Windings of star-delta starter while starting and during running are connected in _______.

Correct option is D

· In the star-delta starting method of induction motor, a two-way switch is used to connect the stator winding in star while starting and in delta while running at normal speed.
· In the star-delta starting method of induction motor, the starting current is reduced approximately by 1/3 times as compared to the original.
· The starting torque will 1/3 times that it will be for delta connected winding.
· During starting the stator winding is star connected, so that voltage over each phase in the motor will be reduced by a factor of $$\frac{1}{\sqrt{3}}$$nof that would be for delta connected winding.

· Hence a star-delta starter is equivalent to an auto-transformer of ratio $$\frac{1}{\sqrt{3}}$$​​

or 57.73% reduced voltage.