This type of alternator has a rotor with clearly visible and protruded poles. The salient poles are created by the windings placed within slots in the rotor's surface. These slots are connected to the rotor coils, which are used for generating the magnetic field. The protruding poles have a significant impact on the winding distribution and the air-gap between the rotor and stator.
Characteristics of Salient Pole Alternator:
1. Construction: Salient pole alternator has distinct magnetic poles located on the rotor surface, which gives it the name "salient".
2. Field Excitation: Requires a separate DC current for field excitation to generate a magnetic field in the rotor.
3. Synchronous Speed: The synchronous speed of a salient pole alternator depends on the number of poles, the rotational speed of the rotor, and the frequency of the generated power.
4. Voltage Regulation: Salient pole alternators have inherently poor voltage regulation due to the variable air gap between the stator and rotor.
5. Power Factor: At leading power factors (inductive loads), salient pole alternators provide less stable operation due to the change in the air-gap reluctance.
6. Applications: Salient pole alternators are generally used in low to medium power applications, such as power generation plants, marine propulsion, and industrial equipment.
Non-salient pole alternator:
Unlike the salient pole alternator, the non-salient pole alternator features a smooth cylindrical rotor without any visible or protruding poles. Instead, the stator of a non-salient pole alternator has slots distributed uniformly around its inner periphery. These slots house the stator conductors.
Characteristics of Non-Salient Pole Alternator:
1. Construction: Non-salient pole alternators have a smooth cylindrical rotor without distinct magnetic poles projecting out.
2. Field Excitation: Similar to salient pole alternators, they also require external DC excitation to generate a magnetic field in the rotor.
3. Synchronous Speed: The synchronous speed is governed by the same principles as salient pole alternators, based on the number of poles, rotational speed, and frequency.
4. Voltage Regulation: Due to the uniform air-gap between the stator and rotor, non-salient pole alternators offer better voltage regulation compared to salient pole alternators.
5. Power Factor: Their performance is less sensitive to different power factor conditions, providing stable operation at leading and lagging power factors.
6. Applications: Non-salient pole alternators are commonly employed in high power applications, such as large power generators, industrial machinery, and high-performance electric motors.
In summary, salient pole alternators have visible poles on the rotor and require field excitation, while non-salient pole alternators have smooth cylindrical rotors and provide improved voltage regulation and stability at various power factors.
