EE8552_POWER ELECTRONICS UNIT 1_PART 2

RC snubber circuit is used to limit the rate of

• Rise of current in SCR

• Rise of voltage across SCR

• Conduction period

• All of the above

The thyristor is turned -off when the anode current falls below_____

• Forward current

• Latching current

• Holding current

• Breakover current

In a thyristor circuit, the angle of conduction is changed by changing______

• Anode voltage

• Gate current

• Forward current

• Anode current

In AC voltage regulator, TRIACS cannot be used for a

• Back emf load

• Resistive load

• R-L Load

• Inductive load

In a thyristor

• The holding current is greater than latching current

• The two current are equal

• The latching current is greater the holding current

• None of the above

In a thyristor the ratio of latching current to holding current is

• 0.5

• 1

• 2.7

• 5

In a thyristor, dv/dt protection is achieved through the use of

• L across thyristor

• RC across thyristor

• R across thyristor

• RL across thyristor

In a thyristor di/dt protection is achieved through the use of

• L in series with the thyristor

• R across thyristor

• RC across thyristor

• RL across thyristor

A resistor connected across the gate and cathode of a thyristor increase its

• Turn off time

• di/dt rating

• Noise immunity

• Holding current

Inverter converts

• DC to AC

• AC to DC

• DC to DC

• AC to AC