What is the purpose of connecting resistors in series with each stator lead in a primary-resistance starter?

Connecting resistors in series with each stator lead in a primary-resistance starter serves to decrease the potential difference across the motor's windings during the starting phase. This configuration effectively reduces the voltage applied to the motor, allowing it to start under controlled conditions without drawing excessive current. By limiting the voltage, the resistors ensure that the inrush current – which can be several times higher than the normal operating current – is restricted, preventing damage to the motor or electrical components.

While resistors would not typically enhance torque or stabilize current in a direct sense, their primary role in this setup is to manage the voltage applied to the motor initially. This method facilitates a smoother start, allowing the motor to gradually build up speed, which can ultimately lead to better performance and longevity of the motor system.