Which statement is true for latching current ___________?

Related Mcqs:

1. If holding current of a thyristor is 2 mA then latching current should be_____?

   A. 0.01 A.
   B. 0.002 A.
   C. 0.009 A.
   D. 0.004 A.

2. The latching current of GTO should be of order

   A. 100 mA
   B. 500 mA
   C. 1 A
   D. 2 A

3. Which statement is true ?

   A. Reverse recovery time ( trr ) > gate recovery time (tgr)
   B. Device turn OFF time ( tq ) > reverse recover time (trr)
   C. Circuit turn OFF time > device turn OFF time ( tq )
   D. All of these

4. An SCR has half cycle surge current rating of 3000 A for 50 Hz supply. One cycle surge current will be_____?

   A. 1500 A.
   B. 6000 A.
   C. 2121.32 A.
   D. 4242.64 A.

5. If the anode current is 800 A, then the amount of current required to turn off the GTO is about____________?

   A. 20 A
   B. 200 A
   C. 600 A
   D. 400 A

6. CB used for over current protection of thyristor operates when the fault current is__________?

   A. of long period
   B. of short duration
   C. both (A) and (B)
   D. neither (A) nor (B)

7. The reverse recovery time of diode is trr = 3 μs and the rate off all of the diode current is di/dt = 30 A/μs. The storage charge current QRR is___________?

   A. 130 μs
   B. 135 μs
   C. 140 μs
   D. 145 μs

8. 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

9. When a large surge current of very short duration flows through a thyristor then which one of the following device will operate to protect the thyristor ___________?

   A. CB
   B. Snubber circuit
   C. Voltage clamping device
   D. Fast acting current limiting device (FACL fuse)

10. Which of the following is true about SIT?

    A. SIT is a high power, high frequency device
    B. SIT is a high power, low frequency device
    C. SIT is a high power, high voltage device
    D. SIT is a low power, high frequency device