Q. Assertion (A): A cycloconverter may be line commutated or forced commutated

Reason (R): A step up cycloconverter requires forced commutation.

View solution

Q. When thyristors are connected in series and parallel, it may be necessary to have :

View solution

Q. A single phase half wave regulator uses

View solution

Q. A Shockley diode can be used

View solution

Q. An SCR has a turn on time of 4 μs. The gate pulse should have a duration of about

View solution

Q. In a multiphase chopper, the different choppers operate in

View solution

Q. In a dual converter both converters work as rectifiers.

View solution

Q. A single phase full wave regulator feeds R-L load. The best gating signal is

View solution

Q. A 3 phase induction motor is fed by a 3 phase ac regulator to change the stator voltage. The variation in speed will be more if

View solution

Q. A cycloconverter cannot give a frequency higher than input frequency.

View solution

Q. A thyristor has internal power dissipation of 40W and is operated at an ambient temperature of 20°C. If thermal resistance is 1.6° C/W, the junction temperature is

View solution

Q. In a single phase dual converter, α1, and α2 are firing angles of the two converters. Then

View solution

Q. The number of gates in an SCR is

View solution

Q. The waveshape of output voltage of half bridge inverter is

View solution

Q. A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the speed is 1440 rpm. At 25 Hz, the speed is likely to be

View solution

Q. The gate current required to turn on an SCR is

View solution

Q. Assertion (A): A high dv/dt may cause triggering of a thyristor.

Reason (R): A high dv/dt results in charging current in the thyristor.

View solution

Q. Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V.

Reason (R): When an SCR is conducting, the junction temperature is about 200°C.

View solution

Q. When the core of a saturable reactor is saturated, the inductance is high.

View solution

Q. In controlled heating circuits, thyristors act as

View solution