The function of snubber circuit connected across the SCR is to___________?

Related Mcqs:

1. Snubber circuit is used with SCR_________________?

   A. in series
   B. in parallel
   C. either series or parallel
   D. anti parallel

2. The turn-on time of an SCR with inductive load is 20 µs. The puls train frequency is 2.5 KHz with a mark/space ratio of 1/10, then SCR will___________?

   A. Turn on
   B. Not turn on
   C. Turn on if inductance is removed
   D. Turn on if pulse frequency us increased to two times

3. Why resistor is used in Snubber circuit_________________ ?

   A. To minimize the loss
   B. To minimize the charging current
   C. To minimize the discharging current
   D. All of these

4. An RC snubber network used in BJT__________?

   A. Divert the collector current during turn – off
   B. Improves the reverse bias safe operating area
   C. Dissipates a fair amount of switching power
   D. All of these

5. 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_____________?

   A. 5, 7
   B. 4, 6
   C. 7, 5
   D. 6, 4

6. ON state voltage drop across SCR lie between the range_____________?

   A. 0 – 0.5 V.
   B. 0.5 – 1 V.
   C. 1 – 1.5 V.
   D. 1.5 – 2 V.

7. The sum of all phase current in a star connected primary winding with no neutral connection is equal to___________?

   A. Phase current
   B. Three times the phase current
   C. Three times the line current
   D. Zero at all times

8. For series connected SCR’s dynamic equalising circuit consists of___________?

   A. R and C in series but with diode across C
   B. R and C in series but with diode across R
   C. Series R and diode with C across R
   D. Series R and diode with C across R

9. In a full bridge VSI, in order to avoid the short circuit across the DC bus and the undefined AC output voltage condition, the modulating technique should ensure that___________?

   A. Top switch of each leg is on at any instant
   B. Bottom switch of each leg is on at any instant
   C. Either A. or B.
   D. None of these

10. Gate circuit or triggering circuit of a thyristor is

    A. lower power circuit.
    B. high power circuit.
    C. magnetic circuit.
    D. may be low power or high power circuit