INTKHTOLL TRUNK COXCENTRATINO IXilll'.M KXT 



315 



associated with that iiicoiniiiji; ti'imk is relea.sod a(l\'aiiciii<i; the sclcclioii 

 path to the next incoming trunk to he served. When the last incoming 

 trunk within the gate has been selected the kxd ichiy r(>k^ases, signifying 

 the end of selections in that group and enahHng the controUer to advance 

 to the next group, 'ilie rek^ase of the kxd relay releases the units g.vte 

 relay restoring the operating patii foi' all u relays. 



Select Magnet Operaling Circuit 



The select magnet operating circuit is shown in V'\g. 7. Two of these 

 circuits are pro\-ided in accordance with the philosophy that no single 

 trouble should block the concentrator. One of these circuits is associated 

 with each direction of selection. When the units gate relay operates 

 as described in the preceding paragraph, battery is connected through 

 the windings of the xs and ss relays, chains on the group relays (gp-), 

 chains on the ot relays, to the select magnet associated with the lowest 



INCOMING 

 TRUNKS 



r 



X 



LU2 



N OR O 



■^lll 



1 



~ A 

 iR O 



ODD OR EVEN UNITS 

 RELAYS 



HT1 

 OR 

 HT2 



r 



El 

 OR 

 E2 



OR 



LU2 CC1 

 L OR E OR F 



y^ — I — w\^ — III 



*LOCK> UNITS 

 RELAYS 



1 



X 



UG1 

 Et OR 



OR UG2 

 E2 



El 

 OR 

 E2 



UNITS GATES 

 RELAYS 



E OR F 



■AAA lllh 



1 



*LOCK UNITS RELAY DESIGNATIONS: 

 --1 ARE INCOMING LOW TO HIGH 

 - -2 HIGH TO LOW 



Fig. 6 — Units, unit gates and lock unit relays 



