salientpole

A salient pole, or salient-pole, refers to a pole of a magnet or magnetic circuit that protrudes from the main body, creating a pronounced magnetic region. In electrical machinery, the term is most often used to describe a rotor or a stator with discrete, projecting poles.

In synchronous machines, a salient-pole rotor consists of a laminated iron core with outward-projecting pole shoes around which windings are placed. The poles are spaced around the circumference, producing a magnetic field that aligns with the stator windings to generate torque at specific electrical frequencies. Salient-pole rotors are typically used in low-speed machines, such as hydroelectric generators, where the shaft speed is relatively slow and few poles can still achieve the desired synchronous speed. They are easier to manufacture for large, heavy machines and provide high torque at low speeds.

Compared with non-salient (smooth) rotors, salient-pole designs exhibit greater rotor saliency and reluctance torque, which can improve performance at low speeds but introduce torque ripple and require careful control of excitation. Smooth rotors, by contrast, have a continuous circumference and are favored for high-speed turbo generators due to reduced windings and air-gap variations.

Salient-pole machines can be found in power generation and motors where operating speed remains low to moderate, and where the mechanical design benefits from projecting poles. They are a key alternative to cylindrical rotors in the broader study of synchronous machine design.