Improvements in Electrical Installations for Producing Alternating Currents.
Year: 1892

page_text: Date of Application, 25th July, 1892
Complete Specification Left, 19th Apr., 1893-Accepted, 15th July, 1893
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. SIEMENS & HALSKE, of Berlin, in the
German Empire, Electrical Engineers.]
Improvements in Electrical Installations for Producing Alternating
Currents.
We, SIEMENS BROTHERS & CO. LIMITED of 12 Queen Anne's Gate, West-
minster in the County of Middlesex, Electrical Engineers, do hereby declare the
nature of this invention to be as follows:-
This invention relates to a system of parallel arranged alternate current
generating machines which has the advantage that all the machines belonging to
the system have exactly the same number of alternations and consequently, when
they are to be connected in parallel, they do not require first to be brought to
synchronous motion, and in addition they cannot get out of step. For such a
system at least two alternate current generating machines are required, of which
the one may be called the exciting machine and the other the main machine. The
exciting machine can be an alternate current machine of any known construction;
it is only necessary that its field magnets shall either be permanent magnets, or
shall be continuously excited in the same sense by means of continuous currents or
commuted alternating currents.
This machine supplies current to the collecting bars at the station, to which bars
the above mentioned main alternating current machine is also connected.
This machine has two cores of divided iron, which close each other's magnetic
circuit, and of which the one receives motion relatively to the other from the motor
which drives the machine. The one iron core carries the winding for the current
generation, and the other a closed circuit winding of any kind.
As soon as the armature winding of the main machine is connected to the
collecting bars which are already connected to the exciting machine, or is otherwise
connected in parallel with the exciting machine, the armature core, and with it the
iron core of the closed circuit winding will be periodically magnetised and there
are produced electric currents in the closed circuit winding.
If now the armature and the closed circuit winding are moved relatively to each
other by means of the motor driving the machine at a suitable speed (in case of
poly-phase machines, also in a suitable direction) the currents induced in the closed
circuit winding will produce in the armature winding an electromotive force, the
periods of which will coincide with those of the exciting machine, and whose phase
is identical with the phase of the current actually passing through the main
machine. To this electromotive force is added the electromotive force of the
self-induced currents of the machine which are retarded 90° relatively thereto as
regards their phase. If now, by employing a suitable speed, the sum of the
electromotive forces is greater than the sum of the electromotive forces acting on
the main machine from the exciting machine (or from the network), the main
machine will give off the energy transferred to it from its motor as electrical
energy to the collecting bars, and the distributing network, in the form of an
alternating current whose number of alternations is only dependent upon the number
of alternations of the exciting machine, and not, as was heretofore the case, upon the
number of rotations of the rotating part. Any number of main machines of the
described arrangement can therefore be connected just as simply in parallel with
their exciting machine as continuous current machines are connected in parallel
with each other.
In order that, at the moment of connecting a main machine, this may not have
too strong a current passing through it, there is introduced before such connection,

page_text: a sufficiently great regulatable resistance into the closed circuit armature, or a
suitable speed is produced, so as to insure that the electromotive forces at the time
of connection to the collecting bars shall be such that the armature shall have so
called idle currents "
passing through it, which only serve for exciting the
machine. The electric circuits which are connected in parallel in the described
system need not be directly the circuits of the exciting machine; they may also
be the circuits of secondary coils of transformers of any known kind, which are
induced by the currents generated by the machines.
In place of the above mentioned single exciting machine there may of course be
employed several.
In many cases it is advisable to employ the special arrangement wherein the
exciting machine is coupled with a continuous current machine which is connected
to an accumulator battery.
As the exciting machine also acts in the described manner if it is driven by the
main machine acting as its motor, then with the described arrangement, if one of
the main machines is running, the accumulator battery can be charged and can
afterwards, when there is only a small consumption of current, serve for driving
the exciting machine which is then alone active.
At the same time the accumulator battery can serve for the magnetising of the
field magnets of the exciting machine.
On the accompanying drawing is shewn by way of example such an arrangement
for rotary phase current generating machines. D' and D2 are the rotary phase
current machines which are driven by suitable motors such as steam engines.
These rotary phase current machines have a stationary iron core with rotary phase
current winding, within which revolves a closed-circuit armature. E is the exciting
machine for D and D2; it is a rotary phase current generating machine, whose
armature is excited by rotating magnets excited by continuous currents from the
continuous current generator C. The machine E operates with constant potential
on the network which is represented by bars S¹, S2, and S³ in connection with
lamps A and electromotors B, D' and D are constructed just like rotary phase
current machines with closed circuit armature. Their rotating part when
generating current runs at a rather greater speed than would correspond to
synchronous working.
The action of the arrangement will be readily understood from what has been
above stated without further description. It may be mentioned that the before
mentioned coupling of the exciting machine with a continuous current machine
connected to an accumulator battery is very simply effected in rotary phase current
stations, as in this case the rotary phase current armature and the continuous
current armature can be combined in the known manner.
Dated this 25th day of July 1892.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Electrical Installations for Producing Alternating
Currents.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate, West-
minster in the County of Middlesex, Electrical Engineers, 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 a system of parallel arranged alternate current
generating machines which has the advantage that all the machines belonging
to the system have exactly the same number of alternations and consequently,
when they are to be connected in parallel, they do not require first to be

page_text: brought to synchronous motion and in addition they cannot get out of step. For
such a system at least two alternate current generating machines are required, of
which the one may be called the exciting machine and the other the main machine.
The exciting machine, can be an alternate current machine of any known
construction; it is only necessary that its field magnets shall either be permanent
magnets, or shall be continuously excited in the same sense by means of continuous
currents or commuted alternating currents.
This machine supplies current to the collecting bars at the station to which bars
the above mentioned main alternating current machine is also connected.
This machine has two cores of divided iron, which close each others' magnetic
circuit, and of which the one receives motion relatively to the other from the inotor
which drives the machine. The one iron core carries the winding for the current
generation, and the other a closed circuit winding of any kind.
As soon as the armature winding of the main machine is connected to the
collecting bars which are already connected to the exciting machine, or is otherwise
connected in parallel with the exciting machine, the armature core and with it the
iron core of the closed circuit winding will be periodically magnetised and there
are produced electric currents in the closed circuit winding.
If now the armature and the closed circuit winding are moved relatively to cach
other by means of the motor driving the machine at a suitable speed (in case
of poly-phase machines, also in a suitable direction) the currents induced in the
closed circuit winding will produce in the armature winding an electromotive
force, the periods of which will coincide with those of the exciting machine, and
whose phase is identical with the phase of the current actually passing through
the main machine. To this electromotive force is added the electromotive force
of the self-induced currents of the machine which are retarded 90° relatively
thereto as regards their phase. If now, by employing a suitable speed, the sum
of the electromotive forces is greater that the sum of the electromotive forces
acting on the main machine from the exciting machine (or from the network),
the main machine will give off the energy transferred to it from its motor as
electrical energy to the collecting bars, and the distributing network, in the form
of an alternating current whose number of alternations is only dependent upon
the number of alternations of the exciting machine, and not, as was heretofore
the case, upon the number of rotations of the rotating part. Any number of
main machines of the described arrangement can therefore be connected just as
simply in parallel with their exciting machine as continuous current machines are
connected in parallel with each other.
In order that, at the moment of connecting a main machine, this may not have
too strong a current passing through it, there is introduced before such connection,
a sufficiently great regulatable resistance into the closed circuit armature, or a
suitable speed is produced, so as to insure that the electromotive forces at the time
of connection to the collecting bars shall be such that the armature shall have
so called idle currents" passing through it, which only serve for exciting the
machine. The electrical circuits which are connected in parallel in the described
system need not be directly the circuits of the exciting machine; they may also
be the circuits of secondary coils of transformers of any known kind, which are
induced by the currents generated by the machines.
In place of the above mentioned single exciting machine there may of course be
employed several.
In many cases it is advisable to employ the special arrangement wherein the
exciting machine is coupled with a continuous current machine which is connected
to an accumulator battery.
As the exciting machine also acts in the described manner if it is driven by the
main machine acting as its motor, then with the described arrangement, if one of
the main machines is running, the accumulator battery can be charged and can
afterwards, when there is only a small consumption of current, serve for driving
the exciting machine which is then alone active."

page_text: At the same time the accumulator battery can serve for the magnetising of the
field magnets of the exciting machine.
On the drawing accompanying our Provisional Specification is shown by way of
example such an arrangement for rotary phase current generating machines.
D and D2 are the rotary phase current machines which are driven by suitable
motors such as steam engines.
These rotary phase current machines have a stationary iron core with rotary
phase current winding, within which revolves a closed circuit armature. E is the
exciting machine for D' and D²; it is a rotary phase current generating machine,
whose armature is excited by rotating magnets excited by continuous currents from
the continuous current generator C.
The machine E operates with constant potential on the network which is
represented by bars S1, S2, and S³ in connection with lamps A and electromotors B.
D and D are constructed just like rotary phase current machines with closed
circuit armature. Their rotating part when generating current runs at a rather
greater speed than would correspond to synchronous working.
Fig. 1 of the accompanying drawing shews a diagrammatic section of the above
mentioned exciting machine E, and Fig. 2 is a similar section of one of the main
machines D or D². In each machine the core is composed of an outer ring shaped
part F and F and an inner part G and G. The ring shaped part is constructed
the same in both machines. Its winding is divided into three groups. The first
one commences at A', from which point the wire passes at the back end to the
topmost groove through which it passes forward, and at the front end it passes to
the fourth right hand groove, situated at 90° to the top groove; in this groove the
wire again passes to the back end and then back again to the first groove, thus
forming a loop. If each groove is to contain several wires the wire is passed
repeatedly round and round in the above described manner until the required
number of wires is contained in the grooves.
The wire then passes at the back end from the fourth groove to the lowermost
groove, in which it passes forward and at the front end it passes to the groove at El
in which it passes to the back end and then back to the bottom groove. By this
means a second loop is formed, which repeated as often as the first one, the end
of the winding being brought at the back to the point E
In the same way the windings A' E and A³ E³ are prepared. The three
ends E E E of these groups are then connected together. The windings are
consequently situated only in the grooves and on the end surfaces and not on the
outer cylindrical surface of the ring.
Within the ring F of the machine E is the cross shaped four polar piece G
whose limbs are alternately North and South poles, having windings supplied with
continuous current as above described, and rotated by a motor. By such rotation,
rotary phase currents are produced in the outer windings which are taken off
at A A² A³ and are led through the bars S1 S2 S3 into the ring of the main
machine D, so that there is also produced in the latter a four polar rotary field.
The inner cylindrical part of G₁ of this machine has a short circuited winding;
this may be formed as shewn, the wire passing from the back end forward in the
topmost groove, then over the front end to the fourth groove to the right, then
back in the latter and to the bottom groove, in which it passes forward, then to
the fourth groove to the left, and backward in this, and lastly back to the topmost
groove. This winding, which may consist of a single or a number of wires, is short
circuited. In the same way two other closed circuit windings are formed in the
other grooves as indicated.
If now this inner part G¹ be driven by a motor, the part F1 being stationary or
driven at a slower speed, there will be induced in its short-circuited windings,
currents which will in their turn produce in the windings of Fan electromotive
force, the periods of which will coincide with those of the exciting machine, as
herein before described, and which will be given off to the collecting bars S¹ S² S³.
It may be mentioned that the before mentioned coupling of the exciting machine

page_text: with a continuous current machine connected to an accumulator battery is very
simply effected in rotary phase current stations, as in this case the rotary phase
current armature and the continuous current armature can be combined in the known
manner.
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 electrical installations, the combination, firstly of a number of alternate
current generators arranged in parallel having each a fixed core and a rotatable
core driven by the motor, of which cores the one carries the current generating
winding, and the other a short circuited winding of any kind, and secondly one or
more alternate current generators arranged in parallel with the first named
generators and serving to excite them, and whose field magnet is either a permanent
magnet or an electro magnet excited with the same polarity, either by a continuous
current or by a commutated alternating current, substantially as described.
2. In the arrangement of alternate current generators referred to in the preceding
claim, coupling the exciting machine with a continuous current machine that is
connected with an accumulator battery, in order that when the exciting machine
is driven by the main machine as a motor it can effect the charging of the
accumulator battery, the current from which can afterwards either serve
magnetise field magnets of the exciting machine or to work the continuous current
machine as a motor for driving the exciting machine, substantially as described.
Dated this 19th day of April 1893.
to
ABEL & IMRAY,
Agents for the Applicants.