<Dd> N = Synchronous speed, in revolutions per minute </Dd> <Dd> F = AC power frequency </Dd> <Dd> p = Number of poles per phase winding </Dd> <P> Actual RPM for an induction motor will be less than this calculated synchronous speed by an amount known as slip, that increases with the torque produced . With no load, the speed will be very close to synchronous . When loaded, standard motors have between 2 - 3% slip, special motors may have up to 7% slip, and a class of motors known as torque motors are rated to operate at 100% slip (0 RPM / full stall). </P>

How many types of ac motors are there