Improved Electric Current Generator for Ordinary and Multiple Phase Alternating Currents.
Year: 1891

page_text: Date of Application, 15th Aug., 1891
Complete Specification Left, 4th May, 1892-Accepted, 4th June, 1392
PROVISIONAL SPECIFICATION.
Improved Electric Current Generator for Ordinary and Multiple
Phase Alternating Currents.
I, JOHANNES SOHLMAN, of Frederickshamn, Finland, Engineer, du hereby
declare the nature of this invention to be as follows:-
The alternating current generators heretofore employed having polar armatures,
have the disadvantage that in consequence of the great speed at which the reversion
of the magnetism of the iron cores takes place, on the one hand a great portion of
the mechanical energy required for generating the electric current is lost, being
converted into heat, while on the other hand other disadvantages, such as vortex
currents are produced by the varying magnetic resistance.
Furthermore, it has not yet been possible to produce at will, in one and the same
machine, either ordinary or multiple phase alternating currents, as also, to feed
with one and the same machine rotary phase multiple conductor systems having a
varying number of conductors.
It was consequently also heretofore necessary in transmitting electromotive force
by the means available, through a rotary phase alternating current system with
several conductors, to make the windings of the current generator to correspond
with those of the electro motor, and in consequence hereof it was always necessary
to employ with a certain system of electric motors, a certain construction of
current generators, any change in former, necessitating a corresponding change in
the latter.
The present invention relates to an alternate current machine in which the
reversal of the magnetism of the iron cores, and the resulting heating thereof is
obviated, and in which the advantages of the machines with polar armatures (low
magnetic resistance and avoidance of vortex currents in the windings, even when
these are thick) are combined with those of machines with armatures without cores
(constant magnetic resistance).
The arrangement furthermore has the advantage, that with one and the same
alternate current machine, according to requirements, either two conductor systems
for ordinary alternating currents, or multiple conductor systems for rotary phase
currents, with varying number of phases, can be worked.
Fig. 1 of the accompanying drawing shews a front view of an electric current
gencrator constructed according to this invention, shewing on each side of the
vertical centre line a different form of armature poles and field magnets.
Fig. 2 shews a section on line x x Fig. 1, the poles being formed according to
one or other of the two arrangements.
A is the outer cast iron casing of the machine, within each end of which is
adjustably fixed by screws a ring shaped armature B formed of sheet iron.
On the several poles of these armature rings are placed the induction coils b',
the free ends of which are led to the screw terminals 1, 2, 3, on the outside of the
casing A (assuming that two or three-phase rotary current is to be produced, to be
distributed through three conductors I, II, III).
The shaft W carries within the casing A two systems D of pole pieces formed
either of layers of sheet iron, or solid, which are advantageously made of such a
width that they can simultaneously cover one half of two adjacent armature poles.
The middle part of the shaft W is increased in size in order to reduce the magnetic
resistance to a minimum, and carries an exciting coil C which is stationary if the
machine is independently excited, but which revolves with the shaft if the machine
is self excited (with commutator for the exciting coils).
As the two armature rings B, and the two field magnets D have an equal number

page_text: of poles it will be seen that by shifting either the armature poles or the field
magnet poles relatively to each other, either an ordinary or a two-phase alternating
current can be produced. If, for example, the two armature rings B are so adjusted
that their poles accurately cover each other when looking in the axial direction,
and if the field magnets D are so placed that their poles are also in line with each
other, then both rings will act as a single armature ring, and ordinary alternating
currents will be produced. In this case both armature circuits can be either
connected in parallel or in series. If on the other hand either the armature
rings B are somewhat shifted relatively to each other while the field magnets D
remain in their original position, or if the armature rings be left in their original
position, and the field magnets D be shifted relatively to each other, then, if the
free ends be connected to the terminal 2, and the conductors 12 13 to the
terminals 1 and 3, a two-phase alternating current will be produced. If the con-
ductors I and II, II and III are connected by branch conductors, there will be
produced in these branches alternating currents of different phases.
But if in the distributing network I be combined II, II with III and in addition,
I with III, the two-phase current is divided into three currents of different phases.
If the phase difference of the two-phase current is equal to 120°, the phase
difference of the three currents in the branch conductors is equal to 60°, and all
three currents are of equal intensity. With transmission of power with three-
phase rotary phase currents the rings are therefore so placed that the phase
difference of the electromotive force in the two rings is equal to 120°.
The number of armature rings B and also the number of field magnets can be
increased at will, if alternating currents with more than three phases are to be
produced.
The magnetic resistance is rendered constant by making the magnet poles of
such a width that the surface of the air space passed over is rendered constant.
The constancy of the magnetic resistance can however be advantageously further
increased by connecting the pole pieces of the armature rings with each other in
the manner indicated at the lower right hand part of Fig. 1. In this case the form
of the poles of the field magnets is unimportant.
It is also possible to arrange the exciting coil C on the pole pieces themselves,
instead of on the shaft W, and the rings D may serve as armatures, in which case
the exciting coil is fixed on the shaft W or on the poles of the rings B. In this
case annular sliding contacts would have to be provided for taking the current
from the induction coils. The number and dimensions of the poles can be suitably
varied.
The armature poles can also be directed to either side. In this case the two
armature rings can be connected directly with each other, forming a machine with
a single ring but with two different pole circles.
Dated this 15th day of August 1891.
0
DAV
ABEL & IM RAY
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Electric Current Generator for Ordinary and Multiple
Phase Alternating Currents.
I, JOHANNES SOHLMAN of Frederickshamn, Finland, 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 alternating current generators heretofore employed having polar armatures,
have the disadvantage that in consequence of the great speed at which the reversion
of the magnetism of the iron cores takes place, on the one hand a great portion of
the mechanical energy required for generating the electric current is lost, being

page_text: converted into heat, while on the other hand other disadvantages, such as vortex
currents, are produced by the varying magnetic resistance.
Furthermore, it has not yet been possible to produce at will, in one and the same
machine, either ordinary or multiple-phase alternating currents, as also, to feed
with one and the same machine rotary phase multiple conductor systems having a
varying number of conductors.
It was consequently also heretofore necessary in transmitting electromotive force,
by the means available, through a rotary phase alternating current system with
several conductors, to make the windings of the current generator to correspond
with those of the electro motor, and in consequence hereof it was always necessary
to employ with a certain system of electric motors, a certain construction of
current generators, any change in the former, necessitating a corresponding change
in the latter.
The present invention relates to an alternate current machine in which the
reversal of the magnetism of the iron cores, and the resulting heating thereof is
obviated, and in which the advantages of the machines with polar armatures (low
magnetic resistance and avoidance of vortex currents in the windings, even when
these are thick) are combined with those of machines with armatures without cores
(constant magnetic resistance).
The arrangeinent furthermore has the advantage, that with one and the same
alternate current machine, according to requirements, either two-conductor systems
for ordinary alternating currents, or multiple-conductor systems for rotary phase
currents, with varying number of phases, can be worked.
Fig. 1 of the drawing accompanying my Provisional Specification shews a front
view of an electric current generator constructed according to this invention,
shewing on each side of the vertical centre line a different form of armature poles
and field magnets,
Fig. 2 shews a section on line a Fig. 1, the poles being formed according to
one or other of the two arrangements.
A is the outer cast iron casing of the machine, within each end of which is
adjustably fixed by screws a ring shaped armature B formed of sheet iron.
On the several poles of these armature rings are placed the induction coils,
the free ends of which are led to the screw terminals 1, 2, 3 on the outside of the
casing A (assuming that a two or three-phase rotary current is to be produced, to
be distributed through three conductors I, II, III).
The shaft W carries within the casing A two systems D of pole pieces formed
either of layers of sheet iron, or solid, which are advantageously made of such a
width that they can simultaneously cover one half of two adjacent armature poles.
The middle part of the shaft W is increased in size in order to reduce the magnetic
resistance to a minimum, and carries an exciting coil C which is stationary if the
machine is independently excited, but which revolves with the shaft if the machine
is self excited (with commutator for the exciting coils).
As the two armature rings B, and the two field magnets D have an equal number
of poles it will be seen that by shifting either the armature poles or the field
magnet poles relatively to each other, either an ordinary or a two-phase alternating
current can be produced. If, for example, the two armature rings B are so
adjusted that their poles accurately cover each other when looking in the axial
direction, and if the field magnets D are so placed that their poles are also in
line with each other, then both rings will act as a single armature ring, and
ordinary alternating currents will be produced. In this case both armature
circuits can be either connected in parallel or in series. If on the other hand
either the armature rings B are somewhat shifted relatively to each other while
the field magnets D remain in their original position, or if the armature rings
be left in their original position, and the field magnets D be shifted relatively
to each other, then, if the free ends be connected to the terminal 2, and the
conductors to the terminals 1 and 3, a two-phase alternating current will be
produced. If the conductors I and II, II and III are connected by branch

page_text: conductors, there will be produced in these branches alternating currents of
different phases.
But if in the distributing network I be combined with II, II with III and in
addition, I with III, the two-phase current is divided into three currents of
different phases. If the phase difference of the two-phase current is equal
to 120°, the phase difference of the three currents in the branch conductors is
equal to 60°, and all three currents are of equal intensity. With transmission
of power
with three-phase rotary phase currents the rings are therefore so
placed that the phase difference of the electromotive force in the two rings is
equal to 120º.
The number of armature rings B and also the number of field magnets can be
increased at will, if alternating currents with more than three phases are to be
produced.
The magnetic resistance is rendered constant by making the magnet poles of
such a width that the surface of the air space passed over is rendered constant.
The constancy of the magnetic resistance can however be advantageously further
increased by connecting the pole pieces of the armature rings with each other in
the manner indicated at the lower right hand part of Fig. 1. In this case the form
of the poles of the field magnets is unimportant.
It is also possible to arrange the exciting coil C on the pole pieces themselves,
instead of on the shaft W, and the rings D may serve as armatures, in which case
the exciting coil is fixed on the shaft W or on the poles of the rings B. In this
case annular sliding contacts would have to be provided for taking the current
from the induction coils. The number and dimensions of the poles can be suitably
varied.
The armature poles can also be directed to either side. In this case the two
armature rings can be connected directly with each other, forming a machine with
a single ring but with two different pole circles.
Having now particularly described and ascertained 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. Alternate current machines having one or more pole armatures or pole rings
in which the magnetism is not reversed, but only varies between zero or near zero
and a maximum in the several poles, while the total magnetism is maintained as
constant as possible, substantially as described.
2. In machines such as are referred to in the first claim, maintaining the
magnetic resistance constant by making the magnetic poles of such a size that
each one can cover simultaneously the halves of two armature poles, substantially
as described.
3. In machines such as are referred to in the first claim, maintaining the
magnetic resistance constant by making the armature poles of such a size as to be
in contact with each other or to be only separated by narrow spaces, in which case
the magnet poles may be of any desired form, substantially as described.
Dated this 4th day of May 1892.
ABEL & IMRAY,
Agents for the Applicant.