APPENDIX B 

 FUNCTION OF WAVE GENERATOR COMPONENTS 



Section IV gives the major components of the SPTB portable wave gen- 

 erators and the major function of each. This appendix describes the 

 procedure for starting the generators and component interaction. 



1. The main a.c. drive motor was started. This caused rotation of 

 some of the differential gears, including those connected to the two d.c. 

 motor armatures. Since these gears were rotated at the same speed, there 

 was no output from the differential at this point. 



2. The d.c. rectifier-amplifier was activated by slowly applying 

 voltage through a variable transformer or variac. As this was done, the 

 generator crank arms were observed to determine that the drive shaft of 

 the generator remained stationary, except for perhaps a quarter turn to 

 seek the "lock-in" position. If the shaft rotated more than a quarter 

 turn, the variac was turned down until the rotation stopped. The two 

 thyratron tubes in the amplifier were then balanced by the balancing poten- 

 tiometer on top of the amplifier chassis. This was done by again raising 

 the voltage while turning the potentiometer clockwise a sufficient amount 

 to prevent rotation of the generator crankshaft. Expertise in this adjust- 

 ment was achieved largely by experience. The procedure was continued 

 until full voltage was reached. 



3. The varidrive was started. This drive had been previously adjusted 

 to rotate at a speed which would cause the generator bulkhead to produce 

 the desired wave period. The speed reference shaft, which was connected 



to the varidrive, and the generator crankshaft were compelled by electro- 

 servo action to rotate at fixed ratios determined by the gear selector 

 box in the wave generator. The rotation of the master resolver, connected 

 to the speed reference shaft, initiated a sequence of electrical events 

 between the two resolvers and the d.c. amplifier, and caused the two d.c. 

 motors to rotate at different speeds. Thus, differential output began, 

 imparting motion through the drive train to the crankshaft and bulkhead. 

 At the same instant that output rotation began, both the slave resolver 

 and d.c. tachometer became activated. As the varidrive and master resolver 

 accelerated, imbalance between the resolvers and the d.c. amplifier con- 

 tinued, and the speed difference of the two d.c. motors increased propor- 

 tionally with increased varidrive speed until the two resolvers and the 

 amplifier reached a steady-state or in-phase relationship. Provided the 

 generator load capability was not exceeded, the generator would continue 

 to operate "in step" with the control drive mechanism. To assist in 

 maintaining a steady-state condition under varying bulkhead loading, the 

 tachometer supplied a d.c. voltage to the thyratron tubes of the amplifier 

 which caused the tubes to supply more or less power as required. A "phase- 

 shift" signal from a "leading" or "lagging" resolver had the same effect- 

 on the tubes, but in a slightly different manner. 



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