Shovel Electrodes.
Large plate electrodes used in a medical bipolar bath. (See Bath,
Bipolar.)
Shunt.
In a current circuit a connection in parallel with a portion of the
circuit. Thus in a dynamo a special winding for the field may have its
ends connected to the bushes, from which the regular external circuit
also starts. The field is then wound in shunt with the armature. In the
case of a galvanometer a resistance coil may be put in parallel with it
to prevent too much current going through the galvanometer; this
connection is a shunt.
The word is used as a noun, as "a shunt," or "a connection or apparatus
in shunt with another," and as an adjective, as "a shunt connection," or
as a verb, as "to shunt a battery."
Shunt Box.
A resistance box designed for use as a galvanometer shunt. (See Shunt,
Galvanometer.) The box contains a series of resistance coils which can
be plugged in or out as required.
Shunt, Electro-magnetic.
In telegraphy a shunt for the receiving relay consisting of the coils of
an electro-magnet. It is placed in parallel with the relay. Its poles
are permanently connected by an armature. Thus it has high
self-induction.
On opening and closing the circuit by the sending key, extra currents
are produced in the shunt. The connections are so arranged that on
making the circuit the extra current goes through the relay in the same
direction as the principal current, while on breaking the circuit the
induced current goes in the opposite direction.
Thus the extra currents accelerate the production and also the cessation
of signalling currents, tending to facilitate the operations of sending
despatches.
Shunt, Galvanometer.
A resistance placed in parallel with a galvanometer, so as to short
circuit its coils and prevent enough current passing through it to
injure it. By knowing the resistance of the shunt and of the
galvanometer coils, the proportion of current affecting the galvanometer
is known. This gives the requisite factor for calculation. (See
Multiplying Power of Shunt.)
Shunt Ratio.
The coefficient expressing the ratio existing between the current in a
shunt and in the apparatus or conductor in parallel with it. (See
Multiplying Power of/ Shunt.)
Shunt Winding.
A dynamo or motor is shunt-wound when the field magnet winding is in
shunt or in parallel with the winding of the armature.
Shuttle Current.
A current alternating in direction; an alternating current.