A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of $$5\% $$

If an auto-transformer is used for reduced voltage starting to provide $$1.5$$ per unit starting torque, the auto-transformer ratio $$\left( \% \right)$$ should be

A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of $$5\% $$

If a star-delta starter is used to start this induction motor, the per unit staring torque will be

A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of $$5\% $$

If a starting torque of $$0.5$$ per unit is required then the per unit starting current should be

A $$3$$ phase, $$10$$ $$kW$$, $$400$$ $$V,$$ $$4$$ pole, $$50$$ $$Hz$$, star connected induction motor draws $$20$$ A on full load. Its no load and blocked rotor test data are given below.
No Load Test: $$400V$$ $$6A$$ $$1002W$$
Blocked Rotor Test: $$90V$$ $$15A$$ $$762W$$
Neglecting copper loss in No Load Test and core loss in Blocked Rotor Test, estimate motor's full load efficiency.