Question 51 : The converter circuit which employs turn on and turn off when the voltage and/or current through the device is zero at the instant of switching is ____________
1. a conventional converter
2. a resonant converter
3. a zero switching circuit
4. none of the mentioned
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Question 52 : The factors governing the induction heating are
1. resistivity
2. relative permeability
3. magnetic field intensity
4. all of the mentioned
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Question 53 : Static UPS requires __________
1. only rectifier
2. only inverter
3. both inverter and rectifier
4. none of the mentioned
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Question 54 : Usually __________ batteries are used in the UPS systems.
1. NC
2. Li-On
3. Lead acid
4. All of the mentioned
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Question 55 : __________ is used in the rotating type UPS system to supply the mains.
1. DC motor
2. Self excited DC generator
3. Alternator
4. Battery bank
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Question 56 : HVDC transmission has ___________ as compared to HVAC transmission.
1. smaller transformer size
2. smaller conductor size
3. higher corona loss
4. smaller power transfer capabilities
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Question 57 : In a three phase half-wave cycloconverter ___________
1. both inverting and converting action takes place
2. only inversion action takes place
3. only converting action takes place
4. none of the mentioned
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Question 58 : SPMS are based on the ________ principle.
1. Phase control
2. Integral control
3. Chopper
4. MOSFET
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Question 59 : TRIAC is used in
1. chopper
2. speed control of induction machine
3. speed control of universal motor
4. none of the mentioned
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Question 60 : Two six pulse converters used for bipolar HVDC transmission system, are rated at 1000 MW, +- 200 kV. Find the dc current in the transmission line.
1. 500 A
2. 25 A
3. 2500 A
4. 5 A
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