Transformer, Commuting.
A type of continuous current transformer, resembling a dynamo with
armature and field both stationary, but with revolving commutator, by
which the magnetic polarity of a double wound armature is made to
rotate. This secures the desired action, of a change or lowering of
potential.
Transformer, Continuous Alternating.
An apparatus for transforming a continuous into an alternating current
or the reverse. The combination of a continuous current dynamo with an
alternating current one is sometimes employed. It is a form of motor
dynamo.
Another type is a regular dynamo with ordinary commutator and with, in
addition thereto, two, three or four contact rings, connecting to as
many symmetrically disposed points in the winding of the armature. This
will give out or receive alternating currents of two, three or four
phases according to the number of collecting rings. One winding serves
for both alternating and continuous currents.
Transformer, Continuous Current.
A machine of the dynamo type for changing the potential of a circuit. In
one form two armatures are mounted on one shaft in a single field or in
separate fields; one is a motor armature driven by the original current;
the other generates the new current. This is a motor dynamo. In 1874
Gramme constructed a machine with ring armature with two windings, of
coarse and fine wire respectively, and with independent commutators.
Such dynamo could transform currents up or down.
Continuous current transformers have attained an efficiency of 83 per
cent. at full load, and of 75 per cent. at half load. Owing to the
balancing of the self-inductions of the two windings these machines do
not spark. As the driven and driving parts are contained in one rotating
part their friction is very slight.
Transformer, Core.
A transformer wound upon an enclosed core, such as the hedgehog
transformer (see Transformer, Hedgehog), or common induction coil.