Armature Winding vs Field Winding: Understanding the Key Differences in Electric Machines
Electric machines like motors and generators work on one fundamental principle: interaction between a magnetic field and an electric current. This interaction is made possible by two critical components — armature windings and field windings.
While they work hand-in-hand, their roles are quite different. Understanding the distinction between them is essential for anyone learning electrical engineering or working in power systems.
What is an Armature Winding?
Definition:
The armature winding is the “working” winding in an electric machine. It’s the part where the main energy conversion takes place — either from electrical to mechanical energy (motor) or mechanical to electrical energy (generator).
Functions:
In generators: Converts mechanical energy into electrical energy by inducing voltage.
In motors: Converts electrical energy into mechanical torque.
Location:
The armature winding can be placed on the rotor (rotating part) or the stator (stationary part) depending on the machine type.
Current Type:
Carries the main load current or induced current (often AC, even in DC machines due to commutation).
Construction:
Many turns of thin wire to handle high induced voltage.
Designed for maximum interaction with the magnetic field.
What is a Field Winding?
Definition:
The field winding creates the magnetic field required for the armature to work. Without it, the armature wouldn’t be able to generate torque or voltage.
Functions:
Produces the magnetic flux that interacts with the armature.
Enables voltage generation in generators and torque production in motors.
Location:
Can be placed on the rotor or stator — generally on the opposite part to the armature winding.
Current Type:
Carries field current (often DC in many machines) to produce a stable magnetic field.
Construction:
Fewer turns of thick wire to handle high current.
Designed for strong and consistent magnetic field production.
Difference Between Armature and Field Winding
| Aspect | Armature Winding | Field Winding |
|---|---|---|
| Role | Main energy conversion (voltage induction or torque) | Produces magnetic field for the armature to work |
| Function in Motor | Converts electrical energy into mechanical motion | Creates magnetic field for torque generation |
| Function in Generator | Converts mechanical energy into electrical energy | Creates magnetic field for voltage generation |
| Location | On rotor or stator, depending on design | On rotor or stator, opposite of armature location |
| Current Type | Carries main load/induced current | Carries field excitation current |
| Wire Size | Many turns of thin wire | Few turns of thick wire |
| Voltage Handling | High induced voltage | Low voltage, high current |
How They Work Together
Imagine an electric motor:
Field winding creates a magnetic field.
Armature winding interacts with this field — and due to current flow, torque is produced.
In a generator, the process is reversed
Mechanical movement makes the armature cut through the magnetic field from the field winding.
Voltage is induced in the armature winding, producing electrical power.
Applications in Real Life
DC Motors: Armature on rotor, field winding on stator.
Alternators (AC Generators): Stationary armature, rotating field winding for easy voltage regulation.
Traction Motors: Designed for high torque — heavy-duty armature winding and strong field winding.
Final Thoughts
The armature winding is where the action happens — it’s the part that directly handles energy conversion. The field winding is the enabler, creating the essential magnetic field. Both are crucial, and their proper design determines the performance, efficiency, and reliability of any electric machine.
✅ Pro Tip for Students: If you remember just one thing —
Armature = Energy conversion point. Field winding = Magnetic field creator.