Improvements in Transformers for Continuous Electric Currents.
Year: 1899

page_text: Improvements in Transformers for Continuous Electric Currents.
11
We, ALFRED WYDTS, of 339, Rue des Pyrénées, and GUSTAVE WEISSMANN, of 3,
Rue Chaptal, both of Paris, in the Republic of France, Engineers, do hereby declare.
the nature of this invention to be as follows:-
The principle of electrical transformers, is based, as is well known, upon the
phenomena of induction which are themselves subordinated to the possibility of
creating a flux of variable and periodic force.
The variation of this flux of force may be obtained either by the periodic variation
of the primary current (as is the case with alternating current transformers) or by the
relative displacement of the primary and secondary circuits (as in the case of
transforming motors).
As it has hitherto been impossible to effect the transformation of a continuous
current in a practical manner, without the production of arcs which deteriorate the
apparatus, it has only been possible to utilise transforming motors, the poor efficiency:
of which is well known.
This invention relates to a transformer for continuous electric currents the efficiency.
of which is equal to that of alternating current transformers.
+
Our transformer, the principle of which consists in creating practically with a
continuous current a variable magnetic field, is constituted by two field-magnets coils
of an equal number of sections, each comprising the same number of convolutions ;,
these coils are mounted either upon the same core of soft iron or upon two distinct,
cores, the various sections of each coil being connected respectively to different
divisions of a circular commutator, to the brush of which is imparted a movement of.
rotation.
The divisions of this commutator are connected in pairs in such a manner that
the continuous current passed invariably, without interruption, whatever may be the
position of the brushes, into the same number of convolutions, the intensity of the
current thereby remaining constant.
As the current passes in a continuous minner, it creates in the soft iron core or
cores traversing the field-magnet coils a variable magnetic field the value of which
depends upon the relative positions of the sections which are brought into action.
The object of these variations of the magnetic-field is to create secondary currents
in one or more induction coils mounted upon the soft iron core or cores.
Our transformer comprises two coils consisting of an equal number of sections, each
of which is provided with the same number of convolutions and is wound upon a core,

page_text: consisting of iron sheets, which is closed upon itself and forins the magnetic circuit of
the transformer.
For the sake of simplicity each coil is hereinafter described as being composed of
three sections only, but it will of course be understood that each coil will be composed
of a larger number of sections, such number varying according to the various appli-
cations of the transformer; a greater or less number of sections merely imparting
to the inducing current a greater or less constancy, as is hereinafter explained.
The different sections of each coil are connected respectively to the divisions of a
circular commutator; a brush rotates upon the dial of the commutator in the direction
right to left in such a manner as to successively connect the diametrically opposite
divisions of this commutator, these divisions are in addition connected one with the
other by means of cords which place their respective divisions in communication in
such a manner that the continuous current invariably traverses the same number of
.convolutions.
The primary inducing current is conveyed by the primary wires to suitable
terminals.
Upon the core are also wound two secondary coils or armature circuit, the two
extremities of the wire of which end at other suitable terminals.
Our apparatus operates in the following manner;
The brush occupying the position (the first diametrically opposite divisions) the
inducing or field-magnet current enters at the positive terminal, passes through the
three sections of the first coil, returns through the connection wire to the first division of
the commutator, the brush conducts it to the division diametrically opposite and it
finally returns through-the-connecting wire to the negative terminal.
In this first phase, the current circulates around the magnetic core in the direction
left to right and consequently produces therein a magnetic flux, the direction of
which is left to right.
'
APT
Designating the value of the flux due to the magnetising action of a section of the
first coil by the letter "a," as the current passes into the three sections the value of
the resultant magnetic flux may be represented by "3"."
When the brush has rotated through one division, it places the next two diametri-
cally opposite divisions in communication, the current then traverses the first and
second sections of the first coil and is conducted through its connecting wire to the
second division of the commutator, passes to its diametrically opposite division and
traverses the third section of the second coil and finally regains the negative
terminal. The current, however, circulates in the convolution of the second coil in
the direction right to left and produces in the magnetic core a flux the direction of
which is right to left, this flux is thus of contrary sign to that produced by the first
coil. There are therefore two sections producing a magnetic flux in the direction
left to right and one section only of the second coil producing a magnetic flux in the
direction right to left.
Designating by the letter "b" the value of the magnetic flux due to the passage
of the current in one of the sections of the second coil, the resultant flux will be
equal to 2a + b, but as b , this resultant flux will be equal to a.
-
The magnetic flux is always due to the passage of the current through three
sections, two of the first coil and one of the second coil.
The brush continuing to rotate, places the third diametrically opposite divisions of
the commutator in communication, the inducing current then traverses only the
third section of the first coil in the direction left to right and second and first
sections of the second coil in the direction right to left.
-
-
"
The value of the resultant magnetic flux will then be equal to a + 2b, but as
b' = a this is equivalent to a 2, that is to say to " a. This flux is
invariably due to the magnetising action of three sections one of the first coil and
two of the second coil.
When the brush places the fourth diametrically opposite divisions in com-
munication, the inducing current no longer traverses any of the convolutions of the
1

page_text: first coil, but proceeds directly to the second coil passing through the connecting
wires and the brush.
The curreut circulating in the three sections of the second coil in the direction
right to left produces a magnetic flux the direction of which is right to left and of
which the value will be equal to "3b," that is to say to " 3. "
-
The brush then places the fifth divisions of the commutator in communication;
the inducing current entering at the positive terminal traverses the first section of
the first coil is conducted by the connecting wire and the connecting cord to the
opposite fifth division and returns to the negative terminal by its connecting cord
the connecting wire and the two-sections (second and third) of the second coil.
1
The value of the resultant magnetic flux is then equal to a + 2b, that is to say
to "a."
.
The brush then reaches the sixth divisions of the commutator and the current
then passes through the first and second sections of the first coil and the third
section of the second coil; the value of the magnetic flux then again becomes " a."
Then, when the brush reaches the seventh divisions the current traverses the three
sections of the first coil without passing through the second coil, and the value of
the magnetic flux again becomes "3."
This action continues, the brush again reaching the first divisions; the same
phases are repeated, the value of the magnet flux starting from "3" "falls to " - 3"
and again becomes " 3*."
1
For half a revolution of the brush, this latter starting from the position of the
first divisions the value of the magnetic flux falls from "3" to
" and
then rises from "
to "3"; this value therefore becomes zero twice during
this half revolution.
3a
It follows from what has been stated that the induced or armature circuit is the
seat of induction currents the electro-motive force of which is a function of the ratio
of the convolutions of the first coil or of the second coil to the total number of
convolutions of the secondary or.armature coils. .
'
Owing to our arrangement, the number of sections which are rendered operative
is always the same (three in the case which has been assumed) the intensity of the
inducing current is therefore constant, this current is never interrupted and there is.
consequently no sparking.
A movement of rotation is imparted to the brush by means of a small motor of
any suitable kind electric or otherwise; the power absorbed being insignificant as a
small motor of from one to two kilogramme-metres is capable of operating a trans-
former of from 10 to 15 horse-power.
The direction of the induced currents being always the same for the same angular
positions of the brush, it becomes easy to rectify the alternating currents produced
by employing a shell redressing commutator, of any suitable kind, mounted upon
the axis and rigidly connected with the brush.
r
If the magnetic circuit is divided into two portions upon the axis and if we
separate the two halves thus obtained without in any way varying the number of:
inducing convolutions with which they are provided, the device then comprises two
distinct and open magnetic fields.
We will consider what takes place in one half of the transformer, for example;
When the brush rests upon the first diametrically opposite divisions, the current
traverses the three sections of the first coil and creates a magnetic flux which
traverses the core...
This brush having rotated through one division, rests upon the second opposite
divisions and the current then passes through the first and second sections only of
the first coil; this diminution in the number of convolutions rendered operative
corresponds to a diminution of the magnetic flux, and this demagnetisation corre-
sponds to a direct induced current which has its origin in the induced convolutions
or secondary-coil...
When the brush reaches the third opposite divisions the current traverses the first
..
1.
.

page_text: section only of the first coil; this results in a fresh diminution of the magnetic flux
and consequently in a fresh induced current in the same direction as before.
.
The demagnetisation is total when the, brush rests upon the fourth divisions and
consequently the induced current is nil.
In the fifth position of the brush the current again passes into the first section
of the first coil, resulting in a fresh magnetisation of the core and consequently in an
induced current, but in the reverse direction.
When the brush occupies the sixth position, the current again traverses the first
and second sections of the first coil; an increase of the magnetic field is thus pro-
duced resulting in an induced current.
The same phenomena are produced in the other half of the transformers but the
magnetic field increases in said half in proportion as it diminishes in the first half
and vice versa.
.
In the arrangement above described the induced coils are connected in series in
order that the effects may be combined, but we may also employ, in certain cases, a
single coil only.
It will of course be understood that our transformer may vary in form and
dimensions and that we reserve the right to modify its arrangements of detail
according to the various applications of which it is capable.
1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in Transformers for Continuous Electric Currents.
We, ALFRED WYDTS, of 339, Rue des Pyrenees, and GUSTAVE WEISSMANN, of 3, Rue
Chaptal, both of Paris, in the Republic of France, 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 :-
The principle of electrical transformers is based, as is well known, upon the
phenomena of induction which are themselves' subordinated to the possibility of
creating a flux of variable and periodic force.
The variation of this flux of force may be obtained either by the periodic variation
of the primary current (as is the case with alternating current transformers) or by
the relative displacement of the primary and secondary circuits (as in the case of
transforming motors).
.
As it has hitherto been impossible to transform a continuous current in a practical
manner, without producing arcs which deteriorate the apparatus, it has only been
possible to utilise transforming motors, the low efficiency of which is well known...
This invention relates to a transformer for continuous electric currents the
efficiency of which is equal to that of alternating current transformers.
Our transformer, the principle of which consists in creating, practically with a
continuous current, a variable magnetic field, is constituted by two field-magnet coils
of an equal number of sections, each comprising the same number of convolutions;
these coils are mounted either upon the same core of soft iron, or upon two separate
cores, the various sections of each coil being connected respectively to different
divisions of a circular commutator, to the brush of which is imparted a movement of
rotation.
The divisions of this commutator are connected in pairs in such a manner, that
the continuous current passes without interruption, whatever may be the position of
the brushes, through the same number of convolutions, the intensity of the current
thereby remaining constant.
As the current passes in a continuous manner, it creates in the soft iron core or

page_text: cores traversing the field-magnet coils, a variable magnetic field, the value of which
depends upon the relative positions of the sections which are brought into action.
The object of these variations of the magnetic-field is to create secondary currents
in one or more induction coils mounted upon the soft iron core or cores.
In order that our invention may be readily understood, we have represented in the
accompanying drawing, but by way of example only, our improved transformer.
Figure 1 illustrates our transformer, the soft iron core being closed upon itself.
Figure 2 illustrates a modified form of our transformer, presenting two separate
magnetic fields.
In these figures similar letters of reference indicate like parts.
As shown in these drawings our transformer comprises two coils A, B consisting of
an equal number of sections, each of which is provided with the same number of con-
volutions and is wound upon a core consisting of iron sheets F, which is closed upon
itself (Figure 1) and forms the magnetic circuit of the transformer.
For the sake of simplicity each coil is shown and hereinafter described as being
composed of three sections only, a¹ a² a³ 61 62 63, and it will of course be understood
that each coil will be composed of a larger number of sections, such number varying
according to the various applications of the transformer; a greater or less number of
sections merely imparting to the inducing current a greater or less constancy, as is
bereinafter explained.
The different sections of each coil are connected respectively to the divisions c¹, c²,
c³, c, c, c, c7, and d¹ d² d³ d4 d5 do d' of a circular commutator; a brush e rotates upon
the dial of the commutator in the direction of the arrow f and thereby successively
connects the diametrically opposite divisions of this commutator, these
are connected with the other by wires g¹, g², g³, h1, h2, h³ which division's
'the
divisions c¹ and c, c² and c, c³, and c, d¹ and d", d2 and do, respectively into com-
munication one with the other, in such a manner, that the continuous current
invariably traverses the same number of convolutions.
The primary inducing current is conveyed by the primary wires to the terminals L
and L¹.
Upon the core F are also wound two secondary coils S S¹ or armature circuit, the
two ends of the wire of which lead to the terminals, M and M¹.
The action of our apparatus is as follows:
The brush e occupying the position represented in Figure 1, the inducing, or
field-magnet current enters at the positive terminal L, passes through the three
sections a' a² a of the coil A, thence through the connecting wire to the first
division c of the commutator, whence the brush e conducts it to the division, d¹
diametrically opposite, and it finally returns through the connecting wire to the
terminal L'.
.
In this first phase, the current circulates around the magnetic core F in the direc-
tion indicated by the arrow X, and consequently produces therein a magnetic flux in'
the direction indicated by the arrow X'.
:
Designating the value of the flux due to the magnetising action of a section of the
coil A by the letter "a," as the current passes into the three sections a¹, a², a³, the
value of the resultant magnetic flux may be represented by "3"."
When the brush e has rotated through one division, it places the divisions c² and d²
in' communication, the current then traverses the two sections a¹ and a² of the coil A
and is conducted through the connecting wire i² to the division c², thence passing to
the division d2 and traverses the section 63 of the coil B and finally regains the
terminal L'. The current, however, circulates in the convolution of the coil B in the
direction of the arrow Z and produces in the magnetic core F a flux, the direction of
which, is shown by the arrow Z¹, this flux is thus of contrary sign to that produced by
the coil A. There are therefore two sections producing a magnetic flux in the direction
of the arrow X¹ and one section only of the coil B producing a magnetic flux in the
direction of the arrow Z¹.
The magnetic flux is always due to the passage of the current through three
sections, two of the coil A and one of the coil B.

page_text: The brush e continuing to rotate, places the divisions .c³ and d³ of the com-
mutator in communication, the inducing current then traverses only the section a³ of
the coil A in the direction of the arrow X, and sections 62 61 of the coil B in the
direction of the arrow Z.,
b
I
:
':
"
The value of the resultant magnetic flux will then be equal to a +2,, but as
a or really a 24, this is equivalent to "-a," this flux is invariably due to
the magnetising action of three sections, one of the coil A and two of the coil B.1
When the brush e places the divisions c and d in communication, the inducing
current no longer traverses any of the convolutions of the coil, A, but proceeds
directly to the coil B, passing through the connecting. wire i, and the brush e, and the
⚫ connecting wire j...
+;
8
"
The current circulating in the three sections of the coil B in the direction of the
arrow, 7, produces a magnetic flux, the direction of which is indicated; by, the
arrow Z, and of which the value will be equal to "3"," that is to say to "-3"," 142
The brush e then places the divisions c and d in. communication; the inducing
current entering at the terminal L traverses the section a¹ of the coil A, is conducted
by the connecting wire and the connecting wire g¹ to the divisions passes to the
division d and returns to the terminal I by the connecting wire h¹, the connecting
wire and the two sections b2 63 of the, coil B.
The value of the resultant inagnetic flux is then equal to a +2b, that is.to say
to a."
"
The brush e then reaches the divisions o and do and the current then passes through
the two sections al a² of the coil A and the section 63 of the coil B; the value of the
magnetic flux then again becomes "
a.
Then, when the brush reaches the divisions c, d, the current traverses the three
sections of the coil A without passing through the coil B, and the value of the
magnetic flux again becomes "3"
This action continues, the brush again reaching the divisions c¹; the same phases
are repeated, the value of the magnet flux starting from "3" falls to "3a" and
again becomes "3ª."
For half a revolution of the brush e,-this latter starting from the position c¹, d¹‚—
the value of the magnetic flux falls from "3" to "-3" and then rises from " -3"
to "3"; this value therefore becomes zero twice during this half revolution.
It follows from what has been stated that the induced or armature circuit S S¹ is
the seat of induced currents, the electro-motive force of which is controlled by the
ratio of the convolutions of the coil A, or of the coil B, to the total number of con-
volutions of the coils S and S¹.
According to our invention; the number of sections in operation, are always the
same (three in the case which has been assumed) the intensity of the inducing:
current is therefore constant, the current is never interrupted and there is conse-
quently no, sparking.
1.
A movement of rotation is imparted to the brush e by means of a sinall motor of.
any suitable kind, electric or otherwise; the power absorbed being insignificant as a
small motor of from one to two kilogramme-metres is capable of operating a trans-
former of from 10 to 15 horse-power..
The direction of the induced currents being always the same for the same angular
positions of the brush e, it will be easy to rectify the alternating currents produced,
by employing a shell redressing commutator of any suitable kind, mounted upon the
axis, and rigidly connected with the brush e.
If the magnetic circuit is divided into two portions upon the axial line o, o¹, and if
we separate the two halves thus obtained without in any way varying the number of
inducing and induced convolutions with which they are provided, the device then
comprises two distinct and open magnetic fields F1, F2 (Figure 2)...
We will consider what takes place in one half of the transformer, F1, for example:
When the brush e rests upon the divisions e¹ d', as shown in Figure 2, the current
traverses the three sections a¹ a² a³ of the coil A and creates a magnetic flux which
traverses the core F!.

page_text: This brush having rotated through one division, covers the divisions e² d², and the
current then passes through two sections a¹ a² only of the coil A; this diminution in
the number of convolutions rendered operative, corresponds to a diminution of the
magnetic flux, and this demagnetisation corresponds to a direct induced current which
has its origin in the induced convolutions S.
When the brush reaches the divisions c³ d³, the current traverses one section a¹,
only, of the coil A; this results in a fresh diminution of the magnetic flux and con-
sequently in a fresh induced current in the same direction as before.
The demagnetisation is complete when the brush e rests upon the divisions c^ d²,
and consequently the induced current is nil.
In the position c³ d³ of the brush e the current again passes into the section a¹ of
the coil A, resulting in a fresh magnetisation of the core and consequently in an
induced current, but in the reverse direction.
When the brush occupies the position 6 do, the current again traverses the two
sections a¹ a² of the coil A; an increase of the magnetic field is thus produced
resulting in an induced current.
The same phenomena are produced in F, but the magnetic field there increases F2
in proportion as it diminishes in F and vice versa.
In the arrangement represented in the drawing the induced coils are connected in
series, in order that the effects may be combined, but we may also employ, in certain
cases, a single coil only.
It will of course be understood that our transformer may vary in form and
dimensions and that we reserve the right to modify its arrangements of detail
according to the various applications of which it is capable.
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 :-
:-
A transformer for continuous electric currents enabling the practical creation, with
a continuous current, of a variable magnetic field, and constituted by two inducing
coils consisting of an equal number of sections, each comprising the same number of
convolutions, the different sections of each coil being connected respectively to the
different divisions of a circular commutator, to the contact brush of which is
imparted a movement of rotation, the divisions of this commutator being connected
in pairs, in such a manner that the continuous current invariably passes, without
interruption, whatever may be the position of the brushes, into the same number of
convolutions, and that the intensity of this current therefore remains constant, the
continuous passage of the current creating, in the soft iron core or cores which
traverse the inducing coils, a variable magnetic field the value of which depends
upon the relative positions of the sections rendered operative; these variations of
the magnetic field serving to create secondary currents in one or more induc-
tion coils mounted upon the soft iron core or cores, substantially as above
described, for the purpose specified with reference to the accompanying drawings,
which is given by way of example.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.