AUTOMATIC MACHINE FOR TESTING CAPACITORS AND NETWORKS 1 197 

 IXSULATION RESISTANCE TEST CIRCUIT OPERATION 



In general, the insulation resistance test consists of a charging period 

 and a test period. The charging of the unit inider test recjuires 10 posi- 

 tions or 30 seconds time to insure that the unit is thoroughly charged 

 before it reaches the test position. At the test position the capacitor or 

 network on test is connected to form part of a voltage divider in the 

 grid circuit of a sensitive balanced detector. This sets up relays to accept 

 or reject the unit vmder test depending on whether the unit meets the 

 limits for which the circuit was preset and calibrated. Two insulation 

 resistance circuits are rec^uired, one for each unit in a dual unit capacitor 

 or network. A calibrating circuit is provided by switch S23 and resistors 

 lUl, IU2, and R43. 



The discussion that follows is a detailed description of the sequence of 

 operation of the insulation resistance test circuit. The component desig- 

 nations are those shown on Fig. 12. The discussion is divided into two 

 headings A and B as follows: 



A . Insulation Resistance Test on Dual Unit Capacitors or Networks 



The capacitor or network on test is automatically connected in suc- 

 cession to the INITIAL CHARGE POSITION, the LONG SOAK POSITION and 



FIVE CONDITIONING POSITIONS which assures that the acceptable product 

 is thoroughly charged before it reaches the test position. The switching 

 circuits K28, K29, K30, K31 switch S18, and the temperature compen- 

 sating switch S17 are manual preset switch circuits for the particular 

 code on test. 



For the sake of simplicity, the balanced detector and the reset solenoid 

 for sensitrol relay K3-1: for test circuit No. 2 are not shown. If the insula- 

 tion resistance of the imits on test meets the limits for which the circuit 

 was calibrated and preset, the contactor on K33 and K34 both close on 

 the "A" contacts. Switch S20 is then cammed closed to apply power 

 through the "A" contacts on the sensitrol relays to energize the accept- 

 ance solenoid K36 to accept the units on test. At the close of the test, 

 capacitor discharge timing switch S22 is cammed closed, thereby closing 

 the capacitor discharge relay K32 which discharges the imits on test 

 before they are ejected as acceptable product. It may be readily observed 

 from the schematic that a unit or units defective for insulation resistance 

 will fail to close either or both of the "A" contacts on the sensitrol relays 

 K33 and K34, which leaves the acceptance solenoid circuit K3G open, 

 thereby rejecting the units tested. 



