IMPROVEMENTS IN DYNAMO- ELECTRIC MACHINES
Year: 1883

page_text: LETTERS PATENT to Marcel Deprez of Boulevard Saint-Denis 1 at Paris
Electrician Engineer for an Invention of "IMPROVEMENTS IN DYNAMO-
ELECTRIC MACHINES'
"
PROVISIONAL SPECIFICATION left by the said Marcel Deprez at the Offico
of the Commissioners of Patents on the 21st June 1883.
MARCEL DEPREZ of Boulevard Saint Denis 1 at Paris, Electrician Engineer
"IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES
"
The first part of my invention has reference to the construction of a continuous
current dynamo electric machine based on the reciprocal magnetic actions of iron
upon iron which for equal weight are much more energetic than those of iron upon
copper.
In order to explain the machine I will suppose the number of inducing electro
magnets to bo reduced to the minimum (four), but in practice it would be of
advantage to employ as large a number of them as possible. Suppose therefore, as
is seen in Figure 1 of the annexed drawings, four electro magnets A A¹ B B¹-placed
in the form of a cross and composed of an equal number of sections wound in the
same direction on A and A' and in the same direction on B and B so as to have
for example in A and B a north pole and in A' and B' a south pole. In the
Centre of the system thus formed I place an ordinary Siemens coil C composed
essentially of a double T iron wound with wire. The inlets or entrances and
outlets or exits of all the sections of the inductors are connected to different
tongues or plates of a collector in such order that when all the sections of A and A¹
are traversed by the current those of B and B' are not, and reciprocally. In order
to make the explanation clear I will consider the machine in question as a motor,
D being the cylindrical collector which for greater simplicity I will suppose to be
displayed. It is composed for each quarter of metal tongues or plates and A
insulated from each other and on them the rubbers d and take different positions.
At each tongue terminate the wires to and from the sections of the inductors A
D

page_text: and A¹ and at each tongue П terminate the wires to and from the inductors B
and B', it being observed that the groups A A¹ and B B¹ are put in tension and
that the rubbers d and have a separation such that they can put in connection
with the current only a number of tongues equal to the number of sections which a
single inductor contains.
This being so, suppose the rubbers to be in the position seen in Figure 1
and send through these rubbers themselves a current into the inductors.
Under these conditions the sections 1, 2 and 3 only of the inductors would be
traversed by the current. In A and B a north pole is formed and a south pole
in A¹ and B¹ and the coil takes up the position seen in Figure 1 inclined at 45°.
If at this moment I impart to the rubbers a longitudinal movement from bottom
to top for example it will be seen that in A and A' the number of sections
traversed by the current will go on increasing while the inverse effect will be
produced in B and B' and that at the end of the stroke the inductors A and A¹
only being excited the coil will take up the vertical position. If the rubbers then-
continue their movement (for the figure represents only one fourth of the collector)
the inverse action will be produced and the poles of the electro magnets changing
their denomination, the coil continues its movement in the same direction.
Such being the case it will be remarked that the coil being always magnetized in
the same manner in approaching or receding from the pole of each electro magnet
modifies the magnetic field developed by them and gives rise in the electro-magnet
itself to an electro motive force which is added for each conductor; a current is
generated in consequence and this same current traversing the wire wound on the
coil again increases its magnetization.
It will therefore be understood that the machine becomes a generator if under
these conditions the same movement of rotation is given to the coil and to the
brushes d d'. In this case owing to the remanent magnetism the machine primes
or charges itself and as is indicated in Figure 2 the brushes e e¹ put in tension the
whole of the electro magnets and the coil; it is easy to collect the current
produced. As can be seen the same result could be obtained by employing
permanent magnets and by an identical grouping of wires to produce in the coil
itself slow demagnetization and the reversal of the poles which I have above
explained.
The next part of my invention relates to the automatic or arbitrary regulator of
the electric field in dynamo electric machines. The apparatus which I have
designed for this purpose is essentially based on the employment of inductors
similar to an ordinary Paccinotti-Gramme induced body of a particular form.
Suppose two cylinders of soft iron parallel and connected at their ends by two
similar iron breeches A and B (Figure 3); on each of the cylinders wind insulated
copper wire divided into six sections for example for each branch, viz, a, b c d e f;
a¹ b¹ c' d¹ e¹ f¹. Group them as in a Gramme ring that is to say connect them to
the different keys of a collector: (1) the inlet wire and exit wire of a and a¹;
(2) the exit of a and inlet of b; (3) exit of b and inlet of c
(7) exit off and inlet of ₤1; (8) exit of f¹ and inlet of e¹
(12) exit of band inlet of a¹.
Things being thus arranged suppose that through the brushes g g'a current
from a battery P or other source of electricity is sent into the whole and assume
that the wire has been wound in such manner as to produce in A a north pole for
example and in B a south pole. Under these conditions if, as in Figure 3, tho
rubbers gg occupy the position 1 and 7 it will be seen that the current passes in
the same direction through all the sections top and bottom which therefore
co-operate in maintaining the polos in the position which the figure indicates to
give the maximum magnetic field. At this moment if a rotary movement be
given to the rubbers so as to make them occupy the positions 2 and 8, it will be
seen at once that the direction of the current is changed in sections a' and f and
that if the actions of the other spirals dominate although it may be to preserve

page_text: the same direction to the magnetism there is nevertheless produced in A and B a
diminution of magnetization which the variable number of the sections can render
as considerable or as feeble as is desired. If the rotary movement of the rubbers
be continued so as to bring them to 4 and 10 it will be seen that if the sections
abcfe' d' only concur in maintaining in the magnetization the original direction
the 6 other sections a¹ b¹ c¹, fed act in the inverse direction and the breeches A
and B lose all magnetization. It will be seen therefore that with such an arrange-
ment a variation of 90° in the wedging of the brushes suffices to produce very
powerful poles at the breeches and to make them disappear entirely at will. For
the same reasons if the rotary movement of the rubbers continues the magnetiza-
tion reappears by degrees but in the contrary direction until it has reached its
maximum intensity on leaving which point it decreases in its turn following the
same variations as those already stated.
The principle being laid down its adaptation to a dynamo-electric machine is
easy. If the whole apparatus arranged as above described be bent into a seini-
circle it will be possible to place a Paccinotti induced body or armature (induit)
(separated or connected in tension with the inductor) which can be caused to turn
between A and B by an arrangement analogous to that shown in Figure 4. I can
besides for the employment of inductors constituted as above indicated avoid a new
form of dynamo and only transform certain known types of machine in order to
regulate their magnetic field. Take a Gramme machine; the four arms of the
inductors A A¹ and a a¹ can be sectioned and by grouping the whole as shown in
Figure 5 that is to say by connecting at each plate of a collector the inlet wire of
each section to the exit wire of the next, there will be at N two north poles and
at S two south poles the power of which can be varied at will. If a quarter turn
be given to the brushes the magnetic resultant will take the position N S and
the magnetic field will be annulled; if the movement bo continued in the same
direction a rotation of the brushes to an extent of 180° will reverse completely
the direction of the original magnetization by creating at N a south and at S a
north pole.
The solution of the regulation of a magnetic field which I have just explained
is quite general. I have shown how it can be applied to an electro magnet with
two arms, and it is easy to demonstrate how it can be applied to a straight electro
magnet. Take (Figure 6) an ordinary Paccinotti-Gramme ring but with the
sections a b c a¹ b c¹ separated in such manner that their projections on tho
horizontal diameter for example are placed side by side by alternating a b₁;
a b c c. As the horizontal diameter take a bar of soft iron instead of an
imaginary line, and group upon this bar sections of copper wire as were tho
projections of those of the ring. It is clear that we will bo led to the arrange-
ment shown in Figure 7 and if the position of the brushes ff' remains the same
all the sectious concur in creating at A a north pole and at B a south pole. Then
as before turn the whole of the rubbers and it is evident that the phenomenon
above stated will take place and that the two poles will gradually meet near the
middle of the iron bar, a point where all magnetization will disappear, each section
working in the opposite direction to its neighbour. After a rotation of 180° in
the same direction the two poles will as it were cross at the centre of the electro
magnet and the direction of the original magnetization will be entirely reversed.
With any of the arrangements above described it is easy to realize the important
problem of the distribution of electric energy.
In thus constructing dynamo machines there can be given to the current
engendered by the rotation of the induced body the intensity strictly necessary
for the variable number of motors or other apparatus in action on the line.
Although the regulation of the magnetic field can be effected by hand, it becomes
automatic if by any suitable arrangement the rubbers are worked by an apparatus
which being placed in the circuit will itself register the exact work expended on
the line. Further if on the contrary these rubbers move in unison with the

page_text: induced body it is easy to reverse the current at determined intervals of time so
as to adapt the continuous current machine to electric candles or lights.
The rotation of the polar line of the magnetic field, a rotation which constitutes
the mode of regulation forming the object of the arrangements I have described
can be effected without the necessity of moving any part. For this purpose
instead of one circuit the inductors will have two distinct circuits each of which is
divided into sections as in the arrangement previously described; these coils are
juxtaposed and interlaced so that their actions combine. Each of these circuits
one of which is composed of the sections drawn in broken lines and the other of the
sections drawn in full lines in Figure 8 is arranged so that the current is divided
therein into two parts A B A' B' and produces in the inductors a polar line as has
already been explained. Only the inlet and exit points of one of the circuits
tend to place the poles of the magnetic field in the plane of the induced pieces and
corresponding to the maximum inducing action, while the inlet and exit points of
the other circuit tend to place the polar line according to a direction forming a
small angle with the axis of rotation of the induced body and corresponding to a
feeble inducing action. If a distinct current be passed into each of these circuits
the polar line of the magnetic field will occupy an intermediate position. the
situation of which will depend upon the relative intensities of the two currents; I
can therefore effect at will the rotation of this resultant by varying the intensity
of the two currents which traverse the two inducing circuits.
It will be remarked that wtih this arrangement the inlet points of the currents
into the inducing circuits are fixed; there is therefore no disc or cylinder with
keys as in the other arrangement. This method allows of constructing a machine
with an intensity automatically constant. For this purpose I pass into one of the
inducing circuits the useful current produced by the machine itself the other
circuit being traversed by a constant current either from a foreign source or from
a derivation of the main current; if the intensity of the useful current tends to
vary, the polar line of the magnetic field will immediately be displaced and the
currents can be combined in such manner that the displacement of the poles of the
magnetic field compensates automatically for the variation which would tend to be
produced in the intensity of the useful current. It likewise allows of constructing
a machine with difference of potential automatically constant; in this case one of
the inducing circuits would be formed of a large number of turns of fine wire and
traversed by a derived current taken at the binding screw of the machine.
In all the cases which have been considered the plane in which the polar line of
the magnetic field is displaced always passes through the axis of rotation of the
induced body; it follows that this displacement is translated as regards induction
by a simple enfeebling of the magnetic field. The result is that the wedging
of the brushes has not to change and that they always remain in a good
situation for taking up the current whatever be the position of the poles of the
inducing field
I can obtain quite a different result by placing the inductors in the plane of the
rotation (see Figure 9) that is to say perpendicular to the axis. In this case the
displacement of the polar line of the magnetic field (whether it be obtained
mechanically or by the electrical combination above described) causes the rotation
of the lines of force of the field around the axis of rotation of the induced body;
it follows that at every new position of the field the collecting brushes without
being displaced are found more or less separated from the position which gives the
maximuin current; this is another mode of regulating the intensity of the current
given off by the machine.
It will be remarked that in all these arrangements or methods of regulating by
displacement of the poles of the magnetic field it is of no importance for the iron
of the inductors to be saturated.
In the other modes of regulating the variation of the field depending on the
magnetization of the iron it is absolutely indispensable to keep up to the point of

page_text: saturation, a condition sometimes very difficult to fulfil; in the mode of regulation
which I have just described this condensation is of no importance
Another of my improvements has reference to the construction of dynamo-
electric machines so as to make a machine with a magnetic field of variable extent.
The continuous current dynamo machine thus improved therefore differs from
existing machines by the constitution of a magnetic field the extent of which is
variable at will by the single fact that the arrangement I am about describe allows
of exciting at will a variable number of inductors. Take the vertical section seen
in Figure 10. Let A be the ring and 1, 11, 2, 21, 3, 31, &c be the inductors tho
number of which may be very large in practice but for the moment we will
suppose there are 14, seven constituting the N pole and 'seven the S pole. It should
be remarked first that whatever be the number of inductors excited the induced
body and the inductors can be grouped either in series or in derivation; the current
can at will traverso 1, 3, 5, 7, &c, for each pole.
The current enters the electro magnet 1 leaves it as shown by the track line to
enter the magnet 1' which it leaves in turn and following the track line goes to
the tongue a of the distributor D. If the slide G be for example at G¹ the current
leaves by the plate D after having traversed only the magnets 1 and 1'. If on the
contrary the slide G is at the other end of its course as seen in the figure in contact
only with the tongue & the current as is easily seen by following the different
track lines which indicate the connections of the inductors traverses all the
inductors and the magnetic field has its maximum extent.
It is easy to see by referring to the figure that by putting the slide G in an
intermediate position between the two extremes I can send the current which
animates the inducing electro magnets into an optional number of them and
consequently vary at will the extent of the magnetic field and therefore the electro
motive force of the induced body which turns in this field.
My invention also relates to the construction of large dynamo electric machines.
1. General arrangement.-As electrical science advances and its applications
become more and more numerous whether for the translation and distribution of
energy or for lighting, the role of dynamo machines of great power becomes
preponderating, and as their dimensions increase difficulties arise of a purely
mechanical nature not previously met with. The mode of construction to which
my invention refers overcomes these difficulties and can be applied as is herein-
after shown to machines of any power varying from 50 to several thousand horses.
The principle which serves as the base for the arrangement of the different parts
consists in utilizing the space so as to obtain as completely as possiblo in the
smallest compass the most considerable power. For this purpose the magnetic field
is constituted as seen in Figure 11 of a number of double electro magnets E of.
large diameter arranged in the form of a crown or ring. In front of the poles of
these magnets moves a double ring A A¹. This can be repeated a greater or less
number of times, but always an even number, according to the power which it is
desired to obtain. For the purpose of explanation I will suppose the induced body
to be composed of two double rings A. A connected in tension section to section
by means of wires and binding screws xx and terminating in a single collector C
formed always of as many plates as there are sections in a single ring, and the
inductor is formed of two crowns or rings of horse shoe electro magnets E.
2. Construction of the induced body. Take a single ring A and I will explain its
mode of construction which will be the same for all the others. Figure 12 is a
transverse section of it. perpendicular to the axis. The soft iron is composed of a
series of similar plates cut from sheet iron and placed side by side perpendicularly
to the axis. The length of plates is the same for all but I arrange them so that
they permit of sectioning into 16 parts for example by fitting upon each other in
accordance with imbrications like those shown in Figure 15. These plates are
separated from each other by a layer of oxide or a layer of paint, or by paper or
by air. On each of the iron voussoirs of the ring is wound insulated copper wire

page_text: which is itself sectioned into a greater or less number of parts according to the
dimensions of the machine, say five sections for example, the inlet and exit wires
of which would unite later at the different plates of the collector. These parts
which I have supposed to be 16, a number which can be varied, are hooped with
strips of brass fixed by screws at the two ends. They are connected to a wheel
made of oak with the felloe slightly notched so as to carry on all the circumference
the copper wire and the iron of each section. They are fixed therein as shown in
Figure 14 by iron straps and one or more bolts traversing all the rings and thus
forming a stay. The whole thus formed is connected to the shaft by a cast iron
nave M keyed like the fly wheel of an engine and by wrought or cast iron spokes
fixed to the felloe J as seen in Figure 13 and connected to the nave M by a fork or
by tenons strengthened in either case by bolts
As has been already stated all the rings of the induced body are constructed in
the same manner and by means of binding screws fixed on the wood all the
sections of the same generator are connected in tension but wound two and two in
the same direction only so as to collect the current engendered.
3. Construction of the Inductor. The magnetic field is formed of a series of
double electro magnets E which Figures 11 and 12 show in front view and
longitudinal section. Each pair of magnets is connected to a cast iron segment S
by two bolts which pass through the breech, and all the segments are connected
together around the induced body by bolts and fish plates so as to form two
double circular vaults which a cast iron frame B supports at the lower part.
4. Collector and Brushes. On one of the transverse faces of the induced body is
placed the collector C. There is nothing special in it and whatever be the
dimensions it is constructed of bronze plates separated froin each other by an
insulating body first and then by layers of air, more and more thick in proportion
to the dimensions. On the surface of the collector the brushes b rub; they can at
will by a suitable arrangement be lifted or applied to the surface. The brushes as
is seen in Figure 11 aro connected to a metal disc D loose on the shaft of the
machine but they are insulated from it so that at two binding screws the current
can be taken up. The disc D has a part d toothed at its outer surface to gear
with a pinion 2. The shaft of this pinion is held in two bearings fixed to one of
the supportsf of the shaft a in such manner that the wedging of the brushes can
be varied by hand even during work if necessary. The machine arranged as
above described is mounted on a horizontal shaft a turning in supports and
terminating in a portion on which can be mounted the toothed wheel or pulley or
other device by which the rotary motion is to be given to the induced body or
this movement is to bo transmitted therefrom as the case may be.
As will be seen the mode of construction which I have described will answer
for machines of all powers. Starting from small dimensions I can first by
magnetizing them in any direction increase at the same time the power of the
machine and finally having arrived at a certain limit I can by adding on the shaft
another pair of rings with their crown or ring of electro magnets transform an
established generator into one much more powerful.
Further the arrangement of the inductor allows of a considerable magnetic field
being obtained with the minimum of material possible and of an excitation which
is very economical electrically speaking. The induced body and the inductors can
besides be put in tension or theso can be excited separately but in all cases, the
adaptation of my systems of regulation is very easy in distributing electrical
energy.
Instead of respectively connecting the sections of the rings together as I havo
above explained, I can connect them in the following manner (see Figure 16).
Let A, A, A, be three consecutive sections of the first ring and A A A be three
sections likewise consecutive situated in the prolongation of the first on the second
ring. The grouping of these sections together is effected as the figure shows by
making the exit wire of A. communicate with the inlet wire of A; the exit wire

page_text: of A with the inlet of A,, the exit of A, with the inlet of A, the exit of A with
the inlet of A, and so on. The connecting wires ¹¹ª³ ³ of these sections
load to the respective plates of a single collector, the number of the plates being
therefore double the number of sections in each ring. If instead of two rings, the
5 machine has four, six or eight it is easy to apply thereto what has just been
explained and then the collector would have a number of plates 4, 6 or 8 times as
great as the number of sections of each ring."
It will be understood that in certain cases it will be of advantage, when a
magnetic field of variable extent is not used, not to allow the current to pass
Q.uselessly into all the non-excited parts of the ring; I then employ together with
this machine with variable magnetic field an arrangement of three brushes (one of
which is movable) for each magnetic field.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Marcel Deprez in the Great Seal Patent Office on the 11th December
1883.
MARCEL DEPREZ of Boulevard Saint Denis 1 at Paris Electrician Engineer
"IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES
33
The first part of my invention has reference to the construction of a continuous
current dynamo-electric machine based on the reciprocal magnetic actions of iron
upon iron which for equal weight are much more energetic than those of iron upon
copper.
In order to explain the machine I will suppose the number of inducing electro-
magnets to be reduced to the minimum (four) but in practice it would be of
advantage to employ as large a number of them as possible. Suppose therefore,
as is seen in Figure 1 of the annexed drawings, 4 electro magnets A A¹ B B¹
placed in the form of a cross and composed of an equal number of sections wound
in the same direction on A and A¹ and in the same direction on B and B¹ so as to
have for example in A and B a north pole and in A' and B¹ a south pole. In the
centre of the system thus formed I place an ordinary Siemens coil C composed
essentially of a double T iron wound with wire. The inlets or entrances and
outlets or exits of all the sections of the inductors are connected to different tongues
or plates of a collector in such order that when all the sections of A and A' are
traversed by the current those of B and B are not, and reciprocally. In order to
make the explanation clear I will consider the machine in question as a motor,
D being the cylindrical collector which for greater simplicity I will suppose to bo
displayed. It is composed for cach quarter of metal tongues or plates and l
insulated from each other and on them the rubbers d d take different positions.
At each tongue terminato the wires to and from the sections of the inductors A
and A' and at each tongue terminato the wires to and from the inductors B
and B', it being observed that the groups A A¹ and B B are put in tension and
that the rubbers d and d have a separation such that they can put in connection
with the current only a number of tongues equal to the number of sections which
a single inductor contains.
This being so, suppose the rubbers to be in the position seen in Figure 1 and
send through these rubbers themselves a current into the inductors. Under these
conditions the sections 1, 2 and 3 only of the inductors would be traversed by the
current. In A and B a north pule is formed and a south pole in A and B and
the coil takes up the position seen in Figure 1 inclined at 45°. If at this moment
1 impart to the rubbers a longitudinal movement from bottom to top for example
it will be seen that in A and A¹ the number of sections. traversed by the current
will go on increasing while the inverse effect will be produced in B and B¹ and
that at the end of the stroke the inductors A and A' only being excited the coil
will take up the vertical position. If the rubbers then continue their movement
(for the figure represents only one fourth of the collector) the inverse action will
be produced and the poles of the electro magnets changing their denomination, the
coil continues its movement in the saine direction.
Such being the case it will be remarked that the coil being always magnetized
in the same manner in approaching or receding from the pole of each electro
magnet modifies the magnetic field developed by them and gives rise in the electro
magnet itself to an electro motive force which is added for each conductor, a current
is generated in consequence and this same current traversing the wiro wound on
the coil again increases its magnetization.

page_text: It will therefore be understood that the machine becomes a generator if under
these conditions the same movement of rotation is given to the coil and to the
brushes d d. In this case owing to the remanent magnetism the machine primes
or charges itself and as is indicated in Figure 2 the brushes e e¹ put in tension the
whole of the electro magnets and the coil; it is easy to collect the current produced.
As can be seen the same result could be obtained by employing permanent
magnets and by an identical grouping of wires to produce in the coil itself slow
demagnetization and the reversal of the poles which I have above explained.
The next part of my invention relates to the automatic or arbitrary regulator of
the electric field in dynamo electric-machines. The apparatus which I have
designed for this purpose is essentially based on the employment of inductors
similar to an ordinary Paccinotti-Gramme induced body of a particular form.
Suppose two cylinders of soft iron, parallel and connected at their ends by two
similar iron breeches A and B (Figure 3); on each of the cylinders wind insulated
copper wire divided into six sections for example for each branch, víz a b c d e f;
a b c d e f Group them as in a Gramme ring that is to say connect them to
the different keys of a collector: (1) The inlet, wire and exit wire of a and a¹;
(2) the exit of a and inlet of b; (3) exit of b and inlet of c
(7) exit off and inlet of f'; (8) exit of f¹ and inlet of e¹
(12) exit of b¹ and inlet of a'.
Things being thus arranged suppose that through the brushes g g' a current
from a battery P or other source of electricity is sent into the whole and assumo
that the wire has been wound in such manner as to produce in A a north pole for
example and in B a south pole. Under these conditions if, as in Figure 3, the
rubbers g g occupy the position 1 and 7 it will be seen that the current passes in
the same direction through all the sections top and bottom which therefore co-
operate in maintaining the poles in the position which the figure indicates to give
the maximum magnetic field. At this moment if a rotary movement be given to
the rubbers so as to make them occupy the positions 2 and 8, it will be seen at
once that the direction of the current is changed in sections a¹ and f and that if
the actions of the other spirals dominate although it may be to preserve the same
direction to the magnetism there is nevertheless produced in A and B a diminution
of magnetization which the variable number of the sections can render as con-
siderable or as feeble as is desired. If the rotary movement of the rubbers be
continued so as to bring them to 4 and 10 it will be seen that if the sections a
befe d¹ only concur in maintaining in the magnetization the original direction
the 6 other sections a¹ b' c¹ƒe d act in the inverse direction and the breeches A. .
and B lose all magnetization. It will be seen therefore that with such an arrange-
ment a variation of 90° in the wedging of the brushes suffices to produce very
powerful poles at the breeches and to make them disappear entirely at will. For
the same reasons if the rotary movement of the rubbers continues the magnetization
reappears by degrees but in the contrary direction until it has reached its maximum
intensity on leaving which point it decreases in its turn following the same
variations as those already stated.
The principle being laid down its adaptation to a dynamo electric machine is
casy. If the whole apparatus arranged as above described be bent into a semi-
circle it will be possible to place a Paccinotti induced body or armature (induit).
(separate or connected in tension with the inductor) which can be caused to turn
between A and B by an arrangement analogous to that shewn in Figure 4. I can
besides for the employment of inductors constituted as above indicated avoid a
new form of dynamo and only transform certain known types of machine in order
to regulate their magnetic field. Take a Gramme machine, the four arms of the
inductors A A¹ and a a¹ can be sectioned and by grouping the whole as shown in
Figure 5 that is to say by connecting at cach plate of a collector the inlet wire of
each section to the exit wire of the next, there will be at N two north poles and
at S two south poles the power of which can be varied at will. If a quarter turn
be given to the brushes the magnetic resultant will take the position¸ Ñ S and the

page_text: magnetic field will be annulled; if the movement be continued in the same
direction a rotation of the brushes to an extent of 180° will reverse completely the
direction of the original magnetization by creating at N a south and at S a north
pole.
The solution of the regulation of a magnetic field which I have just explained is
quite general. I have shown how it can be applied to an electro magnet with two
arms, and it is easy to demonstrate how it can be applied to a straight electro
magnet. Take (Figure 6) an ordinary Paccinotti-Gramme ring but with the
sections a b c a b c separated in such manner that their projections on the
horizontal diameter for example are placed side by side by alternating α₁ b₁; α¦ b¦ ;
G₁₁. As the horizontal diameter take a bar of soft iron instead of an imaginary
line, and group upon this bar sections of copper wire as were the projections of
those of the ring. It is clear that we will be led to the arrangement shewn in
Figure 7 and if the position of the brushes ff¹ remains the same all the sections
concur in creating at A a north pole and at B a south pole. Then as before turn
the whole of the rubbers and it is evident that the phenomenon above stated will
take place and that the two poles will gradually meet near the middle of the iron
bar, a point where all magnetization will disappear, each section working in the
opposite direction to its neighbour. After a rotation of 180° in the same direction
the two poles will as it were cross at the centre of the electro magnet and the
direction of the original magnetization will be entirely reversed. With any of the
arrangements above described it is easy to realize the important problem of the
distribution of electric energy.
In thus constructing dynamo machines there can be given to the current
ongendered by the rotation of the induced body the intensity strictly necessary
for the variable number of motors or other apparatus in action on the line.
Although the regulation of the magnetic field can be effected by hand, it becomes
automatic if by any suitable arrangement the rubbers are worked by an apparatus
which being placed in the circuit will itself register the exact work expended on
the line. Further if on the contrary these rubbers move in unison with tho
induced body it is easy to reverse the current at determined intervals of time
so as to adapt the continuous current machine to electric candles or lights.
The rotation of the polar line of the magnetic field, a rotation which constitules
the mode of regulation forming the object of the arrangements I have described
can be effected without the necessity of moving any part. For this purpose
instead of one circuit the inductors will have two distinct circuits each of which
is divided into sections as in the arrangement previously described; these coils
are juxta-posed and interlaced so that their actions combine. Each of these
circuits one of which is composed of the sections drawn in thin lines and the
other of the sections drawn in thick lines in Figure 8 is arranged so that the
current is divided therein into two parts A B A' B' and produces in the inductors
a polar line as has already been explained. Only, the inlet and exit points of one
of the circuits tend to place the poles of the magnetic field in the plane of the
induced pieces and corresponding to the maximum inducing action, while the
inlet and exit points of the other circuit tend to place the polar line according to
a direction forming a small angle with the axis of rotation of the induced body
and corresponding to a feeblo inducing action. If a distinct current be passed
into each of these circuits the polar line of the magnetic field will occupy an
intermediate position the situation of which will depend upon the relative
intensities of the two currents; I can therefore effect at will the rotation of this
resultant by varying the intensity of the 2 currents which traverse the two inducing
circuits.
t
It will be remarked that with this arrangement the inlet points of the currents
into the inducing circuits are fixed; there is therefore no disc or cylinder with
keys as in the other arrangement. This method allows of constructing a machine
with an intensity automatically constant. For this purpose I pass into one of the
inducing circuits the useful current produced by the machine itself the other

page_text: circuit being travorsed by a constant current either from a foreign source or from
a derivation of the main current, if the intensity of the useful current tends to
vary, the polar line of the magnetic field will immediately be displaced and the
currents can be combined in such manner that the displacement of the poles of
the magnetic field compensates automatically for the variation which would tend
to be produced in the intensity of the useful current. It likowise allows of
constructing a machine with difference of potential automatically constant; in
this case one of the inducing circuits would be formed of a large number of turns
of fine wire and traversed by a derived current taken at the binding screw of the
machine.
In all the cases which have been considered the plane in which the polar line of
the magnetic field is displaced always passes through the axis of rotation of the
induced body; it follows that this displacement is translated as regards induction
by a simple enfeebling of the magnetic field. The result is that the wedging of
the brushes has not to change and that they always remain in a good situation
for taking up the current whatever be the position of the poles of the inducing
field.
I can obtain quite a different result by placing the inductors in the plane of the
rotation (see Figure 9) that is to say perpendicular to the axis. In this case the
displacement of the polar line of the magnetic field (whether it be obtained
mechanically or by the electrical combination above described) causes the rotation
of the lines of force of the field around the axis of rotation of the induced body;
it follows that at every new position of the field the collecting brushes without
being displaced are found more or less separated from the position which gives the
maximum current; this is another mode of regulating the intensity of the current
given off by the machine.
It will be remarked that in all these arrangements or methods of regulating by
displacement of the poles of the magnetic field it is of no importance for the iron
of the inductors to be saturated.
In the other modes of regulating, the variation of the field depending on the
magnetization of the iron, it is absolutely indispensable to keep up to the point
of saturation, a condition sometimes very difficult to fulfil; in the mode of
regulation which I have just described this consideration is of no importance.
Another of my improvements has reference to the construction of dynamo
electric machines so as to make a machino with a magnetic field of variable extent.
The continuous current dynamo machine thus improved therefore differs from
existing machines by the constitution of a magnetic field the extent of which is
variable at will: by the single fact that the arrangement I am about to describe
allows of exciting at will a variable number of inductors. Take the vertical
section seen in Figure 10. Let A be the ring and 1, 11, 2, 21, 3, 3¹, &° be the
inductors the number of which may be very large in practice but for the moment
we will suppose there are 14; seven constituting the N pole and seven the S pole.
It should be remarked first that whatever be the number of inductors excited the
induced body and the inductors can be grouped either in series or in derivation;
the current can at will traverse 1, 3, 5, 7 & for each pole.
The current enters the electro magnet 1 leaves it as shewn by. the track line to
enter the maguet 1' which it leaves in turn and following the track line goes to
the tongue a of the distributor D. If the slide G be for example at G¹ the current
leaves by the plate D after having traversed only the magnets 1 and 12. If on tho
contrary the slide G is at the other end of its course as seen in the figure in
contact only with the tongue & the current as is easily seen by following the
different track lines which indicate the connections of the inductors traverses all
the inductors and the magnetic field has its maximum extent. It is easy to see by
referring to the figure that by putting the slide G in an intermediate position
between the 2 extremes I can sond the current which animates the inducing electro
magnets into an optional number of them and consequently vary at will the extent

page_text: of the magnetic field and therefore the electro motive force of the induced body
which turns in this field.
My invention also relates to the construction of large dynamo electric machines.
1. General arrangement. As electrical science advances and its applications
become more and more numerous whether for the translation and distribution of
energy or for lighting, the role of dynamo machines of great power becomes
preponderating, and as their dimensions increase difficulties arise of a purely
mechanical nature not previously met with. The mode of construction to which
my invention refers overconies these difficulties and can be applied as is herein-
after shewn to machines of any power varying from 50 to several thousand horses.
The principle which serves as the base for the arrangement of the different parts
consists in utilizing the space so as to obtain as completely as possible in the
smallest compass the most considerable power. For this purpose the magnetic
field is constituted as seen in Figure 11 of a number of double electro magnets E
of large diameter arranged in the form of a crown or ring. In front of the poles of
these magnets moves a double ring A A¹. This can be repeated a greater or less
number of times, but always an even number according to the power which it is
desired to obtain. For the purpose of explanation I will suppose the induced
body to be composed of two double rings A A' connected in tension section to
section by means of wires and binding screws and terminating in a single
collector C formed always of as many plates as there are sections in a single ring,
and the inductor is formed of two crowns or rings of horse shoe clectro magnets E.
2. Construction of the induced body. Take a single ring A and I will explain
its inode of construction which will be the same for all the others. Figure 12 is a
transverse section of it perpendicular to the axis. The soft iron is composed of a
series of similar plates cut from sheet iron and placed side by side perpendicularly
to the axis. The length of plates is the same for all but I arrange them so that
they permit of sectioning into 16 parts for example by fitting upon each other in
accordance with imbrications like those shown in Figure 15. These plates are
separated from each other by a layer of oxide or a layer of paint, or by paper or
by air. On each of the iron voussoirs of the ring is wound insulated copper wire
which is itself sectioned into a greater or less number of parts according to the
dimensions of the machine, say 5 sections for example, the inlet and exit wires of
which would unite later at the different plates of the collector. These parts which
I have supposed to be 16, a number which can be varied, are hooped with strips of
brass fixed by screws at the 2 ends. They are connected to a wheel made of oak
with the felloe slightly notched so as to carry on all the circumference the copper
wire and the iron of each section. They are fixed therein as shewn in Figure 14
by iron straps and one or more bolts traversing all the rings and thus forming a
stay. The whole thus. formed is connected to the shaft by a cast iron nave M
keyed like the fly wheel of an engine and by wrought or cast iron spokes fixed to
the felloe J as seen in Figure 13 and connected to the nave M by a fork or by
tenons strengthened in either case by bolts. As has been already stated all the
rings of the induced body are constructed in the same manner and by means of
binding screws fixed on the wood all the sections of the same generator are con-
nected in tension but wound two and two in the same direction only so as to
collect the current engendered.
3. Construction of the Inductor. The magnetic field is formed of a series of
double electro magnets E which Figures 11 and 12 shew in front view and
longitudinal section. Each pair of magnets is connected to a cast iron segment S
by two bolts which pass through the breech, and all the segments are connected
together around the induced body by bolts and fish plates so as to form two double
circular vaults which a cast iron frame B supports at the lower part.
4. Collector aud Brushes. On one of the transverse faces of the induced body is
placed the collector C. There is nothing special in it and whatever be the
dimensions it is constructed of bronze plates separated from each other by an

page_text: insulating body first and then by layers of air more and more thick in proportion
to the dimensions. On the surface of the collector the brushes b rub; they can at
will by a suitable arrangement be lifted or applied to the surface. The brushes as
is seen in Figure 11 are connected to a metal disc D loose on the shaft of the
machine but they are insulated from it so that at two binding screws the current
can be taken up. The disc D has a part d toothed at its outer surface to gear with
a pinion p. The shaft of this pinion is held in two bearings fixed to one of the
supports of the shaft a in such manner that the wedging of the brushes can bo
varied by hand even during work if necessary. The machine arranged as above
described is mounted on a horizontal shaft a turning in supports fand terminating
in a portion on which can be mounted the toothed wheel or pulley or other devico
by which the rotary motion is to be given. to the induced body or this movement
is to be transmitted therefrom as the case may be.
As will be seen the mode of construction which I have described will answer for
machines of all powers. Starting from small dimensions I can first by magnetizing
them in any direction increase at the same time the power of the machine and
finally having arrived at a certain limit I can by adding on the shaft another pair
of rings with their crown or. ring of electro magnets transform an established
generator into one much more powerful.
Further the arrangement of the inductor allows of a considerable magnetic field
being obtained with the minimum of material possible and of an excitation which
very economical electrically speaking. The induced body and the inductors
can besides be put in tension or these can be excited separately but in all cases
the adaptation of my systems of regulation is very easy in distributing electrical
energy.
Instead of respectively connecting the sections of the rings together as I have
above explained, I can connect them in the following manner (see Figure 16).
Let A, A, A, be 3 consecutive sections of the first ring and AAA be 3.-
Sections likewiso consecutive situated in the prolongation of the first on tho
second ring. The grouping of these sections together is effected as the figure
shows by making the exit wire of A₁ communicate with the inlet wire of A; tho
exit wire of A with the inlot of A, tho exit of A, with the inlet of A, the exit
of A with the inlet of A, and so on. The connecting wires Z¹ Z Z³ Z Z Z° of
these sections lead to the respective plates of a single collector the number of the
plates being therefore double the number of sections in each ring. If instead of
two rings the machine has 4, 6 or 8 it is easy to apply thereto what has just
been explained and then the collector would have a number of plates 4, 6 or
8 times as great as the number of sections of each ring.
It will be understood that in certain cases it will be of advantage, when a
magnetic field of variable extent is not used, not to allow the current to pass
uselessly into all the non-excited parts of the ring: I then employ together with
this machine with variable magnetic field an arrangement of three brushes (one
of which is movable) for each magnetic field.
Having now described the nature of the said Invention-and in what manner
the same is to be performed-I claim as my improvements in dynamo electric
machines :-
1. Constructing dynamo electric machines as herein before described in such
manner that the slow and progressive magnetization of the electro magnets and
the reversal likewise slow of the poles either of the inductor or of the induced
body are produced by means of a sectional winding of the wire and a collector
such as described with reference to Figures 1 and 2.
2. The arrangements described with reference to Figures 3 to 7 in which the
magnetic field is regulated by dividing the wire of the inductors into a certain
number of sections.
3. The modifications of these arrangements as described with reference to
Figures 8 and 9.
4. The means or arrangement whereby a greater or less number of inductors can

page_text: be separated from the circuit while the machine is at work as described with
reference to Figure 10.
5. The employment of a distributor the action of which, combined with the last
preceding arrangement, by causing the current to pass into a variable number of
inductors allows of giving to the electro motive force such value as is wished and
this either by hand or automatically and in a continuous manner or at determined
intervals of time as described.
6. The arrangement of the induced body separated into several rings side by side
as described with reference to Figures 11, 12, 13, 14 and 15.
•
7. The mode described of constructing each ring divided into independent sections
allowing in case of accident of prompt and easy repairs without interfering with
the absolute continuity of the soft iron of the ring.
8. The formation of the magnetic field (or magnetic fields in cases where it is
-required-to-have-several alternate-fields-in-the-same-ring-and-which-are-necessarily
of even number) by electro magnets with two arms arranged in the form of a crown
or ring with separato polar surfaces for each of them as described with reference to.
Figures 11 to 15.
9. Constructing dynamo electric machines as hereinbefore described.
In witness whereof I the said Marcel Deprez have hereunto set my hand
and Seal this tenth day of December One thousand eight liundred and eighty
three
Witness:
-
ALBERT CAHEN
Civil Engineer
of Boulevard Saint Denis N° 1
-
_ at. Paris_.
11
MARCEL DEPREZ (L.S.).