induction coil

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induction coil

a transformer for producing a high voltage from a low voltage. It consists of a cylindrical primary winding of few turns, a concentric secondary winding of many turns, and often a common soft-iron core
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

induction coil

[in′dək·shən ‚kȯil]
A device for producing high-voltage alternating current or high-voltage pulses from low-voltage direct current, in which interruption of direct current in a primary coil, containing relatively few turns of wire, induces a high voltage in a secondary coil, containing many turns of wire wound over the primary.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Induction coil

A device for producing a high-voltage alternating current or high-voltage pulses from a low-voltage direct current. The largest modern use of the induction coil is in the ignition system of internal combustion engines, such as automobile engines. Devices of similar construction, known as vibrators, are used as rectifiers and synchronous inverters. See Ignition system

The illustration shows a typical circuit diagram for an induction coil. The primary coil, wound on the iron core, consists of only a few turns. The secondary coil, wound over the primary, consists of a large number of turns.

Induction coils of a different type are used in telephone circuits to step up the voltage from the transmitter and match the impedance of the line. The direct current in the circuit varies in magnitude at speech frequencies; therefore, no interrupter contacts are necessary. Still another type of induction coil, called a reactor, is really a one-winding transformer designed to produce a definite voltage drop for a given current. See Reactor (electricity)

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.


A coil of wire that generates a magnetic field when current is passed through it. The strength of the magnetic field is measured in henrys (H). When the current is removed, as the magnetic field disintegrates, it "induces" a brief current in the opposite direction of the original. Thus "electromagnetic induction" is caused by the opening and closing of a DC circuit or the continuous changing of directions in an AC circuit.

High-Frequency Filters
An induction coil impedes the flow of high-frequencies in an AC circuit, which is why inductors are used as surge protectors, choking off any high-frequency shifts. The tiny donuts placed on the end of signal cables and the load coils placed into telephone networks are examples. See electromagnetic induction.
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References in periodicals archive ?
(12)-(21), the total magnetic flux [[PHI].sub.1](x, [x.sub.1], t), [x.sub.1] [member of] [0,x] in the TCR-antenna induction coils is calculated for several shunt points.
The induction coil can be placed in or on the mould, or between the open mould halves.
It was found that when the casting temperature was lower than required in one of the billet induction coils, "knit" lines subsequently occurred in the cast component, resulting in low impact strength.
This relied upon measuring forces between a solenoid and an induction coil where the magnetic flux was calculated from dimensional measurements.
An induction coil in the rotor and an adjacent coil in the stator work together as a radio frequency rotary transformer.
The induction coils themselves are only warm to the touch.
According to Dill, the design will not put magnets or induction coils into the shuttle.
He also notes that earlier attempts to use induction barrel heating put the induction coils in direct contact with the hot barrel, which prevented the use of more efficient inductor coils and raised the coils' electrical resistance, further reducing their efficiency.
A selection of four different size induction coils are changed within five seconds without the need to power down the system.
based on the comparison, Chaisson asserts that if a low-permeability slip plane material is used, it can perform an important function of mitigating the conductive gases to the induction coils.