1180 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 

 DESIGN CONSIDERATIONS 



In the development of this machine, the designer was faced with the 

 same problems that obtain in the conception and design of any unit of 

 complex equipment. These included the economic feasibility, reliability, 

 simplicity, and versatility of such a machine. 



Economic Feasihilitij 



This can be determined by comparing the cost of performing the opera- 

 tions to be made by the proposed machine with the cost by alternative 

 methods. Estimates indicated that the cost of the machines could be re- 

 covered within two years by the saving in labor that would be effected. 



Reliability 



Reliability has two connotations, (1) freedom from interruptions of 

 production because of mechanical or electrical failure and (2) consistent 

 reproducible performance. A rugged mechanical design combined with 

 the use of the most reliable electrical components available is necessary. 

 In addition, safeguards are required to protect the equipment from me- 

 chanical or electrical damage. To achieve consistent reproducible per- 

 formance, it is important that testing circuits of adequate stability be 

 used. Besides, it was recognized that each circuit should be so ar- 

 ranged that in case of a circuit failure, there would be immediate and 

 positive action by the machine to prevent acceptance of defective prod- 

 uct. All circuits are designed to provide positive acceptance. This means 

 that the machine must take action to accept each item of product at 

 each test position. In the case of the dielectric strength tests, a self- 

 checking feature is included. 



Fig. 1 — Types of capacitors and networks tested. 



