Improvements in or Connected with Dynamo-electric Machines.
Year: 1888

page_text: COMPLETE SPECIFICATION.
Improvements in or Connected with Dynamo-electric Machines.
I, ERNST HEINRICH GEIST, Engineer, of Cologne, in the German Empire, do
hereby declare the nature of my invention, and in what manner the same may
be performed, to be particularly described and ascertained in and by the following
statement :-
The present invention has for its object to construct dynamo-electric machines in
such a manner, that they may be joined in parallel while giving off alternating
currents.
Fig. 1, of the annexed drawing represents a 6 pole dynamo-machine in which the
inducing magnets or coils surround the induced magnets or armature.
I will suppose, that the machine is turned in the direction of the arrow, and that the
direction of the current in the coils is as indicated in the drawing. If now the
direction of the current in the inducing coils is reversed, the induced currents will
also tako an opposite course. Consequently, if the coils of the inducing magnets are
fed with alternating currents, the induced coils (or the armature) will likewise give
out alternating currents. If several machines of this kind are excited by the same
alternating current machine, they will, if coupled in parallel, give out current which
at any given inoment has the same direction and tension in all machines.
In order that the inducing magnets of dynamo-electric machines may be fed with
alternating currents, it is necessary to construct the iron core of these magnets in
such a manner, that electric currents cannot be generated in the iron, or only to a
harmless degree, and that consequently the iron core of the inducing or field magnets
satisfies the same requirements as the iron of the induced magnets or armature.
For this reason the said core must be composed of insulated iron wire or insulated
iron-tape placed approximately parallel to the axis of the magnet, or of other suitably
shaped iron parts, or if massive iron is used, it must be recessed or sub-divided in
such a manner, that no currents can be produced in the iron, or only to a harmless
degree.
Fig. 2, represents the same machine as in Fig. 1, except that the pole pieces are
omitted, because their connection with the iron core constructed as described would

page_text: be difficult, and because they become superfluous when tho radial depth of the coils or
of the winding is so small that the induction will be sufficiently perfect without.
them.
The inducing magnets, like the induced magnets, are therefore wound along their
entire length.
A special case of this arrangement as represented by Fig. 3, is that, in which the
current has the same direction in all parts of the equally wound coils of the single
inducing magnet, the inducing magnet being therefore pole-less, as well as the
armature, so that in the latter the current has at any given moment the same
direction in all parts of its equally wound coils.
The winding of the induced magnet may be interrupted at one or more places, the
different parts, being joined in parallel and connected with the commutator rings,
supply current to the external circuit.
Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same may be performed, I declare that I claim :
1. A dynamo-electric machine in which the iron parts of the field magnets are
composed of insulated wire or tapo (or of wires, tapes or sections insulated or
separated from each other) the longitudinal axes of the said wires or tapes being
parallel or nearly parallel to the axes of the magnets, similar to the iron cores of
armatures or transformers; also the exciting of field magnets constructed as described
with alternating currents, and the combination of several machines excited as described
and joined in parallel.
2. A dynamo-electric machine without pole piece, substantially as described.
3. A dynamo-electric machine without pole, substantially as described.
Dated this 28th day of July 1888.
ERNST HEINRICH GEIST.
By Fairfax & Wetter,
433, Strand, London,
Sub-agents.