In case of 3-phase induction motors, plugging means__________?

A. improve starting torque
B. reduce copper losses
C. improve efficiency
D. improve power factor

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. at the unit value of slip
B. at the zero value of slip
C. at the value of the slip which makes rotor reactance per phase equal to the resistance per phase
D. at the value of the slip which makes the rotor reactance half of the rotor

A. 200 Hz
B. 50 Hz
C. 2 Hz
D. 0.2 Hz

A. star connected only
B. delta connected only
C. A. and B. both
D. none of the above

A. Block rotor test only
B. No load test only
C. Block rotor test and no-load test
D. Block rotor test, no-load test and stator resistance test