Automatic Machine for Testing Capacitors 

 and Resistance-Capacitance Networks 



By C. C. COLE and H. R. SHILLINGTON 



(Manuscript received May 8, 1956) 



The modern telephone system consists of a variety of electrical components 

 connected as a complex network. Each year, millions of relays, capacitors, 

 resistors, fuses, protectors, and other forms of apparatus are made for use in 

 telephone equipment for the Bell System. Each piece of apparatus must meet 

 its design requirements, if the system is to function properly. This article 

 describes an automatic machine developed hy the Western Electric Company 

 for testing paper capacitors and resistance-capacitance networks used in 

 central office switching equipment. 



INTRODUCTION 



The capacitors discussed in this article are the ordinary broad Hmit 

 units made ^^dth windings of paper and metal foil, packaged in a metal 

 case. They include both single and double units in a package, connected 

 to two, three, or four terminals. The networks consist of a capacitor of 

 this same type connected in series with a resistor. 



The testing requirements for capacitors include dielectric strength, 

 capacitance, and insulation resistance. These same tests plus impedance 

 measurements are specified for networks. In general, requirements of 

 the kind involved here could be adequately verified by statistical sam- 

 pling inspection. However, in equipment as complex as automatic tele- 

 phone switching frames, even the minor number of dielectric failures 

 that would elude a properly designed sampling inspection would result 

 in an intolerable expense in the assembly and wiring operations. While 

 engineering considerations thus called for a detailed inspection for di- 

 electric breakdown, it was recognized that detailed inspection of the 

 other electrical requirements could be obtained at no additional expense 

 for labor with automatic testing machines. 



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