Chapter 36, Problem 1SQ

Are the secondary resistors connected in three uniform wye or delta sections?

To determine

Explain whether the secondary rotor resistors are connected in wye or delta sections.

Answer to Problem 1SQ

The secondary rotor resistors are connected in wye sections.

Explanation of Solution

The secondary resistor starter is typically used for an automatic acceleration of wound rotor motors. It comprises of line starter for connecting primary (stator winding) circuit to the line and more number of accelerating contactors is used to shunt out resistance in the secondary circuit when rotor speed increases.

Refer to Figure 36-1 in the textbook which shows typical control circuit for accelerating a slip ring induction motor. In the circuit, the secondary resistor consists of three sets of uniform wye sections. Each wye section is connected to slip rings of the wound rotor motor. The wye section is also called as star section.

Conclusion:

Thus, the secondary rotor resistors are connected in wye sections.