Power Electronics Questions

• The number of gates in an SCR is
• 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.
• A thyristor has maximum allowable junction temperature of 110° C and the ambient temperature is 40°C, If the maximum internal power dissipation is 50 W, the thermal resistance is
• 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
• To protect an SCR against high di/dt we connect
• A single phase half wave regulator uses
• 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
• In a 3 phase semiconverter, the dc output voltage for a certain firing angle is 50% of the maximum possible value. The firing angle is
• A single phase half wave converter is used to charge a battery of 50 V. The thyristor is continuously fired by dc signal. Input voltage is v = Vm sin ωt. The thyristor will conduct
• Assertion (A): A GTO circuit is more compact than SCR circuit Reason (R): A GTO can be turned off by negative gate pulse.
• In a stud mounted SCR, the stud is
• McMurray Bedford full bridge inverter uses
• In a single phase full wave regulator feeding an R-L load, the power factor angle of load is θ. The range of control of firing angle a is
• If a step down chopper is fed by a dc voltage V with Ton and Toff are on and off periods then is
• In a thyristor the gate lead is connected to the n layer near the p layer to which anode is connected.
• The characteristics of which device has peak point and valley point
• The two-transistor model of a thyristor consists of two transistors :
• Which of these commutation methods uses an external pulse for commutation?
• In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is
• Assertion (A): The turn on time of SCR is about 1 to 4 ms. Reason (R): The turn off time of SCR is about 10 to 300 ms.