Improved Method of and Apparatus for Transforming Continuous Electric Currents into Continuous or Alternating Currents of Different Voltage.
Year: 1899

page_text: Date of Application, 30th Mar., 1899
Complete Specification Left, 29th Nov., 1899-Accepted, 3rd Mar., 1900
Improved Method of and Apparatus for Transforming Continuous
Electric Currents into Continuous or Alternating Currents of
Different Voltage.
We, ALFRED WYDTS, of 339, Rue des Pyrenees, Electrical Engineer, and GUSTAVE
WEISSMANN, of 3, Rue Chaptal, Engineer, both of Paris, in the Republic of France, do
hereby declare the nature of this invention to be as follows:-
This invention relates to a novel method of transforming continuous electric
currents into currents of different voltage, for the purpose of enabling the utilisation of a
continuous current, supplied at a fixed tension, by any source of electricity.
Our invention consists, in principle in rendering a continuous current alternating
in order to enable it to be readily transformed by means of electromagnetic induction,
the secondary alternating current of this transformer being than rectified by means
of a commutator operated by the same mechanical device as that employed for
rendering the original continuous current alternating, in such a manner that the
secondary alternating current is rectified synchronously, because the phases of the
secondary current, although behind those of the primary current, are synchronous
with them, the difference of displacement being taken into account."
Our method of current transformation therefore comprises in principle the following
operations:
1. Passing the continuous current, the voltage of which is to be either increased or
diminished, into the armature of a continuous current motor, in such a manner that
this continuous current is transformed into an alternating current.
2. Causing this alternating current to pass into the primary circuit of an electro-
magnetic transformer of any suitable kind, in order to obtain, in the secondary circuit,
an alternating current of the desired voltage.
3. Rectifying this alternating current, which has, been brought to the desired
voltage in the inanner described, by means of a rectifying or redressing commutator,
keyed upon the same axis as the collectors which have produced the deformation of
the original continuous current, in such a manner that synchronisin is assured
between the emissions of the inducing current and those of the rectified secondary
alternating current.
In order that our invention may be readily understood, we have represented by way
of example in the accompanying drawing, a method of practically carrying the same
into effect.
Between the poles of a magnet or of an electro-magnet, NS. there is displaced in
the direction indicated by the arrow, f, a dynamo armature A, of the Gramme type
for example, provided with a collect or C and two brushes B and B¹, upon the same
axis as the collector C and rotating with it, are fixed four continuous collecting
rings 1, 2, 3, 4 communicating respectively with four brushes 11, 21, 31, 4' which rest
upon them, and two half rings 5 and 6, each of which is in contact, first with the
brush & and then with the brush y, according to the position of these two half rings
which rotate and are consequently displaced with respect to the two brushes x and y,
which are fixed... These two-brushes are suitably insulated and supported at the
extremities of a cross-piece D resembling the brush bolder of an ordinary bipolar

page_text: dynamo; this part D, which is capable of rotating around the axis a, enables the
brushes andy to be brought into a suitable commutation plane.
The continuous collecting rings 1 and 2 are respectively in communication with
two strips V Z of the collector C which are diametrically opposite one to the
other.
The rings 3 and 4 communicate respectively with the two half rings 5 and 6 which
constitute the rectifying commutator. The brushes B and B are in communication
respectively with the primary terminals E and E¹ through which the continuous
current to be transformed enters. The brushes 3' and '4' are in communication with the
secondary terminals F and F, at which the current to be transformed is collected.
The brushes 1 and 2 are connected with the terminals H H at which terminate
the extremities of the primary wire of the monophase transformer T ; the
two extremities of the secondary wire of this transformer terminate at the two
terminals M 'M' which are connected to the brushes and y of the rectifying
commutator.
This novel form. of transformer-operates in the following manner:
When a continuous current is conducted to the terminals E E¹, the ring A
commences to rotate, and its velocity increases until the counter electromotive force
developed in its winding, tends to balance the electromotive force which produces
the movement.
The primary circuit of the transformer T, by means of the brushes 11 and 21
and of the rings 1 and 2, is the seat of an alternating electromotive
force; the tension of this electromotive force is equal to that of the
continuous current which passes through the brushes B B₁, when these latter
are in contact with the strips V Z and the collector C. This tension is also equal in
absolute value to the tension of this current, but with the sign, when the collector
has become displaced through 180° in the direction of rotation (indicated by the
arrow), and it becomes zero when the diameter which joins the strips V Z is at
right angles to the diameter which joins the brushes B and B₁ at their point of
contact with the collector.
An alternating electromotive force is thus produced in the primary circuit of the
transformer T, the secondary circuit is then the seat of an alternating electromotive
force, the tension of which, as is well known, is a function of the ratio of the
number of primary windings to the number of secondary windings.
It is also well known that this secondary electromotive force is displaced by a
certain angle with respect to the primary electromotive force; it is for this
reason that the brushes x y, which are in communication with the extremities of the
secondary circuit, may be displaced themselves, as above stated, by means of a
cross-piece D which supports them. It is therefore only necessary to ascertain the
angle of fixing which gives the maximum of electromotive force at the
terminals F F¹. The alternating current supplied by the secondary circuit to
the transformer T, is conducted by the brushes xy to the two half rings 5 and 6 of
the rectifying commutator in electrical communication with the two continuous
rings 3, 4 against which the brushes 31 41 connected with the terminals F F¹
bear.
When the direction of the current changes in the brushes x, y, the brushes of the
half rings 5, 6 are changed and the current which reaches the terminals F F is
therefore practically continuous.
Our invention enables a continuous current to be transformed without transforming
the electrical energy into dynamic energy and the dynamic energy into electrical
energy, the process which has hitherto been employed and of which the efficiency is
known to be very low.
Our novel form of transformer, which may be employed for any voltage, is
especially adapted for enabling the employment of the current supplied by public
distributing stations at a tension of from 110 to 120 volts. for all application which
require either a greater or a smaller voltage. It being very rarely the case that,
apart from illuminating purposes, the voltage of stations for the distribution of

page_text: to say a rheostat of
50 a
= 2 ohms.
The energy thus transformed into heat and entirely wasted amounts to
50 a x 99-6 y = 4980 watts per second.
As the charging of the elements would be completed in 10 hours at this rate, it
would be necessary to absolutely waste 49.8 kilowatt-hours in order to charge this
battery of 4 kilowatt-hours only.
It is practically the same thing in the case of the charging of electric motor
vehicles as at present performed by means of the ordinary-current supplied to
private persons by public distributing stations.
Electrotypers also are unable to utilise the ordinary town current for their work,
as, seeing that they require a maximum force of 5 to 6 volts., a very large part of the
energy would be wasted in the manner above described.
If it is a question of distributing motive force to small industries where motor's
of 2 to 3 kilogramme meters are sufficient, a low tension current is still, to be
preferred, because it is an extremely costly and a very delicate operation to
construct small motors capable of operating normally with a current of 110. volts.
or thereabouts; 10 or 20 volt. motors, on the other hand are large wire niotors, they
are also strong and may be readily and inexpensively constructed.
The same thing holds good with regard to lighting purposes; low tension lamps
have a short and thick filament, and one which is consequently not fragile, they
are capable of supporting a current far greater than that to which lamps provided
with fine filaments can be exposed with impunity. The result is a higher
illuminating power.
Electrolysis in general, electro-metallurgy, the use of electric furnaces, and so
forth require intense currents of relatively low tension, which hitherto always
necessitated special installations, as the ordinary town current does not give
satisfactory results.
With our device, on the other hand, electro-typing, the charging of secondary
batteries and so forth, may be carried out under very good conditions, as the
secondary current is absolutely nil at the moment when the brushes x y pass
on to different half-rings upon the rectifying commutator; consequently there is
no fear of sparking taking place upon this commutator and the brushes y may
therefore completely leave one -half-ring before coming in contact with the other
half-ring.
:
As a result of this the two terminals F F¹, which by means of the collecting
rings 3, 4 are in communication with the rectifying commutator, are never short-
circuited; a result which has not hitherto been obtained with ordinary redressed
current machines.
In the case of other applications of which the electric current is capable, it may on
the contrary be necessary to increase the tension; a continuous current transformer
is indispensable in this case also. Many forms of continuous current rotary trans-
formers are in existence, but their low efficiency is well known (they are of the
coupled motor and dynamo type). In the case of--low powers especially, their
efficiency does not always attain 2%. For this reason the employment of a simple
rheostat, although also extremely wasteful, is often preferred on account of its
great simplicity.
:
Our form of transformer enables still further combinations to be obtained.

page_text: Thus, if instead of taking the current at the terminals FF, it is taken
at M M, an alternating current may be obtained which is of either low or high
tension according to the method of winding the transformer; for example, an
alternating current may be obtained at H H due to the direct deformation of
the continuous current which enters at E E¹.
If the continuous electromotive force at E E¹ is called, the efficient alternating
electromotive force at H H¹ is:
which, for an electromotive force of 110 volts. at the terminals E E¹, for example,
gives an efficient alternating electromotive force of:
In our form of transformer, the two extremities of the secondary circuit of the
electromagnetic transformer T, may be connected with the terminals F F1 which
correspond to the brushes 31 41, and the rectified current is then obtained upon the
brushes
y.
We also reserve the right to employ in our novel apparatus a multipolar electric
motor, for the purpose either of increasing the frequency of the current, or of
actuating polyphase transformers.
It will of course be understood that we are at liberty to establish our novel trans-
former in any suitable form, to vary the dimensions and the constructional details
according to the various applications of which it is capable, without in any way
altering the principle of our invention.
Improved Method of and Apparatus for Transforming Continuous
Electric Currents into Continuous or Alternating Currents of
Different Voltage.
We, ALFRED WYDTS, of 339, Rue des Pyrenees, Electrical Engineer, and GUSTAVE
WEISSMANN, of 3, Rue Chaptal, Engineer, both of Paris, in the Republic of France,
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 novel method of transforming continuous electric
currents into currents of different voltage, for the purpose of enabling the
utilisation of a continuous current, supplied at a fixed tension, by any source of
electricity.
Our invention consists, in principle, in rendering a continuous current alternating
in order to enable it to be readily transformed by means of electromagnetic
induction, the secondary alternating current of this transformer being then rectified
by means of a commutator operated by the same mechanical device as that employed
for rendering the original continuous current alternating, in such a manner that the
secondary alternating current is rectified synchronously, because the phases of the

page_text: secondary current, although behind those of the primary current, are synchronous
with then, the difference of displacement being taken into account.
Our method of current transformation therefore comprises in principle the
following operations:
1. Passing the continuous current, the voltage of which is to be either increased
or diminished, into the armature of a continuous current motor, in such a manner
that this continuous current is transformed into an alternating current.
2. Causing this alternating current to pass into the primary circuit of an electro-
inagnetic transformer of any suitable kind, in order to obtain, in the secondary circuit,,
an alternating current of the desired voltage.
3. Rectifying this alternating current, which has been brought to the desired
voltage in the manner described, by means of a rectifying or redressing commutator,
keyed upon the same axis as the collectors which have produced the deformation of
the original continuous current, in such a manner that synchronism is assured
between the emissions of the inducing current and those of the rectified secondary
alternating current.
In order that our invention may be readily understood, we have represented by
way of example in the drawings accompanying our Provisional Specification, a
method of practically carrying the same into effect.
Between the poles of a magnet or of an electromagnet N S, there is displaced in
the direction indicated by the arrow f, a dynamo armature A, of the Grammne type
for example, provided with a collector C and two brushes B and B1; upon the same
axis as the collector C and rotating with it, are fixed four continuous collecting rings
1, 2, 3, 4 communicating respectively with four brushes 11, 21, 31, 4' which rest upon
them, the two half rings 5 and 6, each of which is in contact first with the brush x
and then with the brush y, according to the position of these two half rings which
rotate and are consequently displaced with respect to the two brushes x and.y, which
are fixed. These two brushes are suitably insulated and supported at the extremities
of a cross-piece I resembling the brush holder of an ordinary bipolar dynamo; this
part D, which is capable of rotating around the axis a, enables the brushes x and y
to be brought into a suitable commutation plane.
The continuous collecting rings 1 and 2 are respectively in communication with
two strips V Z of the collector C which are 'diainetrically opposite one to the
other.
The rings 3 and 4 communicate respectively with the two half rings 5 and 6
which constitute the rectifying commutator. The brushes B and B are in com-
munication respectively with the primary terminals E and E' through which the
continuous current to be transformed enters. The brushes 31 and 4 are in com-
munication with the secondary terminals F and F1, at which the current to be
transformed is collected. The brushes 1 and 2 are connected with the
terminals H H¹ at which terminate the extremities of the primary wire of the mono-
phase transformer T; the two extremities of the secondary wire of this transformer
terminate at the two terminals M M which are connected to the brushes and y of
the rectifying commutator.
This novel form of transformer operates in the following manner:
When a continuous current is conducted to the terminals E E¹, the ring A
commences to rotate, and its velocity increases until the counter electromotive force
developed in its winding, tends to balance the electro motive force which produces
the movement.
:
The primary circuit of the transformer T, by means of the brushes 11 and 21 and of
the rings 1 and 2, is the seat of an alternating electromotive force; the tension of
this electromotive force is equal to that of the continuous current which passes.
through the brushes B B¹, when these latter are in-contact with the strips V Z of the
collector C. This tension is also equal in absolute value to the tension of this
current, but with the sign, when the collector has become displaced through 180°
in the direction of rotation (indicated by the arrow f), and it becoines zero when

page_text: .
the diameter which joins the strips V Z is at right angles to the diameter which
joins the brushes B and B at their point of contact with the collector.
An alternating electromotive force is thus produced in the primary circuit of the
transformer T, the secondary circuit is then the seat of an alternating electromotive
force, the tension of which, as is well known, is a function of, the ratio of the.nuinber
of primary windings to the number of secondary windings.
It is also well known that this secondary electromotive force is displaced by a
certain angle with respect to the primary electromotive force; it is for this reason
that the brushes ry, which are in communication with the extremities of the
secondary circuit, may be displaced themselves, as above stated, by means of a cross-
piece D which supports them. It is therefore only necessary to ascertain the angle
of fixing which gives the maximum of electromotive force at the terminals F F.
The alternating current supplied by the secondary circuit to the transformer T, is
conducted by the brushes x y to the half rings 5 and 6 of the rectifying commutator
in electrical communication with the two continuous rings 3, 4 against which the
brushes 31 41 connected with the terminals F F¹ bear.
When the direction of the current changes in the brushes x, y, the brushes of the
half rings 5, 6 are changed and the current which reaches the terminals F F¹ is
therefore practically continuous.
Our invention enables a continuous current to be transformed without transformning
the electrical energy into dynamic energy, and the dynamic energy into electrical
energy, the process which has hitherto been employed and of which the efficiency is
known to be very low.
Our novel form of transformer, which may be employed for any voltage, is
especially adapted for enabling the employment of the current supplied by public
distributing stations at a tension of from 110 to 120 volts., for all application which
require either a greater or a smaller voltage. It being very rarely the case that,
apart from illuminating purposes, the voltage of stations for the distribution of
electricity is applicable indifferently to the various uses of which the electric current
is capable.
For example, it is frequently required to charge a secondary battery which may
occasionally comprise no more than 3 or 4 elements; assuming that it is desired to
charge a battery of four elements each having 50 kilogrammes of plates, it would be
necessary, if the elements are connected for tension, to employ a current of 520 watts
at 104 volts., in the proportion of 26 volts. per element, but seeing that a current
of 110 volts. only is available, it would be necessary to interpose in the path of the
charging current a rheostat capable of absorbing the difference, that is to say a
rheostat of
V
99.6 v
50 a
2 ohins.
The energy thus transformed into heat and entirely wasted amounts to 50 a X 99-6
4980 watts per second.
As the charging of the elements would be completed in 10 hours at this rate, it
would be necessary to absolutely waste 49.8 kilowatt-hours. in order to charge this
battery 4 kilowatt-hours only.
It is practically the same thing in the case of the charging of electric motor
vehicles as at present performed by means of the ordinary current supplied to private
persons by public distributing stations.
Electrotypers also are unable to utilise the ordinary town current for their work, as,
seeing that they require a maximum: force of 5 to 6 volts., a very large part of the
energy would be wasted in the manner above described.
If it is a question of distributing motive force to small industries where motors of
2 to 3 kilogramme meters are sufficient, a low tension current is still to be preferred,
because it is an extremely costly and a very delicate operation to construct small
motors capable of operating normally with a current of 110 volts. or thereabouts;
10 or 20 volt. motors, on the other hand are large wire motors, they are also strong
and may be readily and inexpensively constructed.
The same thing holds good with regard to lighting purposes; low tension lamps

page_text: have a short and thick filament, and one which is consequently not fragile, they are
capable of supporting a current far greater than that to which lamps provided with
fine filaments can be exposed with impunity. The result is a higher illuminating
power.
Electrolysis in general, electro-metallurgy, the use of electric furnaces, and so forth
require intense currents of relatively low tension, which hitherto always necessitated
special installations, as the ordinary town current does not give satisfactory
results.
With our device, on the other hand, electrotyping, the charging of secondary
batteries and so forth, may be carried out under very good conditions, as the secondary
current is absolutely nil at the moment when the brushes y pass on to different half-
rings upon the rectifying commutator; consequently there is no fear of sparking
taking place upon this commutator and the brushes ay inay therefore completely
leave one half-ring before coming in contact with the other half-ring.
As a result of this the. two terminals F F¹, which by means of the collecting
rings 3, 4 are in communication with the rectifying commutator, are never short-
circuited; a result which has not hitherto been obtained with ordinary redressed
current machines.
In the case of other applications of which the electric current is capable, it may on
the contrary be necessary to increase the tension; a continuous current transformer
is indispensable in this case also. Many forms of continuous current rotary
transformers are in existence, but their low efficiency is well. known (they are of
the coupled motor and dynamo type). In the case of low powers especially, their
efficiency does not always attain 25%. For this reason the employment of a simple
rheostat although also extremely wasteful, is often preferred on account of its great
simplicity.
One form of transformer enables still further combinations to be obtained.
Thus, if instead of taking the current at the terminals F F1, it is taken at M M³,
an alternating current may be obtained which is of either low or high tension according
to the method of winding the transformer; for example, an alternating current may
be obtained at H H due to the direct deformation of the continuous current which
enters at E E. If the continuous electromotive force at E E¹ is called, the efficient
alternating electromotive force at H H¹ is:
In our form of transformer, the two extremities of the secondary circuit of the
electromagnetic transformer T, may be connected with the terminals F F which
correspond to the brushes 31 41, and the rectified current is then obtained upon the
brushesy.
We also reserve the right to employ in our novel apparatus a multipolar electric
motor, for the purpose either of increasing the frequency of the current, or of
actuating polyphase transformers.
It will of course be understood that we are at liberty to establish our novel transformer
in any suitable form, to vary the dimensions and the constructional details according
to the various applications of which it is capable, without in any way altering the
principle of our invention. Our invention is obviously applicable to transformers for
use in connection with any kind of dynamo-electric machines, the construction of
which is well known, and need not be described here.

page_text: 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 novel method of transforming continuous electric currents into continuous
currents of different voltage, for the purpose of enabling the utilisation of a
continuous current supplied, at a pre-determined tension, by a source of electricity
of any kind; this method of transformation consisting in rendering the continuous
current, the voltage of which is to be either increased or diminished, alternating,
in order to the more readily effect its transformation by electromagnetic induction,
and to then rectify the secondary alternating current of this electromagnetic
tranformer by means of a commutator operated by the same mechanical device as
that which has rendered the original continuous current alternating, in such a
manner that the second alternating current of the electromagnetic transformer may
be rectified synchronously substantially as herein described..
2. A form of transformer enabling the tension of a continuous electric current to
be either increased or decreased by means of the method of transformation described
above, comprising a dynamo electric machine through the armature of which
passes the continuous current to be transformed, and an electromagnetic transformer
the two extremities of the primary circuit of which are connected with two brushes
rubbing against two continuous rings, mounted upon the same axis as the armature
of the dynamo and connected respectively to two diametrically opposite strips of
the collector of the dynamo and of which the two extremities of the secondary
circuit are connected with two brushes rubbing successively against two half-rings
insulated one from the other and which are also mounted upon the same axis as
the armature of the dynamo aud in communication respectively with two continuous
rings upon which rab two brushes by means of which the transformed continuous
current is collected, substantially as herein described.
3. The whole constructed arranged and combined substantially as described above
with reference to the accompanying drawing.
Dated this 29th day of November 1899.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.