Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

coil
a conductor shaped to form a closed geometric path. Note that the coil will not be a closed conducting path unless the two ends of the coil are shorted together. Coils may have multiple turns, and may have various constructions including spool, preformed, and mush-wound. The coil may be wrapped around an iron core or an insulating form, or it may be self-supporting. A coil offers considerable opposition to AC current but very little to DC current.
coil pitch

See coil span
coil side
that portion of a motor or generator winding that cuts (or is cut by) lines of magnetic flux and, thus, contributes to the production of torque and Faraday EMF in the winding.
coil span
the distance, measured either in number of coil slots or in spatial (mechanical) degrees, between opposite sides of a winding of an electric machine. A full-span (full-pitch) winding is one in which the winding span equals the span between adjacent magnetic poles. Windings with span less than the distance between adjacent magnetic poles are called short-pitch, fractional-pitch, or chorded windings.

See coil pitch
low voltage holding coil
a holding coil that keeps the main-line contactor closed on low voltage conditions. Controllers that contain this feature are used in places where the motor is vital to the operation of a process, and it is necessary to maintain control of the motor under low voltage conditions.
no voltage holding coil
a holding coil that keeps the main-line contactor closed on zero voltage conditions. DC motor controllers that contain this feature are used in places where the motor is vital to the operation of a process. These controllers can maintain control to the motor under momentary line power loses, by using the CEMF of the coasting armature to keep power to the main-line coil/contactor. If power to the motor controller is not restored within a short period of time, the motor coasts to a speed where it can no longer keep the main-line contactor closed. At this point, the m-coil drops out to insure starting resistors are placed back in the circuit.
potential coil
a long, finely wound, straight coil, similar in operation to a Chat-tuck coil, that is used with a fluxmeter to measure magnetic potential difference between a point in a magnetic field and a flux-free point in space.
recoil permeability
the average slope of the minor hysteresis loop, which is roughly the slope of the major hysteresis loop at zero applied field (H ), and is most often used to determine the effect of applying and removing a demagnetizing field to and from a magnetic material.
search coil
a solenoid that is wound with an air core or around a magnet or permeable component of a magnetic circuit to measure the change of flux within the coil; used with a fluxmeter.
teaser coil

See teaser transformer
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