Coil and Plunger, Differential.
An arrangement of coil and plunger in which two plungers or one plunger
are acted on by two coils, wound so as to act oppositely or
differentially on the plunger or plungers. Thus one coil may be in
parallel with the other, and the action on the plunger will then depend
on the relative currents passing through the coils.
Coil, Choking.
A coil of high self-induction, used to resist the intensity of or
"choke" alternating currents. Any coil of insulated wire wound around
upon a laminated or divided iron core forms a choking coil. The iron
coil is usually so shaped as to afford a closed magnetic circuit.
A converter or transformer acts as a choking coil as long as its
secondary is left open. In alternating current work special choking
coils are used. Thus for theatrical work, a choking coil with a movable
iron core is used to change the intensity of the lights. It is in
circuit with the lamp leads. By thrusting in the core the self-induction
is increased and the current diminishes, lowering the lamps; by
withdrawing it the self-induction diminishes, and the current increases.
Thus the lamps can be made to gradually vary in illuminating power like
gas lights, when turned up or down.
Synonyms--Kicking Coil--Reaction Coil.
Fig. 97. DIFFERENTIAL COILS AND PLUNGERS.
Fig. 98. BISECTED COILS.