Improvements in and having relation to Dynamo Electric Machines.
Year: 1894

page_text: Date of Application, 9th Feb., 1894
Complete Specification Left, 13th Mar., 1894-Accepted, 5th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in and having relation to Dynamo Electric
Machines.
A communication to him from abroad by ISAAC NEWTON LEWIS, of New York,
United States of America, Electrician.
I, WILLIAM LLOYD WISE, of No. 46 Lincoln's Inn Fields, in the County of
London, Consulting Engineer and Chartered Patent Agent, do hereby declare the
nature of this invention to be as follows:-
This invention relates more particularly to dynamo electric machines. operated
by a power which drives the machine at a varying or fluctuating speed.
As is well known the voltage or output of a dynamo of ordinary construction
will, other things being equal, rise with the speed of rotation of its armature.
The principal aim of this invention is to secure a practically constant voltage or
output irrespective of the speed.
As will be apparent the invention applies especially to cases where the current
demanded of the machine for operating the translating device or devices, is
practically constant in amount.
This invention consists in a method of automatically regulating a dynamo
machine to deliver a substantially constant potential irrespective of the speed by
increasing the strength of a current which cuts down the field magnetism with an
increase of speed and vice versa, thereby automatically regulating the voltage so
that any tendency to increase thereof with increase of speed will be practically
compensated for by the decrease of the magnetic field.
In carrying out this invention the opposing or neutralizing current which responds
to or varies automatically with the speed may be obtained and applied in any way,
the only essential being that it shall rise with the rise of speed in sufficient amount
or in such ratio to the main magnetizing power that the strength of the field
magnetism shall decrease and thereby keep down the voltage. The most obvious
and simple manner of obtaining and applying such current is to include an opposing
or demagnetizing coil in a circuit with the armature of the machine, the effect being
that the higher the speed of the armature and the higher the voltage thereof the
greater the current which will flow in said coil. I do not limit myself, however, to
using the armature current of the machine itself or to varying the opposing current
by variations in the voltage of the armature itself, since, as will be obvious, the
increase of current might be brought about in other ways where the speed rises.
As will be obvious a dynamo having its voltage governed in accordance with this
invention in its simplest form may be said to be a compound wound dynamo having
its series coil reversed or so proportioned in its effect to another source of field
magnetism that the increased current passing through the series coil upon an
increase of speed weakens the magnetic field and thereby keeps the voltage down
at the increased speed. The field magnetism may be obtained either in shunt from
the armature of the machine or from any other independent source, but it is
preferred to use an independent or separate source of excitation which determines
the polarity of the machine and is practically constant or varies only in such degree
as not to prevent the increased current in the main from cutting down the field
strength at the increased speed. The shunt coil may, as well understood in the art,
be a shunt across the brushes of the armature direct or may be a shunt across the
whole external circuit

page_text: In all cases there is of course a critical speed determined by the winding up to
which the voltage when the machine starts into operation will increase but beyond
which any
further increase of speed will be accompanied by the compensating or
regulating action above described, resulting in a practical constancy of voltage
although the speed may fluctuate within any limits above such critical speed.
This invention is particularly applicable to cases where the external resistance is
low and the resistance of the armature itself is low since under these conditions a
small increase in the voltage will produce a large increase in the amount of current
flowing in the main circuit coil and when the machine is shunt wound will produce
a comparatively small increase in the derived circuit coil.
Dated this 9th day of February 1894.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.
COMPLETE SPECIFICATION.
Improvements in and having relation to Dynamo Electric
Machines.
A communication from abroad by ISAAC NEWTON LEWIS, of Fort Wadsworth,
Richmond County, New York, United States of America, Electrician.
I, WILLIAM LLOYD WISE of No. 46 Lincoln's Inn Fields in the County of
London, Consulting Engineer and Chartered Patent Agent, do hereby declare
the nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
This invention relates more particularly to dynamo electric machines operated
by a power which drives the machine at a varying or fluctuating speed.
As is well known the voltage or output of a dynamo of ordinary construction
will, other things being equal, rise with the speed of rotation of its armature.
The principal aim of this invention is to secure a practically constant voltage or
output irrespective of the speed.
As will be apparent the invention applies especially to cases where the current
demanded of the machine for operating the translating device or devices, is
practically constant in amount.
The invention consists in the combination with the field magnet excited from any
suitable source, of an opposing or demagnetizing coil in the main or principal
circuit with the armature of the machine, the effect being that the higher the
speed of the armature and the higher the voltage thereof the greater the current
which will flow in said coil.
As will be obvious a dynamo having its voltage governed in accordance with
this invention may be said to be a compound wound dynamo having its series coil
reversed or so proportioned in its effect to another source of field magnetism that
the increased magnetism passing through the series coil upon an increase of speed
weakens the magnetic field and thereby keeps the voltage down at the increased
speed. The field magnetism may be obtained either in shunt from the armature of
the machine or from any other independent source, but I prefer to use an
independent or separate source of excitation which determines the polarity of the
machine and is practically constant or varies only in such degree as not to prevent
the increased current in the main from cutting down the field strength at the
increased speed. The shunt coil may, as well understood in the art, be a shunt
across the brushes of the armature direct or may be a shunt across the whole
external circuit and as will be presently explained in connection with the
drawings wherein;

page_text: Fig. 1, is a diagram illustrating a machine adapted for carrying out the
invention; and—
Fig. 2, a diagram of another arrangement of circuits.
In the drawings T, typifies the armature and B2, the field magnet.
13, indicates the translating device or devices which are operated by current.
taken from the armature and delivered thereto over the wires or connections a, b.
b, in Fig. 1, is a field magnet coil which forms the principal field energizing coil
In Fig. 1, I
of the machine and is supplied with current from any desired source.
have shown it as connected at the points x, y, to the circuit 9, 10, so as to be fed.
in shunt to the whole external circuit. When so fed as a shunt it is preferably.
made of fine wire as well understood in the art. The said principal coil might,
however, be fed from an independent source typified at D', as a storage battery or
other generator of electricity.
a, is the regulating coil which in Fig. 1, is illustrated as a main circuit coil so.
that its current will vary directly with any variation of voltage of the armature.
itself. The coil a, as shown, is wound reversely to the coil b, so as to act as a
demagnetizing or opposing coil tending to cut down the field magnetism and,.
therefore, to reduce the voltage of the armature. The proportioning of the effects
of the two coils by the number of turns and their resistance is made such that when
the voltage of the armature rises from increase of speed the opposing effects of the
main circuit coil shall rise in proper ratio with respect to any increase of current.
in the other coil, to result in the production of a field which is weaker with the
increase of speed. As will be seen any tendency to increase of voltage of the
armature due to increase of speed will be thereby automatically compensated for
as the increased current thereby flowing in coil a, will cut down the field
magnetism and bring the voltage or electro-motive force of the armature back to
normal.
It will be understood by electricians that the proportions of the various coils are
I have shown the
to be determined by the particular circumstances of each case.
regulating coil a, as wound directly upon the field magnet itself but, as well under-
stood by electricians, it might be applied in other ways or in other positions so as
to have the effect, when the increased current flows through it, of cutting down the
electro-motive force in the armature coils. Hence it to be understood that the
use of the coil in the manner shown directly upon the field magnet is simply
typical of any coil that operates in a similar manner to control the voltage or
electro-motive force of the armature when the speed increases.
In the diagram Fig. 2, I illustrate that modification of the invention before.
referred to which involves the use of a principal energizing coil b, supplied in a
shunt directly across the terminals of the arinature.
In all cases there is of course a critical speed determined by the winding up to
which the voltage when the machine starts into operation will increase but beyond
which any further increase of speed will be accompanied by the compensating or
regulating action above described, resulting in a practical constancy of voltage
although the speed may fluctuate within any limits above such critical speed.
The invention is particularly applicable to cases where the external resistance is.
low and the resistance of the armature itself is low since under these conditions a
small increase in the voltage will produce a large increase in the amount of current
flowing in the main circuit coil and when the machine is shunt wound will produce.
a comparatively small increase in the derived circuit coil.
Having thus particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
The combination in a dynamo electric machine for delivering constant potential
with variable speed of driving, of two field magnet coils one of which is the
principal energizing field coil while the other is wound to oppose the effect of the

page_text: first and is connected into the main circuit of the armature so as to cut down the
field magnetism when the speed of the armature rises, as and for the purpose
described.
Dated this 13th day of March 1894
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.