Question: In forward blocking mode of a thyristor________?

• 1. junction J2 is in reverse bias and J1, J3 is in forward bias.
• 2. junction J3 is in forward bias and J1, J2 is in reverse bias.
• 3. Junction J1, J3 is in reverse bias and J2 is in forward bias.
• 4. Junction J1 and J2 is in forward bias and J3 is in reverse bias.

Question: In reverse blocking mode of a thyristor______?

• 1. junction J2 is in reverse bias and J1, J3 is in forward bias.
• 2. junction J3 is in forward bias and J1, J2 in reverse bias.
• 3. junction J1, J3 is in reverse bias and J2 is in forward bias.
• 4. junction J1 and J2 is in forward bias and J3 is in reverse bias.

Question: If holding current of a thyristor is 2 mA then latching current should be_____?

• 1. 0.01 A
• 2. 0.002 A
• 3. 0.009 A
• 4. 0.004 A

Question: A step up chopper has input voltage 110 V and output voltage 150 V. The value of duty cycle is_____?

• 1. 0.32
• 2. 0.67
• 3. 0.45
• 4. 0.27

Question: A single phase one pulse controlled circuit has a resistance R and counter emf E load 400 sin(314 t) as the source voltage. For a load counter emf of 200 V, the range of firing angle control is _____?

• 1. 30° to 150°.
• 2. 30° to 180°.
• 3. 60° to 120°.
• 4. 60° to 180°.

Question: A single phase full bridge inverter can operated in load commutation mode in case load consist of______?

• 1. RL.
• 2. RLC underdamped.
• 3. RLC overdamped.
• 4. RLC critically damped

Question: An SCR is considered to be a semi controlled device because_______?

• 1. it can be turned OFF but not ON with a gate pulse.
• 2. it conducts only during one half cycle of an alternating current wave.
• 3. it can be turned ON but not OFF with a gate pulse.
• 4. it can be turned ON only during one half cycle of an AC

Question: The typical value of SCR for modern alternator is____________?

• 1. 1.5.
• 2. 0.5.
• 3. 1.0.
• 4. 1.2.

Question: An SCR has half cycle surge current rating of 3000 A for 50 Hz supply. One cycle surge current will be_____?

• 1. 1500 A
• 2. 6000 A
• 3. 2121.32 A
• 4. 4242.64 A

Question: A Triac has three terminals viz ___________?

• 1. Drain, source, gate
• 2. Two main terminal and a gate terminal
• 3. Cathode, anode, gate
• 4. None of the above