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Full text of "BT-502173 Selector Circuit - Incoming from Spl. "A" Switchboard with No Test Keys"

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Western Electric Co., Incorporated, ( 6 P ages , Page 1 ) 

Equipment Engineering Branch, Hawthorne. Ieeu e 3 BT 602173 

October 5, 1923. (*) 


This 2. of 0. Sheet was prepared from Xeeue 14 of t-502173. 

m op o.g ox gui m 

SELECTOR CIRCUIT 

Incoming from Spl. "4" Switchboard With Ho Test Keys At "A" Position* Panel 
Machine Switching System. 

J22Q9&SSEBB. 

1. PURPOSE OP CIRCUIT 

This circuit is used to establish connections for calls Incoming from 
an "A" switchboard in a full mechanioal office* It is used by the sero 
operator in verifying persistent busy reports and re-establishing cut-off 
connections* 

2. WORK I EG LIMITS 

Hone* 

OPSRATIOK 

3. PRINCIPAL PUHOTIOHS 

This circuit selects an idle sender and establishes connections between 
the "A" operator's cord circuit and a final selector# Its principal 
functions are as follows: 

3.1 Selection of idle sender and proper idle final seleotor, repeat** 

ing pulses from final during final selection and dismissing sender. at 

end of selection. 

3.2 Establishing the talking connection* 

3*3 Returning to normal. 

4. COKHECTIHS CIRCUITS 

This oirouit connects with an intercepting and sero operator's cord 
circuit, an incoming trunk sender and a final selector. 

BZS CaiPTIOH OF 0PERATI0H 

5. SEKPERHIKTISS 


When the sero operator inserts the plug of a cord in the outgoing Jack, 
the (SL) relay operates over the sleeve thru its winding in series. The 


( 6 Pages, Page 2 } 
Iseae^BT^glZS 
October 5. 1923* Ill 


ISL) relay operated, lights the 2-J busy lamps, which remain lighted until 
the circuit returns to normal* The (PLS) relay also operates over the tip 
and ring of the cord* The (PLS) relay operated, operates the (BEL) relay 
which in turn operates the (L) relay thru its secondary (800 ohm) winding* 
The (L) relay operated, locks thru its primary (1200 ohm) winding to 
ground on cam I and operates the R magnet, advancing the switch to posi- 
tion 2. As the switch enters position 1 3/4, the (L) relay locks thru 
its primary winding to ground in the associated sender circuit over the 
test lead (TST) if the selector is on a busy sender and the (?) relay 
operates, opening the operating circuit for the (L) relay* The (P) re- 
lay operated, locks to ground on the armature of the (REL) relay and ope- 
rates the sender selector stepping magnet (SEL.STP), starting the selec- 
tor hunting for an idle sender* When an idle sender is found the (L) re- 
lay releases as there is now no ground on the test lead (TST)* The (L) 
relay released, puts ground on the TST lead making it busy to other hunt- 
ing selectors and operates the R magnet, advancing the sequence switch to 
position 3* In positions 2 3/4 to 11, the sender is made busy by ground 
on the armature of the (P) relay* When the sequence switch enters posi- 
tion 3, the (Cl) relay operates* The (Cl) relay operated connects the 1, 
BBS, FT, TR and Cl leads thru to the sender* 

6. TRANSFERRING THOU SATO 3 REGISTRATION 

While the selector is hunting for an idle sender, the sero operator 
may dial the thousands digit in which case the (PLS) relay releases and 
reoperates in synchronism with the impulses sent out by the dialo The 
(REL) relay being a slow release relay, remains operated, causing the 
TH-STP magnet to operate and release with each impulse from the dial thus 
setting up the thousands digit on the TH register* The (ADV) relay ope- 
rates and being slow release relay remains operated while the impulses 
are being sent out by the dial* Each time the (RL3) relay releasea, the 
(B) relay operates thru the break contacts of the TH-STP magnet* The (B) 
relay operated, (a) connects ground to the (REL) relay thus preventing it 
from momentarily releasing during dialing lb) connects ground to the TH- 
STP magnet thus insuring its operation in case the impulses from the (?LS) 
relay are not of sufficient duration* The (B) relay remains operated until 
the TH-STP magnet has operated, at which time it releases* The (ACV) re- 
lay operatad, short circuits the inductive winding of the (TR) relay, pre- 
venting it from operating as the TH-2 brush steps off normal, Aftar the 
digit has been dialed the (APV) relay releases, allowing the (TR) relay 
to operate. The (TR) relay operated, (a) transfers the impulse lead 
from the TH-STP magnet to the I lead of the sender (b) connects battery 
to the TH-4 TH-5 and TH-6 registers which set up the register relays in 
the sender over leads REG, FT and FR, as determined by the setting of ' 
the TH register* 


(_6 Pages, Pag* 3 ) 

I s su e 3 B T 5Q2173 
October 5. 1923, (*) 


flSUga aamw '» «•»» * eoseepee**d* 

' *f* ‘O ftorx* .,*rtW ed? 

The succeeding digits registration is set up on registers in the send- 
er« As soon as the first i!spulses of the hundreds digit is dialed, the 
sender functions and oonnects ground to lead Cl, operating the (CH) 
relay* The ( Cl— 1 ) relay operated, (a) holds the (TR) relay operated to 
ground on the Cl lead (b) disconnects the battery used in thousands re- 
gistration from the TH-4, TH-5 and TH-6 registers le) operates the TH-3TP 
magnet thru the TH-1 brush and off-normal terminal under control of its 
break contact stepping the register to normal (d) operates the (CI-2) re- 
lay* The (CI-2) relay operated, disconnects the RES, FT and FS leads 
from the ares of the TH register and connects the Pf and FR leads for 
brush selection and the BEG lead for registration of the succeeding digits « 


then the FT and FR leads are closed thru to the sender, the (L) re- 
lay operates in a circuit from battery through its primary winding cam F, 
(CI-2) relay operated, brush 4, orer lead FT, thru the sender, back over 
lead FR, brush 5, (CI-2) relay operated, to ground on cam I* The (L) 
relay operated locks orer cam £ and the fundamental circuit, advances 
the sequence switch to position 4, and operates the UP magnet* As the 
selector mores upward, ground from the A commutator is Intermittently 
connected to the FT lead, causing the stepping relay in the sender to 
release and re-operate until the proper brush has been selected* bhen 
sufficient impulses hare been sent back to satisfy the sender, the fund- 
amental elrcult is opened in the sender, releasing the (L) relay. The 
(L) relay released, releases the UP magnet stopping the upward movement 
of the selector and advances the sequence switch to position 5, With the 
sequence switch in position 5, the trip magnet (TV) operates* 


After hundreds registration has taken place in the sender and with 
the sequence switch in position 5, the fundamental circuit Is again closed 
over leads FT and FR operating the (L) relay* The (L) relay operated (a) 
locks thru cam N and orer the fundamental elroult (b) operates the UP 
magnet for group selection. The trip magnet (TI T ) being operated in posi- 
tion 5 to 7 causes the previously selected set of brushes to trip as the 
selector mores upward. Ground is intermittently connected to the FT 
lead by the B cosnratator, causing the stepping relay to release and re- 
operate until the proper group has been selected. ’.Then sufficient im- 
pulses hare been sent back to satisfy the sender, the fundamental circuit 
is opened, releasing the (L) relay. The (L) relay released, releases the 
UP magnet thus stopping the brushes at the selected group and advances 
the sequence to position 7* The (L) relay re-operates in position ? thru 
its secondary winding to ground on cam M and advances the sequence switch 
to position 8* Should the first trunk of the selected group be idle, as 


_Pages, Pag* 4 } 


the* sequence awiteh enters position 8, the (L) relay releases but should 
the first, trunk of the group be busy, the (L) relay locks thru its primary 
winding to ground on the sleeve of the busy trunk* 


The (L) rt-lsy held operated in position 8, operates the UP magnet* 
causing the selector to travel upward* The (L) relay is held operated 
between terminals thru its secondary winding to ground on the C commu- 
tator* * hen an idle trunk is found* the (L) relay releases there is 
no ground on the sleeve terminal * The (L) relay released, releases the 
UP magnet* stopping the brushes on the selected trunk terminals and 
advances the sequence switch to position 9. The (L) relay released 
ground the sleeve of the trunk making it busy to other hunting selec- 
tors* in position 8 3/4 to 16 the trunk is made busy by ground on 
cam I* 


Vlth the sequence switch in position 9* ths (L) relay operates thru 
its primary winding to ground on cam I* The (L) relay operated, locks 
over the ring to ground in the final selector and advances the sequence 
switch to position 10, In position 10 the tip side of the fundamental 
oirouit is closed to ths tip terminal of the selected final trunk for 
selection beyond* 


12. TAUriKfl 


Vvhan the selection beyond has been completed, ground 5- removed from 
the ring in the final, releasing the((L) relay* The (L) relay released, 
advances the sequence switch to position 11, the A cam advancing it to 
position 16 thereby connecting the tip and ring thru to the cord circuit 
for talking* fith the sequence switch in positions 11 to 18, the high 
resistance winding of ths (SL) relay is short circuited* thus operating 
a marginal relay in the cord circuit which connects talking battepy to 
the tip and ring* 


tthen the sequence switch leaves position 10* the (PLS) relay re- 
leases , releasing in turn the (REL) , (P), (Cl)* (CI*1 )*»t£X^&) ;aat-(TH) 

relays* The sender is now disconnected from this oireuit* 


When the plug of the sero cord is removed from ths Jack, the (SL) 
relay releases* Ths (SL) relay released, advances the P. switch to 


( 6 p ages. Page 5} 

Issue 3 BT 502173 


position 18* In position 18, the down (p) magnet operates, returning 
the selector brushes to normal* fthen the brushes reach the bottom of the 
frame, ground on the Y commutator advances the sequenoe switch to nor- 
mal* 

15, OVERFLOW 

Should all the trunks in a group be busy, the selector while trunk 
hunting (in position 8) goes to the top of the group and rests on the 
overflow terminals. As the sleeve of the overflow terminals is not 
grounded, the (L) relay releases, releasing the OP magnet and advancing 
the switch to position 9, Ground on the Z commutator advances the 
sequence ewitoh to position 12, the A cam advancing it to position 16, 

In position 16, the Z commutator advances the switch to position 17, 

In position 17, the #160 or f 149 interrupter and 500 ohm resistance 
are connected across the tip and ring thereby flashing the supervisory 
lamp in the cord circuit as an Indication that all the trunks in the 
group are busy. When the plug of the cord is withdrawn from the jack, . 
the (SL) relay releases and advances the sequenoe switch to position 16. 
From this point on, the switch and selector are returned to normal aa 
described in paragraph 14. 

Should the selector travel to the top of the frame during selection, 
ground on the X connutator advances the switch to position 10. As the 
ring is not connected thru to a final the (L) relay releases and ad- 
vances the switch to position 11, ground on the X' comutator advancing 
it to position 17. In position 17, the supervisory lamp in the cord 
circuit flashes and the circuit returns to normal when the plug of the 
cord is withdrawn from the jack as described under paragraph 15. 


'A 4 ti' 


If the operator desires to establish a connection with a busy line, 
the 69-A nmltiple key is depressed, operating the (NT) relay. The (NT) 
relay operated, (a) locks in position 1 3/4 to 11, (b) in position 10 
connects the secondary winding of the (Li relay and the 500 ohm resist- 
ance (F) in parallel with the primary winding of the (L) relay which is 
locked over the ring to ground thru a marginal relay in the final. The 
marginal relay (P.B.X. ) in the final, due to the low resistance of the 
parallel combination, operates and causes the final to omit the busy 
test. When ground is removed from the ring in the final, the (L) re- 
lay releases, advancing the sequence switch and causing the circuit to 
function as in paragraph 12. If "No Test" Feature is not used omit 
paragraph 17. 



t 6 P ages. Page 6 ) 
Issu e 3 3 f 502173 
October 5. 1925. 1*) _ 


18. 




TIPS BEJOEB CALL IS OQIPMTSg - 


Should the plug of the cord be withdrawn from the jack In any posi- 
tion from 3 to 17 of the sequence switch, the (SL) relay releases, ad- 
vancing the switch to position 18, the switch and Selector being restored 
to normal as described under paragraph 14. 



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CHK’D. BY: J.I. 



EKGt J • C • Pi 
January 26, 1925 
GO 


APP’D: H. L. MOYNES 
E.E.C. 




(10 Pages] Page #81 
Issue I - BT-502173< 
January 20, 1922. 


THE IEAIHU5T 


SHOWN BELOW ARE FOR MAINTENANCE USE ONLY . 


178-AD 

(ADV) 


17 8 -AH 
(REL) 


E530 

(CI-1) 

(NT) 


1533 

(L) 

Inner 

w*3g. 

(1200 

ohms) 


OPERATE 


NON-OPERATE 


RELEASE 


Special requirements to insure slow release. 


After a soak of 
approximate ly » 
.900 amp. 

Readtj . .107 amp. 
Test .113 amp. 
W.C.C. .640 amp. 
Hold: 

W. C.C..371 amp. 


(On open circuit) 


NOTE: To prevent chattering, the "make- 
before-break" spring combination 
of this relay shall be so adjust- 
ed that the spring which normal- 
ly makes on the back contact, will 
give the greatest possible contact 
pressure against the back contact. 


Special requirements to insure slow release. 

Readj. .018 amp. Readj 
Test .019 amp. Test 
W.C.C. .041 amp. 


.001 amp. 
.0009 amp. 


NOTE: 


To prevent chattering, the "make- 
before-break" spring combination 
of this relay shall be so adjust- 
ed that the spring which normal- 
ly makes on the back contact, will 
give the greatest possible contact 
pressure against the back contact. 


Readj. .013 amp. 
Test .017 amp. 
W.C.C. .021 amp. 


Readj • .002 amp. 
Test .001 amp. 


Special require manta to insure fast operation. 
Readj . .017 amp. Readj. .012 amp. 

Test .0178 amp. Test .0114 amp. 

W.C.C. .018 amp® 




(10 Pages) Page #9. 
Issue 1 - BT-502173. 
•January 20, 1922, 



OPERATE E0N-0PERAT E RELEASE 


Test .045 amp, 

W.C.C. .053 amp. 

NOTE: Relay to be equipped, with special armature stop 
(piece part 163914) unless an El relay cover is 
furnished • 


Outer 
Wdg. 
(800 
ohms) . 


Special Requirements to insure fast operation. 
Readj. ,0145 amp. Readj . .013 amp. 

Test .015 crap. Test .0125 amp. 

W.C «C • .026 amp. 


Outer Test ,020 amp. 

wdg. 

(500 ohms) . 

EB28 Special Requirements to insure fast operation. 

(B) Readj. .0095 amp. Readj. .0065 amp. 

Test .010 amp. Test .006 amp. 

W.C.C. .075 amp. 

(Armature travel .015 ,, J . 


E827 

(PIS) 

Inner 

Wdg. 

(500 

Ohms) • 


E1173 

Readj . .021 

amp. 

Readj . 

•012 amp. 

(CI-2) 

Test .025 

amp. 

Test 

.011 amp. 


W.C.O. .029 

amp. 



E1205 

Readj. .015 

amp. 

Readj. 

.010 amp. 

(TR) 

Test .018 

amp. 

Test 

.0095 amp, 

Inner 

W.C.C. .021 

amp. 



wdg. 





E1359 

Readj. .017 

amp. 



(P). 

Test .023 

amp. 




W.C.C. .029 

amp. 




Readj. .002 amp. 
Test .0019 amp. 


NOTE: To prevent chattering, the "make- 
bef ore-break" spring combination 
of this relay shall be so adjust- 
ed that the spring which normal- 
ly makes on The back contact will 
give the greatest possible contact 
pressure against the back contact. 




I 



(10 Pages) Page *10. 
Issue 1 - BT-502173. 
January 20, 1922. 



CIRCUIT RETIREMENTS 

THE ADJUST REQUIREMENTS SHOWN BELOW ARE FOR MAINTENANCE USE ONLT 


OPER^Ta 


NON- OPERATE 


RELEASE 



E1370 

Readj . .027 amp. 

Eeadj . 

(Cl) 

Test .035 amp. 

W.C.C. .043 amp. 

Test 

El 439 

Test requirement of 

inner winding is proportional 

(SL) 

to test requirements 

of windings in series. 

Inner 

Read.j . .074 amp. 

Read,} . .050 amp. 

wag. 

Test .095 amp. 

Test .0475 amp. 

(34 

Hold: 

. 

ohms) . 

W.C.C. .129 amp. 


V/ags , 

Test .027 amp. 


in series 
aiding . 

W.C.C. .052 amp. 



.003 amp, 
.0015 amp. 



ENG » — T?I:ML. CmC'D.— ACIH:C7/P APPROVED - C.L. SLUYTER, G.JI.L. 

2/2G/22.