Improvements in or appertaining to Self-regulating Dynamo-electric Machines, and Improvements in the Method of Generating and Maintaining thereby Electric Currents of Constant or Approxi- mately Constant Quantity in Circuits of Varying Resistance.
Year: 1889

page_text: Date of Application, 31st Dec., 1889
Complete Specification Left, 30th Sept., 1890-Accepted, 22nd Nov., 1890
PROVISIONAL SPECIFICATION.
Improvements in or appertaining to Self-regulating Dynamo-electric
Machines, and Improvements in the Method of Generating and
Maintaining thereby Electric Currents of Constant or Approxi-
mately Constant Quantity in Circuits of Varying Resistance.
A communication from abroad by WILLIAM STANLEY, Junior, of Great Barrington,
State of Massachusetts, United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster & 323 High Holborn, in the County of Middlesex, Civil
Enginner, do hereby declare the nature of this invention to be as follows:-
The invention relates to the construction and operation of that class of electric
generators employed for maintaining a constant current in the work-circuit while
the amount of work being done in such circuit is varied.
The object of the invention is to provide a simple and efficient form of generator
which will operate automatically to deliver a constant or approximately constant
current throughout considerable variations in the load placed upon it, without
necessitating the employment of external regulating apparatus.
In constructing a generator for delivering a constant current under varying loads,
it must be borne in mind that the current flowing is dependent, first upon the electro-
motive force originating the current, and second upon the resistance which the
current encounters, being directly proportional to the former and inversely propor-
tional to the latter. It follows then that in order that the current may remain constant,
the electromotive force must be increased in proportion as the resistance is increased,
and vice versa. The electromotive force varies, in any given instance, with the number
of lines of force cut per unit of time by the armature coils. For this reason it has
been customary to increase the field of force of a generator when an increase of
electromotive force is desired, and to decrease the field of force as the value of the
electromotive force desired is diminished.
The purpose of the present invention is to produce the required variations in the
electromotive force for delivering a constant or approximately constant current, by
causing variations in the resistance of the work-circuit to occasion sufficient changes
in the inductive actions taking place between the armature and field-magnet to vary
the number of lines of force cutting the armature coils proportionately to the variations
in the electromotive force required. This is accomplished by developing opposing
magnetic potentials on the part of the field-magnet and armature, and permitting the
excess of the former to develop resultant lines of force which thread through or cut
the armature coils, and by varying the magnetic potential of the armature by the
variations in the phase, time and strength of the current flowing in the coils, so that
the excess of the effective magnetic potential of the field-magnet above that of the
armature, will vary directly as the work being done. From this it will follow that
the number of lines of force threading the armature coils will vary with variations
in load.
For the purpose of obtaining very considerable variations in electromotive force
from slight variations in current, the armature core is wound with coils having a large
number of convolutions, so that a slight decrease, for instance, in the value of the
current, will result in a great decrease in the number of ampère turns in the armature.
This tends to correspondingly lessen the magnetic potential of the armature and permit
more lines of force to develop and thread the armature coils. The number of armature
convolutions being great, these additional lines of force will produce a great increase
in the electromotive force. By properly proportioning the parts, this increase of

page_text: electromotive force may be made of such value that the current delivered will vary
only between narrow limits under all conditions.
The revolution of the armature carrying the coils past the poles of the field-magnet
tends to produce an alternating current in the armature coils, and were the rise and
fall of the alternate armature-poles, due to this current, coincident with the passage
of the coils across the alternate north and south poles of the field-magnet, then the
magnetic polarization of the armature would occur at such times as to allow practically
no lines of force to flow through the armature coils, for there would be a magnetic-
potential on the part of the field-magnet due to a given number of ampère turns,
opposed by the magnetic potential on the part of the armature, due approximately to
the same number of ampère turns.
In practice, the relative time between the appearance of maximum armature
polarization due to the current in the armature coil, and the passage of a pole thus
produced across the field-maguet pole, varies with the resistance of the external circuit.
It is evident that the difference in the time of the occurrence of the maximum armature
polarization and the passage of the armature pole across the field-magnet pole, will,
to a great extent, determine the number of lines of force permitted to thread. the
armature coils and therefore the electromotive force which will be produced in the
armature coils with a given field of force.
The relative positions of the armature pole at the time of maximum strength and
the field-magnet pole vary with the resistance in the external circuit of the
armature, the displacement between the two opposing poles being increased as the
resistance of the external circuit is increased, thereby lessening the opposing effect
of the armature upon the field-magnet and allowing more lines of force to pass
through the armature coils, thus increasing the electromotive force of the armature.
The opposing effect of the armature current in cutting down the field-magnet potential
is thus diminished with an increase of load, not only by the diminution in the quantity
of the current flowing but also by the shifting of the positions which the armature
poles occupy with reference to the field-magnet when the maximum armature
polarization appears.
In constructing a machine, a field strength for operating upon the armature is
selected according to the well-known principles governing the construction of dynamo
electric machines, reference being had to the size of the machine and output desired,
and then having selected the current required to be delivered by the machine, wire is
wound upon the armature preferably in such a manner as to produce strong local poles,
and of such length that when traversed by the normal current for which the machine
is designed it will produce a magnetic potential upon the part of the armature approxi-
mately the same as the magnetic potential of the field-magnet, that is to say,
the number of ampère turns in both the field-magnet and armature would be
approximately equal. The energizing force of the field-magnet remains practically
constant, but the magnetic potential or number of lines of force produced with a con-
stant energizing force depends upon the condition of the magnetic circuit provided
therefor. It is the function of the armature of the machine to vary the magnetic
conductivity of this magnetic circuit, and this it does by opposing to the field-
magnetic potential the counter magnetic potential of the armature, which counter
magnetic potential varies with the work being done.
An application of the invention will be described in connection with the accompany-
ing drawings, in which Figure 1 is a side elevation of a field-magnet and armature,
and Figure 2 is an enlarged detail showing the armature in a different position with
reference to the field-magnet poles.
Referring to the figures, A represents the armature and F the field-magnet of an
electric generator. The field-maguet is constructed with poles N. S. N. S., in this
instance, eight in number. The poles are wound with coils f f which may be con-
nected in the circuit of an independent source of currents or excited in any manner
serving to secure constant excitation.
The armature is shown as having eight polar projections a¹, a, a³, etcetera. These
polar projections have in this instance laterally projecting flanges or lugs b.

page_text: Coils c¹, 2, 3, having a great number of convolutions, are wound about the poles and
beneath the lugs and tend to produce strong magnetic poles at the polar projections.
The direction of the winding upon the armature poles is reversed at each succeeding
pole, as indicated, so that the tendency of the current traversing the coils is to produce
opposite polarities at alternate poles. The alternate field-magnet poles are also of
opposite polarity. The coils of the armature consist of many convolutions, so that a
slight variation in the quantity of current flowing through the coils produces con-
siderable variation in the ampère turns.
The principal features entering into the operation of the machine are the following:
The field-magnet tends to develop a large number of lines of force. The revolution
of the armature carrying the coils through these lines of force develops an alternating
current in the coils. This alternating current tends to set up, inthe armature core,
lines of force at such moments as to oppose or stem back a portion of the lines of force
of the field-magnet pole toward which it is moving, thus permitting only comparatively
few to be effective in generating an electromotive force in the armature coils. These
two tendencies to establish lines of force may properly be considered as the magnetic
potentials of the field and armature. The excess of the magnetic potential of the
field above that of the armatureatthe time when the field poles are effective in sending
lines of force through the armature core is that which is effective in producing electro-
motive force in the armature coils. The number of lines of force resulting from this
difference of magnetic potentials and which are thus effective in developing current in
the armature coils will remain approximately constant so long as the resistance offered
to the flow of the current on the work-circuit remains constant, but as the resistance
increases, the tendency of the armature current to be diminished will, for the reasons
already stated, allow a greater number of lines of force to cut the armature coils, thus
increasing the electromotive force sufficiently to hold the current approximately at a
predetermined value. In practice, there will be a slight decrease in the current unless
certain compensation is secured by other means. As already set forth, the shifting of
time of development of maximum polarization of the armature with reference to the
passage of the armature poles across the field-magnet poles, by changes in the
resistance of the armature circuit, will be effective in producing the compensation,
and in practice such shifting may be made of sufficient effect to render the current
very nearly constant in value.
In order to obtain the full effect of the counter influence of the shifting of time of
maximum magnetic potential of the armature, the lateral flanges or lugs bb may be
provided. These encompass such a portion of the armature periphery as to afford a
more or less perfect path for the lines of force of the field-magnet from one pole to its
neighbour when in certain positions of the armature. It is evident that by this con-
struction a less displacement of the phase of the armature magnetization is necessary
in order to produce the required opposition to the field-magnetic potential to stem back
the lines of force and prevent them from threading the armature coils.
In practice, excellent results are obtained by employing a field-magnet with eight
poles and having a cylindrical opening 15inches in diameter and 11 inches in
length, the core projections being about 3 inches thickandhaving their ends bevelled,
the width of the face between the edges of the bevels being 12 inches. These poles
are each wound with 588 turns making a total of 4704 turns. The size of wire is
No. 11. The armature is also made with eight poles and is 10 inches in length,
and 15 inches in diameter. The width of the pole cores is 3 inches and the lugs
projecting one inch on each side make a total width of 5 inches. The poles are
wound with seven layers of No. 16 wire, twenty-three turns per layer.
This machine may be run at 1425 revolutions per minute, and, with a current
of five and a half to six ampères in the field-magnet coils, will yield nine or
mine and a half ampères, at an electromotive force of 3800 volts.
Dated this 30th day of December 1889.
WM. P. THOMPSON & Co.,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in or appertaining to Self-regulating Dynamo-electric
Machines and Improvements in the Method of Generating and
Maintaining thereby Electric Currents of Constant or Approxi-
mately Constant Quantity in Circuits of Varying Resistance.
A communication from WILLIAM STANLEY, Junior.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, and 323, High Holborn, in the County of Middlesex,
Civil Engineer, 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:―
The invention relates to the construction and operation of that class of electric
generators employed for maintaining a constant current in the work-circuit while the
amount of work being done in such circuit is varied.
The object of the invention is to provide a simple and efficient form of generator
which will operate automatically to deliver a constant or approximately constant
current through considerable variations in the load placed upon it, without necessitating
the employment of external regulating apparatus.
In constructing a generator for delivering a constant current under varying loads,
it must be borne in mind that the current flowing is dependent, first upon the electro-
motive force originating the current, and secondupon the resistance which the current
encounters, being directly proportional to the former and inversely proportional to
the latter. It follows then that, in order that the current may remain constant, the
electromotive force must be increased in proportion as the resistance is increased, and
The electromotive force varies, in any given instance, with the number
of lines of force cut per unit of time by the armature coils. For this reason it has
been customary to increase the field of force of a generator when an increase of
electromotive force is desired, and to decrease the field force as the value of
the electromotive force desired is diminished.
vice versa.
The purpose of the present invention is to produce the required variations in the
electromotive force for delivering a constant or approximately constant current, by
causing variations in the resistance of the work-circuit to occasion 'sufficient changes
in the inductive actions taking place between the armature and field-magnet to vary
the number of lines of force cutting the armature coils proportionately to the variations
in the electromotive force required. This is accomplished by developing opposing
magnetic potentials on the part of the field-magnet and armature,and permitting the
excess of the former to develop resultant lines of force which thread through or
cut the armature coils, and by varying the magnetic potential of the armature
by the variations in the phase, time and strength of the current flowing in
the coils, so that the excess of the effective magnetic potential of the field-magnet
above that of the armature will vary directly as the work being done. From
this it will follow that the number of lines of force threading the armature
coils will vary with variations in load.
For the purpose of obtaining very considerable variations in electromotive force
from slight variations in current, the armature core is wound with coils having a large
number of convolutions, so that a slight decrease, for instance, in the value of the
current will result in a great decrease in the number of ampère turns in the armature.
This tends to correspondingly lessen the magnetic potential of the armature and
permit more lines of force to develop and thread the armature coils. The number
of lines of armature convolutions being great, these additional lines of force will
produce a great increase in the electromotive force. By properly proportioning
the parts, this increase of electromotive force may be made of such value that the
current delivered will vary only between, narrow limits under all conditions.

page_text: The revolution of the armature carrying the coils past the poles of the field
magnet, tends to produce an alternating current in the armature coils, and, were the
rise and fall of the alternate armature poles, due to this current, coincident with
the passage of the coils across the alternate north and south poles of the field mangets,
then the magnetic polarization of the armature would occur at such times as to
allow practically no lines of force to flow through the armature coils, for there would
be a magnetic potential on the part of the field magnet due to a given number of
ampère turns, opposed by the magnetic potential on the part of the armature, due
approximately to the same number of ampère turns.
In practice, the relative time between the appearance of maximum armature
polarization due to the current in the armature coil and the passage of a pole thus
produced across the field magnet pole varies with the resistance of the external
circuit. It is evident that the difference in the time of the occurrence of the maximum
armature polarization and the passage of the armature pole across the field magnet
pole will, to a great extent, determine the number of lines of force permitted to thread
the armature coils, and therefore the electromotive force which will be produced in
the armature coils with a given field of force.
+
The relative positions of the armature pole at the time of maximum strength and
the field magnet pole vary with the resistance in the external circuit of the armature,
the displacement between the two opposing poles being increased as the resistance of the
external circuit is increased thereby lessening the opposing effect of the armature upon
the field magnet and allowing more lines of force to pass through the armature coils,
thus increasing the electromotive force of the armature. The opposing effect of the
amature current in cutting down the field magnet potential is thus diminished with
an increase of load, not only by the diminution in the quantity of the current flowing,
but also by the shifting of the positions which the armature poles occupy with reference
to the field magnet when the maximum armature polarization appears.
In constructing a machine, a field strength for operating upon the armature is
selected according to the well-known principles governing the construction of dynamo
electric machines, reference being had to the size of the machine and output desired,
and then, having selected the current required to be delivered by the machine, wire
is wound upon the armature, preferably in such a manner as to produce strong local
pcles and of such length that when traversed by the normal current for which the
machine is designed, it will produce a magnetic potential upon the part of the
armature approximately the same as the magnetic potential of the field magnet, that
is to say, the number of ampère turns in both the field magnet and armature, would
be approximately equal. The electromotive force applied to the field magnets
remains practically constant, but the magnetic potential or number of lines of force
produced with the energising force depends upon the conditions of the magnetic
circuit provided therefor.
It is the function of the armature of the machine to vary the magnetic con-
ductivity of this magnetic circuit, and this it does by opposing to the field magnetic
potential, the counter magnetic potential of the armature, which counter magnetic
potential varies with the work being done.
An application of the invention will be described in connection with the accom-
panying drawings, in which-
Figure 1. is a side elevation of a field magnet and armature, and-
Figure 2. is an enlarged detail showing the armature in a different position with
reference to the field magnet poles.
Referring to the figures,-
A. represents the armature and F the field magnet of an electric generator.
The field magnet is constructed with poles N. S. N. S. in this instance, & in
number. The poles are wound with coils ff which may be connected in the circuit
of an independent source of currents, or excited in any manner serving to secure an
approximately constant electromotive force at its terminals.
The armature is shown as having eight polar projections a¹, a², a³.
projections have in this instance laterally projecting flanges or lugs b.
These polar
Coils c¹, c², c³,

page_text: having a great number of convolutions, are wound about the poles and beneath the
lugs, and tend to produce strong magnetic poles at the polar projections.
The direction of the winding upon the armature pole is reversed at each succeeding
pole, as indicated, so that the tendency of the current traversing the coils is to
produce opposite polarities at alternate poles. The alternate field magnet poles are
also of opposite polarity. The coils of the armature consist of many convolutions, so
that a slight variation in the quantity of current flowing through the coils produces
considerable variation in the ampère turns.
The principal features entering into the operation of the machine are the
following:
The field magnet tends to develop a large number of lines of force. The revolution
of the armature carrying the coils through these lines of force develops an alternating
current in the coils. This alternating current tends to set up, in the armature core,
lines of force at such moments as to oppose or stem back a portion of the lines of
force of the field magnet pole towards which it is moving, thus permitting only com-
paratively few to be effective in generating an electromotive force in the armaturo
coils. These two tendencies to establish lines of force may properly be considered as
the magnetic potentials of the field and armature. The excess of the magnetic
potential of the field above that of the armature at the time when the field poles are
effective in sending lines of force through the armature core is that which is effective
in producing electromotive force in the armature coils. The number of lines of force
resulting from this difference of magnetic potentials and which are thus effective in
developing current in the armature coils, will remain approximately constant so long
'as the resistance offered to the flow of the current on the work-circuit remains
constant, but as the resistance increases, the tendency of the armature current to be
diminished will; for the reasons already stated, allow a greater number of lines of
force to cut the armature coils, thus increasing the electromotive force sufficiently
to hold the current approximately at a predetermined value. In practice, there
will be a slight decrease in the current unless certain compensation is secured by
other means.
As already set forth the shifting of time of development of maximum polarization
of the armature with reference to the passage of the armature poles across the field
magnet poles, by changes in the resistance of the armature circuit will be effective
in producing the compensation, and, in practice, such shifting may be made of
sufficient effect to render the current very nearly constant in value.
In order to obtain the full effect of the counter influence of the shifting of time
of maximum magnetic potential of the armature the lateral flanges or lugs b, b, may
be provided. These encompass such a portion of the armature periphery as to afford
a more or less perfect path for the lines of force of the field magnets from one pole
to its neighbour when in certain positions of the armature.
It is evident that, by this construction, a less displacement of the phase of the
armature magnetisation is necessary in order to produce the required opposition to
the field magnetic potential to stem back the lines of force and prevent them from
threading the armature coils.
In practice excellent results are obtained by employing a field magnet with eight
poles and having a cylindrical opening 15thsinches in diameter and 11 inches in
length, the core projections being about 3 inches thick, and having their ends
bevelled, the width of the face between the edges of the bevels being 12 inches.
These poles are each wound with 588 turns, making a total of 4,704 turns. The
wire is 4-1728 square millimetres in sectional area. The armature is also made with
eight poles, and is 104 inches in length, and 153 inches in diameter. The width of
the pole cores is 3 inches, and the lugs project 1 inch on each side, making a
total width of five inches. The poles are wound with seven layers of wire having
23 turns per layer, the wire having a sectional area of 1:309 square millimetres.
This machine may be run at 1,425 revolutions per minute, and, with a current of
5 to 6 ampères in the field magnet coils, will yield 9 to 9 ampères at an electro-
motive force of 3,800 volts.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion (as communicated to me by my foreign correspondent) and in what manner the
same is to be performed, I declare that what I claim is:-
CLAIMS.
1. The method of generating and maintaining a nearly constant current in a
circuit of varying resistance, which consists in applying an approximately constant
electromotive force to the field terminals of a dynamo electric machine, winding the
armature of said machine to have a large number of ampère turns so as to produce
an opposing magnetic potential to that of the field variable with slight changes in the
current and to alter the phase of the current in the armature with reference to the
relative position of the armature and field magnet at time of maximum current
in the former, whereby only enough lines are allowed to thread the armature to
produce in it an electromotive force requisite to maintain approximately constant
the current flowing through the external circuit.
2. The method of governing the output of a dynamo machine by altering the ratio
of the magnetic potentials of field and armature, and by the displacement of the
phase of the current in the armature due to the resistance of the external circuit
substantially as described.
3. The winding of a toothed armature substantially as described, so that a small
increase of current flowing through it will greatly increase the number of ampère
turns in it, and will alter the time of maximum current with reference to the position
of the armature relatively to the field thus securing an approximately constant current
in the external circuit.
4. The apparatus for generating and maintaining electric currents of constant
or approximately constant quantity, in circuits of varying resistance, constructed
substantially as described.
1
C
1
1000
WM. P. THOMPSON & Co.,
Agents: