Improvements in Alternate Current Motors.
Year: 1892

page_text: Date of Application, 27th Dec., 1892
Complete Specification. Left, 6th Sept., 1893-Accepted. 14th Oct., 1893
PROVISIONAL SPECIFICATION.
Improvements in Alternate Current Motors.
I, CHARLES EUGEN LANCELOT BROWN, of Baden, Switzerland, Engineer and
Manufacturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in alternate current motors whereby such
motors can be worked with non-synchronous currents or non-synchronously and
without collectors or sliding contacts; that is, similarly to motors for multiphase
currents.
It is found by experiment that a conductor placed in the field of a magnet
excited by an alternating current (see Fig. 1) if set rotating at a certain velocity,
will adjust itself to practically synchronous rotation which it will then maintain
with a certain torque. The alternating magnetic field induces currents in the
conductor whose action, however, so long as the latter is at rest is completely
neutral with regard to the inducing field and which consequently produces no
turning moment. This condition however ceases as soon as the conductor is set in
motion, and a turning moment, is then produced which increases as the rate of
rotation of the conductor approaches synchronism. With a solid disc conductor,
for example, the speed of rotation falls more or less below synchronism according
to the load. With a deeply serrated conductor, on the other hand, or one consisting
of but few copper bars, there is a tendency to keep to synchronous rotation and if
brought below this speed the torque falls considerably.
The direction of rotation is optional the tendency to synchronous rotation being
in the direction in which the conductor is first set in motion.
The arrangement shown in Fig. 1 is simply diagrammatic and cannot be
advantageously adopted in practice.
In the design of a motor according to this invention the following points
should be observed:-The alternating field should be as strong as possible and
Care should further
all magnetic resistances should be reduced to a minimum.
be taken that eddy currents in either iron or copper be avoided as much as
possible. These requirements can be met in the following way:-The inducing
windings (in direct connection with the mains) as well as the induced windings (in
which current is induced) are provided with iron cores which are preferably formed
of discs of sheet iron insulated from one another.
In order to reduce the magnetic resistance of the air gap the conductors may be
placed either in perforations of suitable form in the iron core, as shown in Fig. 2
or between teeth thereon as in Fig. 3. In the latter case they may be secured by
a winding of iron wire as in Fig. 4 or the spaces may be partly closed by projections
from the teeth as in Fig. 5. These methods may of course be combined if desired.
The inducing winding may be wound in any of the usual ways (drum, ring etc.)
with any suitable number of poles and may be connected in parallel or in series or
partly in each.
The induced part which usually is the rotating part, since sliding contacts are
thereby avoided, carries a short circuited winding which is preferably insulated
The short circuiting of this
from the iron core in order to avoid eddy currents.
winding may be attained either by connecting all the ends on each side by means
of two copper rings or by short circuiting the wires in small groups. Points
similarly situated with regard to the poles may also be connected together; or
again the winding may be similar to the outer inducing part that is a two- or
For regulating the
multi-pole ring drum etc. with a short circuiting connection.
speed suitable resistances or impedance coils may be included in the induced
circuit

page_text: A motor designed in accordance with this invention is shown diagrammatically
in Figs. 6 and 7. The inductor I is fixed and consists of a cylindrical core of
laminated iron. On the inside of the ring the dises are perforated and carry the
winding W which is arranged as a ring (it might also be arranged as a drum).
In the drawing the ring is not shown completely overwound, but it may be so
constructed. The connections are so made as to produce poles at P P.
8
The rotating part consists principally of a laminated iron cylinder carrying in
holes formed therein round its circumference insulated copper wires which are
connected together on each side by stout copper rings K. A slightly different
arrangement is shown in Figs. 8 and 9.
Such a motor has the property of rotating almost synchronously with the rate of
alternation of the current. In this construction the number of copper conductors
is comparatively small. In Figs. 10 and 11 a rotating part is shown having a kind
of ring winding with the peculiarity that almost the whole of the winding is
surrounded with iron giving it a high self-induction. The connections are similar to
a ring winding and at opposite points are joined to contact rings so that a resistance
may be inserted in the circuit for regulating the speed.
Dated this 27th day of December 1892.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Alternate Current Motors.
I, CHARLES EUGEN LANCELOT BROWN, of Baden, Switzerland, Engineer and
Manufacturer, 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 to improvements in alternate current motors whereby such
motors are adapted to work with ordinary or single phase alternate currents, non-
synchronously, and without collectors or sliding contacts, that is to say similarly to
motors for multiphase currents.
In the drawings filed with my Provisional Specification
:-
Fig. 1 is a diagrammatic perspective view of a motor for the purpose of
illustrating my invention.
Figs. 2, 3, 4 and 5 are side views of parts of holders for the induced windings.
Fig. 6,is an end view of my improved motor.
Fig. 7 is a vertical longitudinal sectional elevation of the same.
Fig. 8 is an end view of a modified construction of the rotating portion of my
improved motor; and
Fig. 9 is a vertical longitudinal section thereof.
Fig. 10 is an end view of a modified construction of the rotative part of my
improved motor; and
Fig. 11 is a vertical longitudinal section thereof.
Similar letters of reference indicate corresponding parts in the several views.
"
It is found by experiment that a conductor placed in the magnetic field of an
alternating current (see Fig. 1) will if set rotating at a certain velocity, itself rise
to practically synchronous rotation, which it will then maintain with a certain
torque. The alternating magnetic field induces currents in the conductor, the
action of which, however, as long as the induced conductor is at rest, is completely
neutral with regard to the inducing field and which currents consequently produce
no turning moment. This condition, ceases however, as soon as the conductor is
set in motion, and a turning moment is then produced, which increases as the rate
of rotation of the conductor approaches synchronism. The following should also
be noted. With a solid disc conductor for example, the speed of rotation falls
1.

page_text: more or less below synchronism according to the load. With a deeply serrated
conductor, on the other hand, or one consisting of but a few copper bars, there is
a tendency to keep to synchronous rotation, and if brought below this speed the
torque falls considerably.
It is to be particularly noted that the direction of rotation is indeterminate. The
tendency to synchronous rotation is always in the direction in which the conductor
is set in motion.
The arrangement shown in Fig. 1 is simply diagrammatic and cannot be
advantageously adopted in practice.
In order to design a motor to work on the above principles the following
points must be observed:-The alternating field must be as strong as possible,
and all magnetic resistances must be reduced to a minimum. Care should further
be taken, that eddy currents both in the iron and copper employed in the con-
struction of the motor should be avoided as much as possible. These various
requirements can be met in the following way :-The inducing windings which
are placed in direct connection with surface or supply mains, as well as the induced
windings in which the current is induced by the former windings, are provided with
iron cores formed of discs of sheet iron insulated from one another.
In order to reduce the magnetic resistance of the air.gap and consequently also
the exciting current, the conductors may be placed either in perforations of suitable
form in the iron core, as shown in Fig. 2 or between teeth thereon as in Fig. 3.
In the latter case the spaces may be completely closed by a winding of iron wire
as in Fig. 4 or partly by projections from the teeth as in Fig. 5. These methods
may of course be combined if desired.
The inducing winding may be wound in any of the usual ways (drum or ring
windings) with any suitable number of poles and the coils, of which the winding
consists, may be connected in parallel, or in series, or partly in ench.
The induced part, which is usually also the rotating part. because sliding
contacts are thereby avoided, carries a short-circuited winding which is preferably
insulated from the iron core in order to avoid eddy currents.
The short-circuiting
of this winding may be effected either by connecting all the ends at each side
or end of the rotating part by means of two copper rings, or by short-circuiting
the wires in small groups. Points similarly situated with regard to the poles
may also be connected together. Or again the said induced winding may be
similar to the outer inducing part, that is to say a two- or multi-pole ring or
drum with a short circuiting connection. For regulating the speed a suitable
resistance or a device having considerable self-induction or capacity, may be
included in the induced circuit.
A motor designed in accordance with the above principles is shown diagram-
matically in Figs. 6 and 7. The inductor I is fixed and consists of a hollow
cylindrical core of laminated iron. At the inner portion of this inductor the sheet
metal rings or annular plates of which the core is built up, are perforated and carry
the winding W which is arranged as a ring though it might also be arranged as
a drum if desired. In the drawing the ring is not shown completely overwound,
but it may be constructed in that manner.
The connections are so made as to
produce poles at P and P¹.
The rotating part consists principally of a laminated iron cylinder carrying in
holes formed therein round its circumference, insulated copper wires s which are
connected together at each end of the rotating part by stout copper rings K.
A slightly modified arrangement is shown in Figs. 8 and 9, which has the
property herein before mentioned, of almost synchronous turning.
The copper
wires in this case are larger in size than in the previous case but fewer in
number.
In Figs. 10 and 11, a rotating part is shown having a ring winding so arranged
that almost the whole of it is surrounded with iron thereby giving it a high self-
induction. This is accomplished by passing the wires s through two annular sets
of apertures arranged concentrically. Each wire may be short circuited in itself

page_text: as shown in Fig. 10; or the connection may be made in such a way that the
winding is similar to that shown in Fig. 6 and called W. In this case the ends
of the winding are connected to contact rings as shown in Fig. 11, so that a
resistance may be inserted in the induced circuit for the purpose of regulating
the speed of the motor. It is advantageous to place a second winding in the
polar spaces between the two sections of the first winding and connected in the
same way to collecting rings, thus in Fig. 10, each winding would have six turns
divided into two diametrically situated sections of three turns each: It will be
still more advantageous to connect each separate pair of diametrically situated
windings with separate collecting rings. This arrangement may be simplified by
connecting one end of all such pairs together, the other end of each pair being
connected to a separate collecting ring. Resistances may in this case, as in
Fig. 11, be inserted between the rings for the purpose of regulating the speed of
the motor.
Having now 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 :-
1. An alternate current motor having its inductor winding adapted to be placed
in direct connection with the service or supply maius, and its induced winding in
which currents are induced by the said inductor winding, short-circuited on itself,
substantially as herein set forth, for the purpose of working non-synchronously and
without collectors and brushes.
2. A motor of the kind referred to in the preceding claim for use with ordinary
or single phase alternating currents, having its windings imbedded in holes or
apertures formed in laminated iron cores, for the purpose of reducing the magnetic
resistance, and in consequence thereof, the necessary exciting current, to a minimum,
substantially as set forth.
3. Alternate current motors constructed, arranged and operating as hereinbefore
described with reference respectively to and shown in Figs. 6 and 7; in Figs. 8
and 9; and in Figs. 10 and 11 of the drawings annexed.
Dated this 6th day of September 1893.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.