Exercise :: Power Electronics - Section 1
| 16. | The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by |
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Answer: Option B Explanation: Value of C is proportional to maximum difference between reverse charge of SCRs in series. |
| 17. | A chopper |
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Answer: Option B Explanation: A chopper is a dc-ac converter. It converts a fixed dc voltage into a variable dc voltage. |
| 18. | Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous. |
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Answer: Option C Explanation: If duty cycle is low, current may become discontinuous. |
| 19. | In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally |
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Answer: Option A Explanation: Firing angles are kept equal to get symmetrical output voltage. |
| 20. | An electric heater is controlled by thyristors through on-off control. If a = 0.4, the heating is |
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Answer: Option B Explanation: Vl = V a. Therefore Vl2 - V2 (a). Heating is proportional to a. |