Which type of motor maintains constant speed with changing loads?

The shunt motor is known for maintaining a relatively constant speed even when loads change. This characteristic is due to its construction, where the field windings are connected in parallel (or shunt) with the armature windings. As the load increases, the armature current increases but the field current remains nearly constant, leading to only a small reduction in the magnetic field strength. This allows the motor to sustain its speed more consistently compared to other motor types.

In contrast, series motors experience a significant change in speed as the load varies because the field winding is connected in series with the armature. When the load increases, the current flowing through the motor increases, which strengthens the magnetic field and can lead to higher speeds, potentially resulting in unstable operation under varying loads.

Induction motors, while efficient and widely used, do not inherently maintain a constant speed under varying loads. Their speed varies with load due to slip, which is the difference between the synchronous speed of the magnetic field and the actual speed of the rotor.

Universal motors can operate on both AC and DC and can also adapt to variable speeds, but like series motors, they tend to speed up under lighter loads, making them less stable under fluctuations in load conditions.

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