198 COMMERCIAL ELECTRICAL TESTING 



lower potential. Connections for this test are shown in 

 Fig. 66. 



The volts primary and volts secondary should be read 

 on the same voltmeter by using a double-throw switch. 

 Throw the switch to the primary and bring the voltage 

 up to the correct reading on the check voltmeter B. 

 Throw the switch to the secondary, bring up the voltage 

 to that noted on the check voltmeter, and read the 

 secondary voltage. Take these readings at maximum 

 "boost," neutral, and maximum lower positions. The 

 turns of the handwheel from maximum "boost" to neu- 



Fig. 66 

 Connections for Boost and Lower on Regulator 



tral and from neutral to maximum lower should be 

 counted and recorded. The induced secondary voltage 

 must be added to the primary voltage at maximum boost 

 and subtracted from it at maximum lower. 



Check the index plate on the handwheel to see if it 

 is correct ; that is, see that the voltage is boosted when the 

 index is turned in the direction indicated by "raise." 

 In addition to the boost and lower test, the induced 

 voltage of the secondary coil should be taken at maxi- 

 mum boost and maximum lower with full voltage on the 

 primary coil. This is to act as a check on the boost and 

 lower test. In taking readings for the boost and lower 

 curve, great care should be taken in obtaining points 

 near the end of the segment. About twenty points in all 

 should be taken from maximum boost to maximum lower, 

 holding the primary voltage constant and reading second- 

 ary volts at different positions of the armature. 

 Impedance 



Impedance is always measured on the secondary 

 winding, as it is impossible to force full load current 



