Fig. 104. RESISTANCE COILS AND CONNECTIONS, SHOWING PLUG.
Coil, Rhumkorff.
The ordinary induction coil with circuit breaker, for use with original
direct and constant current, is thus termed. (See Coil, Induction.)
Synonym--Inductorium.
Coil, Ribbon.
A coil made of copper ribbon wound flatwise, often into a disc-like
shape, and insulated by tape or strips of other material intervening
between the successive turns.
Coils, Compensating.
Extra coils on the field magnets of dynamos or motors, which coils are
in series with the armature windings for the purpose of keeping the
voltage constant. In compound wound machines the regular series-wound
coil is thus termed. In a separately excited dynamo a coil of the same
kind in circuit with the armature may be used as a compensator.
Coils, Henry's.
An apparatus used in repeating a classic experiment in electro-magnetic
induction, due to Prof. Henry. It consists in a number of coils, the
first and last ones single, the intermediate ones connected in pairs,
and one of one pair placed on the top of one of the next pair. On
opening or closing the circuit of an end coil the induced effect goes
through the series and is felt in the circuit of the other end coil.
Prof. Henry extended the series so as to include seven successive
inductions, sometimes called inductions of the first, second, third and
other orders. Frequently ribbon coils (see Coil, Ribbon,) are used in
these experiments.
Coils, Sectioned.
A device for prolonging the range of magnetic attraction. It consists of
a series of magnetizing coils traversed by an iron plunger. As it passes
through them, the current is turned off the one in the rear or passing
to the rear and turned into the next one in advance. The principle was
utilized in one of Page's electric motors about 1850, and later by
others. The port-electric railroad, q. v., utilizes the same principle.