Polyphase Induction Motors

A. resistance rise method
B. thermometer method
C. embedded temperature method
D. all above methods

A. slip ring type
B. squirrel cage type
C. any of the above
D. none of the above

A. decreases the rotor current
B. increases the rotor current
C. rotor current becomes zero
D. rotor current rernains same

A. reduces starting torque as well as maximum torque
B. increases starting torque as well as maximum torque
C. increases starting torque but maxi-mum torque remains unchanged
D. increases starting torque but maxi-mum torque decreases

A. it is run on load
B. it is run in reverse direction
C. it is run on voltage higher than the rated voltage
D. e.m.f. is injected in the rotor circuit

A. rotor leakage reactance
B. stator reactance
C. the reactive lagging magnetizing current necessary to generate the magnetic flux
D. all of the above

A. supply frequency
B. supply voltage
C. copper losses in motor
D. none of the above

A. sR2X2 = 1
B. sR2 = X2
C. R2 = sX2
D. R2 = s2X2

A. high inductance arid low resistance
B. low inductance and high resistance
C. low inductance and low resistance
D. high inductance and high resistance

A. the power factor will be low
B. windage losses will be more
C. bearing friction will reduce
D. copper loss will reduce In an induction motor