Question 21 : Find the expression for peak capacitor voltage in case of a current commutated chopper circuit.
1. Io √(L/C)
2. Vs + √(L/C)
3. Vs + Io √(L/C)
4. Zero
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Question 22 : Which type of commutating circuit will have highest switching losses for same rating of all the components?
1. current commutated chopper
2. voltage commutated chopper
3. load commutated chopper
4. forced commutated chopper
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Question 23 : A type C chopper consists of __________ diodes and _________ switches in anti-parallel.
1. 2, 2
2. 3, 3
3. 4, 4
4. 3, 4
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Question 24 : In case of current commutation of SCR
1. a diode is connected in series with the main SCR
2. a diode is connected in parallel with the main SCR
3. a diode is connected in anti-parallel with the main SCR
4. none of the mentioned
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Question 25 : The expression for a step-up/step-down chopper with α as the duty cycle and Vs as the dc input voltage is
1. Vs/1 - α
2. α x Vs
3. Vs (α/1-α)
4. Vs (α/1+α)
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Question 26 : A current commutated chopper is fed from a source of 230 V. Its commutating components are L = 20 μH and C = 50 μF. Find the value of peak commutating current.
1. 233 A
2. 59 A
3. 363 A
4. 198 A
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Question 27 : For a type D chopper, the average value of output voltage will be positive when
1. T_on = T_off
2. T_on < T_off
3. T_off = 0
4. T_on > T_off
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Question 28 : In case of variable frequency system __________ is varied
1. T
2. Ton
3. Toff
4. supply frequency
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Question 29 : In case of frequency modulation system, ________ is kept constant.
1. T
2. Ton
3. Toff
4. Either Ton or Toff
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Question 30 : In the current limit control method, when the load current reaches a predefined lower value, then
1. the chopper is switched off
2. the chopper is switched on
3. the source voltage is removed
4. load voltage goes to zero
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