SCRs are used in series to meet_______________?

Related Mcqs:

1. 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

2. Practical way of obtaining static voltage equalization in series connected SCRs is by the use of____________?

   A. One resistor across the string
   B. Resistors of the same value across each SCR
   C. Resistors of different values across each SCR
   D. One resistor in series with each SCR

3. To meet high current demand we use SCRs in______________?

   A. series connection.
   B. parallel connection.
   C. anti parallel connection.
   D. both B and C.

4. 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

5. 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

6. 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 %

7. 4 thyristors rated 200 V in series. The operating voltage of the string is 600 V. Derating factor of the string is_____________________?

   A. 0.75
   B. 0.7
   C. 0.2
   D. 0.25

8. Double fourier series analysis of PWM is_____________?

   A. Two dimensional functions
   B. Three dimensional functions
   C. One dimensional functions
   D. All of these

9. What is used to protect the SCR from over current ________________?

   A. CB and fuse.
   B. Heat sink.
   C. Snubber circuit.
   D. Voltage clamping device.

10. A modern power semiconductor device that combines the characteristic of BJT and MOSFET is_____________?

    A. IGBT
    B. FCT
    C. MCT
    D. GTO