Which type of motor maintains a constant speed with changing loads?

The shunt motor is designed to maintain a relatively constant speed under varying load conditions, which makes it particularly useful in applications where speed regulation is essential. This is achieved through its field winding configuration; the field windings are connected in parallel with the armature winding. As the load increases and the armature current rises, the magnetic field strength from the shunt winding also increases, which helps to compensate for the drop in speed that results from the added load.

When load changes occur, the shunt motor can adjust its torque output while maintaining stable operation, making it ideal for applications that require consistent performance regardless of variations in load. This characteristic of maintaining speed under different operational circumstances, coupled with the ability to provide sufficient starting torque, makes shunt motors widely employed in industrial settings and other applications where precision is critical.

In contrast, series motors increase their speed with reduced load, which can lead to excessive speeds under low-load conditions. Universal motors, while capable of operating on both AC and DC, also tend to have speed characteristics that vary with the load. Induction motors, while robust and commonly used, typically do not provide the same level of speed regulation as shunt motors under varying load.