In star-delta starting, which configuration is used during the starting phase?

In star-delta starting, which configuration is used during the starting phase?

• A. Delta
• B. Star
• C. Autotransformer action
• D. Parallel

Answer: (B)

Starting with a star (Y) connection is used because it lowers the voltage each winding sees, V_line/√3, which greatly reduces the current drawn from the supply and the starting torque. This gentler start minimizes electrical inrush and mechanical stress. Once the motor reaches sufficient speed, the configuration switches to delta so every winding gets the full line voltage for normal running, providing full torque.

Starting with a star (Y) connection is used because it lowers the voltage each winding sees, V_line/√3, which greatly reduces the current drawn from the supply and the starting torque. This gentler start minimizes electrical inrush and mechanical stress. Once the motor reaches sufficient speed, the configuration switches to delta so every winding gets the full line voltage for normal running, providing full torque.