Glossary · Automation fundamentals, platforms and components
Rotor
Also known as: Armature (rotating)
German: Rotor
In electrical machines, the rotor is the rotating part that interacts with the magnetic field of the stator to produce torque (in a motor) or voltage (in a generator). Depending on the machine type, it carries a squirrel-cage winding, a wound winding or permanent magnets.
- Automation components
In one sentence
The rotor is the rotating part of an electric motor or generator; it carries a cage, winding or permanent magnets and produces torque with the stator.
Example
A squirrel-cage induction motor's rotor has aluminum bars cast into the laminated core and needs no brushes or slip rings.
How it applies
- Engineering: Rotor type determines motor behavior: squirrel-cage rotors in induction motors are robust and simple; permanent-magnet rotors in synchronous servo motors give high dynamics and efficiency but produce Cogging torque.
- Maintenance: Rotor imbalance and bearing wear show up as vibration; vibration monitoring detects them early.
- Safety: A rotating permanent-magnet rotor induces voltage in the Stator winding even when the drive is switched off, for example if a load drives the motor. Maintenance instructions must address this.
- Documentation: Use "rotor" and "stator" consistently, and state rotor inertia in data sheets, since drive sizing depends on it. Spare part documentation should state whether rotor and stator are replaced as a unit.
Rotor vs. stator
The rotor turns; the Stator is the stationary part around it.