This type of single-phase motor is the so-called universal, whose operating principle is completely different from the induction motor Gates 4L320 Truflex V-Belts . Several home appliances, especially kitchen, and various portable tools use the universal motor. It is a variable speed motor, with low speeds for large torque and high speeds for small loads. The starting conjugate is also high. Because of this, they are commonly used in small appliances, such as electric drills and sanders, in need of high torque, and in blenders, vacuum cleaners and centrifugal pumps, which require high speed.
The rotor is made of a winding distributed in grooves and connected in series with the coils of the stator, which is called the armature. Generally they are manufactured for fractional powers of up to 3/4 HP. For powers above a few CVs, they work precariously in alternating current. The name of universal motor derives from the fact of being able to operate as much under power of alternating current as continuous and strictly, it is a motor of direct current in series. For alternating current operation, the stator and rotor shall be made of laminated plates to prevent losses by hysteresis and parasitic currents. Typically the stator is a set of protruding poles with coils wound on them.