Do any motors run with out slip and if so what kind?

Question

MOTORS

Answer 1

On a bigger scale there are 3 phase synchronous motors. They run without slip because they have a rotor which can be powered with DC to provide a fixed North and South pole.

Other common 3 phase motors are Induction motors and rely upon relative motion between the rotor and stator. This causes the rotor to receive an induced magnetic field. If the rotor traveled at the same speed as the rotating magnetic field of the stator, there would be no relative motion between the two. In turn there would be no induced field in the rotor to oppose or attract the field of the stator.

In a 3 phase synchronous motor. The field is given to the rotor through slip rings or other means therefore induction is not necessarily required nor is the relative motion between the two. Since relative motion is not required the rotor is able to lock in perfect step with the rotating magnetic field of the stator.

Another unique feature of the 3 Phase Synchrouous motor is the ability to correct its own power factor and the power factor of induction motors connected to the same circuit.

The speed is dependant upon the frequency of the applied voltage and the number of stator poles.

Synchronous Speed = (120 * Hz) / # of Poles

Answer 2

Rscanner has it right. You know where you can find such a motor easily? And how obvious it is that the motor does not slip? Just find a cheap electric clock (non digital). There is the motor. In fact, since the electric power system has such a high accuracy to its frequency (good reason, but too deep for this discussion), those clocks make very excellent time pieces.

Answer 3

They are called Synchronous Motors.