Problems

Author: E.E. Kimberly

	Problem	Answer
1	A 60-cycle, 120/60-volt phase-shifter is to be built by using a center-tapped transformer and an inductance coil of 3 henrys and 300 ohms resistance. Calculate the magnitude of the control voltage and its phase angle with respect to the secondary terminal voltage if the series resistor of the phase-shifter has a resistance of 2000 ohms. Calculate the phase angle for alternate positions of the phase-shifter elements.
2	The accompanying circuit is set up and found to be correct. On which end of the transformer primary OF should the dot be placed? If the load inductance L is large enough to insure constant tube current during the conduction period, what is the average load current for a firing angle of 30 degrees? The plate-to-plate voltage is 282.8 volts rms and RL is 20 ohms.