A single-phase triac based AC voltage controller feeds a series RL load. The input AC supply is . The values of  and  are  and , respectively. The minimum triggering angle of the triac to obtain controllable output voltage is

Thyristor  is triggered at an angle  (in degree), and  at angle 180° + α, in each cycle of the sinusoidal input voltage. Assume both thyristors to be ideal. To control the load power over the range 0 to 2 kW, the minimum range of variation in a is:

A single-phase SCR based ac regulated is feeding power to a load consisting of  resistance and 16mH inductance. The input supply is 230V, 50Hz ac. The maximum firing angle at which the voltage across the device becomes zero all throughout and the rms value of current through SCR, under this operating condition, are

In the single phase voltage controller circuit shown on the figure, for what range of triggering angle (α), the output voltage is not controllable?

The triac circuit shown in figure controls the ac output power to the resistive load. The peak power dissipation in the load is

A single phase voltage source of magnitude  and frequency ω (rad/s) is connected to an inductance L through an anti-parallel back-to-back pair of thyristors. The forward and reverse conducting thyristors are fired at an angle of  from the positive going and negative going zero crossings of the supply voltage respectively, in each cycle.

Obtain an expression for the inductor current in each cycle for a given value of α.

The voltage drop across the thyristors, when either of them is in conclusion, may be assumed to be negligible.

Thyristor circuits that directly convert poly-phase ac voltages from one frequency to another frequency are called _________________