What Is the Difference Between the Rotor and Armature?

AIP shares with you the" What Is the Difference Between the Rotor and Armature?".

October 26, 2023

What Is the Difference Between the Rotor and Armature?

In the world of electrical engineering and motor technology, terms like rotor and armature are commonly used, but they can sometimes cause confusion due to their similarities. Both play pivotal roles in electrical machines, particularly in motors and generators. To clear up any confusion, this article aims to explain the fundamental differences between the rotor and armature.

The Rotor

The rotor is a crucial component in electric motors and generators. It is primarily associated with the rotating part of the machine, and its design and function vary depending on the type of machine it is used in.


In motors, the rotor is the part that rotates to produce mechanical motion. There are two main types of rotors in electric motors: the squirrel cage rotor and the wound rotor. The squirrel cage rotor consists of laminated iron cores and aluminum or copper bars embedded in them. It operates under the influence of the rotating magnetic field produced by the stator (the stationary part of the motor) and generates mechanical motion.

In contrast, the wound rotor features a set of windings on its core, and these windings are connected to external resistors. This design allows for greater control over the motor's performance and is often used in applications where variable speed and torque control are essential.

The Armature

The armature is primarily associated with generators and dynamo-type devices, although it can also be found in certain types of motors. The armature is the stationary component of the machine and consists of a core with windings wound around it. When the rotor (or the part that rotates) spins within the armature's magnetic field, it induces electrical current in the armature windings.


In generators, the armature is responsible for converting mechanical energy (usually from a rotating turbine or some other source) into electrical energy. This electrical energy is then transmitted to power grids or stored for later use.

Key Differences

Function: The most significant difference between the rotor and armature lies in their function. The rotor is responsible for generating mechanical motion in motors, while the armature serves to convert mechanical energy into electrical energy in generators.

Location: The rotor is the rotating part of the machine, whereas the armature is stationary.

Components: Rotors are often simpler in design and can be made with laminated iron cores and conductive bars. Armatures typically consist of a stationary core with windings.

Application: Rotor-based machines, such as electric motors, are used for mechanical work like spinning fans, moving conveyors, and more. Armature-based machines, like generators, are used to produce electrical power.


Understanding the difference between the rotor and armature is essential for anyone working in the field of electrical engineering or dealing with electric motors and generators. While both components play critical roles in these machines, their functions, designs, and applications are distinct. Whether you're designing electrical machinery or troubleshooting issues, knowing the roles of the rotor and armature is fundamental to your success in the field.

Rotor tester                         Armature tester

                                                                                                    (Rotor tester)                                                   (Armature tester)

For more information about the rotor tester and armature tester or another motor tester,  please feel free to contact AIP via Tel/Whatsapp: +86-13969776659, E-mail: international@aipuo.com.