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Power Electronics

Study 217 Electrical Engineering MCQs with correct answers and explanations.

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101Electrical EngineeringMedium

In ac – dc conversion, when the switch is closed then the sum of voltages around the loop is________?

AEqual to the sum of voltage when switch is open

BNon zero

CZero

DTwice of the voltage when switch is open

Correct answer

B. Non zero

Explanation

The correct answer is Non zero.

102Electrical EngineeringMedium

In constant frequency PWM, at perturbation the amplitude of the sinusoidal component is a________?

ALinear function

BConstant function

CNon linear function

DNone of these

Correct answer

D. None of these

Explanation

The correct answer is None of these.

103Electrical EngineeringMedium

Harmonics in 3 phase inverters can be reduced by using________?

ABoth passive and active filters

BActive filter

CPassive filter

DNone of these

Correct answer

A. Both passive and active filters

Explanation

The correct answer is Both passive and active filters.

104Electrical EngineeringMedium

If the anode current is 800 A, then the amount of current required to turn off the GTO is about________?

A600 A

B20 A

C400 A

D200 A

Correct answer

D. 200 A

Explanation

The correct answer is 200 A.

105Electrical EngineeringMedium

The curve between V and I of SCR when anode is positive w.r.t cathode and when anode is negative w.r.t cathode are known as________?

Aformer as reverse characteristics and later as forward characteristics

Bboth as forward characteristics

Cboth as reverse characteristics

Dformer as forward characteristics and later as reverse characteristics

Correct answer

D. former as forward characteristics and later as reverse characteristics

Explanation

The correct answer is former as forward characteristics and later as reverse characteristics.

106Electrical EngineeringMedium

Maximum di / dt in a SCR is________?

ADirectly proportional to Vm of supply voltage

BBoth A and C

CInversely proportional to Vm of supply voltage

DInversely proportional to L in the circuit

Correct answer

A. Directly proportional to Vm of supply voltage

Explanation

The correct answer is Directly proportional to Vm of supply voltage.

107Electrical EngineeringMedium

If energy is taken from the AC side of the inverter and sends it back into the DC side, then it is known as________?

ARegenerative mode operation

BBraking mode operation

CNone of these

DMotoring mode operation

Correct answer

A. Regenerative mode operation

Explanation

The correct answer is Regenerative mode operation.

108Electrical EngineeringMedium

Switching frequency of SITH is________?

A60 KHz

B5 KHz

C10 KHz

D100 KHz

Correct answer

D. 100 KHz

Explanation

The correct answer is 100 KHz.

109Electrical EngineeringMedium

The turn-on time of an SCR with inductive load is 20 µs. The puls train frequency is 2.5 KHz with a mark/space ratio of 1/10, then SCR will________?

ATurn on

BTurn on if pulse frequency us increased to two times

CTurn on if inductance is removed

DNot turn on

Correct answer

A. Turn on

Explanation

The correct answer is Turn on.

110Electrical EngineeringMedium

Unipolar modulation is generally used in________?

AAC – DC converters

BDC – DC converters

CDC – AC converters

DAC – AC converters

Correct answer

B. DC – DC converters

Explanation

The correct answer is DC – DC converters.

The curve between V and I of SCR when anode is positive w.r.t cathode and when anode is negative w.r.t cathode are known as________?

Aformer as reverse characteristics and later as forward characteristics

Bboth as forward characteristics

Cboth as reverse characteristics

Dformer as forward characteristics and later as reverse characteristics

Correct answer

D. former as forward characteristics and later as reverse characteristics

Explanation

The correct answer is former as forward characteristics and later as reverse characteristics.