Manual / Guide · 1959

AE Training Bulletin 815: The Test and Verification Switch Train

Explains AE test distributors, test connectors and verification switches used to test lines and switch trains.

Author: Automatic Electric Co.
Year: 1959
Type: Manual / Guide
Credit: Telephone Collectors International (TCI) Library, telephonecollectors.info (retrieved via Internet Archive Wayback Machine)

5 u AUTOMATIC ELECTRI(1 TRAINING The TEST and VER s TELEPHONE TCH TRA ! TEST AND 1. Gl3XERu Every automatic telephone exchange i t s provided with f a c i l i t i e a f o r t e s t i n g t h e outside cable p l a n t , s u b s c r i b e r s 1 equipment, and. c e n t r a l o f f i c e equipment. A c e r t a i n amount of t h i s t e s t i n g can be done d i r e c t l y from a t e s t desk l o c a t e d i n a c e n t r a l d i a l o f f i c e , a s w i l l be explained i n this b u l l e t i n . I n a multi-off i c e exchange, t e s t i n g can be handled on a centralize& o r aon-centralized b a s i s , o r on a combined c e n t r a l i z e d and i n d i v i d u a l t e s t - d e s k b a s i s . The l a t t e r method i s the one most cornonly used, a s it expedites t h e handling of compl-aints and i n c r e a s e s t h e e f f i c i e n c y of t h e t e s t e r s and sub-station repairmen, permitting more c3conomical opsrati on. The t e s t switch t r a i n is made up of two o r three types of switches depending on whether t h e exchange is a single o f f i c e or multi-off:Lce system ged, i n t h e l a t t e r system, upon t h e number of o f f i c e s . I n a s i n g l e o f f i c e exchan,ge and i n some of the multi-office exchanges, t h e switches used are a t e s t distributorand a t e s t connector. I n other multi-of f i ce exchanges a test-distribut o r s e l e c t o r is required i n a d d i t i o n t o t h e aforementioned two types of switches. The t e s t d i s t r i b u t o r s e l e c t o r i s a switch s i m i l a r i n appearance t o an ordinary selector, except t h a t bo&h of i t s banks have double contacts. Like t h e selector, it has a dial-controlled1 v e r t i c a l motion and a n automatic r o t a r y motion. The t e s t d i s t r i b u t o r and the test c m e c t o l r are both similar i n appearance t o an ordinary connector and, l i k e t h e cannector,theyhave dial-controlled v e r t i c a l and r o t a r y motions. The t e s t d i s t r i b u t o r , however, h a s a 600-point bank. The t e s t - d i s t r i b u h r s e l e c t o r s a r e located i n t h e same off i c e a s t h e c e n t r a l i z e d t e s t desk, and a r e connected t o it by means of four--conductor trunks. The t e s t d i s t r i b u t o r s a r e connected t o t h e t e s t - d i s t r i b u t o r s e l e c t o r s by four-wire inter-of f i c e trunks, and t h e t e s t connectors, one f o r each hundred-line group, a r e connected t o t h e banks of t h e t e s t d i s t r i b u t o , r s i n t h e same o f f i c e by means of six-conductor trunks. The purpose of t h e t e s t - d i s t r i b u t o r selector is t o s e l e c t an i d l e t e s t d i s t r i b u t o r i n any one of t h e offices of t h e exchange network:; t h a t of t h e t e s t distributor, t o s e l e c t the t e s t connect o r associated with any one of the hundred-line groups i n t h e o f f i c e ; and t h a t of t h e t e s t connector, t o s e l e c t t h e l i n e t o be t e s t e d i n a p a r t i c u l a r one-hundred l i n e group. Multi- o f f i c e exchanges having o n l y a few o f f i c e s employ d i r e c t trunks from t h e t e s t desk t o t h e t e s t d i s t r i b u t o r s i n each o f f i c e , t h u s doing away with t h e t e s t - d i s t r i b u t o r s e l e c t o r . A s t h e l a t t e r system i s simpler, while s t i l l containing a l l o f the e l e m n t s of the t e s t i n g scheme, t h e l a t t e r c i r c u i t w i l l be t h e one explained herein. 2. THE TEST SWITCH T W N CIRCUIT 2.1 Impulsing t o t h e Test Distributor The c i r c u i t of the t e s t switch t r a i n i s shown i n Fig. 1. The testnmn operates the d i s t r i b u t o r key, which energizes t h e polarizing winding of r e l a y F-1 and completes a connection t o t h e t e s t - d i s t r i b u t o r . - After operating t h e d i a l key, t h e c i r c u i t between t h e t e s t desk and t h e t e s t d i s t r i b u t o r i s t r a c e d from ( - ) b a t t e r y through the winding of t h e l i n e r e l s y 4 contacts of t h e reversing relay F, n-tr l i n e , t1distributorfl key, HreleaseR key, fldialn key, d i a l , 60-ohm winding of relay F-1, 500-ohm resistance, nconnector releasen key, nB, C, 0. key, ndialn key, ndistributorw key, n+w l i n e , contact r e l a y F, winding of l i n e r e l a y G t o ( + ) b a t t e r y . F-1 does not operate a t t h i s time, as the cwrrrent i n i t s two windings a r e i n opposition. K e l ~ y s A and G c l o s e p a r a l l e l c i r c u i t s t o r e l a y B, which operates. Relays A and G r e l e a s e on each impulse from t h e d i a l , but only A is concerned with t h e impulsing path. The v e r t i c a l magnet i s operated from ( + ) b a t t e r y a t the contact of r e l a y A, contact r e l a y B, off-normal springs, winding of relay C, through t h e v e r t i c a l magnets t o ( - ) battery. A f t e r t h e l a s t impulse of t h e f i r s t s e r i e s , r e l a y C f a l l s back and t r a n s f e r s t h e impulsing c i r c u i t from t h e v e r t i c a l magnet t o the r o t a r y magnet. Each t h e r e l a y A f a l l s back, during impulsing, a c i r c u i t is closed t o r e l a y J and t o t h e rotary magnet. Relay J, operating, closes t h e c i r c u i t from pound a t B, t o r e l a y H, which operates and disconnects the f f t e s t f ll i n e s from the lltestfl wipers, so t h a t the t e s t d i s t r i b u t o r w i l l not i n t e r f e r e with t h e t e s t connectors, over t h e terminals of which i t s wipers r o t a t e . Relay J a l s o opens a p a r t of t h e incomplete c i r c u i t t o r e l a y D, s o t h a t r e l a y D w i l l not operate when H operates. Due t o i t s slow-tor e l e a s e action, r e l a y J remains operated during the impulsing and holds H operated. TEST P a l l 'IrERIFIG 2 2.2 Dialed Test Connector Busy The busy t e s t i s not made a t once, bcrt occurs when r e l a y J Tails back a t the end of t h e s e c a s e r i e s o f impulses. I n c a s e t h e d i a l e d t e s t c o n n e c t o r i s i n use, r e l a y J, on r e s t o r i n g , t r a n s f e r s t h e c i r c u i t of H, by means of makebefore-break contacts, from ( + ) b a t t e r y a t B t o ( + ) b a t t e r y on t h e E.C. wiper through t h e 250-oh winding of the busy relay E E Buy relay E operates through i t s 25%-ohm winding in serf ea with H ; opens a p a r t of t h e incomplete c i r c d t t o t h e r o t a r y magnet, so t h a t the rotary magnet w i l l not opelrste i f t h e c i r c u i t t o A i s again i n t e r r u p t e d ; opens t h e c i r c u i t t o D, so t h a t D w i l l not operate a t t h i s time; places the bwy t o n e on t h e ( + ) l i n e back t o t h e t e s t desk; and c l o s e s t h e c i r c u l t t o r e l a y F, from ground a t a make contact of E. Relay F operates and r e v e r s e s t h e c u r r e n t on t h e l i n e , o g e r a t i n g t h e polarized: relay F-1 and causing the superv i s o r y p i l o t Lamp t o glow. Thus t h e t e s t e s r e c e i v e s both a busy tone and a v i s u a l s i g n a l when t h e dialed t e s t connector is i n use. The t e s t e r i s not forced t o r e l e a s e but may hold t h e t r u n k u n t i l t h e connector becomes i d l e . 2.3 Test Connector I d l e When t h e t e s t connector becmes available, r e moval 0% ground from t h e E.G, wiper opens t h e c i r c u i t t o H and t h e 250-ohm winding of E, Rslay E, r e s t o r i n g , removes t h e busy tone :Prom t h e line, opens the c i r c u i t t o relay P, whioh causes F-1 t o r e s t o r e , extinguishing t h e p i l o t lamp; and c l o s e s t h e c i r c u i t t o D from ground a t B. Relay H, due t o i t s slug, remains operated long enough t o insure the operation of relay D, which operates and closes i t s locking c i r c u i t s o tha% it w i l l not r e s t o r e when H f a l l s back, Relay D a l s o c l o s e s t h e loop c i r c u i t t o t h e t e s t connector through the contacts of A and the noperaten wipers, s e i z i n g t h e connector. Relay H, r e s t o r i n g , connects the rftestlr l i n e s through t o t h e n t e s t a wipers. The absence of t h e busy tone and t h e v i s u a l s i g n a l inform t h e t e s t e r t h a t t h e d i a l e d connector i s now a v a i l a b l e , 2.4 Impulsing t o t h e Test Connector The l a s t two d i g i t s a r e t h e n dialed, r e l a y A r e p e a t i n g t h e impulses t o t h e t e s t coimector, Relay J, a s before, operates on each s e r i e s of impulses and c l o s e s t h e c i r c u i t t o r e l a y B e Relay J a l s o opens t h e incomplete ci1:cui.t t o F from t h e C wiper t o keep t h e cir-cuit open a f t e r t h e o p e r a t i o n of H e Relay H o p e r a t e s and d i s c o n n e c t s t h e t e s t l i n e s f r o m t h e t e s t wipers, s o t h a t t h e t e s t connector w i l l not i n t e r f e r e with t h e l i n e s aver which the wipers pass . A s before, t h e bwy t e s t is notmade the instant the wipers come t o r e s t , but wcurs when relay J of t h e t e s t d i s t r i b u t o r f a l l s back a t t h e end of +he l a s t s e r i e s of impulses. If t h e dialed l i n s is busy, relay F operates from ( + ) battery a t t h e c o n t r o l wiper of the t e s t connector, C wiper of t h e t e s t d i s t r i b u t o r , make contact of relay H ( r e l a y H, being slow t o release, remains operated temporarily a f t e r J r e l e a s e s ) , break contact of J, through t h e winding of r e l e p P t o ( -) battery, When H restores, it t r a n s f e r s t h e c i r c u i t t o r e l a y F t o another c i r c u i t from the same ground on t h e C wiper, and connects t h e t e s t l i n e s t o the t e s t wipers. The p i l o t I m p a t the t e s t desk glows, because of the operation of F and F-1, but the busy tone is not rseceivst$. The t e s t e r may e i t h e r wait l o r the l i n e t o become a s a i l a b l e o r r e l e a s e t h e connection. When t h e l i n e becomes f r e e , assuming t h e t e s t e r waits, r e l a y F r e l e a s e s , i n t u r n r e l e a s i n g F-1, and thus ex-binguishing t h e p i l o t l m g a t t h e t e s t desk. The d i a l key i s restored t o normal upon completion of t h e connection t o t h e l i n e t o be t e s t & . The t e s t d i s t r i b u t o r remains operated by t h e loop through t h e 60-ohm winding of" r e l a y F-I, 2.5 Testing The t e s t i n g c i r c u i t i s closed from t h e t e s t appwatus through the d i s t r i b u t o r key, the t e s t trunk, contacts of r e l a y H, t e s t wipers of t h e t e s t d i s t r i b u t o r , wipers of the t e s t connector t o t h e l i n e under t e s t . The ( + ) battery, which i s connected t o t h e control wiper of t h e t e s t connector through a make contact of G, causes the B.C.O.relayof t h e l i n e equipment t o operate and c l e m t h e l i n e of attachments. To make an ffinwardn t e s t through t h e l i n e equipment, t h e ttB.C.O,R key i s operated, allowing r e l a y G t o f a l l away, thus opening t h e holding c i r c u i t t o the B.C.O. r e l a y of t h e l i n e under t e s t . Relay A remains operated from ground ( 6 ) a t t h e B.C.0, key, when t h i s key is operated, i n order t o hold the t e s t d i s t r i b u t o r operated. The B.C.0, relay r e s t o r e s t o normal and connects t h e l i n e r e l a y of t h e l i n e equipment across t h e t e s t l i n e s . The l i n e equipment operates and connects t h e l i n s t o a f i r s t selector. To t e s t additional l i n e s i n the same one-hundred gmup, the t e s t e r momentarily -operates the #conn e c t o r releasen key, causinp r e l a y A t o f a l l back r e l e a s i n g t h e t e s t connector, but not t h e d i s t r i b u t o r , Relay G i s held from ( -) b a t t e r y a t t h e connector r e l e a s e key i n o r d e r t o hold the t e s t distributor. The t e s t e r then diale the l a s t two d i g i t s of the next desired l i n e , When t h e r e i s more than one l i n e on t h e same connector bevel t o be tested, the t e s t connector need not be r e l e a s e d , but only an addition& d i g i t dialed t o r o t a t e the t e s t connector wipera t o t h e next l i n e . This f e a t u r e i s g e n e r a l l y employed when r o u t i n e t e s t s a r e made on all telephone l i n e s . TEST AND VERIFICATION SWITCH TRAIN 3. TTERIFICATION SERVICE Aside from t h e u s e o f t h e t e s t swi.tch t r a i n f o r t e s t i n g purposes, it can a l s o be u t i l i z e d by c e r t a i n operators f o r v e r i f i c a t i o n and t o l l o f f e r i n g services. I n these cases, a separate group of t e s t d i s t r i b u t o r s o r t e s t - d i s t r i b u t o r s e l e c t o r s , having access t o t h e same t e s t connectors used by the t e s t e r , a r e u s u a U y furnished f o r t h e operators' exclusive use. ?hese t e s t d i s t r i b u t o r s o r s e l e c t o r s a r e generally termed "verification switches.fr By means of .this a t e s t and v e r i f i c a t i o n switch traintf it i s possible f o r an operator a t a position on which the veriterminate, t o d i a l a busy t e l e f i c a t i o n truphone number and l i s t e n i n on the Line t o verify whether it i s busy, o r t o inform one of t h e talking parties that a t o l l c a l l i s being held, awaiting t h e terminat i o n of t h e conversation. The t o l l c a l l , however, i s completed over t h e r e g u l a r channel provided f o r t h e purpose and not over the t e s t and v e r i f i c a t i o n switch train. 3.1 Verification Switch C i r c u i t When used f o r v e r i f i c a t i o n s e r v i c e , t h e t e s t d i s t r i b u t o r has t h e l i n e and t e s t wires cannected by 2-FT.F, condensers, a s shown dotted t o t h e l e f t i n Pig. 1. These condensers f u r n i s h t h e c i r c u i t by means of which t h e v e r i f i c a t i o n operator 1 s telephone ' i s connected t o t h e t e s t l i n e s and hence t o t h e d i a l e d l i n e . Reprinled March 1959 Printed in U.S.A. by John S. Swift Co., Inc. 3-59