Methods of and Apparatus for Varying the Frequency and Number of Phases in a Polyphase Electric Current, and for Converting Alternating Electric Currents into Continuous Currents, and for other purposes.
Year: 1894

page_text: Date of Application, 7th June, 1894
Complete Specification Left, 22nd Feb., 1895-Accepted, 13th Apr., 1895
PROVISIONAL SPECIFICATION.
Methods of and Apparatus for Varying the Frequency and Number
of Phases in a Polyphase Electric Current, and for Converting
Alternating Electric Currents into Continuous Currents, and for
other purposes.
I, HENRY AUGUSTUS ROWLAND, of 913 Cathedral Street, Baltimore, Mary-
land, United States of America Professor of Physics at Johns Hopkins
University, do hereby declare the nature of this invention to be as follows:-
My invention relates to methods of varying the frequency and number of
phases in a polyphase current and the object of this invention is to produce
means for starting synchronous and other motors and causing them to run at
different speeds, and to accomplish with other translating devices a variety of
other results of a like nature.
To accomplish this I use the combination with a commutator which may be
either stationary or revolving of brushes which may be either revolving or
stationary. The bars of the commutator are jointed to conductors from the
source of electricity, either directly or by means of contact rings and brushes,
and the current is carried from the commutator by brushes rubbing thereon,
these latter brushes being either fixed or revolving independently of the com-
mutator, as will be hereinafter described. Or the current may enter the brushes
and be carried off from the commutator bars, if desired. Currents from these
brushes or commutator bars may be taken directly from them when they are
stationary, or through contact rings and other brushes when revolving.
Reference is had to the accompanying drawings, in which the same parts are
indicated by the same letters, throughout the several views.
Fig. 1 represents a perspective view of a commutator and brushes mounted
on independent shafts and capable of revolving independently of each other.
Fig. 2 represents a modification of the same device in which the brushes only
revolve, the conductors being jointed directly to the bars of the commutator, which
is fixed.
Fig. 3 represents a further modification of the device shown in Fig. 1, with the
conductors jointed directly to the brushes, which are fixed, while the commutator
is adapted to revolve.
Fig. 4 represents a revolving cominutator and fixed brushes, the conductors
leading directly from the brushes to the contact brushes of a motor or dynamo.
Fig. 5 differs from Fig. 4, in having the commutator stationary and the brushes
revolving.
Fig. 6 shows a lead of the conductors somewhat different from the construction
shown in Fig. 4.
Fig. 7 shows a lead of the conductors somewhat different from the construction
shown in Fig. 5.
Fig. 8 is a similar view to that shown in Fig. I and shows a further method of
preventing the revolving brushes from leaving the commutator surface under the
action of centrifugal force.
Fig. 9 represents an end view of the revolving brushes shown in Fig. 8.
Fig. 9 represents an end view of another device for adjusting the revolving
brushes against the action of centrifugal force.
Fig. 10 shows in section a means of gearing together the shaft carrying. the

page_text: commutator and the one carrying the brushes, so that they will maintain a fixed
ratio in their speeds.
Fig. 10 represents a section along the line of Fig. 9A.
Fig. 11 represents an end view of the gearing shown in Fig. 10.
Fig. 12 represents a diagrammatic view of the revolving commutator and brushes
shown in Fig. 1, with conductors leading from the side of the revolving brushes to
the contact brushes of a motor or dynamo.
Fig. 13 represents the revolving brushes shown in Fig. 1, mounted to revolve on
the commutator of a dynamo or motor.
Fig. 14 shows the method of indicating graphically the intensity and phase of an
electro-motive force.
Fig. 15 shows the method of finding the intensity and phase of an electro-motive
force, which is the resultant of two electrc-motive forces of.different phases, acting
in series.
Fig. 16 shows the graphic method of determining the ratio of the windings in
the secondary coils of a transformer designed to produce an electro-motive force of
a different number of phases from that acting in the primaries. It also shows the
method of connecting the transformers to obtain an eight-phase from a two-phase
electro-motive force.
Fig. 17 shows one method of connecting the coils of two transformers, to obtain
an eight-phase from a two-phase current.
.
Fig. 1 shows another method of arranging the said coils to accomplish the
same result as is derived from the device shown diagrammatically in Fig. 17,
the secondary coils being in open circuit connection, and but two of said coils
being shown, the rest being omitted for the sake of clearness in the drawings.
Fig. 18 shows the ratio of the secondary winding and method of connecting the
coils of transformers to obtain a six-phase system from three transformers for closed
circuit method.
'Fig. 19 shows the ratio of the secondary of transformer coils and method of
connecting them to obtain a twelve-phase system from three transformers for closed
circuit method.
Fig. 20 shows the arrangement of the coils of three transformers to obtain a
twelve-phase system from a three-phase system.
Fig. 21 represents a diagrammatic view of a transformer constructed as
indicated in Fig. 14 connected by means of the device shown in Fig. 1 to a
synchronous motor.
Fig. 22 shows a source of an eight-phase current connected to a motor having
its commutator and brushes revolving independently.
Fig. 23 represents the transformer shown in Fig. 17, with connections to any
one of the cominutators and brush arrangements shown in Figures 4 to 7.
A represents a commutator which may be fixed and connected by conductors to
the source of polyphase currents; or may be supported on and revolve with the
shaft B, and receive the current from the windings of the generator as shown in
13 or from any other source of polyphase currents as indicated in Fig. 1.
Fig. from
each other, each ring being connected by a conductor of electricity to a bar of the
commutator.
DD, &c., are brushes rubbing on the contact rings C C, &c.
EE &c., are conductors of electricity, jointed at one end to the brushes D D &c.,
and at the other to any source of polyphase current. The number of brushes D,
and rings C, is the same as the number of phases of the polyphase current. The
number of brushes D, and rings C is the same as the number of phases of the
polyphase current. The number of bars on the commutator may be the same as
those of the brushes D and rings C; or may be any multiple of the number of
phases, the rings in the latter case being joined to two or more bars and the speed
of the commutator correspondingly reduced. Or the conductors may be connected
directly to the commutator bars as shown at E'.

page_text: FF &c., are moving brushes. rubbing on the commutator A, carried on and
revolving with the shaft G. The number of brushes need not always be the same
as the number of the commutator bars. These two shafts B and G may revolve
independently, or they may be clamped so as to revolve together, or they may
be
fitted with a fixed or a variable gear by which the speed of one may be made to
bear any ratio to the other.
F&F are fixed brushes which rub on the revolving commutator. Since there
will be a tendency of the moving brushes F to fly off from the commutator, due to
centrifugal force, I preferably provide some compensation for the tendency, such
for. instance as is shown in Figs. 8, 9, 9, 10, and 10. In Figures 8, 9, and 10,
f represents the pirot about which the brush F turns, and f³ is a weight to prevent
the brushes leaving the surface of the commutator, in consequence of the centrifugal
force produced by the revolutions. This may also be prevented by the use of
springs for by a combination of the weight and the springs. In the device shown
in 'Figures 94 and 10, F represents a revolving disk slotted as at f° into which
dovetailed slots, lugs from the brush holders F holding the brushes F° and also
lugs from the sliding weights F* project. These slots allow free longitudinal.
motion to the brush holders F and to the counterpoise weights F, and both brush
holders and weights are provided with racks and f' in their sides which mesh in.
the pinion F pivoted to the disk F between the two. It will be evident, that any
outward motion of the brush would be resisted by the outward motion of the
sliding weight in juxtaposition thereto.
In order to give a constant bearing of the brush Fo on the commutator A, the
weight is preferably made to balance. the weight of the brush and holder, and
the brush is pressed forward by a spring f" arranged in the slot f° and bearing, on
the lugas shown in Fig. 10. Instead of balanced brushes a commutator may
be used in which ordinary brushes rub on the face of a disk commutator.
HH &c., are metallic rings, electrically insulated from each other and
from the shaft G, and each connected by a conductor of electricity to one of the
brushes F.
1'1 &c., are brushes rubbing on the rings H H.
The shafts B and G may be revolved in any convenient way, such, for instance,
as the pulley P shown in Fig. 13.
KK &c., are conductors of electricity joined at one end to the brushes I l'and
leading to the translating device or devices which are to be operated, such, for
instance, as the synchronous or Tesla motor shown in diagram in Fig. 21. Or these.
conductors may be connected directly to the brushes F¹ as shown at K in
Figs. 3, 4 and 6..
While the foregoing description refers to the current as entering the commutator.
bars by the wires E and E' and being carried off from the brushes by K or K', it
may be caused to flow in the reverse direction, as the operation of the apparatus
does not depend upon the direction of the current; and wherever the operation.of
the apparatus is described with reference to the commutator and brushes having
different angular velocities, it will be understood that a commutator bar is the
equivalent of a brush and vice versá.
L. represents the shaft of a motor or other trauslating device.” L"
L shown in
Fig. 21 represents a synchronous or Tesla motor. L.shown in Figs. 13 and 22
represents a dynamo or other translating device having fixed. brushes L in addition
to the revolving brushes F. .1
Figs. 10 and 11 show a method of gearing, the shaft G which carries the
brushes F'to the shaft B which carries the commutator A. The shaft G is, hollow
allowing the shaft B to pass through it... On the end of shaft. B is a cog-wheel. B',
meshing with the cog-wheel N, which turns on the pin n secured to the rigid arm M.
The wheel N which may form part of wheel N meshes, with the cog-wheel G₁, which
is rigidly secured to the shaft G, thus causing the shaft G to revolve in a fixed ratio
to the shaft B.
:

page_text: It is obvious that a variable speed gear or any other suitable gearing for
connecting the two shafts may be adopted if desired.
Q, R, S, T, are the conductors of a two-phase system.
U and U in Figs. 17, 21, and 22 and also U in Fig. 20 are the primary coils of
the transformers.
When the apparatus is at rest, the current flowing from the conductors K K will
be identical in all respects to that entering at E E, provided the number of
brushes, rings and bars is the same throughout.
If the commutator A is driven by a synchronous motor the brushes F remaining
at rest, any pair of these brushes will yield a continuous current, which can be
taken off directly from the brushes or from the corresponding conductors K.
If the brushes F are now driven by a synchronous motor they will assume a fixed
position relative to the commutator A, and the current passing out at K K' will be
identical in every respect to that entering at E E.
'It is evident from. the above, that since in passing from a current of zero
frequency to one equal in frequency to that entering at E, the intermediate stages
have been passed corresponding to the different speeds of the brushes F F
Therefore if the brushes F F are driven at any other speed than that of synchronism
the current passing through the conductors K K will have a different frequency
than that entering at E.E.. This frequency will depend on the original frequency
combined with the difference in speed of the two parts..
From this it follows that it is entirely immaterial whether the commutator alone
revolves, or whether the brushes alone revolve, or whether both revolve, so long, as
the difference in speed of the two parts is the same.
If a part of the brushes F F only are used, the number of phases of the current.
flowing through the corresponding conductors K K will be proportionally
reduced.
The number of commutator bars to conductors, E, can be different from the
brushes and conductors K. Such a commutator will transform any polyphase
current into any other, the number of phases being in proportion to the number of
conductors E and K and the difference of the frequencies being determined by, the
relative rates of revolution of the brushes and commutators.
This device may be utilized in a variety of ways:-
(1.) To make a dynamo capable of giving out currents of any frequency
Mount, the device on the shaft of the dynamo as shown in Fig. 13, or indicated in
Fig. 2. The commutator may now become the commutator of the dynamo, and the
armature conductors may be conducted directly to the bars of the commutator.
On now revolving the brushes a polyphase current of any frequency can be obtained
from the brushes 1. The brushes can be driven from the shaft at any desired, speed
by gearing or belts,.or may be independently driven by a motor..
Pin Fig: 13 represents a pulley for driving the shaft G.
(2) This same device shown in Fig. 13 'makes a motor capable of starting and
running in a variety of ways.
1
..
a. It is a self-starting synchronous motor provided the brushes are revolved
at the proper speed and afterwards clamped to belts, gearing, etc., so as to
preserve the fixed ratio of speed.
b. When the brushes are run by a small, synchronous motor and they are fed
by a polyphase current, the motor will then be fed by a continuous current and
will start, run and stop like such a continuous current motor.
c. When running in either of these ways continuous current. can be taken off.
by a pair of fixed brushes and used for exciting the field magnets or any other
purpose.
d. The device mentioned in section a can be used to convert continuous into a
polyphase alternating current of any number of phases and any frequency.
(3.) If used to start or to vary the speed of a Tesla' or synchronous motor,
Figs. 4, 5, 6, 7, 12 and 22 show the connections for the various methods of using,

page_text: this device. The brushes F may be at rest as it is only necessary to revolve one.
part. The connections to the motor and to the source of current may be made from
either side of the device. By this arrangement current can be supplied to the
motor at any desired frequency and it is will be self starting. By regulating
the speed of the moving part, by belt, gearing or other devices the frequency of the
current reaching the motor can be controlled, and consequently its speed which will,
be in synchronism with the current reaching it. The speed of the moving part may
be decreased as the motor speed increases, and when brought to rest the motor will
reach synchronism with the original current. If the commutator be made the.
commutator of a motor and a polyphase current be supplied through the brushes FF,
Figs. 2 and 13, then the frequency of the current reaching the armature,
and the consequent speed of the armature can be varied by varying the speed of
the brushes.
(4.) To start a motor under a load, Figs. 4, 5, 6, 7, 13 and 21 and 22.
By driving the brushes by a synchronous motor, the large motor will start under a
load and run at a speed depending on the electro-motive force.
(5.) To start a synchronous motor under a load-Applied as above a synchronous.
motor will start under a load, and following the increase in the frequency of the
current reaching it, will run up to synchronism with the current from the original.
source.
(6.) Applied to the armature of a motor of the Tesla type having a laminated.
field with coils closed on themselves, it makes it a variable speed motor. The
armature and field may obviously be interchanged.
The source of polyphase currents may be a generator or a transformer or
transformers. Moreover the transformers may be so constructed that a polyphase.
current of one system is converted into a polyphase current of another system.
In Fig. 14 Oy and OX represent co-ordinate axes. The intensity of an electro-
motive force may be represented by the length of a line O Z, its phase by the angle
the line makes with another line, as L the angle it makes with OX.
In Fig. 15, a 6' and a' d' represent the intensity and phases of two electro-
motive forces. When joined in series the resultant electro-motive force will be..
represented in magnitude and phase. by the line a¹.c¹.
In the transformers of a polyphase system, electro-motive forces in different,
phases are induced, and the intensity depends on the ratio of the primary and
secondary windings. Hence any polyphase current can be obtained from any two
transformers whose phases differ in any degree from each other, although for.
symmetry all the transformers of the system should be used."
Figs. 16 and 17 represent an eight-phase system of electro-motive forces, derived
from a pair of transformers of the two-phase system. The two transformers are,
each wound with six secondary coils, the windings of two coils being proportional
to ai and of four coils proportional to i b. The coils, shown in Fig. 17 are
connected as shown in Fig. 16, the wires leading from eight points, a, b, c, d, e, f, g, h..
forming the conductors of the eight-phase system.
The conductors Q, R, S, T represent. the conductors of the two-phase system,
U and Uthe primary coils of the transformers.. In Fig. 17 an open circuit.system.
is shown, the arrangement of the wires in the secondary coils being similar, to that..
indicated by the single pair of coils a i and.i b in open circuit as shown.
On each transformer there will then be, in this case four large and four small,
coils, connected as shown in the diagram in Fig. 17ª.
Fig. 18 represents the method of connecting the secondary coils and the relation
of the windings to produce a six-phase system, and Fig. 19, that of a twelve-phase
system derived from a three-phase.
The connections are as shown in Fig. 17.
In all the examples here shown the number of transformers is equal to the number
of phases of the primary current. This, however, is not necessary as the same
principle allows us to use a different number of transformers. Thus two
transformers can be used for any polyphase primary current or a greater number

page_text: may be used at. will. For simplicity, the drawings only show the number of
transformers equal to the number of primary current phases.
Also it will be evident that the current may be carried to the transformers in the
reverse direction, the secondary coils then becoming the primary. Also that
the both primary and secondary coils may be wound as shown in the secondary
.coils.
Fig. 21 shows the combination of an eight-phase system derived from a two-
phase as in Fig. 17, with the device for varying the frequency shown in Fig. 1, and
a synchronous motor operated thereby. If the brushes F remain fixed and thie
commutator A is revolved by a synchronous motor, a continuous current is
produced in the conductors K. If not run synchronously an alternating current is
produced. If, when the commutator A is run by a synchronous motor, the
brushes F are revolved, an alternating current is produced whose frequency depends
on the original frequency and on the difference in speed between the brushes F and
the commutator A.
Any other translating device may be substituted for the synchronous motor
shown in this figure.
The conductors from the transformers may also be connected to the brushes I,
and a motor may be mounted on the shaft B, as shown in Fig. 22, in which the
brushes Fare made to revolve on the commutator A of the motor L'. If revolved
synchronously, a continuous current will be supplied to the motor, but at any other
speed an alternating current will be supplied, and hence either a continuous current
motor or au alternating current motor may be used at L².
In the diagram shown in Fig. 23, the closed circuit transformer of Fig. 17 or the
open circuit transformer of Fig. 17ª is connected to one of the combinations of
armature and brushes shown in Figs. 4 to 7.
The transformer is represented as connected to the upper device on the sheet,
and the dotted lines indicate that it may be connected to any one or more of. the
other devices. It will be seen that a continuous current will be carried off by the
pairs of conductors to the right of the said diagram, provided these devices are run
in synchronism with the current, while an alternating current will be carried off at
any other relative speed, the polyphase current from the transformer being
converted into a continuous current or an alternating by means of the commutator A
and brushes F or F¹ either or both of which may be made to revolve.
It is evident that the speed of the commutator necessary to produce continuous
currents can be reduced ; 3, etc., by making the number of the commutator
bars 2, 3, etc., times the number of wires from the transformer.
In the Specification a continuous current is considered to be an alternating
current of zero frequency.
It will thus be seen that by an arrangement similar to that herein shown, it
is possible to transform an alternating current of any number of phases and
frequency to an alternating current of any desired number of phases and frequency,
and to further change this latter current either into a continuous current, or an
alternating current of greater or less number of phases and frequency, to run
a synchronous or Tesla motor thereby at any desired speed, to start the same under
a load, and to accomplish the great variety of results hereinbefore described,
as well as many others that would readily suggest themselves to any skilled
electrician.
A
Deted the 7th dow of June 190
PHILIP M. JUSTICE;
55 & 56, Chancery Lane, London; Chartered Patent Agent,
For the Applicant.

page_text: Methods of and Apparatus for Varying the Frequency and Number
of Phases in a Polyphase Electric Current, and for Converting
Alternating Electric Currents into Continuous Currents, and for
other purposes.
I, HENRY AUGUSTUS ROWLAND of 913 Cathedral Street, Baltimore, Maryland,
United States of America, Professor of Physics at Johns Hopkins University,
lo 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:-
My invention relates to methods of varying the frequency and number of phases
in a polyphase current, and the object of this invention is to produce means for
starting synchronous and other motors and causing them to run at different speeds,.
and to accomplish with other translating devices a variety of other results of a like
nature.
To accomplish this I use the combination with a commutator which may be
either stationary or revolving of brushes which may be either revolving or
stationary. The bars of the commutator are jointed to conductors from the source
of electricity, either directly or by means of contact rings and brushes, and the
current carried from the commutator by brushes rubbing thereon, these latter
brushes being either fixed or revolving independently of the commutator, as will
be hereinafter described. Or the current may enter the brushes and be carried off
from the commutator bars, if desired. Currents from these brushes or commutator
bars may be taken directly from them when they are stationary, or through contact
rings and other brushes when revolving.
Reference is had to the drawings accompanying the Provisional Specification
in which the same parts are indicated by the same letters, throughout the several
views.
Fig. 1. represents a perspective view of a commutator and brushes mounted on
independent shafts and capable of revolving independently of each other.
Fig. 2 represents a modification of the same device in which the brushes only.
revolve, the conductors being jointed directly to the bars of the commutator, which
is fixed.
Fig. 3 represents a further modification of the device shown in Fig. 1, with the
conductors jointed directly to the brushes, which are fixed, while the commutator
is adapted to revolve.
Fig. 4 represents a revolving commutator and fixed brushes, the conductors
leading directly from the brushes to the contact brushes of a motor or dynamo.
Fig. 5 differs from Fig. 4, in having the commutator stationary and the brushes
revolving.
Fig. 6 shows a lead of the conductors somewhat different from the construction
shown in Fig. 4.
Fig. 7 shows a lead of the conductors somewhat different from the construction
'shown in Fig. 5.
Fig. 8 is a similar view to that shown in Fig. 1 and shows a further method of
preventing the revolving brushes from leaving the commutator surface under the
.action of centrifugal force.
Fig. 9 represents an end view of the revolving brushes shown in Fig. 8.
Fig. 9 represents an end view of another device for adjusting the revolving
brushes against the action of centrifugal force.
Fig. 10 shows in section a means of gearing together the shaft carrying the

page_text: what they WILI
mautam a xed
ratio in their speeds.
Fig. 10 represents a section along the line x x of Fig. 9.
Fig. 11 represents an end view of the gearing 'shown in Fig. 10.
Fig. 12 represents a diagrammatic view of the revolving commutator and brushes
shown in Fig. 1; with conductors leading from the side of the revolving brushes to
the contact brushes of a motor or dynamo.
Fig. 13 represents the revolving brushes shown in Fig. 1, mounted to revolve on
the commutator of a dynamo or motor.
Fig. 14 shows the method-of-indicating graphically the intensity and phase of
an electro-motive force.
Fig. 15 shows the method of finding the intensity and phase of an electro-motive
force, which is the resultant of two electro-motive forces of different phases, acting
in series.
Fig. 16 shows the graphic method of determining the ratio of the windings in the
secondary coils of a transformer designed to produce an electro-motive force of a
different number of phases from that acting in the primaries. It also shows the
method of connecting the transformers to obtain an eight-phase from a two-phase
electro-motive force.
Fig. 17 shows one method of connecting the coils of two transformers, to obtain
an eight-phase from a two-phase current.
Fig. 17 shows another method of arranging the said coils to accomplish the
same result as is derived from the device shown diagrammatically in Fig. 17, the
secondary coils being in open circuit connection, and but two of said coils being
shown, the rest being omitted for the sake, of clearness in the drawings.
Fig. 18 shows the ratio of the secondary winding and method of connecting the
coils of transformers to obtain a six-phase system from three transformers for closed
circuit method.
Fig. 19 shows the ratio of the secondary of transformer coils and method of
connecting them to obtain a twelve-phase system from three transformers for closed
circuit method.
Fig. 20 shows the arrangement of the coils of three transformers to obtain a
twelve-phase system from a three-phase system.
Fig. 21 represents a diagrammatic view of a transformer constructed as
indicated in Fig. 14 connected by means of the device shown in Fig. 1 to a
synchronous motor.
Fig. 22 shows a source of an eight-phase current connected to a motor having
its commutator and brushes revolving independently.
Fig. 23 represents the transformer shown in Fig. 17, with connections to any
one of the commutators and brush arrangements shown in Figures 4 to 7.
A represents a commutator which may be fixed and connected by conductors to
the source of poly-phase currents; or may be supported on and revolve with the
shaft B, and receive the current from the windings of the generator as shown in
Fig. 13 or from any other source of polyphase currents as indicated in Fig. 1.
CC are metallic rings carried on the shaft B,, but insulated from it and from
each other, each ring being connected by a conductor of electricity to a bar of the
commutator.
D, D, &c., are brushes rubbing on the contact rings C C &c.
The
EE &c., are conductors of electricity, jointed at one end to the brushes D D &c.,
and at the other to any source of polyphase current. The number of brushes D,
and rings C, is the same as the number of phases of the polyphase current.
number of bars on the commutator may be the same as those of the brushes D and
rings C; or may be any multiple of the number of phases, the rings in the latter
case being joined to two or more bars and the speed of the commutator
correspondingly reduced. Or the conductors may be connected directly to the
commutator bars as shown at E'.
F. F.&c. are moving brushes rubbing on the commutator A, carried on and

page_text: revolving with the shaft G. The number of brushes need not always be the same
as the number of the commutator bars. These two shafts B and Ġ may revolve
independently, or they may be clamped so as to revolve together, or they may be
fitted with a fixed or a variable gear by which the speed of one may be made to
bear any ratio to the other.
Since
F1 and F are fixed brushes which rub on the revolving commutator.
there will be a tendency of the moving brushes F to fly off from the commutator,
due to centrifugal force, I preferably provide some compensation for the tendency,
such for instance as is shown in Figs. 8, 9, 9, 10 and 10^. In Figs. 8, 9 and 10,
f represents the pivot about which the brush F turns, and f is a weight to prevent
the brushes leaving the surface of the commutator in consequence of the centrifugal
force produced by the revolutions. This may also be prevented by the use of
springs or by a combination of the weight and the springs.
In the device shown in Figures 9 and 10A, F³ represents a revolving disc slotted
as at into which dovetailed slots, lugs f* from the brush holders F holding the
brushes F and also lugs from the sliding weights F* project. These slots allow
free longitudinal motion to the brush holders F and to the counterpoise weights F,
and both brush holders and weights are provided with racks and f in their
sides which mesh in the pinion Fs pivoted to the disc F2 between the two. It will
be evident that any outward motion of the brush would be resisted by the outward
motion of the sliding weight in juxtaposition thereto.
In order to give a constant bearing of the brush F° on the commutator A, the
weight is preferably made to balance the weight of the brush and holder, and the
brush is pressed forward by a spring f' arranged in the slot ° and bearing on
the lug, as shown in Fig. 10*.
Instead of balanced brushes a commutator may be used in which ordinary brushes
rub on the face of a disc commutator.
HH &c. are metallic rings, electrically insulated from each other and from
the shaft G, and each connected by a conductor of electricity to one of the
brushes F.
II &c. are brushes rubbing on the rings H H. The shafts B and G may be
revolved in any convenient way, such, for instance, as the pulley P shown in
Fig. 13.
Or
KK &c., are conductors of electricity joined at one end to the brushes II and
leading to the translating device or devices which are to be operated, such, for
instance, as the synchronous or Tesla motor shown in diagram in Fig. 21.
these conductors may be connected directly to the brushes F' as shown at K³ in
Figs. 3, 4 and 6.
While the foregoing description refers to the current as entering the commutator
bars by the wires E and E' and being carried off from the brushes K or K', it
may be caused to flow in the reverse direction, as the operation of the apparatus
does not depend upon the direction of the current; and wherever the operation of
the apparatus is described with reference to the commutator and brushes having
different angular velocities, it will be understood that a commutator bar is the
equivalent of a brush and vice versa.
L represents the shaft of a motor or other translating device. L' shown in
Fig. 21 represents a synchronous or Tesla motor. L' shown in Figs. 13 and 22
represents a dynamo or other translating device having fixed brushes 1.º in addition
to the revolving brushes F.
Figs. 10 and 11 show a method of gearing the shaft G which carries the
brushes F to the shaft B which carries the commutator A. The shaft G is hollow
allowing the shaft B to pass through it. On the end of shaft B is a cog-wheel B',
meshing with the cog-wheel N, which turns on the pin n secured to the rigid
arm M. The wheel N meshes with the cog-wheel G which is rigidly secured to
the shaft. G, thus causing the shaft G to revolve in a fixed ratio to the shaft B.
It is obvious that a variable speed gear or any other suitable gearing for
connecting the two shafts may be adopted if desired.
.
B

page_text: Q, R, S, T, are the conductors of a two phase system.
U and U in Figs. 17, 21, and 22 and also U in Fig. 20 are the primary coils of
the transformers:
When the apparatus is at rest, the current flowing from the conductors KK will
be identical in all respects to that entering at E E, provided the number of brushes,
rings and bars is the same throughout.
If the commutator A is driven by a synchronous motor the brushes F remaining
at rest, any pair of these brushes will yield a continuous current, which can be
taken off directly from the brushes or from the corresponding conductors K. If
the brushes F are now driven by a synchronous motor they will assume a fixed
position relative to the commutator A, and the current passing out at K K' will be
identical in every respect to that entering at E E.
It is evident from the above, that since in passing from a current of zero frequency
to one equal in frequency to that entering at E, the intermediate stages have been
passed corresponding to the different speeds of the brushes F F. Therefore if the
brushes F F are driven to any other speed than that of synchronism the current
passing through the conductors K K will have a different frequency than that
entering at E E. This frequency will depend on the original frequency combined
with the difference in speed of the two parts.
From this it follows that it is entirely immaterial whether the commutator alone
revolves, or whether the brushes alone revolve, or whether both revolve, so long as
the difference in speed of the two parts is the same.
If a part of the brushes F F only are used, the number of phases of the current
flowing through the corresponding conductors K K will be proportionally reduced.
The number of commutator bars to conductors, E, can be different from the
brushes and conductors K. Such a commutator will transform any polyphase
current into any other, the number of phases being in proportion to the number of
conductors E and K and the difference of the frequencies being determined by the
relative rates of revolution of the brushes and commutators.
This device may be utilized in a variety of ways:-
1. To make a dynamo capable of giving out currents of any frequency-Mount
the device on the shaft of the dynamo as shown in Fig. 13, or indicated in Fig. 2.
The commutator may now become the commutator of the dynamo, and the armature
conductors may be conducted directly to the bars of the commutator.
On now
revolving the brushes a polyphase current of any frequency can be obtained from
the brushes I. The brushes can be driven from the shaft at any desired speed by
gearing or belts, or may be independently driven by a motor.
Pin Fig. 13 represents a pulley for driving the shaft G.
2. This same device shown in Fig. 13 makes a motor capable of starting and
running in a variety of ways.
a. It is a self-starting synchronous motor provided the brushes are revolved at
the proper speed and afterwards clamped to belts, gearing etc., so as to
preserve the fixed ratio of speed.
b. When the brushes are run by a small synchronous motor and they are fed
by a polyphase current, the motor will then be fed by a continuous current
and will start, run and stop like such a continuous current motor.
c. When running in either of these ways continuous current can be taken off
by a pair of fixed brushes and used for exciting the field magnets or any
other purpose.
d. The device mentioned in section a can be used to convert continuous into a
polyphase alternating current of any number of phases and any frequency.
3. If used to start or to vary the speed of a Tesla or synchronous motor,
Figs. 4, 5, 6, 7, 12 and 22 show' the connections for the various methods of using
this device. The brushes F may be at rest as it is only necessary to revolve one
part. The connections to the motor and to the source of current may be made
from either side of the device. By this arrangement current can be supplied to
the motor at any desired frequency and it will be self, starting.
.

page_text: By regulating the speed of the moving part, by belt, gearing or other devices
the frequency of the current reaching the motor can be controlled, and consequently
its speed which will be in synchronism with the current reaching it.
The speed of the moving part may be decreased as the motor speed increases,
and when brought to rest the motor will reach synchronism with the original
current. If the commutator be made the commutator of a motor and a polyphase
current be supplied through the brushes F F, Figs. 2 and 13, then the frequency
of the current reaching the armature, and the consequent speed of the armature
can be varied by varying the speed of the brushes.
4. To start a motor under a load, Figs. 4, 5, 6, 7, 13 and 21 and 22. By driving
the brushes by a synchronous motor, the large motor will start under a load and
run at a speed depending on the electro-motive force.
5. To start a synchronous motor under a load-Applied as above a synchronous
motor will start under a load, and following the increase in the frequency of the
current reaching it, will run up to synchronism with the current from the original
source.
6. Applied to the armature of a motor of the Tesla type having a laminated
field with coils closed on themselves, it makes it a variable speed motor. The
armature and field may obviously be interchanged.
The source of polyphase currents may be a generator or a transformer or
transformers. Moreover the transformers may be so constructed that a polyphase
current of one system is converted into a polyphase current of another system.
In Fig. 14 Oy and OX represent co-ordinate axes. The intensity of an electro-
motive force may be represented by the length of a line OZ, its phase by the angle
the line makes with another line, as L the angle it makes with O X.
In Fig. 15, a¹ and a' d' represent the intensity and phases of two electro-
motive forces. When joined in series the resultant electro-motive force will be
represented in magnitude and phase by the line a¹ c¹.
In the transformers of a polyphase system, electro-motive forces in different
phases are induced and the intensity depends on the ratio of the primary and
Secondary windings. Hence any polyphase current can be obtained from any two
transformers whose phases differ in any degree from each other, although for
symmetry all the transformers of the system should be used.
Figs. 16 and 17 represent an eight-phase system of electro-motive forces, derived
from a pair of transformers of the two-phase system. The two transformers are
cach wound with six secondary coils, the windings of two coils being proportional
to a' and of four coils proportional to it. The coils shown in Fig. 17 are connected
as shown in Fig. 16, the wires leading from eight points, a, b, c, d, e, f, g, h forming
the conductors of the eight-phase system.
The conductors Q, R, S, T represent the conductors of the two-phase system,
U and U the primary coils of the transformers. In Fig. 17 an open circuit
system is shown, the arrangement of the wires in the secondary coils being similar
to that indicated by the single pair of coils a' and ' in open circuit as shown.
On each transformer there will then be, in this case four large and four small
coils, connected as shown in the diagram in Fig. 17ª.
Fig. 18 represents the method of connecting the secondary coils and the relation
of the windings to produce a six-phase system, and Fig. 19, that of a twelve-phase
system, derived from a three-phase.
The connections are as shown in Fig. 17.
In all the examples here shown the number of transformers is equal to the
number of phases of the primary current. This however, is not necessary as the
same principle allows us to use a different number of transformers. Thus two
transformers can be used for any polyphase primary current or a greater number
may be used at will. For simplicity, the drawings only show the number of
transformers equal to the number of primary current phases.
Also it will be evident that the current may be carried to the transformers in the

page_text: reverse direction, the secondary coils then becoming the primary. Also that the
both primary and secondary coils may be wound as shown in the secondary coils.
Fig. 21 shows the combination of an eight-phase system derived from a two-phase
as in Fig. 17, with the device for varying the frequency shown in Fig. 1, and a
synchronous motor operated thereby. If the brushes F remain fixed and the
commutator A. is revolved by a synchronous motor, a continuous current is produced
in the conductors K. If not run synchronously an alternating current is produced.
If, when the commutator A. is run by a synchronous motor, the brushes Fare
revolved, a an alternating-current-is-produced whose frequency depends on the
original frequency and on the-difference in speed between the brushes F and
the commutator A.
Any other translating device may be substituted for the synchronous motor
shown in this figure.
The conductors from the transformers may also be connected to the brushes I,
and a motor may be mounted on the shaft B, as shown in Fig. 22, in which the
brushes F are made to revolve on the commutator A of the motor L².
If revolved synchronously, a continuous current will be supplied to the motor,
but at any other speed an alternating current will be supplied, and hence either a
continuous current motor or an alternating current motor may be used at L³.
In the diagram shown in Fig. 23, the closed circuit transformer of Fig. 17 or
the open circuit transformer of Fig. 17ª is connected to one of the combinations
of armature and brushes shown in Figs. 4 to 7.
The transformer is represented as connected to the upper device on the sheet, and
the dotted lines indicate that it may be connected to any one or more of the other
devices. It will be seen that a continuous current will be carried off by the pairs
of conductors to the right of the said diagram, provided these devices are run in
synchronism with the current, while an alternating current will be carried off at
any other relative speed, the polyphase current from the transformer being
converted into a continuous current or an alternating by means of the commutator A
and brushes For F¹ either or both of which may be made to revolve.
It is evident that the speed of the commutator necessary to produce continuous
currents can be reduced, etc., by making the number of the commutator
bars 2, 3 etc., times the number of wires from the transformer.
In the Specification and claims a continuous current is considered to be an
alternating current of zero frequency.
It will thus be seen that by an arrangement similar to that herein shown it is
possible to transform an alternating current of any number of phases and frequency
to an alternating current of any desired number of phases and frequency, and to
further change this latter current either into a continuous current, or an alternating
current of greater or less number of phases and frequency, to run a synchronous or
Tesla motor thereby at any desired speed to start the same under a load, and to
accomplish the great variety of results herein before described, as well as many
others that would readily suggest themselves to any skilled electrician.
Having now particularly ascertained and described the nature of my said inven-
tion, and in what manner the same is to be performed; I declare that what I
claim is :-
.
1. The hereindescribed method of producing alternating currents of variable
frequency and phase which consists in electrically connecting a source of polyphase
currents with a commutator or brushes, in taking said currents from said commu-
tator or brushes by means of brushes or commutator bars and in varying the
difference of angular velocity between said brushes and said commutator,
substantially as described.
2. The hereindescribed method of varying the frequency and phase of alter-
nating currents which consists in sending currents of a given frequency to the
primary coils of a plurality of transformers, in transforming said currents to a

page_text: different number of phases in the secondary coils, in electrically connecting said.
secondary coils with a commutator or brushes, in taking off said currents from said
brushes or commutator, and in varying the difference of angular velocity between
said brushes and said commutator, substantially as described.
3. The combination with a source of polyphase currents, of a plurality of
transformers so connected thereto, that some or all of the primary polyphase
currents pass through windings on two or more of the transformers, thus producing
a polyphase current of a different number of phases from the primary current, a
commutator or brushes, and a plurality of electrical conductors connecting said
transformer with said commutator or brushes, of a plurality of brushes or com-
mutator bars adapted to take off the current, means for revolving either said
commutator or said brushes, or both, and a translating device electrically connected
either to said brushes or to said commutator bars, substantially as described.
4. The combination with a source of polyphase currents, of a plurality of
transformers so connected thereto that some or all of the secondary currents pass
through windings on two or more of the transformers, thus producing a polyphase
current of a different number of phases from the primary current, a commutator or
brushes, and a plurality of electrical conductors connecting said transformers with
said commutator or brushes, of a plurality of brushes or commutator bars adapted
to take off the current, means for revolving either said commutator or said brushes,
or both, and a translating device electrically connected either to said brushes or to
said commutator bars, substantially as described.
5. The combination with a source of polyphase currents, of a plurality of
transformers so connected thereto that some or all of both the primary currents
and the secondary currents pass through windings on two or more of the trans-
formers, thus producing a polyphase current of a different number of phases from
the primary current, a commutator or brushes, and a plurality of electrical
conductors connecting said transformer with said commutator or brushes, a
plurality of brushes or commutator bars adapted to take off the current, means
for varying the angular velocity of said commutator relative to said brushes,
and a translating device electrically connected to said brushes or to said
commutator bars, substantially as described.
6. The combination with a source of polyphase currents of a plurality of
transformers so connected thereto, that some or all of the primary polyphase
currents pass through windings on two or more of the transformers, thus pro-
ducing a polyphase current of a different number of phases from the primary
current, a commutator or brushes a plurality of electrical conductors connecting
said transformer with said commutator or brushes and means for driving said
commutator or brushes in synchronism with the current or at any multiple of
said speed for the purpose of converting the polyphase current into a continuous
current, substantially as described.
7. The combination with a source of polyphase currents, of a plurality of
transformers so connected thereto that some or all of the secondary currents
pass through windings on two or more of the transformers, thus producing a
polyphase current of a different number of phases from the primary current, a
commutator or brushes, a plurality of electrical conductors connecting said trans-
former with said commutator or brushes, and means for driving said commutator or
brushes in synchronism with the current or at any multiple of said speed for the
purpose of converting the polyphase current into a continuous current, substantially
as described.
8. The combination with a source of polyphase currents, of a plurality of
transformers so connected thereto that some or all of both the primary currents
and the secondary currents pass through windings on two or more of the
transformers, thus producing a polyphase current of a different number of phases
5 from the primary current, a commutator or brushes, a plurality of electrical
conductors connecting said transformer with said commutator or brushes and
meaus for driving the same in synchronism with the current, or at any multiple

page_text: of said speed, for the purpose of converting the polyphase current into a
continuous current, and means for carrying off said continuous current,
substantially as described.
9. The combination with a plurality of transformers connected to an alter-
nating current machine and having their secondary coils wound to give a
multiphase current of any desired number of phases, a commutator or brushes,
and a plurality of electrical conductors connecting said secondary coils with
said commutator or brushes, a plurality of brushes or commutator bars adapted
-to take off the current, means for revolving either said commutator or said
brushes, or both, and a translating device electrically connected either to said
commutator or to said brushes, substantially as described.
10. The combination with a plurality of transformers connected to an alter-
nating current machine and having their secondary coils wound to give a
multiphase current .of any desired number of phases, a commutator or brushes,
and a plurality of electrical conductors connecting said secondary coils with
said commutator or brushes, a plurality of brushes or commutator bars adapted to
take off the current, means for revolving either said commutator or said brushes or
both, and a synchronous motor electrically connected to said brushes or to said
commutator bars, substantially as described.
11. The combination with a dynamo provided with a rotary armature and
commutator and a plurality of fixed brushes, of a plurality of revolving brushes
making contact with said commutator, and means for carrying off the current from
said revolving brushes, substantially as described.
12. The combination with a rotating armature and its commutator of a plurality
of brushes revolving on said commutator, and means for carrying the current to or
from said revolving brushes, substantially as described.
13. The combination with a dynamo provided with a rotating armature and
commutator and a plurality of fixed brushes, of a plurality of revolving brushes
making contact with said commutator and a synchronous motor electrically
connected to said revolving brushes, substantially as described.
14. The combination with a dynamo provided with a rotating armature and
commutator and a plurality of fixed brushes, of a plurality of revolving brushes
making contact with said commutator and a translating device electrically
connected to said revolving brushes, substantially as described.
15. The combination with a rotating armature and commutator and a plurality
of fixed brushes, of a plurality of revolving brushes making contact with said
commutator, and a polyphase current transformer electrically connected to said
revolving brushes, substantially as described.
16. The combination with a rotating armature provided with a commutator of a
plurality of revolving brushes making contact with said commutator, and a
polyphase current transformer electrically connected to said revolving brushes,
substantially as described.
17. The method of starting a synchronous motor which consists in producing a
continuous current from an alternating one by means of a commutator or brushes
in synchronism with the current and gradually increasing the frequency of the
current by slowing down the commutator or brushes until they come to rest,
substantially as described.
18. The combination with a source of electricity of a commutator or brushes,
a plurality of electrical conductors connecting said source of electricity with said
commutator or brushes, a plurality of brushes or commutator bars adapted to take
off the current, means for varying the angular velocity of said commutator
relative to said brushes, and a synchronous or Tesla electric motor, electrically
connected either to said brushes or to said commutator bars, substantially as
described.
19. The combination with a transformer, of a commutator or brushes and a
plurality of electrical conductors connecting said transformer with said com-
mutator or brushes, a plurality of brushes or commutator bars adapted to take off

page_text: the current, means for revolving either said commutator or said brushes, or both,
and a translating device electrically connected either to said brushes or to sail
commutator bars, substantially as described.
20. The combination with a transformer, of a commutator or brushes and a
plurality of electrical conductors connecting said transformer with said commutator
or brushes, a plurality of brushes or commutator bars adapted to take off the
current, means for revolving either said commutator or said brushes or both, and a
synchronous electric motor electrically connected either to said brushes or to said
commutator bars, substantially as described.
21. The combination and arrangement of parts substantially as herein-
described and shewn in Fig. 4 of the drawings hereunto annexed, substantially
as described.
22. The combination and arrangement of parts substantially as herein-
described and shewn in Fig. 5 of the drawings hereunto annexed, substantially
as described.
23. The combination and arrangement of parts substantially as herein-
described and shewn in Fig. 6, of the drawings hereunto annexed, substantially
as described.
24. The combination and arrangement of parts substantially as herein-
described and shewn in Fig. 7, of the drawings hereunto annexed, substantially
as described.
25. The combination and arrangement of parts substantially as herein-
described and shewn in Fig. 12 of the drawings hereunto annexed.
26. The combination and arrangement of parts substantially as herein-
described and shewn in Fig. 13 of the drawings hereunto annexed.
27. The method of arranging the winding of the primary and secondary coils
of a plurality of multiphase transformers, substantially as hereindescribed and
shewn in Figures 16 and 17 of the drawings hereunto annexed.
28. The method of arranging the winding of the primary and secondary coils
of a plurality of multiphase transformers, substantially as hereindescribed and
shewn in Figures 16 and 17A of the drawings hereunto annexed.
29. The method of arranging the winding of the primary and secondary coils
of a plurality of multiphase transformers, substantially as hereindescribed and
shewn in Figures 19 and 20 of the drawings hereunto annexed.
30. The combination and arrangement of parts substantially as herein shewn
and described, with reference to Fig. 21 of the drawings hereunto annexed.
31. The combination and arrangement of parts substantially as herein shewn
and described, with reference to Fig. 22 of the drawings hereunto annexed..
32. The combination and arrangement of parts substantially as herein shewn
and described with reference to Fig. 23 of the drawings hereunto annexed.
Dated the 22nd day of February 1895.
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicant.