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repulsion motor[ri′pəl·shən ‚mōd·ər]
a single-phase AC motor with transformer-action coupling between the windings of the stator and rotor. The stator is of a nonsalient-pole design and has two series-connected windings, whose axes form a 90° angle. The rotor is similar in design to the armature of a DC machine. The commutator brushes are short-circuited, and the brush holder can be turned with respect to the axis of the motor. If the brush axis is aligned with the axis of one of the stator windings, a current is induced in the rotor winding, as in the secondary winding of a transformer. This current interacts with the magnetic flux of the second stator winding and creates a torque that causes the rotor to rotate. By shifting the brushes around the commutator, the torque can be varied from zero to a maximum value. Thus, different settings of the brushes are used in starting the motor, controlling the rotational speed, and reversing the motor.
There also exist repulsion motors with only one stator winding. The operating principle of such motors is similar to that of the type discussed above, since the magnetic flux of the stator winding can be regarded as the sum of two mutually perpendicular fluxes.
The advantage of repulsion motors is that the rotational speed can be varied within wide limits without the use of auxiliary apparatus. The motors have the disadvantage of being complicated in structure. Repulsion motors are used in low-power variable-speed single-phase AC drives.
REFERENCEKostenko, M. P., and L. M. Piotrovskii. Elektricheskie mashiny, 3rd ed., parts 1–2. Leningrad, 1972–73.
M. D. NAKHODKIN
An alternating-current (ac) commutator motor designed for single-phase operation. The chief distinction between the repulsion motor and the single-phase series motors is the way in which the armature receives its power. In the series motor the armature power is supplied by conduction from the line power supply. In the repulsion motor, however, armature power is supplied by induction (transformer action) from the field of the stator winding. For discussion of the ac series motor See Universal motor, Alternating-current motor
The repulsion motor primary or stationary field winding is connected to the power supply. The secondary or armature winding is mounted on the motor shaft and rotates with it. The terminals of the armature winding are short-circuited through a commutator and brushes. There is no electrical contact between the stationary field and rotating armature (see illustration). See Windings in electric machinery