The typical value of SCR for modern alternator is____________?

Related Mcqs:

1. 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

2. The maximum di/dt in a SCR is____________?

   A. Directly proportional to supply voltage
   B. Directly proportional to inductance in the circuit
   C. Inversely proportional to supply voltage
   D. Both A and B

3. Number of PN junction in an SCR is____________?

   A. Two
   B. Three
   C. Four
   D. Five

4. 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

5. 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

6. For an SCR gate – cathode characteristic is a straight line of 130. For triggered source volume of 15 V and allowable gate power dissipation of 0.5 W compute the gate source resistance_____?

   A. 111.9 Ω.
   B. 11.19 Ω.
   C. 108 Ω.
   D. 115 Ω

7. An SCR is made up of silicon because?

   A. silicon has large leakage current than germanium
   B. silicon has small leakage current than germanium
   C. silicon has small leakage voltage than germanium
   D. silicon has large leakage voltage than germanium

8. In the operation and control of both naturally commutated and forced commutated SCR base converter, commutation plays an important role. The converters is / are ___________?

   A. AC – DC
   B. DC – DC
   C. DC – AC
   D. All of these

9. With gate open, the maximum anode current at which SCR is turned off from ON condition is called____________?

   A. breakdown voltage
   B. peak reverse voltage
   C. holding current
   D. latching current

10. An SCR can be used___________?

    A. as static conductor
    B. for power control
    C. for speed control of dc shunt motor
    D. All of these