Improvements in Alternate Current Motors.
Year: 1893

page_text: Date of Application, 21st Mar., 1893
Complete Specification Left, 18th Dec., 1893-Accepted, 27th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in Alternate Current Motors.
We, OTTO TITUS BLÁTHY, Engineer, of II Hauptgasse 73, Budapest, and
MAX DERI, Engineer, of Wipplingerstrasse 30, Vienna, do hereby declare the
nature of this invention to be as follows:-
This invention relates to alternate current motors that are constructed similarly
to the ordinary continuous current dynamo machines, with the sole difference that
both the iron core of the armature as also the framing of the field magnets are made
of divided iron in the form either of sheet iron or wire.
In such motors alternating currents are introduced both in the field magnet
windings and in the armature windings, the latter being introduced by means of a
collector and brushes in precisely the same manner as with continuous current
motors of known construction.
With alternate currents motors hitherto constructed according to this arrange-
ment, it has been found that a great amount of sparking occurs at the commutator,
the cause of which is to be found in the fact that the brushes are in contact
simultaneously with two or more plates of the collector, whereby one or more
spools of the armature were short circuited.
These spools are situated in the neutral plane of the magnetic field and are
subject to a considerable inductive action from the field magnets, owing to the
magnetisin of the latter being produced by the alternating current and being
consequently subject during a unit of time to a considerable number of changes of
direction.
The magnet windings and the spools of the armature situated in the neutral
plane form, as it were, the primary and secondary windings of a transformer, whose
secondary coil is consequently at intervals short circuited by the brushes, so that
very considerable currents are thus produced in the said coils, which produce not
only the objectionable excessive sparking at the commutator, but also a
considerable loss of energy and weakening of the magnetic field of the machine.
The present invention has for its object to obviate or to greatly reduce these
several detrimental effects; it consists in the following:
The connecting points of two contiguous spools or sections of the winding of an
armature wound in the ordinary manner of dynamos, whether of drum, ring, or disc
form, are not directly connected to one of the plates of the collector, but there is
introduced between the said point of connection and the collector plate an
intermediate piece which either possesses a suitable (Ohmic) resistance, or a
suitable self induction, or both combined. The action of this intermediate piece
consists in that it prevents the increase of induced current in the spool closed by the
brush, beyond a certain degree, thus reducing to a minimum the above named
detrimental effects.
It is best to choose an intermediate piece with such a resistance or such a self
induction, that a current will circulate in the spool, short circuited by the brush,
which is nearly equal to the working current in the other spools of the armature
corresponding to the normal load.
.
It should be mentioned that with self induction the advantage is gained that the
loss of energy on its introduction is less than on the introduction of ordinary
resistances under the same conditions of current, and that consequently the
useful effect of the machine is more favourable in the first case than in the
second.
If the intermediate pieces are constructed as simple wire resistances, they can be

page_text: advantageously arranged on the armature itself; if on the other hand self inducing
resistances are used for the above purpose, there may be provided next the armature
a separate divided iron body on, which the said induction resistances are produced
by wire windings.
The said self induction resistances can however also be wound upon the iron core
of the armature itself. In the latter case the arrangement is such that the
resistance windings are not subject to any other induction beyond the self induction,
whether in consequence of the motion in the magnetic field or in consequence of the
variations in the latter itself.
The following arrangements, among others, have proved suitable.
Those self induction resistances which belong to two contiguous plates of the
collector, are arranged parallel and very near to each other, but wound alternately
in contrary directions round the iron body serving as core.
In consequence of this
arrangement, on the simultaneous contact between two plates by means of the
brush, that is to say, on the closing of the corresponding spool of the armature
winding, the inductive actions of the two contiguous resistances will be added
together in respect of the closed spool; on the other hand, the working current
which is supplied to the armature by the brushes will, on the simultaneous contact
of two plates by the same brush, flow through two resistances in such a direction
that these are rendered free from induction relatively to this current and
consequently do not oppose thereto any appreciable resistance.
In Fig. 1 of the accompanying drawings there is shewn, as example of the above
described invention, a diagram of a ring shaped core, in which, for the sake of
clearness, only two contiguous resistance windings w₁ are shewn, which are
connected to the connecting points of the armature spool; these windings are
coiled in contrary directions upon the ring core a and are connected with the
corresponding contiguous plates cc of the collector.
The ring a may in this case either be an independent core for the induction
resistance windings, or it may be at the same time the iron core of a ring
armature.
It will be seen that when the armature of the motor is a ring and the induction
windings are applied thereto, these resistance windings are so coiled round the ring
that the lines of force produced by the current flowing through the same, are in a
closed condition and do not produce any external poles. The self induction in the
windings is then the greatest, while an inductive action by the magnetic fields of the
machine cannot take place, which is the object aimed at.
With drum armatures the self induction windings can also be wound upon the
armature itself. Here also the consecutive resistances are wound alternately in
contrary directions round the core; also, each two contiguous resistance windings
are arranged as far as possible parallel and close together, and they are so placed
upon the armature that in every position they include an even number of magnet
poles of the motor whereby they are maintained free from the inductive action,
whether by the motion in the magnetic field or by the variation in the intensity of
the magnetic fields.
.
:
With 4, 8, 12, polar armatures the induction resistance windings can be
arranged in a diagonal plane, while with 6, 10, 14,
not be possible.
polar armatures this will
Fig. 2 shews by way of example a diagrammatic view of the drum armature of a
four-pole motor, the operative armature windings being omitted and only two
contiguous resistance windings being shewn.
To the points of connection 6 6 of the armature spool are attached the
resistances w¹ to which are wound in contrary directions and are connected to the
corresponding collector plates c, c. Owing to the fact that these resistance
windings include an even number of magnetic poles (in the present case, two) the
magnetic fields are prevented from exercising any inductive action upon them, as
their actions neutralize each other, as is indicated by the direction of the lines of
force of the magnetic fields indicated by the arrows.

page_text: In conclusion the following may be observed:
The magnet windings of the motors in question can be arranged in series with
the armature windings or they may be in a shunt circuit thereof and the current
for the armature, as also that for the field magnets, can in all cases be transformed
into a current having the required tension and intensity by means of an interpolated
transformer.
Lastly, the field magnets may also alone be supplied with current, while the
armature windings are short circuited by connecting the brushes with each other,
and the current in the same be produced by induction from the field magnets, in
which case the above described advantageous actions of the intermediate pieces are
still obtained.
Dated this Olet day of March 1002
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Alternate Current Motors.
We, OTTO TITUS BLÁTHY, Engineer, of II Hauptgasse 73, Budapest, and
MAX DERI, Engineer, of I Wipplingerstrasse 30, Vienna, 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 alternate current motors that are constructed similarly
to the ordinary continuous current dynamo machines, with the sole difference that
both the iron core of the armature as also the framing of the field magnets are
made of divided iron in the form either of sheet iron or wire.
In such motors alternating currents are introduced both in the field magnet
windings and in the armature windings, the latter being introduced by means of a
collector and brushes in precisely the same manner as with continuous current
motors of known construction.
With alternate currents motors hitherto constructed according to this arrangement,
it has been-found that a great amount of sparking occurs at the commutator, the
cause of which is to be found in the fact that the brushes are in contact simul-
taneously with two or more plates of the collector, whereby one or more spools of
the armature were short circuited. These spools are situated in the neutral plane
of the magnetic field and are subject to a considerable inductive action from the
field maguets, owing to the magnetism of the latter being produced by the alternating
current and being consequently subject during a unit of time to a considerable
number of changes of direction.
The magnet windings and the spools of the armature situated in the neutral
plane form as it were, the primary and secondary windings of a transformer, whose
secondary coil is consequently at intervals short circuited by the brushes, so that
very considerable currents are thus produced in the said coils, which produce not
only the objectionable excessive sparking at the commutator, but also a considerable
loss of energy and weakening of the magnetic field of the machine.
The present invention has for its object to obviate or to greatly reduce these
several detrimental effects; it consists in the following:
The connecting points of two contiguous spools or sections of the winding of an
armature wound in; the ordinary manner of dynamos, whether of drum, ring, or
disc form, are not directly connected to one of the plates of the collector, but
there is introduced between the said point of connection and the collector plate an
intermediate piece which either possesses a suitable (Ohmic) resistance, or a
suitable self induction, or both combined. The action of this intermediate piece
consists in that it prevents the increase of induced current in the spool closed by
the brush, beyond a certain degree, thus reducing to a minimum the above named
detrimental effects.

page_text: It is best to choose an intermediate piece with such a resistance or such a self
induction, that a current will circulate in the spool short circuited by the brush
which is nearly equal to the working current in the other spools of the armature
corresponding to the normal load.
It should be mentioned that with self induction the advantage is gained that
the loss of energy on its introduction is less than on the introduction of ordinary
resistances under the same conditions of current, and that consequently the useful
effect of the machine is more favourable in the first case than in the second.
If the intermediate pieces are constructed as simple wire resistances, they can
be advantageously arranged on the armature itself; if on the other hand self
inducing resistances are used for the above purpose, there may be provided next
the armature a separate divided iron body on which the said induction resistances
are produced by wire windings.
The said self induction resistances can however also be wound upon the iron
core of the armature itself. In the latter case the arrangement is such that the
resistance windings are not subject to any other induction beyond the self induction,
whether in consequence of the motion in the magnetic field or in consequence of
the variations in the latter itself.
The following arrangements, among others, have proved suitable.
Those self induction resistances which belong to two contiguous plates of the
collector, are arranged parallel and very near to each other, but wound alternately
in contrary directions round the iron body serving as core. In consequence of this
arrangement, on the simultaneous contact between two plates by means of the
brush, that is to say, on the closing of the corresponding spool of the armature
winding, the inductive actions of the two contiguous resistances will be added
together in respect of the closed spool; on the other hand, the working current
which is supplied to the armature by the brushes will, on the simultaneous contact
of two plates by the same brush, flow through two resistances in such a direction
that these are rendered free from induction relatively to this current and con-
sequently do not oppose thereto any appreciable resistance.
In Fig. 1 of the drawings accompanying my Provisional Specification there is
shewn, as example of the above described invention, a diagram of a ring shaped core,
in which, for the sake of clearness, only two contiguous resistance windings w¹ 10%
are shewn, which are connected to the connecting points of the armature
spool; these windings are coiled in contrary directions upon the ring core a and are
connected with the corresponding contiguous plates c¹ of the collector.
The ring a may in this case either be an independent core for the induction
resistance windings, or it may be at the same time the iron core of a ring
armature.
It will be seen that when the armature of the motor is a ring and the induction
windings are applied thereto, these resistance windings are so coiled round the ring
that the lines of force produced by the current flowing through the same, are in a
closed condition and do not produce any external poles. The self induction in the
windings is then the greatest, while an inductive action by the magnetic fields of
the machine cannot take place, which is the object aimed at.
With drum armatures the self induction windings can also be wound upon the
armature itself. Here also the consecutive resistances are wound alternately in
contrary directions round the core, also, each two contiguous resistance windings
are arranged as far as possible parallel and close together and they are so placed
upon the armature that in every position they include an even number of magnet
poles of the motor, whereby they are maintained free from the inductive action,
whether by the motion in the magnetic field or by the variation in the intensity of
the magnetic fields.
With 4. 8. 12.... polar armatures the induction resistance windings can be
arranged in a diagonal plane, while with 6. 10. 14. ... polar armatures this will
not be possible.
Fig. 2 shews by way of example a diagrammatic view of the drum armature of ja

page_text: four-pole motor, the operative armature windings being omitted and only two-
contiguous resistance windings being shewn.
To the points of connection of the armature spool are attached the
resistances w¹ to which are wound in contrary directions and are connected to the-
corresponding collector plates c c. Owing to the fact that these resistance windings
include an even number of magnetic poles (in the present case, two) the magnetic
fields are prevented from exercising any inductive action upon them, as their actions.
neutralize each other, as is indicated by the direction of the lines of force of the
magnetic fields indicated by the arrows.
In conclusion the following may be observed: The magnet windings of the motors.
in question can be arranged in series with the armature windings or they may be in
a shunt circuit thereof and the current for the armature, as also that for the field
magnets, can in all cases be transformed into a current having the required tension.
and intensity by means of an interpolated transformer.
Lastly, the field magnets may also alone be supplied with current, while the
armature windings are short circuited by connecting the brushes with each other,
and the current in the same be produced by induction from the field magnets,.
in which case the above described advantageous actious of the intermediate pieces
are still obtained.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In alternate current motors whose armature and magnet cores are constructed:
of divided iron and which have an armature with collector, similar to those of the
ordinary continuous current machines, the employment of intermediate pieces with.
resistance or self induction or both combined which are introduced between the
collector plates and the parts of the armature winding to be connected thereto,.
substantially as and for the purposes described.
2. In the application of intermediate pieces such as referred to in the preceding
claim, so arranging the resistance or self induction or both combined, of the said
intermediate pieces that in the armature winding which is short circuited by the
collector brush, a current is made to circulate that is practically equal to the
operative current passing through the other windings of the armature, which
corresponds to the load on the motor, substantially as described.
3. The application of self induction resistances between the armature windings
and the collector in such manner that relatively to two contiguous collector plates,.
they are coiled alternately in contrary directions round the iron core substantially
as described.
4. The application of self induction resistances between the armature windings.
and the collector in such manner that, relatively to two contiguous collector plates,.
they are coiled alternately in opposite directions round the iron core so as not to
be subject to any inductive action from the magnetic poles of the machine, sub--
stantially as described.
5. In alternate current motors of the kind herein referred to the application
of self induction resistances between the armature windings and the collector in
such manner that they are not subject to any inductive action from the magnetic
poles of the machine substantially as described.
Dated this 18th day of December 1893
ABEL & IMRAY,
Agents for Applicants.