Improvements in and relating to the Distribution of Alternating Currents.
Year: 1895

page_text: Date of Application, 13th Apr., 1895
Complete Specification Left, 9th Jan., 1896-Accepted, 21st Mar., 1898
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Distribution of Alternating
Currents.
We, GALILEO FERRARIS, of Turin via XX Settembre N. 46, Engineer and
Professor of Electrical Technology at the Industrial Museum and RICCARDO
ARNO of Turin, via Sant Anselmo N. 24, Electrical Engineer, both in the
Kingdom of Italy, do hereby declare the nature of this invention to be as
follows:-
This invention relates to a system for obtaining from a given alternating current,
other alternating currents differing in phase, by means of a phase-displacing-
ransformer, and to utilize these currents in polyphase distributions.
The said invention is illustrated in the accompanying drawings the figures of
which are hereinafter referred to.
The present invention is based on the following principle: Take an electric two-
phase rotatory field motor, for example the motor shown in Figure 1, formed of two
coils A A and B B¹ crossed at right angles and by a short circuited armature M.
If an alternating current is passed through one of the coils, for example through A A¹,
and if the armature M is turned round, two alternating electromotive forces are
produced in the two coils A A and B B₁ between which a difference of phase of a
quarter of a period exists. Consequently, if the ohmic resistance of the two coils
be small, there is a difference of phase approximately equal to 90° also between
the potential differences at the ends of A A and B B'. Hence the ends A, A'
and B, B of the two coils can be used as the four poles of a two-phase dynamo-
machine.
L
If, for instance, the ends of two circuits a and b (Figure 2) be united with the
terminals A, A', and B, B¹ and have equal resistance, inductance and capacity,
there are, in these two circuits, currents, whose phases also differ approximately 90°
one from the other. Instead of making both the circuits a and b start from the
poles A, A and B, B', the circuit a can be made to start directly from two
points C and D (Figure 3) taken on the mains P and Q. One of the ends of the
coil A A¹, for instance A, can be united to one of the ends of the coil B, B, for
instance with B, and thus constitute the two circuits a and b, as indicated in the
Figure 4.
To maintain the armature M in rotation, it is sufficient as will be understood to
impel the same at first to a convenient velocity, whilst an alternating current is
passed into the coil A A'. Then in fact the working of the motor is that of the
known asynchronous monophase motor. In such a motor the coil A A¹ is the only
one used in the normal working and the coil B B' is used only for the starting.
Now, instead, owing to the abovenamed principle, the apparatus is used as a
transformer in which the coil A A' is the primary and the coil B B is the
secondary. This transformer has the property of causing the phase in the
secondary coil to be displaced 90° in respect to what it would be in the secondary
coil of an ordinary transformer. We denominate this transformed phase-displacing-
transformer and we use it to obtain, from a given alternating current, another
alternating current, presenting, with regard to that, a difference of phase of about 90°
and to feed in such a mode electric motors and other apparatus that require two
phase currents. By calculating properly the numbers of the turns, in the primary

page_text: coil A A and in the secondary B B¹, the transformer, while producing the
displacement of the phase, can be given that ratio of transformation which is desired.
Examples of the employment of the phase-displacing-transformer are illustrated
by the Figures 5 and 6.
In Figure 5 the phase-displacing-transformer M takes the current from two
mains P and Q of a secondary network belonging to an ordinary alternating
current distribution, and produces the phase-displaced current, which is necessary
for the working of two-phase or monophase motors N N. The figure shows how
it is possible with a third wire R to obtain that, in that part of the net where there
are electric motors to feed, while the lamps L and the other apparata with simple
alternating current receive the current from the mains P and Q.
Instend of three wires P, Q and R, four can be used, that is to say, the two
wires P and Q and two other wires starting from B and B', in which case the
conjunction between A and B, indicated in the figure, is suppressed.
In Figure 6 it is supposed that the phase-displacing-transformer M receives the
current from two mains P and Q of the primary net at high pressure.
In this case
the motors N, as well as the lamps L, are fed by means of ordinary transformers,
as shown at T, T.
All the figures and description above cited have been made, for clearness and
simplicity, on the hypothesis that the electric motor M, adopted as phase-displacing-
transformer, be bipolar; but it is evident that the same is true also in the most
general case, whatever may be the type of the motor.
The method can be generalised in such a manner ns to feed, with phase-
displacing-transformers, any distribution whatever of the polyphase system. In
the phase-displacing-transformers have a primary coil and several
this case
secondary ones.
Dated this 10th day of Ami1 1005
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in and relating to the Distribution of Alternating
Currents.
We, GALILEO FERRARIS of Turin via XX Settembre N. 46, Engineer and
Professor of Electrical Technology at the Industrial Museum and RICCARDO ARNÓ
of Turin, via Sant Anselmo N. 24, Electrical Engineer, both in the Kingdom of
Italy, 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 invention is illustrated in the accompanying drawings the figures of which
are hereinafter referred to.
Take an electric polyphase rotatory field motor, for instance the two phase motor
sketched in Figure 1, formed of two coils A A and B B¹ crossed at right angles
and by a short circuited armature M. If an alternating current is passed in one
of the coils, for example in A A¹, and if meanwhile the armature M is turned
round, two alternating electromotive forces are produced in the two coils A. A'
and B B¹, between which a difference of phase of a quarter of a period exists.
Consequently if the ohmic resistance of the two coils be small, there is also a
difference of phase approximatively equal to 90° between the potential differences at
the ends of A A¹ and B B¹. Hence the ends A, A¹ and B, B' of the two coils can
be used as the four poles of a two phase dynamo-machine.
If, for instance, the ends of two circuits a and b (Figure 2) be united with the

page_text: terminals A, A', and B, B1 and have equal resistance, inductance and capacity,
there are, in these two circuits, currents, whose phases also differ approximatively 90°
one from the other. Instead of making both the circuits a and b start from the
poles A, A and B, B', the circuit a can be made to start directly from two points C
and D (Figure 3) taken on the mains P and Q.
To maintain the armature M in rotation, it suffices, as it is known, to impel the
same at first to a convenient velocity, whilst an alternating current is passed into
the coil A A¹. Then in fact the working of the motor is that of the known
asynchronous monophase motor. In such a motor the coil A A' is the only one
used in the normal working and the coil B B¹ is used only for the starting. Now,
instead, thanks to the above named principle the apparatus becomes used as a
transformer in which the coil A A¹ is the primary and the coil B B¹ is the
secondary.
By calculating properly the numbers of the turns in the primary coil A A' and
in secondary B B, this transformer, while having that ratio of transformation which
is desired, has the property of causing the phase in the secondary coil to be
displaced 90° in respect to what it would be in the secondary coil of an ordinary
transformer. Consequently we can use this voltage- and phase-transformer to
obtain from a given alternating current, another alternating current, presenting,
with regard to that, a different voltage and a difference of phase of about 90°.
Examples of the employment of a voltage- current- and phase-transformer for
feeding alternating current distributions of two phases are illustrated in the
Figures 4, 5, 6, 7, 8.
The method can be generalised in such a manner as to feed any distribution
whatever of the polyphase system. In this case the transformer has a primary coil
and several secondary ones.
In Figures 4 and 5 of the accompanying drawings, CD diagrammatically
represent the two primary conductors of an ordinary high tension alternate current
distribution; T T ordinary alternate current transformers; PQ, PQ the two
secondary low tension conductors; and T, a voltage- current- and phase-transformer
(phase-displacing-transformer), the primary coil of which may be inserted between
the aforesaid low tension secondary conductors PQ (Figure 4) or between the
aforesaid high tension primary conductors CD (Figure 5). If now a double
conductor RS is led from the terminals of the secondary coil B B¹ of the phase-
displacing-transformer T, a low tension alternate current can be obtained, the
voltage and the phase of which is changed. Thus the four branched low tension
two-phase-system which is disposable all over the electric system, consists of the
two secondary conductors P and Q of an ordinary transformer and of the two
conductors R and S of a phase-displacing-transformer.
Consequently, if two wires start from the phase-displacing-transformer, the whole
system may be used for producing a low tension current changed in phase and
for conveying the same to the various transformer-arrangements, according to
the usual scheme of a two phased system (Figure 4); moreover the primary
coil of the phase-displacing-transformer may be so shaped that the same can be
connected to the high tension conductors without an ordinary transformer being
inserted in the circuit; whilst the secondary coil produces the low tension current
changed in phase (Figure 5).
In practice however a disadvantage might be found in many cases in having the
two wires starting from the phase-changing-transformer. It is possible to
provide means, by which the same objects are obtained in a most simple and
practical manner by having only a single wire starting from the phase-displacing-
transformer instead of two.
Let us first explain the improved arrangements by which, with the aid of one
single wire, starting from the phase-displacing-transformer, the low tension current
changed in phase can be generated and conveyed to the various transformer
arrangements of the system.
This can be easily obtained by connecting one terminal B of the secondary coil

page_text: -
to one terminal A of the primary coil of the phase-transformer T, and the
conductors S, or the conductors S. in the case of Fig. 6 the conductors S, of the
secondary electric circuits of the ordinary transformers, by wires having equal cross
sections to that of the wire R which starts from the other terminal B of the
secondary coil of T, (Figure 6). In this manner, by the aid of the phase-
displacing-transformer and of a third wire R connected thereto, a low tension
current with changed phase can be generated and be distributed all over the
system, so that everywhere a three-branched two-phase low tension system of
current is produced, consisting of the two secondary wires of any ordinary
transformer, and of that wire R which is started from the secondary coil of the
phase-displacing-transformer.
Let us now consider the improved means, by which, even on passing a single wire
from the phase-displacing-transformer, the primary coil can be suitably calculated
so as to be directly connected to the primary high tension conductors without the
insertion of an ordinary transformer, and the secondary coil can be so arranged as
to generate the low tension current with changed phase.
In order to explain the essential feature of such arrangements we have to
observe that the same form a three-wire alternating current system with two
electromotive forces differing in phase from each other by 90 degrees. This
system only differs from the ordinary three-wire alternating current system by
the fact that the two alternating electromotive forces, instead of being generated
in the secondary coils of two ordinary transformers, are generated respectively in
the secondary coil bb, (Figure 7) of an ordinary transformer T and in the
secondary coil B B¹ of a phase-displacing-transformer T. The primary
coils a a', A A of these transformers are connected in parallel with the high tension
conductors CD, as in the ordinary three wire alternating-current system. The
primary coil of the phase-displacing-transformer T, being traversed by the high
tension current and the low tension current with changed phase being generated in
the secondary coil, the phase-displacing-transformer is thus utilised for changing
the phase, and to act upon the tension and the strength of the current.
From Figures 6 and 7 of arrangements described hereinbefore originates in
the arrangement illustrated in Figure 8 from which it is apparent that the same
objects which we have achieved by means of two wires, can be attained even by the
use of a single wire starting from the phase transformer T.
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. A transformer of voltage, current and phase, characterised by the combination
in one apparatus of the principle of the ordinary transformer and of the described
property of the two phase or in general polyphase asynchronous motor. Said
transformer, when a current is conducted through the primary winding produces, in
the other winding or windings a secondary current or secondary currents, which, as
in the ordinary transformer, differs or differ from the primary one in voltage and
'strength and in the meantime has a phase or have phases displaced from the
secondary current or currents, that would be produced in the ordinary transformer.
2. In a monophase alternating current system of electric distribution the
combination of several ordinary transformers, of the secondary conductors thereof,
of a phase-transformer supplied from the low tension conductors of one of the
ordinary transformers, and of the two secondary conductors leading from the
phase-transformer and forming with the several secondary conductors of
the ordinary transformers so many four branched two phase low tension system.
3. In a monophase alternating current system of electric distribution, the
combination of the high tension mains, of several ordinary transformers, of the
secondary conductors thereof, of a voltage- and phase-transformer connected
directly to the high tension maius and of the two secondary conductors leading
from the voltage- and phase-transformer and forming with the several secondary

page_text: conductors of the ordinary transformers so many four branched two phase low
tension system.
4. In a monophase alternating current system of electric distribution, the
combination of several ordinary transformers, of the secondary conductors thereof,
of a phase-transformer connected to the secondary circuit of the one of the said
ordinary transformers, of connecting wires between the secondary conductors of
the said ordinary transformers, of a connection between one terminal of the
secondary coil to one terminal of the primary coil of the phase-transformer,
and of a single secondary conductor leading from the other terminal of the
secondary coil of the phase-transformer and forming with the several secondary
conductors of the ordinary transformers so many three branched two phase low
tension system.
5. In a monophase alternating current system of electric distribution, the
combination of the high tension mains, of an ordinary transformer, of the secondary
conductors thereof, of a voltage- and phase-transformer connected directly to the
high tension mains, of a connection between one terminal of the secondary coil of
the voltage- and phase-transformer to one terminal of the secondary coil of the
ordinary transformer, and of a single secondary conductor leading from the other
terminal of the secondary coil of the voltage- and phase-transformer and forming
with the secondary conductors of the ordinary transformer a three-branched two
phase low tension system.
6. In a monophase alternating current system of electric distribution, the
combination of the high tension mains, of several ordinary transformers, of the
secondary conductors thereof, of a voltage- and phase-transformer connected
directly to the high tension mains, of connecting wires between the secondary
conductors of the said ordinary transformers, of a connection between one terminal
of the secondary coil of the voltage- and phase-transformer to one terminal of the
secondary coil of one ordinary transformer, and of a single secondary conductor
leading from the other terminal of the secondary coil of the voltage- and phase-
transformer and forming with the several secondary conductors of the ordinary
transformers so many three branched two phase low tension system.
Dated this 9th day of January 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.