Also, what does it mean when a motor is asynchronous?
In a motor, synchronous speed is the speed at which the magnetic field rotates. Depending on motor design, the actual mechanical speed may be equivalent (synchronous motor) or slightly smaller (asynchronous motor).
The synchronous speed is a function of:
The formula for calculating synchronous speed is:
For example, consider a motor with 4 poles operating at 60 Hz:
If that same motor was used in a country with a 50 Hz electric supply:
Synchronous motors have a DC winding or a permanent magnet in their rotor, and rotate at exactly the synchronous speed. Electric power systems use synchronous generators to ensure that the entire grid has the same frequency.
On the other hand, asynchronous motors generate their rotor field by induction, and rotate slightly below synchronous speed. For example, an asynchronous motor with 4 poles and connected to a 60-Hz supply might rotate at 1750 RPM instead of 1800 RPM. Asynchronous motors are also called induction motors, and there are two main types:
Als Antwort auf Leonardo David:
You might also find this article interesting on The Grid.
Induction and Synchronous Motors: Similarities and Differences