Electrical Engineering Mcqs Practice Test

Question 1

If a shunt motor is started with its field winding open then?

Accepted Answer

C. It will rotate at dangerously high speed

Question 2

A rectifier with an external low pass filter is an example of______________?

Accepted Answer

B. Direct switch matrix circuits

Question 3

What is the advantage of HRC fuses over Rewirable fuses?

Accepted Answer

D. All of the above

Question 4

The power demand can be estimated approximately by___________?

Accepted Answer

C. Statistical method

Question 5

4 thyristors rated 200 V in series. The operating voltage of the string is 600 V. Derating factor of the string is_____________________?

Accepted Answer

D. 0.25

Question 6

Unipolar modulation is generally used in____________?

Accepted Answer

D. DC – DC converters

Question 7

Dynamic equalizing circuit is used for________________?

Accepted Answer

A. equal division of voltage across each thyristor

Question 8

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___________?

Accepted Answer

C. 80

Question 9

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______________________?

Accepted Answer

A. 76.3 %

Question 10

Maximum di / dt in a SCR is________?

Accepted Answer

A. Directly proportional to Vm of supply voltage

Question 11

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_____________?

Accepted Answer

C.  7, 5

Question 12

For series connected SCRÃ¢â‚¬â„¢s dynamic equalising circuit consists of___________?

Accepted Answer

B. R and C in series but with diode across R

Question 13

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

Accepted Answer

D. Derating factor

Question 14

Anode current in an SCR consists of____________?

Accepted Answer

A. holes only

Question 15

To meet high current demand we use SCRs in______________?

Accepted Answer

B. parallel connection.

Question 16

Dynamic equalising circuit is useful____________?

Accepted Answer

D. Both B and C

Question 17

SCRs are used in series to meet_______________?

Accepted Answer

D. high voltage demand

Question 18

Which following is a two terminal three layer device?

Accepted Answer

D. None of above

Question 19

ON state voltage drop across SCR lie between the range_____________?

Accepted Answer

C. 1 – 1.5 V

Question 20

Which of following is not a power transistor?

Accepted Answer

C. TRIAC