. .The train of impulses 2 energizes the relay E 2 and P as several times previously described. At thefirstnumher impulse the relay U was operated and at its contact 8 it 5 it opened the locking circuit of the relay 8 K, which then fell back. After the numerical selection, the relay IC falls back and closes the following circuit: earth, battery, relay 7 7 Sp winding I, front contact 7 c 2/4, back contacts 7 7070 1, 7 770 2, front contacts 7 p 5 and 7 a) 2/3, earth.

, The relay Sp locks itself over: earth, battery, relay 8 Sp winding II, resistance 8 ap, front contacts 8 sp 2 and 8 '21 1/1, earth.

At contact 8 sp 3 was opened the locking circuit of the relay 8 V 2, which soon falls back and by opening its contact 7 p 2/ 3 effects the release of the relays E 2, IC and P.

After the tens selection the following relays are energized in the calling group centre I, V l, T 0, AZ), Sp.

50. Tens selection 2 in the wanted group centre -29.

t this group centre the contact 7 c 2/4 is connected to the relay 7 Z winding I in stead of the contact 7 c 1/4 shown in the ligure. Hence the tens selection takes place as described in 22 to 25. And there the following relays are energized: I, V 1, V 2, Z, ZH, WIV.

51. Units selection 3.

At the group centre 10-19 the beating of the relay I causes no further circuit changes, because the relay V 2 is not energized and the contact 7 c 2 /3 is therefore open, and over it the relays would have to be energized.

At the group centre 20-29 the units selection functions according to 28, to 34, and 36, to 37. I-Ience in the group centre after the selection, the following relays are energized: I, V 1), K, T 3, Ab, Sp. (Condition see end of 3 52. It should be noted that in the group centre -39 only the relays I, V 1 and Sp are energized and not the relays K and A7). Therefore the following ringing current cannot energize the relay 2 W at the group centre 30-39.

53. Ringing the group centre 10-19.

The ringing current transmitted by the o1 erator (see 38), flows over: the a-lead, front contact 2 ab 5, condenser C 4, relay 2 IV, condenser C 2, bank contact 2 j 3, relay 2 It, battery, earth.

The relay IV is operated, but not the relay R. The contact 2 'w energizes the relay 2 F. The contacts 2 f 4 and 2 f 5 connect ringing current directly to the line of the calling subscriber 10. During the pause in the ringing, the relay A is energized over: earth, back contact 2 p 2, relay 2 A winding I, back contacts 2 7' 2 and 2 f 2, front contact 2 a?) 5, a-lead, cord, clearing signal, relay 1 AB winding I, battery, earth.

54. Ringing the wanted group centre 20-29.

In this group centre the relay K is energized (see end of 38). Ringing therefore takes place exactly as described in section 38.

55. The calling subscriber 10 answers first, therefore too soon.

On taking down the receiver, the relay R is operated. Its contact 4 7- 4 removes the short circuit from the relay 4 D. i The latter is operated and the contact 8 (Z 1 closes the following circuit: earth, battery, relay 8 K winding II, front contacts 8 (Z l and 8 8p 1,

back contact 8 u 5,front contact 8 c 1/1, earth.

The relay K is operatedand locks itself over: earth, battery relay 8 K Winding II,

front contact 8 7c i,back' contact 8 5, front contact 8 '2) 1/1, earth. v g g The contact 21' 1 connects the relay A over Q the back contact12 7c 1- tothe a-lead.. The operator asks the party answering the callwhat his number is, If he is the calling party,

she asks him to hangup again and she continues to ring. When the calling party hangsthe receiver up again, the relays R and D fall back again. At the group centre 10-19 are energized the relays I, V 1, T 0, Ab, S p, K

(see end of 49). a i

56. When both subscribers have taken down their receivers, conversation-can commence. In the calling group centre the following relays are energized :I,"V 1, T 0, Ab, D, S79, K, R, While at the Wanted group centre the following relays are energizedz' I,

a v 1, K, T13, Ab, 1),.Sp, R, (see 51 At the group centres that are not used, the relaysI, V 1 and Sp are energized.

At the main exchangethe clearing signal appears when one of the subscribers hangs up. For the release, two cond1t1ons can oc- (a) The operator withdraws the plug when only one subscriber-hangs up. Until the time when the relay AV 2 falls back in the main exchange, the group centre of thesubscriber whohas hung up is released in the usual manner. l

Butat the other group centre R is still energized. Hence the relays T, D and Ab do not fall back, but all the others do so. For this reason, after the relay AV 2 has fallen bac'k at the main exchange, the sub- .scriber again takes into use the line and causes thecalling signal ASZ to appear at the main exchange. The operator answers the call and requests the subscriber to hang up his receiver. After. the clearing signal has appeared, she withdrawstheplugagain,

In order to reclucethe liability of making a double connection (because one subscriber is there already), the "operatorshould not re; lease a revertive call connection until she has cut in and found that both "subscribers have hung up,

(6) Both subscribers have hung up. Belease takes lace 111 the usual manner.

V. '1 7m main emchange'line is engaged 57. The relay V 1 is energized as soon as i the main exchange line is takeniinto use for an incoming or outgoing call, andit then opens the starting circuit at contact 4 '2) 1/3. VVhen' duringthis time a subscriber, for example No. 10 takes down :his receiver, the following circuit is closed earth,.back contact 4 hes, relay 4 Bee, back contact 45: t 0/1,

the relay subscribersloop, back contact a t 0/3, relay 4T 0 windings II and I,battery,earth-. v i The relay Bes has sohigh aresistance that it only and not the relay T O is operated. *At

contact 4 besQthe relay Besopens its own oil"- calling party that the' li ne is engaged.

.DiscOMLe'Ctiaga faulty line i A, The fault on I the subscribers" 'lineis such that a call to the mainexchange origihated, hence the loop is closed, or there is an earth on the Zi-lead of the subscriber.

58; The closing of the loop orthe earthing of the b-lead has the same effect as taking down the receiver. YVhen the operator answers the call, 'thefollowing relays are energized: I, V I, V 2, Tag-Ab, D,K, R (see 8).

The operator gets reply and concludes. that there is a'faultlj The follo wing arrangements are rnade' for disconnecting the faulty line: Every subscribers line extends over 'two backcontacts1(3,4)';si to the calling devices in the grou pjcentre; These back contacts 82" are so fittedonthe known fuse strips, that the known-alarm springs of the fuse open thecontacts, as soon as the fuse melts. The fuse 7 Si itself lies in a local circuit.

The operator inserts the "selecting plug into the selectingjackWVK Iand transmits ten impulsesp In themanner already several times described, the relay E 10 is energized at all the groupcentres and therelay P' is then'likewise operated. .A circuitis closed over: earth, front contacts a 2/3 and 7p 5, back contacts? in 2' andfl *ww 1,;front contacts 7 610/3, 7 lie/40f the xjfaultyfline, fuse 782' of the faulty line,'1resistance tm, battery, earth, irrespective ofwhich group centre contains the fault; 3 The operator withdraws the selecting plug and insertsthe connecting a plug into the jack VK 1. Aftera little while, the fuse ineltsand opens the contacts (3, 4)

s2. andthe clearing signal appears in themain exchangeowing to thewfallingback of, the relayRi l On dialling the number 10, thelirst iinpulse (U is energized)the elay 8 Kis re- Therebythe faulty line is disconnected gized, the relay K would be againpperated earth.

after the relay U hasfallen back,'if therelay, A jWerenot energized over; earth, front contact 2 p 3, relay 2 A winding II, battery,

After the faulty line hasbeen disconnected,

it is necessary to "ascertain in which group centrethefault is located (in order toavoid the fault searcher making unnecessary your neys). For that purpose a plug, is inserted into the connecting ack VK 1, this plug contains an indicator for earth in the a -lead. Now the three tens digits of the three group centres are dialled in succession seamen 115 leased, Asfhowevergthe relay D is enerl ill time previously releasing. On dialling the group centre, in which the disconnection has taken place, the clearing si 'nal will appear immediately. after dialling, the circuit extending over: earth, indicator, plug, (IV-lead, front contact 6 z 1, of the selected group centre, alarm contact bus bar 7 AKS, released strip of the fuse strip 7 Si, resistance 7 toe, battery, earth. This circuit with battery on the (Head can only occur in this case.

lVhen the fault seeker has removed the fault, he must replace the fuse and again close the contacts 821.

B. There is an earth on the subscribers line.

60. This fault does not cause a main eX- change call and does not disturb the setting up of connections. lVhen the subscriber sets up a connection or receives a call, the line' will be noisy, because an earth connection usually gives rise to false currents. Thereby the operator can recognize the fault and record the same.

61. However, the fault also becomes apparent owing to double connections. The earth on the subscribers a-lead renders the blocking of the starting circuit (contacts 4 (Z 3, 4 a?) 3, 4 4) 1/3) inoperative. Hence when a conversation is takingplace over the main exchange line and a callis originated by a subscriber of the group centre, to which the faulty line is connected, its starting circnit will be closed over the faulty earth instead of the busy relay being energized. The fault can be recognized by the double connection.

(S2. The first thing to be done is to find which line is faulty. The test clerk in the main exchange inserts an ordinary selecting plug into the selecting jack WK 1 and inserts a special plug into the connecting jack. The tip of this plug is connected over a head set receiver and a hand generator to earth. The test clerk dials the number 11, and then slowly rotates the hand generator-a If the line 1]. for example be not faulty, alternating current will flow over: earth, generator, receiver, rz-lead, group centre 10-19, frontcontact 2 7c 2, condenser C 1, subscribers bell of the station 11, which is not to be operated, back contact 2 f 3, relay 2 R, battery, earth.

The sound audible in the receiver is weak. But if the (z-lead of the line 11 be earthed, the generator current will flew back over this earth and not over the bell end the relay R. Hence the sound is very much stronger.

' The test clerk thus calls one line after another until he has found the faulty line. It is unnecessary to disconnect this line, because the fault only affects a few connections.

63. If the a-lead of the main exchange line AL be earthed, the relay AB in the main exchange will be energized an d it will give rise to a permanent call. \Vhile a faulty subscribers line (earth on the b-lead) giving rise alead of the to a permanent call causes the calling peter.- tial (earth) to disappear when the (all is answered owing to the relay K being operated in the group centre, earth potential ren'iains when the-external line he earthed and it gives the clearing signal also after the operator has answered the call. Thereby the kind of fault can be recognized. Hero of course unnecessary todialthe number i The line can be marked engaged (blocked) by leaving the plug in the jack. The disappearing of the clearing signal indicates that the fault has been cleared.

If the external main exchange line AL has the b-lead earthed,it impossible for the line to be marked engaged either when an, incoming or an outgoing call is made, because the relays I are short circuited. lit impossible to make a selection.

I11 this condition, when a group centre subscriber originates a call, it gives rise a normal call. But the relays I, V l. and V 2 cannot be operated owing to the relay l, being short circuited. Therefore, after the call has been answered, the clearing signal (lei-s not disappear from the cord circuit, because the relay K cannot be operated. On the other hand it is just possible to communicate over relay V. This clearly indicates the kind of fault.

What is claimed is:

1. In a telephone system, an exchange, a trunk terminating in said exchange, a plurality of line groups in said exchange, a selecting device controlled over said trunk, means for operating said device to select av particular one of said line groups, means au tomatically responsive when the group is selected for restoring said device to normal, an d means for re-operating said device to connect with a particular line of the selected group.

2. In a telephone system, a trunk line comprising two normally disconnected sections, a current feed bridge normally connected to the first section of said trunk, means for applying signalling current to the second section of said trunk, and means responsive to the application of said signalling current for disconnectingsaid bridge and for connecting the two sections of said trunk.

3. In a telephone system, a digit operated device, a plurality of groups of lines, a control relay and a cut-off relay in each of said groups, means controlled by said device for simultaneouslyoperating the control relay of a wanted group and the cut-oil relays of all other groups, and means responsive to the operation of said control relay for rendering said device effective to establish a connection with a particular line in the wanted group.

4.. In a telephone system, an exchange, a plurality of groups of lines in said exchange of which any of said lines may be subject to abnormal conditions, a trunk terminating in said exchange, a directively operated device controlled over one conductor ofsaid trunk, means automatically responsive when an abnormal condition exists on a line for extending aconneotion over another conductor of said trunk, and means controlled by said device for determining the particular group in i which said abnormal condition GXIStS,

5. In combinatioma line subject to abnormal conditions, fuse controlled contacts in the oonductorsof said line, and a reinotely controlled device for blowing said fuses when an abnormal condition exists on said line.

6. In combination, atrunk, a linewhich may become defective due either to a grounded condition or to a short circuit on theline,

means automatically responsive when said line becomes defective for connecting said line to said trunk, and means controllediover I said trunk for disconnecting said line from said trunk and for preventing subsequent con--- nection thereto. t

7. In a telephone system, an operators position, a signal at said position, a line sul ject to abnormal conditions, fuse controlled contacts in the conductors of said line, means automatically responsive when an abnormal): condition exists on saidline for operating said signal, and means controlled by the operator at said position for blowing said fuses to disable said line.

8. In combination, a line subject to ab normal conditions, fuse controlledcontacts in i the conductors of said line, a fuse blowing circuit, means automatically responsive when an abnormal condition exists on said line for connecting said fuses to said circuit, and a remotely controlled device for rendering said circuit effective to blow said fuses.

9. In a telephone system, a subscribers line, normally-closed contacts in the conductors of said line, a fuse controlling said contacts, a trunk, means responsive to an abnormal condition on said linefor connecting said line to said trunk, and means controlled over the trunk for blowing said fuses whereby said contacts are opened to disconnect the line tacts,and a circuit for said fuse independent of the line conductors for blowing the fuse to disable said line when an abnormal con dition exists thereon.

12; In a telephone system, a subscribers said-positionitfon'ioperatingfsai line,L a.ldisconnecting device i in i ilCllJCOIldlIC torvofz'saidilinepanz operatoris position, means 7 responsive to an: abnormahcondition Onsaid line for extending a connectionl fromzthe line to said: posit on, means,

In telephone system; i extend;

' iiig. from a sub ex'ohangezto an operators ntrolled from :7

position iat a main exchange; a I subscriber-"s line:- terminating the subl-exchange, means automatically responsive, when an abnormal condition develops: on said 'line for extending a connection from the line to said" position via saidr'tminlr, and meansatthesub exchange Y controlled from said position overssaid trunk forgopeningipoints in the conductors of: said 111195;, i f i l anInia telephone system, aiplurality of groups: of subscribers lines, "trunk; means responsive to an abnormal condition: on 1 any one of saidelines for connecting :cthat line to saiditrunlni means controlled oven thevtrunk for opening, thevconductorsx: of= thedefective line, and means controlled overthe trunk for determ n ng the particular, group in which thG'ClBIBCtIVE'JllILG/EIS located: V i i. i

15: In telephone systemparr ma in ex change, I plurality of; sub-enchanges, asub+ scribersi-z lines terminating, in I ma subi-eie change, a: trunk lin-xektending ithrough said subi-e-Xchanges to I said: imam: exchange, 2 a

switch in each sub-exchange, meansfoiitrans-i mitting a series of dlgit' impulses overythe trunk to operate said switchessimultaneous- 1y, means for releasing only the switch 'inxthe eirchangedesignated by, said :diigit, and means for: transmitting a seoond series of digit ime pulses over; the trunli line to" reoperate the released SWltCll-tO extend: a connecti onxtona subscribefislinew 16.x In aztelephone system herein connectieins J between two local sub-exchange subscr bersi lines r are set up and icontrolled; over the same""two conductor trunk extending; to a man: enchangenmeans for maintaining the calli g neotion with said itriunlrid'urin subscribers substation ringerin! conment Ora conne'ctioiitothe desiredica'lledsub scribefisvline, and uneans rat' the sub eirohange responsiveito ringing current extending over said trnnli from themaiirexchange foi di rectlyi connecting: the ringing: current: to the substation ringers: of both the: calling and c-alled linesw i i r i i 1%7 telepaone' systemaar main exchange, 1 a sub-exchange, a two-conductor trunln connejotingvssaid exclranges, [lurality of subscribers lines terminating in saidi'snb exchange each iadaptedfto beaconnecteditoisaid trunk, ,a'r-wloealsbattery bridge across-theme ductors of said trunk at the sub-exchang a @miaeiiseniaeacuv ffsaid conductors separating the said battery bridge from the main exchange, and means responsive to ringing c'urrent extending over said trunkfrom the main exchange for disconnecting said battery bridge and for shunting said condensers to directly connect ringing current to the called subscribers line.

18. In a telephone system, a main ex change, a sub-exchange, a two-conductor trunk connecting said exchanges, a plurality of subscribers lines terminating in said subexchange each adapted to be connected to said trunk, a local battery bridge across the conductors of said trunk at the sub-exchange, a condenser in each of said conductors separating the said battery bridge from the main exchange, means responsive to ringing current extending over said trunk from the main exchange for disconnecting said battery bridge and for shunting said condensers to directly connect ringing current to the called subscribers line, a holding circuit including only one of said conductors for maintaining a connection between a calling and a called line, and means at the main exchange for inter rupting said circuit to permit the release of the connection. 1

19; In a telephone system, a main exchange, a sub-exchange, a, two-conductor trunk connecting said exchanges, a plurality of subscribers lines terminating in said subexchange each adapted to be connected to said trunk, a local battery bridge across said conductors at the sub-exchange, an alterating current relay and a condenser bridge across said conductors at the sub-exchange, another relay in the sub-exchange having contacts for disconnecting said battery bridge and for directly connecting said conductors to the substation ringer of the called subscribers line, and contacts on said alterating current relay for controlling said other relay.

20. In a telephone system wherein subscribers lines terminating in a sub-exchange are arranged to be connected to a main ex change trunk line terminating in an operators position at the main exchange and arranged to signal the operator thereat responsive to the initiation of a call, means for maintaining the calling subscribers line in operative connection with said trunk line after the calling subscriber replaces his receiver in response to such request by the operator When calling a local subscriber, means in the subexchange controlled by vimpulses sent over said same trunk line from the operators position for connecting a desired called subscribers line to said trunk line, and means con-- trolled by the operator for signalling both the calling and called subscriber over said trunk line.

In witness whereof, I hereunto subscribe my name this 15th day of December, A. D.

FRITZ APPELIUS.

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