Ⅰ. What is an Armature?

An armature is a part of an electrical machine, such as a motor or generator, that carries alternating current (AC). Even in a direct current (DC) motor, the armature can conduct alternating current, either through a commutator (which periodically reverses the current flow direction) or through electronic commutation (as in brushless DC motors).

The armature supports and houses the armature windings, which interact with the magnetic field created in the air gap between the stator and rotor. The stator can either be the rotating part (rotor) or the stationary part (stator).

Ⅱ. How an Armature Works

How does the armature in a motor work?

Electric motors operate based on the principle of electromagnetic induction, converting electrical energy into mechanical energy. According to Fleming's left-hand rule, a current-carrying conductor placed in a magnetic field experiences a force.

In an electric motor, the stator generates a rotating magnetic field using permanent magnets or electromagnets. Typically, the armature is the rotor, with armature windings connected to the commutator and brushes. The commutator changes the direction of the current in the armature windings as it rotates, ensuring it remains aligned with the magnetic field.

The interaction between the magnetic field and the armature windings produces torque, causing the armature to rotate. A shaft attached to the armature transmits mechanical power to other devices.

How the Armature in a Generator Works

Generators convert mechanical energy into electrical energy through electromagnetic induction. Faraday's law states that a conductor moving through a magnetic field induces an electromotive force (EMF).

In a generator, the armature is generally the rotor, driven by a prime mover like a diesel engine or turbine. The armature has windings connected to the commutator and brushes. The stator uses permanent magnets or electromagnets to produce a fixed magnetic field.

The motion between the magnetic field and the armature windings induces an electromotive force, generating current in the armature windings. The commutator reverses the current direction as the armature rotates, resulting in alternating current (AC).