3 SCRs are connected in series. The string efficiency is 91%. SCRs 1, 2 & 3 have leakage currents 4 mA, 8 mA & 12 mA. Which SCR will block more voltage?

All the three will block equal voltage

The term used to measure the degree of utilization of SCRs connected in series & parallel is

voltage/current utilization ratio

Explore topic-wise MCQs in Power Electronics.

This section includes 4 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.

1.	SCRs with a rating of 1000 V & 200 A are available to be used in a string to handle 6 KV & 1 KV. Calculate the number of series & parallel units required in case the de-rating factor is 0.1. (Round off the fraction to the greatest & nearest integer)
A.	Series = 7, Parallel = 6
B.	Series = 6, Parallel = 7
C.	Series = 6, Parallel = 6
D.	Series = 7, Parallel = 7
Answer» B. Series = 6, Parallel = 7

Discussion

2.	Two parallel connect SCRs have same voltage drop (Vt) having rated current = 2I₁. SCR-1 carries a current of I₁=2.6 A whereas SCR-2 carries a current of I₂=1.4 A. Find the string efficiency.
A.	45 %
B.	77 %
C.	92 %
D.	84 %
Answer» C. 92 %

Discussion

3.	3 SCRs are connected in series. The string efficiency is 91%. SCRs 1, 2 & 3 have leakage currents 4 mA, 8 mA & 12 mA. Which SCR will block more voltage?
A.	SCR-1
B.	SCR-2
C.	SCR-3
D.	All the three will block equal voltage
Answer» B. SCR-2

Discussion

4.	The term used to measure the degree of utilization of SCRs connected in series & parallel is
A.	tuf
B.	string efficiency
C.	voltage/current utilization ratio
D.	rectification efficiency
Answer» C. voltage/current utilization ratio

Discussion

Explore topic-wise MCQs in Power Electronics.

SCRs with a rating of 1000 V & 200 A are available to be used in a string to handle 6 KV & 1 KV. Calculate the number of series & parallel units required in case the de-rating factor is 0.1. (Round off the fraction to the greatest & nearest integer)

Two parallel connect SCRs have same voltage drop (Vt) having rated current = 2I1. SCR-1 carries a current of I1=2.6 A whereas SCR-2 carries a current of I2=1.4 A. Find the string efficiency.

3 SCRs are connected in series. The string efficiency is 91%. SCRs 1, 2 & 3 have leakage currents 4 mA, 8 mA & 12 mA. Which SCR will block more voltage?

The term used to measure the degree of utilization of SCRs connected in series & parallel is

Two parallel connect SCRs have same voltage drop (Vt) having rated current = 2I₁. SCR-1 carries a current of I₁=2.6 A whereas SCR-2 carries a current of I₂=1.4 A. Find the string efficiency.