A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the starting current drawn is 6 times the full load current, and the full load slip is 4%, the ratio of the starting developed torque to the full load torque is approximately equal to

Under no load condition, if the applied voltage to an induction motor is reduced from the rated voltage to half the rated value,

For an induction motor, operating at a slip 's', the ratio of gross power output to air gap power is equal to:

Which three-phase connection can be used in a transformer to introduce a phase difference of 30° between its output and corresponding input line voltages