To meet high current demand we use SCRs in______________?

A. Series connection.
B. Parallel connection.
C. Anti parallel connection.
D. Both b and c.

Anode current in an SCR consists of____________?

A. Holes only
B. Electrons only
C. Either electron or holes
D. Both electron and holes

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

A. String efficient
B. Reliability factor
C. Factor of safety
D. Derating factor

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

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

Maximum di / dt in a SCR is________?

A. Directly proportional to vm of supply voltage
B. Inversely proportional to vm of supply voltage
C. Inversely proportional to l in the circuit
D. Both a and c

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______________________?

A. 76.3 %
B. 91.6 %
C. 83.3 %
D. 90.9 %

A string of n parallel SCRs is operated at 72 KA, the rating of each SCR is 1 KA. If derating factor of the string is 0.1. value of n will be___________?

A. 60
B. 70
C. 80
D. 90

Dynamic equalizing circuit is used for________________?

A. Equal division of voltage across each thyristor
B. Equal division of current through each thyristor in parallel
C. Equal division of voltage across each thyristor in parallel
D. Equal division of current through each thyristor in series

Unipolar modulation is generally used in____________?

A. Ac – ac converters
B. Ac – dc converters
C. Dc – ac converters
D. Dc – dc converters