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Power Electronics

Study 217 Electrical Engineering MCQs with correct answers and explanations.

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81Electrical EngineeringMedium

The output power of the cascaded amplifier / attenuator system can be determined using________?

AActual gain of amplifier

BActual gain of attenuator

CGain in dB of amplifier and attenuator

DActual gain of amplifier and attenuator

Correct answer

D. Actual gain of amplifier and attenuator

Explanation

The correct answer is Actual gain of amplifier and attenuator.

82Electrical EngineeringMedium

For commutation in three phase PAC, normally balanced three phase voltages VR, VY and VB are connected to the three legs of the converter via________?

AThree transistors

BThree capacitances

CThree resistance

DThree inductances

Correct answer

D. Three inductances

Explanation

The correct answer is Three inductances.

83Electrical EngineeringMedium

In EMC signal, the source delivers maximum power to the input of transmission line when the transmission line input impedance

AGreater than the source resistance

BNone of these

CIs equal to the source resistance

DSmaller than the source resistance

Correct answer

C. Is equal to the source resistance

Explanation

The correct answer is Is equal to the source resistance.

84Electrical EngineeringMedium

SCR will be turned off when anode current is________?

A< latching current but greater than holding current and gate signal is 0.

B< latching current but greater than holding current and gate signal is present.

Cboth (A) and (B).

Dless than holding current.

Correct answer

C. both (A) and (B).

Explanation

The correct answer is both (A) and (B)..

85Electrical EngineeringMedium

A single phase full bridge inverter can operated in load commutation mode in case load consist of________?

ARLC overdamped.

BRLC critically damped

CRL.

DRLC underdamped.

Correct answer

D. RLC underdamped.

Explanation

The correct answer is RLC underdamped..

86Electrical EngineeringMedium

In dual converters________?

ABoth rectifiers provide negative current to the load

BBoth rectifiers provides positive current to the load

COne rectifiers provide positive current to the load and the other negative current

DOne rectifier provide positive current to the source and the other negative current to the load

Correct answer

B. Both rectifiers provides positive current to the load

Explanation

The correct answer is Both rectifiers provides positive current to the load.

87Electrical EngineeringMedium

A thyristor can termed as________?

ADC switch

BSquare wave switch

CBoth a and B

DAC switch

Correct answer

A. DC switch

Explanation

The correct answer is DC switch.

88Electrical EngineeringMedium

The reverse recovery time of diode is trr = 3 ÃŽÂ¼s and the rate off all of the diode current is di/dt = 30 A/ÃŽÂ¼s. The storage charge current QRR is________?

A145 ÃŽÂ¼s

B140 ÃŽÂ¼s

C130 ÃŽÂ¼s

D135 ÃŽÂ¼s

Correct answer

D. 135 ÃŽÂ¼s

Explanation

The correct answer is 135 ÃŽÂ¼s.

89Electrical EngineeringMedium

The capacitance of reversed bised junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independant of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?

A1200 V/µs

B600 V/µs

C800 V/µs

D1000 V/µs

Correct answer

C. 800 V/µs

Explanation

The correct answer is 800 V/µs.

90Electrical EngineeringMedium

A step – down choppers can be used in________?

AMachine tools

BElectric traction

CElectric vehicles

DAll of these

Correct answer

D. All of these

Explanation

The correct answer is All of these.

In dual converters________?

ABoth rectifiers provide negative current to the load

BBoth rectifiers provides positive current to the load

COne rectifiers provide positive current to the load and the other negative current

DOne rectifier provide positive current to the source and the other negative current to the load

Correct answer

B. Both rectifiers provides positive current to the load

Explanation

The correct answer is Both rectifiers provides positive current to the load.