Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

amortisseur winding

See damper winding
armature winding
an arrangement of coils carrying the main current, typically wound on the stator of a synchronous machine or the rotor of a DC machine, in which an alternating voltage is induced by the magnetic field.
auxiliary winding
a winding designed to be energized occasionally for a specific purpose, such as starting a single-phase motor. The power to the winding may be controlled by various means including a timer, centrifugal switch, current sensing relay, or voltage (counter EMF) sensing relay.
commutating winding

See interpole
compensating winding
a winding found in DC machines that is placed in the faces of the main field poles, and connected in series with the armature winding, to produce an mmf equal and opposite to the mmf of the armature, thereby reducing the effect of armature reaction.
damper winding
an uninsulated winding, embedded in the pole shoes of a synchronous machine, that includes several copper bars short-circuited by conducting rings at the ends, used to reduce speed fluctuation in the machine by developing an induction-type torque that opposes any change in speed.
primary winding
the transformer winding connected to the energy source.
tertiary winding
a third winding on a transformer. A tertiary winding may be used to obtain a second voltage level from the transformer. For example, in a substation it may be necessary to have low voltage power for the substation equipment in addition to the distribution voltage. Another application of a tertiary winding is in a wye-wye three-phase transformer. Here the tertiary is connected in delta, to provide a path for the triple harmonic components of the exciting current and prevent distortion of the phase voltages.
three-winding transformer
a transformer with three windings, typically primary, secondary, and tertiary. Common three phase, three winding transformers employ wye connected primary and secondary windings and a delta connected tertiary winding.

In some cases, an autotransformer is used to form the primary-secondary combination.
a conductive path, usually wire, inductively coupled to a magnetic core or cell.
winding factor
a design parameter for electric machines that is the product of the pitch factor and the distribution factor.