The Effects of Armature Reaction

Armature reaction is an essential function of electronic machinery. All electronic motors have an armature: usually the device's motor or generator, wound with coiled wire. It may also be an electromagnetic device, including a field magnet or a solenoid device. The armature creates a magnetic field, or electromotive force (EMF), then supplies it with current while the device operates.

The armature of a DC (Direct Current) generator creates a magnetic field. The magnetic field is situated at right angles to the device's generator field, which creates a state of cross-magnetization.

Electromagnets help to drive direct current electonic motors.

Cross-magnetization affects the device's flux pattern. In electronics, flux refers to lines of force that surround any type of permanent magnet or any moving charged particle. As cross-magnetization happens, the armature distorts the main field.

This distortion triggers a change in the device's neutral field (also known as its neutral plane). In the neutral plane, the armature's wound coils move parallel to the device's lines of magnetic flux. This causes a series of brushes to rotate. As the brushes rotate, power flows out of one side and into the other side.

Like batteries, electronic devices have two types of charged fields.

While in the neutral plane, these brushes contact a device called a commutator. The commutator, which is hooked up to the coiled wires of the armature, acts as a switch that reverses the electric current direction. This creates a need for a "new" neutral plane. When the brushes are in the original neutral plane, they short out the armature, which prevents power from arcing out between the armature and the commutator. This shifting from the "old" to the "new" neutral plane is the essence of armature reaction.

Armature reaction varies in strength, depending on the amount of current flowing in the coils. This can interfere with the flow of electric current. Devices called interpoles act to counter-balance the variance of armature reaction. Interpoles have coiled wires, which connect to the armature. The interpoles generate their own energy field, which reacts to the armature's output. It helps to regulate the flow of power and keep it consistent.

An alternate to interpoles, in a DC electronic device, are compensating windings. These are coils wound into the armature. Like interpoles, they generate a counter-energy that almost cancels out the armature's output. They also help to regulate the flow of energy, so that the device will operate smoothly.