Power Electronics Objective Questions – Set 2

Why resistor is used in Snubber circuit ?

Delay time is defined by the interval when

A thyristor string is made of a no. of SCR connected in series and parallel. The string have volume and current of 11 KV and 4 KA. The voltage and current rating of available SCRs are 1800 V and 1000 A. For a string efficiency of 90 % let the number of SCRs in series and parallel are a and b respectively. Then the value of a and b will be

What may happen high dV / dt?

During which time maximum conduction spreading take place in the thyristor during turn ON?

To meet high current demand we use SCRs in

SCRs are used in series to meet

60 thyrsistors are connected in series and parallel to form a 10 KV and 5.5 KA switch. Each thyristor is rated for 1.2 KV, 1 KA. The no. of parallel path are 6. The efficiency of the switch is

Spread time is defined as the interval during which

Maximum power loss occurs during

The latching current of GTO should be of order

4 thyristors rated 200 V in series. The operating voltage of the string is 0.600 V. Derating factor of the string is

Snubber circuit is used with SCR

During reverse recovery time

By which one of the following we can measure the reliability of a string?

Dynamic equalizing circuit is used for

Figure shows two thyristors rated 400 A sharing a load current. Current through T₂ is 180A. Current through T₁ will be

Which statement is true ?

What is used to protect a thyristor from high di / dt conditions?

Rise time is defined by the interval when

Materials used in heat sink should have

The typical time of rising time lies between

Calculate the maximum voltage that can be safely blocked by the string shown in figure, if maximum allowable leakage current is 2 mA?

Which of the following is used in heat sink?

Typical range of thyristor turn OFF time is

ON state voltage drop across SCR lie between the range

During gate recovery time

How can we protect SCR from thermal conditions ?

Which of the following is used in SCR to protect from high dV / dt?

What happen due to high di / dt?