AUTOMATIC TESTING OF RELAY SWITCHING CIRCUITS 



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Fig. 1 — Manual wired unit test set. 



requires that he analyze the circuit conditions and locate the cause of 

 the trouble. Usually a circuit fault must be corrected before testing can 

 proceed. 



Fig. 2 shows a small portion of a simplified circuit test arrangement 

 for such a manual test set. In this illustration a single key, when operated, 

 supplies battery and ground potentials to the winding of a relay in the 

 circuit under test. Assumption is made that the three relay contact 

 terminals are wired directly to the relay unit terminal strip so that 



