EE8353-ELECTRIC DRIVES AND CONTROLS-MODEL EXAMINATION NOV 20

Which duty cycle has on load and off-loads period?

• a) Intermittent duty

  
  

• b) Short time duty

• c) Continuous duty with constant load

• d) Continuous duty with variable load

Electric drives can operate in all the which quadrants of speed-torque plane

• a) four

  
  

• b) one

• c) Two

• d) Three

The curve obtained between temperature rise Vs. time, when drive is loaded is called

• a) Heating curves

• b) Cooling curves

• c) Linear curve

• d) Parabolic curve

The time taken by the machine to reach a temperature rise of maximum temperature rise (θm) is called heating time constant. The value is

• a) 63.2%

• b) 69.2%

• c) 85.3%

• d) 95%

The loads are too short to allow the motor to reach its final steady value while periods of rest are too small to allow the motor to cool down to the which temperature.

• a) ambient temperature

  
  

• b) Room temperature

• c) Nominal temperature

• d) None of the above

Continuous duty with starting and braking duty factor for this duty cycle is

• a) 2

• b) 4

• c) 8

• d) 1

In dc series motor, which is directly proportional to armature current

• a)flux

• b)voltage

• c)current

• d)None of the above

DC series motor should be started with

• a) Heavy load

• b) No load

• c) Light load

• d) some load

Rotating magnetic field always rotates at a speed equal to

• Rotor speed

• synchronous speed

• Both a) and b)

• None of the above

Due to the capacitor connected in series with the auxiliary winding the capacitive circuit draws a leading current which increases the phase angle between

• a) I_m

• b) I_st

• c) I_{m and} I_st

• None of the above