Power Electronics - Section 1 (5)
Power Electronics - Section 1
| 33. | 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. |
| 34. | 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. |
| 35. | 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. |
| 36. | Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time. |
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Answer: Option A Explanation: Low turn off time enables fast switching. |
| 37. | Thyristors are suitable for dc circuit breakers but not for ac circuit breakers. |
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Answer: Option B Explanation: They are suitable for both dc and ac circuit breakers. |
| 38. |
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| 39. |
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Answer: Option C Explanation: v ∝ (i)1/4 ∝ (100)1/4 ≈ 3. |
| 40. | An SCR is triggered at 40° in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80°, the average anode current is likely to be |
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