GATE Prev Year : Power Electronics Test-2

Question 1

The circuit in figure shows a 3-phase half-wave. The source is a symmetrical, 3-phase four-wire system. The line-to-line voltage of the source is 100 V. The supply frequency is 400 Hz. The ripple frequency at the output is

  • A400 Hz
  • B800 Hz
  • C1200 Hz
  • D2400 Hz

Question 2

The speed of a 3-phase, 440 V, 50 Hz induction motor is to be controlled over a wide range from zero speed to 1.5 time the rated speed a 3-phase voltage source inverter. It is desired to keep the flux in the machine constant in the constant torque region by controlling the terminal voltage as the frequency changes. The inverter output voltage vs frequency characteristic should be

  • A
  • B
  • C
  • D

Question 3

Which among the following is the Cuk converter circuit?

  • A
  • B
  • C
  • D

Question 4

A three phase fully controlled bridge converter is feeding a load drawing a constant and ripple free load current of 10A at a firing angle of 30 °. The approximate Total Harmonic Distortion (% THD) and the rms value of fundamental component of the input current will respectively be

  • A31% and 6.8A
  • B31% and 7.8A
  • C66% and 6.8A
  • D66% and 7.8A

Question 5

In the circuit shown in the figure, the switch is operated at a duty cycle of 0.5. A large capacitor is connected across the load. The inductor current is assumed to be continuous.

The average voltage across the load and the average current through the diode will respectively be

  • A10V, 2A
  • B10V, 8A
  • C40V, 2A
  • D40V, 8A

Question 6

Which among the following information is correct in terms of Power factor correction?

  • AIt improves power factor of system by applying suitable devices
  • BIt makes the input to act as purely capacitive
  • CIf the ratio between voltage and current is fixed, then power factor will be infinity
  • DIn this, the input current is not non linear
Categories: Exams

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