Power Electronics - Section 1 (3)
Power Electronics - Section 1
| 17. | The terminals of a power MOSFET are called |
|||||||
Answer: Option B Explanation: In a MOSFET terminals are source, gate, drain irrespective of rating. |
| 18. | In a multiphase chopper, all choppers operate together. |
|||
Answer: Option B Explanation: They operate in a sequence. |
| 19. | A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When a = 0, speed is 500 rpm. If a = 45°, the speed is likely to be |
|||||||
Answer: Option D Explanation: Average output voltage ∝ cos a and therefore reduced to 0.707 of the value for a = 0. Speed is nearly proportional to voltage. |
| 20. | In a circuit using a full wave converter (M - 2 connection) the PIV of each thyristor is 400 V. For the same output voltage and fully controlled bridge converter, PIV will be |
|||||||
Answer: Option C Explanation: In bridge connection PIV is half of that in M-2 connection.
|
| 21. | A 3 kV circuit uses SCR of 800 V rating. If derating is 25%, the number of SCRs in series is |
|||||||
|
| 22. | Assertion (A): Power transistor has lower switching time than SCR Reason (R): Power transistor has greater switching time than SCR |
|||||||
|
rating.
| 24. | If duty cycle is a and the load is a resistance R, the rms value of output voltage is |
|||||||
Answer: Option B Explanation: RMS output voltage VL = √a V. |
