Automatic Manufacturing Testing of 

 Relay Switching Circuits 



By L. D. HANSEN 



(Manuscript received May 18, 1956) 



The large variety and quantity of shop-wired relay switching equipments 

 produced by the Western Electric Company lead to the use of comprehensive 

 and flexible manufacturing testing facilities to insure quality of product and 

 to reduce costs. An older manual type test set is briefly described and used 

 to illustrate the functions and operation of two automatic test sets designated 

 as Card-0-Matic and Tape-0-Matic respectively. 



INTRODUCTION 



Early telephone central office installations were of the manual switch- 

 board type which were relatively simple and refjuired few relay circuits 

 other than those located in switchboards themselves. Installation effort, 

 in addition to actual erection of the switchboards, equipment frames, 

 fuse boards and the like consisted largely of running and terminating the 

 central office cabling. As the telephone art grew, both with the introduc- 

 tion of the dial telephones, and carrier and repeater equipments for long 

 distance calls and the consequent need for interconnection of these 

 various types of systems, a considerable variety of relay switching cir- 

 cuits was required. 



To reduce the installation time and effort the practice of doing as 

 much circuit wiring in the factory as possible was introduced. Relay 

 switching units are now completely assembled, wired to terminal strips 

 and tested in the shop. Since these are in effect working circuits the in- 

 stallation testing effort, after the connection of office cabling, consists 

 largely of overall tests required to insure the proper functioning of the 

 entire office. 



Due to the wide variety and complexity of these units, many of which 

 have optional circuit conditions that can be supplied on order and few 

 of which have sufficient demand to justify specially designed high pro- 



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