Question 61 : A three-phase three pulse type controlled converter is constructed using 3 SCR devices. The circuit is supplying an R load with α < 30°. As such, each SCR device would conduct for
1. 60° each cycle
2. 120° each cycle
3. 180° each cycle
4. 360° each cycle
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Question 62 : A single phase full converter has average & peak voltage values of 133 V and 325 V respectively. Find the value of the firing angle.
1. 40°
2. 140°
3. 50°
4. 130°
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Question 63 : An SCR has the peak forward voltage = 1000 V. Find the maximum voltage that the SCR can handle if employed in a M-2 type full controlled converter circuit. Use factor of safety (FOS) = 2.5
1. 500 V
2. 400 V
3. 200 V
4. 1000 V
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Question 64 : In inverter operation, with output voltage = Vo and a RLE load connected
1. Vo < E
2. Vo = E
3. Vo > E
4. None of the mentioned
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Question 65 : Find the expression for the average value of the output voltage for the below given circuit. Consider the load current to be continuous, firing angle = α, transformer ration 1:1 and Vs = Vm sinωt.
1. (Vm/π)cosα
2. (Vm/π)(1+cosα)
3. (2Vm/π)cosα
4. (2Vm/π)(1+cosα)
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Question 66 : A motor load is connected to a single-phase full converter B-2 type controlled rectifier. The net energy is transferred from ac source to the motor (dc load) when
1. π+α > 90
2. π-α > α
3. π+α > α
4. π-α > 90
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Question 67 : In a p-pulse converter, each SCR conducts for (per cycle)
1. p radians
2. p degrees
3. p/2π radians
4. 2π/p radians
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Question 68 : A single-phase full converter bridge, is connected to a RLE load. The source has a rms voltage of 230 V and the average load current is 10 A. Find the firing angle for which the power flows from the DC load to the AC source. Consider E = 120 V, R = 0.4 Ω, L = 2 Henry.
1. 124°
2. 153°
3. 142°
4. 309°
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Question 69 : For a single phase half-wave thyristor circuit with R load, the power delivered to the resistive load is
1. (average load voltage) x (average load current)
2. (rms supply voltage)²/R
3. (rms load voltage)²/R
4. (average load voltage)/R
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Question 70 : In a B-2 type full controlled bridge converter
1. one SCR conducts at a time
2. two SCRs conduct at a time
3. three SCRs conduct at a time
4. four SCRs conduct at a time
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