Power Electronics Objective Questions – Set 1

In forward blocking mode of a thyristor

The typical value of SCR for modern alternator is

CB used for over current protection of thyristor operates when the fault current is

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

Thyristor can be protected from over voltages by using

Switching frequency of SITH is

Which triggering is the most reliable?

After proper turn on of thyristor

A step up chopper has input voltage 110 V and output voltage 150 V. The value of duty cycle is

In reverse blocking mode of a thyristor

Which statement is true for latching current ?

SCR will be turned off when anode current is

An SCR has half cycle surge current rating of 3000 A for 50 Hz supply. One cycle surge current will be

In a P₁N₁P₂N2 thyristor which layer is less doped ?

An SCR is considered to be a semi controlled device because

Example of a voltage clamping device

The function of snubber circuit connected across the SCR is to

The latching current of SCR is 20 mA. Its holding current will be

Under over voltage condition impedance offered by the voltage clamping device is

The latching current of GTO should be of order

Leakage current flows through the thyristor in

If holding current of a thyristor is 2 mA then latching current should be

When a large surge current of very short duration flows through a thyristor then which one of the following device will operate to protect the thyristor ?

A single phase full bridge inverter can operate in load commutation mode in case load consists of

Under normal operating condition voltage clamping device offers impedance of

What is used to protect the SCR from over current ?

Gate circuit or triggering circuit of a thyristor is

Practical way of obtaining static voltage equalization in series connected SCRs is by the use of

A single phase full bridge inverter can operated in load commutation mode in case load consist of

Light triggering mainly used in