Duty cycle (D) is _______
  • a) Ton÷Toff
  • b) Ton÷(Ton+ Toff)
  • c) Ton÷2×(Ton+ Toff)
  • d) Ton÷2×Toff
AV,rpm,A separately-excited dc motor has an armature resistance of .5 ω. It is fed from single-phase full converter with an ac source voltage ofV, 50Hz. Assuming continuous conduction, the firing angle for rated motor torque at (-rpm is _________
  • a) 122.4°
  • b) 117.6°
  • c) 130.1°
  • d) 102.8°
The unit of angular acceleration is rad/s2.
  • a) True
  • b) False
Calculate the value of the angular acceleration of the motor using the given data: J=kg-mload torque =N-m, motor torque =N-m.
  • a) -.7 rad/s2
  • b) -.6 rad/s2
  • c) -.3 rad/s2
  • d) -.4 rad/s2
The principle of step-up chopper can be employed for the ________
  • a) Motoring mode
  • b) Regenerative mode
  • c) Plugging
  • d) Reverse motoring mode
A Buck-Boost converter is used to _________
  • a) Step down the voltage
  • b) Step up the voltage
  • c) Equalize the voltage
  • d) Step up and step down the voltage
Which of the following converter circuit operations will be unstable for a large duty cycle ratio?
  • a) Buck converter
  • b) Boost converter
  • c) Buck-Boost converter
  • d) Boost converter and Buck-Boost converter
Calculate the shaft power developed by a motor using the given data: Eb =and I =A. Assume frictional losses areW and windage losses areW.
  • a) 4000 W
  • b) 2000 W
  • c) 1000 W
  • d) 1500 W
Which one of the following devices have low power losses?
  • a) MOSFET
  • b) IGBT
  • c) SCR
  • d) BJT
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