Improvements in Synchronous Alternating Current Motors.
Year: 1889

page_text: Date of Application, 27th Mar., 1889
Complete Specification Left, 27th Dec., 1889-Accepted, 1st Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in Synchronous Alternating Current Motors.
We, CARL ZIPERNOWSKY, MAX DERI and OTTO TITUS BLÁTHY, Directors, of
Budapest in the Kingdom of Hungary do hereby declare the nature of our Invention
to be as follows:-
A synchronous alternating current motor will be started and maintained in motion.
by supplying an alternating current to the armature, and when under normal working
conditions the number of the passing-by of armature coils before any one of the
magnet-poles in a given time is equal to the number of reversals of the current
supplied. A magneto-electric or an alternating current dynamo, the magnets of
which are excited from some.extraneous source, can without more aid he used as such
a synchronous motor, still it is necessary to bring such a motor, when starting, up to
the synchronous speed by expending work upon it, not got from the alternating
current; and it is only after attaining the synchronous speed in this way, that the
same will be maintained by supplying the armature with the alternating current, even
against a mechanical resistance (torque) not exceeding the capabilities of the motor
concerned. The excitation of the magnets in a synchronous alternating current
motor may be also effected from the alternating current, which is supplied to the
armuture, for this purpose a commutator rotating with the machine is necessary
giving the proper direction to the pulsations of current in the magnet-coils. In
its simplest form this commutator consists of as many sectors as the motor has
armature coils (or magnet coils); alternate sectors round the commutator are
electrically connected together and each of the two sets of sectors thus made
are connected to different ends of the magnet-coils, the alternating current being
conducted to the rotating commutator by two brushes or sets of brushes. It is
plain, that the speed being synchronous and the brushes properly adjusted on the
sectors of the coinmutator at the moment of the relative position of the magnets
and armature coils, at each reversal of the alternating current the sequence of the
electrical connections between the beads and the magnet coils will also be reversed,
so that when running at normal speed the magnets are supplied with an inter-
mittent but directed current, thus they possess always the same polarity and
consequently the notor may continue to run synchronously.
A diagram of the essential parts of such a motor is given in Figure 1. A is one of
the armature coils of the motor, in this case taken as fixed. Mis.one of the rotating
magnet coils. C is the commutator rotating with the magnets. The shaded sectors
are in electrical connection with one another and with 1, the blank sectors with one
another and with 2. The alternating current for the armature as well as for the
magnets is supplied from the leads Land this may take place simply as shown in
the figure or by the intervention of induction coils-i.e. transformers which if
required may change the conditions of tension and intensity of the current coming
from the supply leads to suit the motor. The brushes B and B are so placed, that
the one slides from a shaded to a blank sector and the other vice versa at the same
instant this taking place as M is passing by A. just when they are opposite to one
another. In a motor with fixed magnets and rotating armature there are two more
pairs of sliding contacts necessary for the purpose of conducting the current to the
armature and to lead away the redressed current from the rotating commutator.
Motors constructed after the manner described can also be made to start with an
alternating current, all' that is required being the sub-division of the iron in the
magnet fields in a well known inanner to guard against the induction of waste
currents therein. Let the magnets and armature be placed in a favourable position
relatively to one another or a slight impulse given to the motor then on switching on

page_text: the alternating current the motor will start and increase its speed gradually until
synchronism is attained, for so long as synchronisin has not been reached, reversals of
the alternating current supplied, occur simultaneously in both armature and magnet
coils so that the mechanical effect between the armature and magnets does not change
direction, the successive impulses aiding themselves in their effect. The reversals of
connections inade necessary by the change of the relative position of magnets and
armature coils are performed by the commutator. A motor such as described would
however be practically useless on account of the excessive sparking at the commutator
which arises especially when starting and continues even when running at full speed
and it is one of the objects of our invention to. attain a non-sparking or at least a
nearly non-sparking synchronous working.
At every alternation of the current supplied to the motor, strong extra currents
are started in the magnet coils which as the brushes pass from one sector to the
other cause great sparking. The alternate current supplied is only sufficiently
intense during a part of each period to maintain the magnetic field above a certain
strength, while for a certain time before and after each reversal the intensity of
this supplied current is not sufficient for maintaining the magnetic field, con-
sequently the magnetism is in the act of disappearing quickly, producing powerful
extra currents in the magnet coils and in the connecting leads which current at
the instant the brushes are changing sectors, finds a path of low resistance, which
being again immediately interrupted causes strong sparking. Besides this, the
strength of the magnetic field being subject to very great variations of strength,
the motor does not work reliably, easily failing out of synchronism.
We have now discovered and confirmed by numerous trials, that all these evils can
be avoided by short circuiting the magnet coils upon themselves, sometime before
the reversal of current occurs, as thus the extra current can flow only in the magnet
coils where it is produced and not also in the connecting leads and being more intense
on this path of low resistance, the magnetic field is maintained at a higher level. The
brushes can then be so placed tha) at the instant they change sectors, the extra
current and the supplied current just balance one another whereby the cause of
sparking is removed. The temporary short circuiting of the magnet coils is effected
by an arrangement of four brushes (or groups of brushes) on the commutator of
these two, and two situated a little apart from one another on the commutator are
connected respectively to the one lead and to the other as shown in Figure 2.
The brushes 1 and 2 are connected with one supplying lead; 3 and 4 with the
other. As may be seen in the position shown in the diagram, the short circuiting of
the magnet coils is just commencing and will not end until the brush 2 has left the
shaded sector; 1 and 2 are in the same relative position to the shaded sectors as 3
and 4 are to the blank sectors. The distance between the ends of the brushes on the
commutator is from to of the circumferential width of one sector. The brushes
which are connected to the same lead must not necessarily touch upon the same sector
but may slide on different sectors of the same set; the position shown in Figure 3 is
identical with that of Figure 2 in as far as effect is concerned. Of course instead of
the separate brushes 1 and 2 (or corresponding groups of brushes) one brush, or
group of such could be employed so thick as to cover the required arc of the
circumference of the commutator.
It has been demonstrated by numerous trials that with the described arrangement.
of short circuiting brushes properly placed there is no sparking at the brushes
when the motor is working synchronously and the motor strives vigorously to keep
up the synchronism. The brushes I and 3 are to be shifted together as also 2 and 4,
therefore each of these pairs has its own brush holder, which is made adjustable in
preference to being fixed, and for this purpose the distribution of brushes on the
commutator as shown in Figure 3 is inore suitable. It is plain that one of the
.4 brushes may be dispensed with, without alteration of effect, still as a rule it will
be preferable to use four brushes, for the sake of being able to replace one without
trouble.
1
Instead of one brush, two or more side by side may be used.

page_text: With an arrangement of brushes such as described, the working of the motor is
tisfactory when synchronism has been reached; starting however is found to be
t least difficult or even impossible, the torque of the motor as long as the speed
emains slow being insufficient to produce the aceleration necessary to reach normal
working speed. In starting either the presence of two brushes only is required as
Figure 1, or of four as in Figures 2 and 3 with a small distance only between
he brushes connected to the saine lead. For the purpose of starting, a switch is
out in circuit in order thereby to disconnect from the supply leads one pair of the
brushes, say 1 and 3 (or 2 and 4) or the brushes of one pair may be shifted near to
he other one on the commutator, this adjustment being conveniently limited by
As soon as the motor has reached the synchronous
steps on the brush-holders.
speed the second pair of brushes is switched into circuit or is adjusted to its proper
position on the commutator for synchronous working.
The short circuiting of the magnet-coils may be effected according to another
method viz. by the arrangement of two commutators in close proximity to one
another the sectors of the one being in eschelon to those of the other at a distance
corresponding to the amount of short circuit required, or as effecting the same
result one commutator with step shaped sectors as in Figure 4 may be used-To
dispense with the short circuit while starting the electrical connections with the
brushes on one of the commutators may be broken, or the one commutator may be
shifted round relatively to the other, this shifting being performed either by hand
or by an automatic regulator as shown in Figure 5. in which the sleeve S which is
moved longitudinally on the commutator spindle by the action of the governor G
has a helical groove into which enters a stud on the commutator C² which is loose
on the spindle.
In order to prevent the current in the supply leads growing too strong during the
time the short circuit is taking place we put a resistance which may or may not be
adjustable in circuit with the brushes. The same purpose may also be served by au
induction coil (transformer) the one coil of which is in circuit with the armature (or
the whole current supplying the motor inay How through it) while the other coil of
this induction coil takes only the current which flows round the magnets as shewn in
the diagram Figure 6 where 11 is the one coil of the induction coil and 12 the second
coil. The mutual induction of the two coils prevents the current in either becoming
too great.
Instead of supplying the magnets with a branch current derived from the supply
leads (excitation by shunt) the magnets and armature may be connected in series
(excitation by series) in which latter case the same current flows through the
armature as alternating current and through the magnets as intermittent directed
What has been stated herein before concerning brushes and commutators
0 applies equally in this last case.
current.
ned this 97th day of March 1889.
IMRAY
DEI
& IMRAY
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Synchronous Alternating Current Motors.
We, CARL ZIPERNOWSKY, MAX DERI, and OTTO TITUS BLTAHY, Directors, of
Budapest, in the Kingdom of Hungary, 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 :-
A synchronous alternating current imotor will be started and maintained in motion
by supplying an alternating current to the armature, and when under normal
working conditions the number of the passings by of armature coils before any one of
the magnet poles in a given time is equal to the number of reversals of the current
supplied. A magneto electric or an alternating current dynaino, the magnets of
which are excited from some extraneous source, can without inore aid be used as such

page_text: chronous motor, still it is necessary to bring such a motor, when starting, u
to the synchronous speed by expending work upon it, not got from the alternatin
current, and it is only after attaining the synchronous speed in this way that th
same will be maintained by supplying the armature with the alternating curren
⚫ even against a mechanical resistance (torque) not exceeding the capabilities of th
motor concerne.. The excitation of the magnet in a synchronous alternatin
current motor may be also effected from the alternating current, which is supplie
to the armature, for this purpose a commutator rotating with the machine i
necessary giving. the proper direction to the pulsations of current in the magne
coils. In its simplest form this commutator consists of as many sectors as the moto
has armature coils (or magnet coils); alternate sectors round the commutator are
electrically connected together and each of the two sets of sectors thus made are
connected to different ends of the magnet coils, the alternating current being conducted
to the rotating commutator by two brushes or sets of brushes.
speed being synchronous and the brushes properly adjusted on the sectors of the
It is plain, that the
commutator in the moment of the opposite position of the magnets and armature
coils at each reversal of the alternating current the sequence of the electrical
connections between the leads and the magnet coils will also be reversed, so that
when running at normal speed the magnets are supplied with an intermittent but
directed current, thus they possess always the same polarity and consequently the
motor may continue to run synchronously.
A diagram of the essential parts of such a motor is given in Figure 1 of the
drawings accompanying our Provisional Specification.
A is one of the armature coils of the motor, in this case taken as fixed. M is one of
the rotating magnet coils. C is the commutator rotating with the magnets. The
shaded sectors are in electrical connection with one another, and with 1, the blank
sectors with one another and with 2.
well as for the magnets is supplied from the leads 1, and this may take place
The alternating current for the armature as
simply as shewn in the figure, or by the intervention of induction coils,
i.e. transformers which if required may change the conditions of tension and intensity
of the current coming from the supply leads to suit the motor.
The brushes B and 132 are so placed that the one slides from a shaded to a blark
sector and the other vice versa at the same instant this taking place as M is passing
by A just when they are opposite to one another.
rotating armature there are two more pairs of sliding contacts necessary for the
In a motor with fixed magnets and
purpose of conducting the current to the armature and to lead away the redressed
current from the rotating commutator.
Motors constructed after the manner described, can also be made to start with
an alternating current, all that is required being the subdivision of the iron in
the magnet fields in a well known manner to guard against the induction of waste 4
currents therein. Let the magnets and armature be placed in a favourable position
relatively to one another or a slight impulse given to the motor, then on switching on
the alternating current the motor will start and increase its speed gradually until
synchronism is attained; for so long as synchronisin has not been reached, reversals
of the alternating current supplied, occur simultaneously in both armature and 4
magnet coils, so that the mechanical effect between the armature and magnets does
not change direction, the successive impulses aiding themselves in their effect. The
reversals of connections made necessary by the change of the relative position of
magnets and armature coils are performed by the commutator.
described would however be practically useless on account of the excessive sparking 50
A motor such as
at the commutator which arises especially when starting and continues even when
running at full speed and it is one of the objects of our invention to attain a non-
sparking or at least a nearly non-sparking synchronous working.
At every alternation of the current supplied to the motor, strong extra currents
re started in the magnet coils which as the brushes pass from one sector to the 55
other cause great sparking. The alternate current supplied is only sufficiently
ntense during a part of each period to maintain the magnetic field above a certain

page_text: strength, while for a certain time before and after each reversal the intensity of this
supplied current is not sufficient for maintaining the magnetic field, consequently the
magnetism is in the act of disappearing quickly, producing powerful extra currents
in the magnet coils and in the connecting leads which current at the instant the
brushes are changing sectors, finds a path of low resistance which being again
immediately interrupted causes strong sparking. Besides this, the strength of the
magnetic field being subject to very great variations of strength, the motor does
not work reliably, easily falling out of synchronism.
We have now discovered and confirmed by numerous trials, that all these evils can
be avoided by short circuiting the magnet coils upon themselves, sometime before
the reversal of current occurs, as thus the extra current can flow only in the magnet
coils where it is produced and not also in the connecting leads and being more
intense on this path of low resistance, the magnetic field is maintained at a higher level.
The brushes can then be so placed that at the instant they change sectors, the extra
current and the supplied current just balance one another whereby the cause of
sparking is removed. The temporary short circuiting of the magnet coils is effected
by an arrangement of four brushes (or groups of brushes) on the commutator of
these two and two situated a little apart from one another on the commutator are
connected respectively to the one lead and to the other as shewn in Fig. 2.
The brushes 1 and 2 are connected with one supplying lead; 3 and 4 with the other.
As may be seen in the position shewn in the diagram, the short circuiting of the
magnet coils is just commencing and will not end until the brush 2 has left the
shaded sector; 1 and 2 are in the same relative position to the shaded sectors as
3 and 4 ure to the blank sectors. The distance between the ends of the brushes
on the commutator is from to of the circumferential width of one sector.
The brushes which are connected to the same lead must not necessarily touch upon
the same sector but may slide on different sectors of the same set; the position shewn
in Fig. 3 is identical with that of Fig. 2 in as far as effect is concerned. Of
course instead of the separate brushes 1 and 2 (or corresponding groups of brushes)
one brush, or group of such could be employed so thick as to cover the required arc
of the circumference of the commutator.
It has been demonstrated by numerous trials that, with the described arrangement
of short circuiting brushes properly placed there is no sparking at the brushes when
the motor is working synchronously and the motor strives vigorously to keep up the
synchronism. The brushes 1 and 3 are to be shifted together as also 2 and 4,
therefore each of these pairs has its own brush holder, which is made. adjustable in
preference to being fixed, and for this purpose the distribution of brushes on the
commutator as shewn in Fig. 3 is more suitable. It is plain that one of the four
brushes may be dispensed with, without alteration of effect, still as a rule it will be
preferable to use four brushes, for the sake of being able to replace one without
trouble.
Instead of one brush, two or more side by side may be used.
With an arrangement of brushes such as described, the working of the motor is
satisfactory when synchronism has been reached; starting however is found to be at
least difficult, or even impossible, the torque of the motor, as long as the speed
remains slow being insufficient to produce the acceleration necessary to reach normal
working speed.
In starting either the presence of two brushes only is required as in Fig. 1, or of
foar as in Figs. 2 and 3 with a small distance only between the brushes connected
to the same lead. For the purpose of starting, a switch is put in circuit in order
thereby to disconnect from the supply leads one pair of the brushes, say 1 and 3
(or 2 and 4) or the brushes of one pair may be shifted near to the other one on the
commutator, this adjustment being conveniently limited by stops on the brush holders.
As soon as the motor has reached the synchronous speed, the second pair of brushes
is switched into circuit, or, is adjusted to its proper position on the commutator
for synchronous working.
The short circuiting of the magnet coils may be effected according to another

page_text: method, viz., by the arrangement of two commutators in close proximity to one
another, the sectors of the one being in eschelon to those of the other at a distance
corresponding to the amount of short circuit required, or, as affecting the saine
result, one commutator with step shaped sectors as in Fig. 4 may be used.
To dispense with the short circuit while starting the electrical connections with the
brushes on one of the commutators may be broken, or the one commutator may be
shifted round relatively to the other, this shifting being performed either by hand
or by an automatic regulator as shewn in Fig. 5 in which the sleeve S which is
moved longitudinally on the commutator spindle by the action of the governor G, bas
a helical groove into which enters a stud on the cominutator C2 which is loose on the
spindle.
In order to prevent the current in the supply leads growing too strong during the
time the short circuit is taking place we put a resistance, which may or may not be
adjustable, in circuit with the brushes. The same purpose may also be served by an
induction coil (transformer) the one coil of which is in circuit with the armature
(or the whole current supplying the motor may flow through it) while the other coil
of this induction coil takes only the current which flows round the magnets as shewn
in the diagramn Fig. 6 where 1 is the one coil of the induction coil and 12 the second
coil. The mutual induction of the two coils prevents the current in either becoming
too great.
Instead of supplying the magnets with a branch current derived from the supply
leads (excitation by shunt), the magnets and armature may be connected in series
(excitation by series) in which latter case, the same current flows through the
armature as alternating current and through the magnets as intermittent directed
current. What has been stated herein before concerning brushes and commutators.
applies equally in this last case.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a synchronous alternating current motor with commutator for redressing
the current for the magnets the method of temporarily short circuiting the magnet
windings at each reversal of current, substantially as and for the purpose herein
described.
2. In a synchronous alternating current motor such as is referred to in the
preceding claim, the use for temporarily short circuiting the magnet windings at
each reversal of current, of three or more brushes or groups of brushes arranged
and operating substantially as herein described.
3. In a synchronous alternating current motor such as is referred to in the
preceding claims, the use of the herein described arrangement of switches for
electrically disconnecting one or more of the said brushes.
4. In a synchronous alternating current motor such as is referred to in the first
claim, the use, for temporarily short circuiting the magnet windings at each reversal
of current, of the herein described arrangement of a second commutator or of a
single commutator with step shaped sectors operating substantially as set forth.
5. In a synchronous alternating current motor such as is referred to in the first
claim, the use of the berein described arrangement of a second moveable commutator
for effecting the temporary short circuiting of the magnet windings by turning the
moveable commutator partly round relatively to the fixed commutator."
6. In a synchronous alternating current motor with one or two commutators
arranged and operating as set forth in the preceding claims, the use of the herein
described arrangement of an induction apparatus, one coil of which is connected in
circuit with the armature in order to prevent the current in the leads growing too
strong during the time the short circuiting takes place.
nated this 27th day of December 1889