218 



COMMERCIAL ELECTRICAL TESTING 



Complete tests on compensators consist of commercial 

 tests, heat runs, impedance, and insulation tests. Com- 

 mercial tests consist of ratio of taps, exciting current at 

 normal voltage, and insulation tests. Insulation tests 

 consist in applying high potential between windings and 

 ground for one minute, operating the compensator 

 at double potential for one minute, and also at 50 per 

 cent above normal potential for five minutes. 



Three-phase 



Motor 





Start 



Front Clip 

 Block Base 



Finish 



Start 



Y Connection 



Fig. 77. Three-Phase Compensator 



Ratio 



Connect the leads to the line terminals of the com- 

 pensator and apply about 100 volts to the lines, throwing 

 the switch on the compensator to "starting" position 

 and leaving all others in the "off" position. On the 

 three-phase compensator read the voltages between the 

 taps; the lowest voltage tap is next to the core. Standard 

 compensators for motors up to and including 17 h.p. 



