Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

asynchronous machine

See induction machine
permanent magnet synchronous machine
a polyphase AC motor with rotor mounted permanent magnets and sinusoidal distribution of stator phase windings. The field windings in the rotor are replaced by permanent magnets to provide the field excitation in these machines.
synchronous machine
an AC electrical machine that is capable of delivering torque only at one specific speed (ns), which is determined by the frequency of the AC system (f) and the number of poles (P) in the machine. The relationship between synchronous speed and the other variables is

ns = 120f/P