Domestic appliances
Operating at normal power line frequencies, universal motors are often found in a range less than 1000 watts. Their high speed makes them useful for appliances such as blenders, vacuum cleaners, and hair dryers where high speed and light weight are desirable. They are also commonly used in portable power tools, such as drills, Sanders, circular and jig saws, where the motor's characteristics work well. An added benefit for power tools used by welders is that classic engine-driven welding machines may be a pure DC generator, and their auxiliary power receptacles will still be DC, even though a typical NEMA 5-15 household configuration. The DC power is fine for typical jobsite incandescent lighting and the universal motors in drills and grinders. Many vacuum cleaner and weed trimmermotors exceed 10,000 RPM, while many Dremel and similar miniature grinders exceed 30,000 RPM.
Universal motors also lend themselves to electronic speed control and, as such, were an ideal choice for domestic washing machines. The motor can be used to agitate the drum (both forwards and in reverse) by switching the field winding with respect to the armature. The motor can also be run up to the high speeds required for the spin cycle. Nowadays, variable-frequency drive motors are more commonly used instead.
Rail traction
Universal motors also formed the basis of the traditional railway traction motor in electric railways.In this application, the use of AC to power a motor originally designed to run on DC would lead to efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron. Although the heating effects are reduced by using laminated pole-pieces, as used for the cores of transformers and by the use of laminations of high permeability electrical steel, one solution available at the start of the 20th century was for the motors to be operated from very low frequency AC supplies, with 25 and 16 2⁄3 Hz operation being common.
Starter motor
Starters of combustion engines are usually universal motors, with the advantage of being small and having high torque at low speed. Some starters have permanent magnets, others have 1 out of the 4 poles wound with a shunt coil rather than series wound coils.
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