Microelectric Machine

an electric machine having a power ranging from fractions of a watt to several hundred watts with a shaft (rotor) rotation speed of up to 30,000 rpm. Such machines are divided into DC, AC, and universal types. They may have a variety of designs, depending on their purpose and service conditions. Miniature drives are used extensively in automatic, motion-picture, photographic, and radio apparatus; tachogenerators are used in systems having feedback elements, as well as in differentiators and integrators. Reluctance electric motors with concentrated stator windings, and also selsyns, are used in synchronizing systems; induction generators are used extensively in gyroscopes and radar equipment, as well as in electric servomechanisms. Stepping electric motors are most often used to drive mechanisms having a start-stop motion or mechanisms having a continuous motion in which the control action is provided by a series of electrical pulses, as in the case of the drives for machine tools with programmed control. Universal commutator electric motors are used in household electrical devices.