Improvements in Converting Transformers.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Converting Transformers.
1. CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
in the County of London, Consulting Engineer and Chartered Patent Agent,
do hereby declare the nature of this invention (as communicated to
abroad by La Société Anonyme pour la Transmission de la Force par l'Electricité,
of 13, Rue Lafayette, Paris, France, Manufacturers,) to be as follows:-
me from
Converting transformers are designed to transform alternating currents of any
tension into continuous currents of any other tension, or, conversely, to transform
continuous currents of any tension into alternating currents of any other tension.
Such a converting transformer consists essentially of :-
(A) A transformer comprising
(1) n primary circuits excited by n alternating electromotive forces of the same
effective magnitude but differing in phase by. of the period, and
1
ዝ
(2) K secondary circuits which should carry 2 K alternating electromotive forces
of the same effective magnitude but differing in phase by
of the period.
2 K
These 2 K secondary circuits are connected like the consecutive sections of the
armature of a continuous current machine divided into 2 K sections.
(B) A collector having 2 K synchronous segments which are connected, either
directly or by means of rings and brushes, to the junction wires of the 2 K secondary
circuits, just as the segments of a commutator of a continuous current machine are
connected to the junctions of the successive sections of the armnature.
Under these conditions, if the frequency of the alternating currents to be trans-
formed is and if a synchronous motor imparts to the collector, or to the diametrically
opposite brushes which bear thereon, a speed of a revolutions per second, a
continuous current is collected in the external circuit connected to the brushes.
Some of the conditions which determine the commutation in a converting
transformer comprising 2 K secondary circuits and without regard to the coefficient of
transformation, are as follows:-
(1) If there is no magnetic leakage in the transformer, the commutation phenomena
are the same as those which would be produced, for the same electric work supplied,
in the machine obtained by transforming into continuous current dynamos the
polyphase current alternators which supply the converting transformer and by
dividing their armatures into 2 K identical sections for this purpose.
(2) As a fact, the coefficient of self induction of each of the sections of the machine
thus obtained ought to be increased by a supplementary coefficient representing the
magnetic leakage of each secondary circuit of the transformer and at the same time
the resistance of these sections ought to be increased by that of a secondary
circuit.
It is thus apparent that it is necessary to construct transformers having as little
magnetic leakage as possible.

page_text: In the apparatus of this class which have already been constructed, the number of
magnetic cores and primary circuits of the transformer equal to the number of
polyphase currents to be utilised and is of necessity small (in practice it is 3 in the
case of three-phase currents and 4 in that of four-phase currents).
Thus, apparatus of great power have been constructed with a small number of large
elements, the magnetic leakage of which attains a high value, rendering commutation
difficult.
This invention therefore relates to a converting transformer constructed of a large
number of elements of small dimensions in which the magnetic leakage is much
reduced.
The principle of the invention may be set forth as follows: Suppose that the three
electromotive forces H1 H2 H3 of the same effective magnitude but of a phase
difference equal to of the period, are so arranged that H₁ = H sin 2 at, H²= H
sin 2 (at + }), H³ = H sin 2 (a + 3).
-
It is required to produce in 2-K distinct secondary circuits 2 K electromotive forces
of the same effective magnitude but differing in phase by
1
2 K
of a period, such as the
Each secondary circuit. will consist of three distinct coils mounted in series and
having each the same number G of turns.
Fig. is a diagrammatic representation of these coils a be
surrounds one of the magnetic cores x y z.
Each of them
These cores are also covered by the primary circuits m p q connected with the
three sources of the electromotive forces H1 H2 H3 and a neutral point o.
The number of turns of these primary circuits is such that if the electromotive
forces developed in all the turns of the cores y and z respectively be designated by
the letters ele2 and the following equations may be written, E and B being two
constants:
et
=
-
E sin 2B) sin 2 wat
(E 2 (B+ })) sin 2 = (a t + } )
In the same way
sin 2 at + sin 2 B
==
sin 2
(at + }) + sin 2
(cos 2
(B + 1/3 )
(t
-
B)
-
cos 2 π (f
=
(cos 2
(a t - B).
+ sin 2 (at + } sin 2 (B + })
+ sin 2 T (at)sin 2 (B + })
-
1
B))
cos 2
(+ B + ¾ ) )
sin 2
cos 2
(at+)+ sin 2
(ut + B) + sin 2
(B+ 3)
==
(cos 2
(at
-
B)
cos 2 π
(a t + B + ) )
T (at+B+) + cos 2 T (at +
B +
)
= 0
4

page_text: If, in passing from one secondary circuit to the next, B is successively varied by an
1
amount equal to these 2 K circuits will carry electromotive forces of the same
2 K:
effective magnitude but successively differing in phase by
2 K
of a period.
The number of turns N N N³ to be assigned to the different primary circuits
exciting the coils of a secondary circuit is determined as follows. Let be the
maximum values of the flux developed in the cores . y = (see Fig. 1) respectively.
Then:
el
=2f sin 2 π a t
27 af sin 2
(at + })
e3
2π a f³ siu 2π (at + })
But on the other hand,
Σπαρ Νι
H
2 π a f² N
HL.
2 π u f³ N³
H
Ru aliminating 31 32 3 and 12₤3 from these three equations there is obtained.
and N
E sin 2 (B+ %)
=
If sin 2 B 0 or sin 2 π (B+}) = 0 or sin 2π (B+3) O the corresponding
primary coil should have an infinite number of turns, but as the secondary coil
which would accompany it would carry no electromotive force, this coil as well as
the magnetic core and the primary coil which ought to excite it will simply be
suppressed.
Each secondary circuit then should surround three distinct magnetic cores each
provided with a special primary circuit. Passing from one core to another, the
inaximum intensities of the flux developed in the three cores will vary according to a
sinusoidal law.
Considering all the cores the primary circuits of which are fed by the same source
of electromotive force, the intensities of flux developed in them also vary according
to a sinusoidal law. Thus it becomes obvious that the sections of these cores should
vary proportionally to the intensities of flux which they are to carry.
It may be remarked, in passing, that the secondary circuit of the rank (n + K)
ought always to carry an electromotive force equal but of contrary sign to that of the
circuit of rank n. It will then be possible to make the same magnetic cores react on
these two circuits by merely taking care to wind one in one direction, the other in
the other direction. In this manner it will be necessary only to arrange 3 K distinct
inagnetic cores instead of 6 K, to excite the 2 K secondary circuits.
In what precedes, only the most common case of three phase currents has been
considered; but the same method is applicable to cases in which p currents differing
in phase by of a period are to be used. It will then be necessary to cause
p distinct magnetic cores to excite each circuit, developing in each turn surrounding
P
alastomative farges

page_text: and the quantity B must be varied by
1
P
in passing from one secondary circuit to
the next. It will be seen that the different magnetic cores forming a part of a
converting transformer may be grouped among themselves in an infinity of ways.
There will be described here, merely by way of example, an apparatus comprising
48 secondary circuits and capable of supplying a continuous current of 1600 ampères
at a tension of 250 volts when fed with three phase alternating currents of 6000 volts
simple tension and having a frequency of 50.
(1) Cross section of the magnetic cores.
Calculation shows that the maximum
value of the electromotive force developed in each secondary circuit ought to be
17.05 volts.
Each secondary circuit has two turns and the maximum specific induction in each
of the magnetic cores is equal to 6000.
By winding two secondary circuits round each core it should be possible to arrange
3 x 24 = 72 distinct cores.
If s¹ s
82 represent the actual cross sections of these cores in
square centimetres the following table shews the values in question :
§¹
üüüüüh
=
0 sq.
cin.
$
213 sq. cm.
§13 = 301 sq. cm.
$19
= 213 sq. cm.
Sº
-
40
$ $
239
"
§14
298
$20
= 184
33
"
22
"
"
2
78
"
5:
$ 9
261
§15 == 291
S21 151
27
22
22
23
"
>:
115
=
278
§16
2
22
1
278
S22
115
"
"
"
""
$5
=
151
Su
291
"
:
§17
261
S23
=
78
"
وو
23
22
29
$6
= 184
23
22
$12 = 298
$18 239
=
S24
-
40
"
"
ور
"
"
(2) Manner of grouping these cores.
In order to avoid all mutual induction
between the primary circuits connected with the different sources of electromotive
force, only those cores which will be the seat of variations of flux of the same phases
are connected magnetically with each other.
On the other hand, it is of advantage, from the point of view of diminishing the
length of the connecting wires, to arrange on one side of the commutator one half of
the secondary circuits and the other half on the other side.
These considerations lead to this arrangement of the cores in six parallel lines and
in order that the apparatus may not be too long in relation to its height the 12 cores
of each line are placed in two storeys.
In this way, the arrangement shewn diagrammatically in Fig. 2 is arrived at.
The cores of the upper storey are represented by circles of diameters rather smaller
than those with which they are concentric and which represent the cores of the lower
storey.
The numbers on the circles give the cross sections in sq. cms of the corre-
sponding cores.
Fig. 3 is a sectional side elevation shewing the magnetic skeleton constituted
by the cores of Fig. 2, their anchor pieces d d and the exterior cores e e, e e.
The numbers have the same significance as those in Fig. 2.
In order to reduce to a minimum the cross sections of the anchor pieces d d and
the exterior cores e e, it is supposed that the fluxes developed in the cores of each
column flow in one direction in the columns of even series and in the contrary
direction of those of odd series.
This flow is represented by the arrows in Fig. 3. By this arrangement only the
difference and not the sum of the fluxes has to pass in the anchor pieces d d and the
cores e e, so that the cross sections of these together with the loss due to hysteresis
of which they are the seat may be much reduced.
This result is attained by winding to the right hand all the primary coils of
the cores represented in Fig. 2 by circles the hatch lines of which are in one
direction and by winding to the left hand all the primary coils of the cores
represented by circles with hatch lines in the other direction.
(3) Primary circuits. The number of turns of these circuits will vary with the

page_text: cross sections of the cores on which they are wound. As there are cores of 12 different
cross sections there should be primary circuits having 12 different numbers of turns.
On the other hand as the numbers of ampère turns developed by each secondary
circuit is the same, and as each primary circuit should always develop a number of
ampère turns very nearly equal to and of opposite sign to that developed by the
secondary circuit surrounding it, the intensity of current in each primary circuit is
inversely proportional to the number of turns therein.
Thus it is proper to vary the cross section of the conductor in passing from one
circuit to the other.
The following table shows the number of turns of the primary circuits surrounding
the cores of the cross sections named, the diameter of wire suitable for winding and
the number of similar circuits comprised in the apparatus.
(4) Secondary circuits. Referring to Fig. 2 it will be seen that the three
cores which should excite each secondary circuit are arranged in lines I, II,
III,... VI.
Around each of these groups of three cores there should be arranged four turns of
which two constitute one secondary circuit and the other two the other secondary
circuit.
For this purpose two copper bands are used, separated by an insulator and wound
as shewn in Fig. 4. When one of the cores is omitted the copper bands are wound as
represented in Fig. 7.
There are thus two windings. Suppose two similar systems with the edges of the
copper bands separated by an insulator f g (see Fig. 6). The ends of the lower
bands are arranged as shewn in Fig. 4, those of the upper bands are shewn in Fig. 5
or conversely. In any case, if the ends of the bands in Fig. 4 be represented by
hijk and those in Fig. 5 by l, q, r, s, the following connections must be made by
vertical copper bands (see Fig. 7) :-
The end is united to the end 1.
The end is united to the end q.
The ends and are prolonged downwards if the bands in Fig. 5 are on the upper
part and upwards if they are on the lower part of the apparatus.
All the bands are separated by insulators and are held together by insulated
holts.
It will be apparent from Figs. 4, 5 & 6 that there are two circuits of two turns
around the three cores.

page_text: The first begins at the end and ends at the ends; it turns from left to right around
the cores.
The second begins at the end k and ends at the end ; it turns from right to left
around the cores.
The diagram Fig. 2 shews how the various secondary circuits should be grouped
among themselves (To facilitate reading of the diagram it is supposed that the
secondary circuits have each only one turn). It also shews how the current terminals
should be arranged along the apparatus between the lines of cores I and IV.
Fig. 8 shews an elevation of that side of the apparatus on which are the cores in
line I of Fig. 2 which are opposite to the commutator.
Fig. 9 represents a commutator similar to those which have been used in earlier
converting transformers, (see Specification No. 17826 of 1892); for it may be sub-
stituted an apparatus of a different system.
This commutator should be installed between lines I and IV of the diagram Fig. 2.
Its terminals follow the same order as those of the transformers, so that it is only
necessary to connect those terminals of the converter and the transformer which are
opposite to each other.
11
ABEL & IMRAY,
Agents for the Applicant.
Improvements in Converting Transformers.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings,
in the County of London, Consulting Engineer and Chartered Patent Agent, do
hereby declare the nature of this invention (as communicated to me from abroad by
La Société Anonyme pour la Transmission de la Force par l'Electricité, of 13, Rue
Lafayette, Paris, France, Manufacturers) and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following state-
ment:
Converting transformers are designed to transform alternating currents of any
tension into continuous currents of any other tension, or, conversely, to transform
continuous currents of any tension into alternating currents of any other tension.
Such a converting transformer consists essentially of :—
(A) A transformer comprising
(1) n primary circuits excited by a alternating electromotive forces of the same
effective magnitude but differing in phase by of the period, and
n
(2) K secondary circuits which should carry 2 K alternating electromotive forces of
1
the same effective maguitude but differing in phase by of the period. These
2 K
2 K secondary circuits are connected like the consecutive sections of the armature of
a continuous current machine divided into 2 K sections.
(B) A collector having 2 K synchronous segments which are connected, either
directly or by means of rings and brushes, to the junction wires of the 2 K secondary
circuits, just as the segments of a commutator of a continuous current machine are
connected to the junctions of the succesive sections of the armature.
Under these conditions, if the frequency of the alternating currents to be trans-
formed is a, the electromotive forces developed between the consecutive contacts of the
collector will be identical with those which would be developed between consecutive
contacts of the collector of a continuous current bipolar dynamo making a revolutions

page_text: per second and having a stationary armature of 2K sections and moving field
inagnets.
A continuous current may be drawn from the collector of such a machine when the
brushes are made to turn round the collector with a speed of a turns per second. The
same result is achieved in the case of the converting transformer by making its brushes
turn at the same speed by means of a synchronous motor. In converting trans-
formers which have already heen constructed, the number of magnetic cores and
primary circuits of the transformer is equal to the number of polyphase currents to be
utilised and is of necessity small (in practice it is 3 in the case of three-phase
currents and 4 in that of four-phase currents).
Thus, apparatus of great power have been constructed with a small number of
large elements, the magnetic leakage of which attains a high value, rendering
cominutation difficult. This invention therefore relates to a converting transformer
constructed of a large number of elements of small dimensions in which the magnetic
leakage is much reduced.
The principle of the invention may be set forth as follows:
Suppose that the three electromotive forces H1 H2 H3 of the same effective
magnitude but of a phase difference equal to of the period, are so arranged that
H Hsin 2 at, H = H sin 2 (at +), H³ H sin 2 (a + ), H heing
a constant electromotive force, the frequency of the alternating currents furnished
by the three sources and t the time.
It is required to produce in 2 K distinct secondary circuits 2 K electromotive forces
1
The constant h is also an electromotive force but may have any relation to
constant H. Each secondary circuit will consist of three distinct coils mounted in
series and having each the same number G of turns. Referring to the drawings
accompanying the Provisional Specification. Fig. 1 is a diagrammatic representation
of these coils a b c. Each of them surrounds one of the magnetic cores x y z.
These cores are also covered by the primary circuits m p q connected with the three
sources of the electromotive forces H1 H2 H3 and a neutral point o.
The number of turns of these primary circuits is such that if the electromotive
forces developed in all the turns of the cores x y and z respectively be designated
by the letters el e² and e³ the following equations may be written, E and B being two
constants, the former an electromotive force and the latter a phase difference.
(E sin 2B) sin 2 π at
e¹
==
=
(E sin 2
=
(E sin 2
(B+)) sin 2 m (at + z )
(B+)) sin 2
(at + })
===
· (e² + e² + €³) = GE
====
sin 2 π a t.
sin 2 π B
+ sin 2
+ sin 2
(at + }) sin 2 π (B+ })
(+) sin 2 (B + })

page_text: an amount equal to
these 2 K circuits will carry electromotive forces of the
2 K,
same effective magnitude but successively differing in phase by
I
of a period.
2 K
The number of turns N N N to be assigned to the different primary circuits
exciting the coils of a secondary circuit is determined as follows. Let be the
maximum values of the flux developed in the cores xyz (see Fig. 1) respectively.
Then:
el
=2fsin 2 π at
e2
= 2 of² sin 2 π (a ! + })
=
23 sin 2π (at + %)
But on the other hand,
2
71
aj¹ N¹
H
2 π a f² N
=
H
2
71
af N³
-
H
By eliminating e' e² eª and ſ^' ƒ from these three equations there is obtained.
If sin 2 B
=
N³
E sin 2 (B+33)
O or sin 2 (B+ 3/3)
=
=
O or sin 2 (B + })
() the corresponding
primary coil should have an infinite number of turns, but as the secondary coil which
would accompany it would carry no electromotive force, this coil as well as the inag-
netic core and the primary coil which ought to excite it will simply be suppressed.
Each secondary circuit then should surround three distinct magnetic cores each
provided with a special primary circuit. Passing from one core to another, the maxi-
muin intensities of the flux developed in the three cores will vary according to a
sinusoidal law.
Considering all the cores the primary circuits of which are fed by the same source
of electromotive force, the intensities of flux developed in them also vary according to
a sinusoidal law. Thus it becomes obvious that the sections of these cores should
vary proportionally to the intensities of flux which they are to carry.
It may be remarked, in passing, that the secondary circuit of the rank (+K)
ought always to carry an electromotive force equal but of contrary sign to that of the
circuit of rank n. It will then be possible to make the same inagnetic cores react on
these two circuits by merely taking care to wind one in one direction, the other in
the other direction. In this manner it will be necessary only to arrange 3 K distinct
magnetic cores instead of 6 K, to excite the 2 K secondary circuits.
In what precedes, only the most common case of three phase currents has been con-

page_text: sidered but the same method is applicable to cases in which p currents differing in
phase by of a period are to be used. It will then be necessary to cause p distinct
magnetic cores to excite each circuit, developing in each turn surrounding them
electromotive forces.
P

page_text: The numbers have the same significance as those in Fig. 2. In order to reduce to
a minimum the cross sections of the anchor pieces d d and the exterior cores e e, it
is supposed that the fluxes developed in the cores of each column flow in one
direction in the columns of even series and in the contrary direction in those of odd
series.
This flow is represented by the arrows in Fig. 3. By this arrangement only the
difference and not the sum of the fluxes bas to pass in the anchor pieces d d and
the cores e e, so that the cross sections of these together with the loss due to
hysteresis of which they are the seat may be much reduced.
This result is attained by winding to the right band all the primary coils of the
cores represented in Fig. 2 by circles the hatch lines of which are in one direction
and by winding to the left hand all the primary coils of the cores represented by
circles with hatch lines in the other direction.
3. Primary circuits. The number of turns of these circuits will vary with the
cross sections of the cores on which they are wound. As there are cores of 12
different cross sections there should be primary circuits having 12 different numbers
of turns.
On the other hand as the numbers of ampèré turns developed by each secondary
circuit is the same, and as each primary circuit should always develop a number of
ampère turns very nearly equal to and of opposite sign to that developed by the
secondary circuit surrounding it, the intensity of current in each primary circuit
is inversely proportional to the number of turns therein.
Thus it is proper to vary the cross section of the conductor in passing from one
circuit to the other.
The following table shows the number of turns of the primary circuits surrounding
the cores of the cross sections named, the diameter of wire suitable for winding and
the number of similar circuits comprised in the apparatus.
4. Secondary circuits.
Referring to Fig. it will be seen that the three cores
which should excite each secondary circuit are arranged in lines I, II, III .
VI.
Around each of these groups of three cores there should be arranged four turns
of which two constitute one secondary circuit and the other two the other secondary
circuit.
For this purpose two copper bands are used, separated by an insulator and wound
as shewn in Fig. 4. When one of the cores is omitted the copper bands are wound
as represented in Fig. 7.

page_text: Suppose two simmar systems with the edges of the copper panus separated by an misu
lator fg (see Fig. 6). The ends of the lower bands are arranged as shewn in Fig. 4,
those of the upper bands as shewn in Fig. 5 or conversely. In any case if the ends
of the bands in Fig. 4 be represented by hij k and those in Fig. 5 by lg r 8, the
following connections must be made by vertical copper bands (see Fig. 6).
The end is united to the end r.
The end is united to the end q.
The ends and are prolonged downwards if the bands in Fig. 5 are on the upper
part and upwards if they are on the lower part of the apparatus.
All the bands are separated by insulators and are held together by insulated
bolts.
It will be apparent from Figs. 4, 5 and 6 that there are two circuits of two turns
around the three cores.
The first begins at the end h and ends at the end 8, it turns from left to right,
around the cores.
The second begins at the end and ends at the end; it turns from right to left
around the cores.
The diagram Fig. 2 shews how the various secondary circuits should be grouped
among themselves. (To facilitate reading of the diagram it is supposed that the
secondary circuits have each only one turn.) It also shews how the current terminals
should be arranged along the apparatus between the lines of cores I and IV.
In this diagram there are two turns shewn in full lines and two in dotted lines.
The turn shewn in full lines and that in dotted lines which are close to the hatched
circles representing the magnetic cores, are supposed to be wound on the magnetic
cores of the upper storey. The other two are on the lower cores.
Starting, for example, from the terminal marked 1 and going towards the top of
the figure, there is:-
(1) A turn from right to left round the three cores of the lower storey, which have
cross sections, 261 and 261 arriving at the conductor No. 2 :
(2) A turn from right to left round the cores of the upper storey, which have cross
sections 40, 239 and 278, arriving at the conductor No. 3;
(3) A turn from left to right round the cores of the upper storey of cross sections
78, 213 and 291, because the winding of the primary coils of the cores of the second
series is the reverse of that of the cores of the first series; the conductor No. 4 is
thus reached;
(4) A turn from left to right round the cores of the lower storey of sections 115,
184 and 298, and so on.
Thus the winding is firstly round the 18 cores of the upper part of the figure and
secondly round the 18 cores of the lower part, the uninterrupted circuit being
represented by dotted lines.
This unites with the uninterrupted circuit shown in full lines which also embraces
the whole 36 cores, the circuit ending at the place where the dotted line circuit
begins.
There is thus a total closed circuit consisting of 48 consecutive sections each
surrounding three cores.
Forty eight terminals are placed on the course of the circuit between the
consecutive sections.
Fig. 8 shews an elevation of that side of the apparatus on which are the cores in
line I of Fig. 2 facing the commutator.
The skeleton of the apparatus is as shown in Fig. 3. It consists of laminated iron
bands and is clearly represented in that figure.
Around the cores shown in this skeleton are the primary coils with a number of
turns varying from one bolbin to the next, enclosed in the insulating cylinders c, c, c,
Fig. 8.
These coils are all included in branch circuits x, x, x (Fig. 8) between a conductor
connected with one of the branches of the main circuit, and a neutral wire.
Three apparatus of the same kind, set up according to the scheme of Fig. 2, are

page_text: placed one behind the other in such a manner that the same secondary windings,
constituted as represented in Figs. 4, 5, 6 and 7, may surround 3 cores, having
their primary coils in the saine row one behind the other, the indications of the
diagram Fig. 2 being always followed.
The terminals are arranged along the median line of the apparatus.
Two groups of 3 apparatus of the same kind are disposed one on each side of the
commutator shewn in Fig. 9.
This commutator comprises 48 terminals o divided into two groups of 24, one on
each side of the apparatus. These terminals are connected by leads with the
terminals of the transformers, and also with the brushes of the commutator, the
supports of which are alone shown in Fig. 9, for the sake of clearness. The supports
are gun metal plates a c'each carrying at its lower end b d one of the terminals o.
These plates are in pairs but are insulated from each other and are held together
by insulated bolts G, but separated by distance pieces H. The bolts G are supported
by end pieces such as P forming part of the framework of the machine.
The plates a b c d carry short rods I which are the axes of the brush holders.
The brushes bear upon consecutive rings, namely 48, one of which is represented
by J; these are connected respectively with the similarly numbered contacts of two
multipolar collectors M, arranged for quantity, by rods K and connections L.
Each of these rods is united to one of the rings but is insulated from all the others.
These two collectors are really only one divided into two parts for convenience of
construction. That is to say, if the contacts of the two collectors be numbered
successively.1, 2, 3 . . . 24, 25 . . 48 and i, 2, 3
24, 25. 48, the ring
connected with current No. 1 of the transformer will communicate with all the
contacts numbered 1 of the two collectors and with these alone.
The whole system comprising the rings J, the collectors M and their connection is
moveable on the axis y carried by bushes R; at each end of the system there is a
synchronous motor S divided into two parts having as many poles as collectors.
The drawing Fig. 10 filed herewith is a diagrain of the connections between the
transformer and the commutator. In the middle line are the 48 rings of the
commutator on which bear the brushes numbered 1 48, shewn alternately on
opposite sides of the rings, as indicated also in Fig. 9.
On either side of the rings the terminals of the transformer are
numerals which correspond with those shewn in the diagram Fig. 2.
is connected by a lead with the brush having the same number.
represented by
Each terminal
The electromotive forces developed in the 48 sections of the low tension winding
of the transformer are the origin of 48 electromotive forces of the same effective
magnitude, of the saine frequency as the alternating currents which it is required
to transform, and of period successively diminishing 1,48 thereof.
These electromotive forces developed between the consecutive contacts of the two
collectors are identical with those which would be developed if these two collectors
were connected with a continuous current machine having the same number of poles
as the continuous current collectors and of which the armature comprised 24 sections
per pole and turned with a speed equal to a divided by half the number 2 n of the
poles of the collectors.
ሳ If then the collectors were made to turn with a speed of 2n turns per second,
there would be a continuous current between their brushes.
This function is fulfilled by two synchronous motors S, S, disposed one on each side
of the collectors as shewn in Fig. 9.
As stated at the beginning of this specification the apparatus is reversible and
may be used to transform a continuous current into polyphase alternating currents.
For this purpose one of the synchronous motors shewn in Fig. 9 is exchanged for a
continuous current motor which can turn the system at the desired speed, and a
continuous current is passed into the apparatus through the brushes bearing on the
collector.
Under these conditions each of the 2 K secondary circuits of the transformer will
be traversed by a current the direction of which will change in sign each time that

page_text: the contacts of the collector between which the circuit is branched pass under the
brushes, and the periods at which this change of sign occurs will succeed each other
regularly from circuit to circuit.
These changes of direction of the current are of necessity accompanied by
variations of the flux in the cores around which the secondary circuits pass.
The variations of flux should be such that the sum of the electromotive forces
which they develop in the various secondary circuits which, at each instant, are
grouped in series between the brushes, are very nearly equal and of contrary sign to
the electromotive force which determines the passage of the continuous current.
A
calculation shews that the variations of flux of which the various cores are then the
seat, are similar to those of which they would be the seat when the apparatus is used
for transforming polyphase currents into continuous current. Under these conditions
all the primary circuits grouped in parallel will be the seat of the same electromotive
forces, but if there are n groups of these circuits branched from the n conductors of
the net-work, the electromotive force developed in each group will have their
variations regularly decreased by 1/n of the period from one group to the next.
apparatus will then furnish n polyphase currents.
The
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. A transformer for converting alternating polyphase electric currents of various
numbers of phases and various tensions into alternating polyphase currents of any
tension but of a greater or less number of phases, this transformer being arranged as
follows:-
For transforming a primary polyphase currents, having consecutive differences of
phase, each of period 1/n into K polyphase secondary currents having period
difference 1/K, the apparatus comprises K secondary circuits all having the same
number of windings, each surrounding n magnetic cores developing n distinct fluxes
by n primary circuits, so that the variations of these fluxes present successive phases.
differing by 1/n of a period and the numbers of primary windings which determines
the passage of these fluxes, vary in passing from one core to another in such a way
that the intensities of the fluxes developed in the n cores are proportional to the
quantities sin B, sin (B+ . . . sin (B+(n-1)²), B being a constant.
(B+27)
2
In passing from one of the K secondary circuits to the next, the primary circuits
which surround the n cores, acting on the new secondary circuit are so disposed that
the intensities of the fluxes developed in these cores are proportional to the
quantities.
brackets in the above expressions have to be increased by 2
All the primary coils which are to develop flux of which the variations are of the
same phase are branched between the same terminals. The number of their turns are
inversely proportional to the intensities of flux which they are to develop.
If for every secondary circuit 1, 2 . . n the above expressions are numbered and
if the same numbers denote the cores which are the seats of fluxes of corresponding
intensities the K cores belonging to the K secondary circuits bearing the same
numbers have all their primary circuits connected in shunt with the same source of
electromotive force.
This transformer is reversible and can transform K currents of
1
phase differences

page_text: and of any tension into n currents of -phase difference and of any tension, the
12
circuits named above secondary becoming primary and conversely.
2. The combination of the transformer above referred to with a collector formed
by grouping among themselves and with the successive plates of the collector
the K circuits above named secondary in the first place as if for the successive groups
of a continuous current armature divided into K group, this connection being made
direct when the collector is stationary and brushes revolve around it or made through
rings and rubbers when the collector revolves and the brushes are stationary. The
object of this combination is to gather the currents formed by the secondary circuits,
when the brushes or the collector have suitable speed, or conversely to transform a
continuous current into alternating polyphase currents of any tension.
Dated this 21st day of December 1900.
ABEL & IMRAY,
Agents for the Applicant.