Common Connections for Squirrel-Cage Induction Motors

Question 1

Typically the squirrel-cage induction motor has _______, ________, _________ or ________ external leads.

Answer 1

three, six, nine or twelve

Question 2

Between which terminals is continuity measured on a nine-lead motor that is delta-connected internally?

Answer 2

(T1, T4, T9), (T2, T5, T7), (T3, T6, T8)

Question 3

Between which terminals is continuity measured on a nine-lead motor that is wye-connected internally?

Answer 3

(T1, T4), (T2, T5), (T3, T6), (T7, T8, T9)

Question 4

Why is a wye connection often used to start larger motors?

Answer 4

Only 58% of line voltage is applied across each winding, therefore line current and torque are reduced to 33% of what they would be if the motor were started delta-connected.