Improvements in Electric Machines and Transformers.
Year: 1893

page_text: Date of Application, 20th June, 1893
Complete Specification Left, 20th Mar., 1894-Accepted, 5 h May, 1894
PROVISIONAL SPECIFICATION.
Improvements in Electric Machines and Transformers.
We, MAURICE HUTIN of No. 46 Rue Caumartin, Paris, Engineer, and
MAURICE LEBLANC of No. 63 Allee du Jardin Anglais, Le Rancy, Seine & Oise,
France, Engineer, do hereby declare the nature of this invention to be as
follows:-
Our invention relates to the arrangement of the commutators and brushes of
electric machines which may be generators or motors, and of transformers,
particularly in cases where alternating eléctric currents are employed, in such
manner as to prevent short circuiting at the passage of the brushes from one
segment of the commutator to the next; and it relates also to the arrangement in
electric machines and transformers of the magnetic fields, and of magnetic screens,
so as to utilise the forces for generating or moving more completely than in
apparatus as they are usually constructed. We employ a number of armature
coils or sections which is a multiple of 4, and provide a commutator with an equal
number of segments insulated from each other. We connect in series all the even
sections of the armature and connect them to the even segments of the commutator ;
and in like manner we connect the old sections and segments, so that practically two
distinct armatures are thus constituted, which may be termed the one even, the
other odd. We provide two brushes placed opposite to each other, but each of
When the
such width that it cannot touch more than two segments at a time.
brushes touch ouly even or odd segments the even or odd armature alone is acting,
when each brush touches at the same time an even and an odd segment the two
armatures are connected in parallel and act together.
In order to prevent sparking at the brushes, we add, above the ordinary plates
of the brush, a number of gauze plates insulated from each other by paper or the
like, and connected through graduated resistances to the body of the brush, so
that as the brush leaves each segment these resistances are successively introduced
before the circuit of the armature is entirely opened.
When machines or transformers are operated with alternating currents, we
provide magnetic screens extending over the portions of the armature which are
not in the magnetic fields so as to prevent any lines of force being directed uselessly.
For dealing with alternating currents we prefer to employ multiple poles, which we
form by annular segments of thin sheet iron, each segment made with numerous
notches along its concave side, so that when the segments are bolted together they
In intervals between those teeth
form a hollow cylinder with deep internal teeth.
are laid coils of insulated wire wound to and fro in such manner as to constitute a
series of polar fields around the interior of the iron cylinder, within which the
armature revolves.
Dated this 20th day of June 1893.
ABEL & IMRAY,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Machines and Transformers.
We, MAURICE HUTIN, of No. 46 Rue Caumartin, Paris, Engineer, and
MAURICE LEBLANC of No. 63 Allee du Jardin Anglais, Le Raincy, Seine & Oise,
France, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particulary described and ascertained in
and by the following statement :-
In a great number of cases, in particular in the distribution of small electrical
energies, it is necessary to be able to employ electromotors the starting of which
only requires the action of an ordinary commutator, which start with the ordinary
current supply, and the speed of which can be regulated at will by the simple
addition to the apparatus of a rheostat.
The continuous current motors have all these properties, and it is of great
importance to provide an alternate current motor which shall also possess them,
and which does not require separate currents to start them.
We have already patented a machine that possesses the above named properties,
the arrangements of which are particularly suited for the production of a consider-
able amount of energy.
Our present invention has mainly for its object to produce small amounts of
energy, but without being in any way limited to this purpose.
The solution of the problem which would naturally present itself to one would
be to employ, as alternate current motor, an ordinary continuous current motor,
the field magnets and armature of which are connected in series.
As the current would change in direction simultaneously in the inducing and
induced circuits, the direction of the motor couple would be constant, consequently
it might be thought that with equal intensity, the motor couple developed on the
axis of the ring would be the same whether using alternating or continuous currents.
Experience has, however, some time since, shewn that the practical realisation
of this solution is subject to two main difficulties.
1. In continuous current machines the commutation can only be effected at the
cost of successively short circuiting all the sections of the armature.
If the machine operates with alternating currents, the variable flux generated
by the inducer produces in the short circuited section very intense currents which
tend to diminish the intensity of the useful flux, causing the useless expenditure of
a large quantity of energy and also causing the production of violent sparking at
the brushes.
This latter inconvenience is in itself sufficiently serious to render working
impossible under these conditions. It was therefore first necessary, in order to render
the ordinary electromotors applicable with alternating currents, to modify their
mode of action in such manner that no circuit which is subject to the action of the
inducers can be short circuited.
2. When an alternating current is substituted for a continuous current of
determined intensity in any electromagnetic system, there are developed phenomena
of self-induction which cause a disproportionate increase of the electromotive
force necessary for passing into the system a current of the same intensity.
This is a very serious inconvenience. It can be counteracted by introducing a
condenser into the system. According to our invention we arrive at the same
result without adding any accessory to the machines.
NEW ARRANGEMENT OF COMMUTATORS AVOIDING SHORT CIRCUITING.

page_text: We
and having an ordinary collector with 4 n contacts insulated from each other.
will number the successive sections of the ring 1, 2, 3, 4. n, and give the same
designation to the contacts of the collector.
We will separate the sections of the ring and contacts into two groups. The
first group includes the sections of the ring and collector that are of even numbers,
while the second includes those that are of uneven number; we then connect in
series the 2n sections of the even numbers of the ring and we connect them
to the even numbered contacts of the collector as though they were alone in
existance.
The same is also done with the 2n odd numbered sections and the 2n odd
numbered contacts.
This method of grouping the sections and contacts of an armature of a continuous
current machine is shewn in the diagram Fig. 1.
We have shewn on this diagram 16 superposed bobbins coiled round a ring of
any kind and connected to a collector with 16 contacts.
The odd sections 1, 3, 5, 7, 9. . 15 are connected together, the points of union of
these bobbins being connected to the odd numbered plates of the collector; the
unions of the section 1 and section 3 for instance is connected to plate 1; the
union of sections 3 and 5 is connected to plate 3, &c.
In the same way the even numbered sections 2, 4, 6 . . . 16 are connected to
each other and their points of union are connected to the even numbered plates of
the collector.
We thus form two distinct armatures, each having its collector; but the two
systems are, as it were, interlaced with each other, and operate simultaneously.
Assuming that upon the collecter formed as above two brushes a and b are
arranged in diametrically opposite positions, and are connected to the poles of an
electric current generator of any kind, then when one of the brushes rests only
upon one of the odd numbered contacts (position a, b, Fig. 1) or on one of the even
numbered contacts, the armature composed of the odd numbered sections, or the
armature composed of the even numbered sections will alone be in action.
When the two brushes rest simultaneously upon two consecutive contacts
(position a Fig. 1) the two armatures will be coupled in parallel and will
operate simultaneously.
It will always be easy to regulate the width of contact of the brushes in such
manner that neither of them can rest simultaneously upon two contacts of the even
series or two contacts of the odd series.
It would be necessary for this for the brush to be wide enough to rest
simultaneously on three consecutive contacts, which can easily be avoided.
From this arrangement it results that none of the sections will ever be short
circuited.
This is the fundamental property of the new arrangement.
The phenomena that result from an apparatus arranged as above will be readily
understood after what has been said. We will assume that the resistance of these
two circuits is very weak, and that the subdivision of the collector is carried
sufficiently far to insure that the electromotive forces produced in the two circuits
are practically equal. Under these conditions, all things being otherwise equal,
the total intensity J developed in the ring will remain constant.
Assuming that the brushes are in the position a, b, the odd numbered circuit
will have the intensity J passing through it; when the brushes pass to the
position a¹ b¹, this intensity will be equally divided between the two circuits, and
J
each of them will receive the intensity 5; lastly when the brushes have passed
this position, the even numbered circuit will alone be in action, and will, in its
turn, receive the total intensity J, and so on.
The modifications to which the electrodynamic equilibrium is subject, are reduced
to these different distributions of the intensity; they cannot give rise to losses of

page_text: energy and difficulties of any kind unless in consequence of these modifications
the potential energy of the system formed by the two circuits is subject to
alterations; now if we leave out of consideration the extreme bobbins of the two
circuits, that is to say, those which are for the time being directly connected to the
plates in contact with the brushes, it will be seen that these two circuits are
identical both as to form and position. The action is therefore the same as though
there were a single circuit of variable form and arrangement, but the wire of
which was of a section that at one time would be doubled in area, and at another
time would be of its natural size, without altering the intensity.
Such a variation would evidently cause no change in the potential energy of the
system.
There could be no other loss of energy than that of the two extreme bobbins,
which, without being short circuited, are subject to a reversal of the direction of
their current.
This loss of energy will always be very small, and could be made as small as
desired by carrying the subdivision of the collector sufficiently far.
It will however not be necessary to carry this division very far. The condition
to be realised is that the potential energy of the two circuits shall be the same at
the moment of commutation, notwithstanding the difference of their position
relatively to the field magnets.
This will be the case if on each side of the line of the brushes there is a certain
neutral region, occupying a greater angle than that corresponding to a plate of the
collector, and in which no lines of force pass from nor enter the armature. This
condition is very approximately realised in most of the machines.
--
Let us consider for example Fig. 2. We have here shown a Gramme ring A A
arranged between two polar pieces + and Generally speaking the inter-
mediate space is sufficiently small for enabling the lines of force that can pass from
or to the ring in the free space between the planes X X and Y Y passing through
the extremities of the polar pieces to be neglected relatively to the number of lines
which pass through the spaces in front of the polar pieces.
In our particular case, where the armature is fed with alternating current, this
result will still be obtained with greater certainty if the extremities of the polar
pieces be connected together by means of conducting plates such as a a b b Fig. 2.
These plates will act as magnetic screens and will oppose the development of all
magnetic flux in the parts under consideration.
There should consequently be theoretically no parasite current in the circuits
and no sparking at the brushes.
As however the theoretical conditions are never satisfied otherwise than
approximately in practice, there might occur a slight amount of sparking at the
brushes when these leave one of the circuits.
Although both theory and practice have proved to us that this can be neglected,
it can be entirely suppressed.
In one
For this purpose it is sufficient to introduce graduated resistances into the
circuit about to be opened before the contact is completely broken. This result
will at once be obtained by using brushes similar to that shewn at Fig. 3.
and the same socket are arranged an ordinary brush m m' and a series of blades of
metal foil insulated from each other and from the brush by paper or other
insulating material. These blades are connected to each other and to the brush
by a series of graduated resistance. It suffices to examine the drawing to see that
when the collector moves relatively to the brush in the direction of the arrow, all
these resistances will be successively introduced into the circuit of the armature
which is to be broken, before such breaking is actually effected.

page_text: In particular when the resistance of the secondary circuit is reduced to the
minimum by the short circuiting thereof, this co-efficient is almost zero; there then
circulate in the field magnet windings a number of ampères equal to that which
circulates in the armature, increased by a small number of ampères sufficient for
determining the flux which, as is known, does not act under these conditions; the
secondary circuit has passing through it a current of the same period as the primary
current, and almost exactly half a phase later than this.
It is possible to obtain the same result with the receiving machines or motors
and consequently to suppress almost entirely the detrimental effects of the self
induction. Fig. 4 shews a ring induced by any known system, the circuits of
which are arranged for commutation as has been described above, and is shewn
at A A; its collector is indicated by the circle C C. On this collector rest two
brushes a, b, permanently short circuited by a conductor a ẞ. This ring is subject
to the action of two pairs of inducing electromagnets 1 1, J J, arranged at right
angles to each other. The plane of the axis of the magnets II coincides with the
plane passing through the axis of the machine and the points of contact of the
brushes a b, the plane of J J being at right angles thereto.
The bobbins of the electromagnets II and J J are mounted in series and are
traversed by the operating alternating currents.
The currents passing through the bobbins of I I develop a variable flux which
passes through the armature ring, and the lines of force will follow the directions
such as shewu by the dotted lines m m, m¹ m'. This flux in passing through the
ring will develop by its alternations electro motive forces and currents which will
be closed by the short circuited branches a b.
The system formed by the electromagnets II and the armature ring A A
constitutes a transformer of which the secondary coil is closed in itself. It results,
according to what has been above said that this system may have a negligible self
induction.
It is sufficient for this purpose to arrange so that its magnetic permeability shall
be very great, which will of course be the case if the space between the field
magnets and the armature is made very small, which can always be effected.
It also results that the ring A A is passed through, as above stated, by an
alternating current of the same period as the current which excites the magnets I I,
and having the opposite phase.
The electromagnets J J on the other hand will develop a flux at right angles to
the preceding one and will cause lines of force to pass through A A, following the
direction of the lines μμ.
The variation of this flux will not develop any current in the ring A. A on
account of its position; it tends to produce electromotive forces which are opposed
to each other at the points P P₁ of the ring, and which consequently neutralise
each other.
But the ring A A, being passed through by the alternating current resulting
from the inductive action of the bobbins of I I, and at the same time being
traversed by the field produced by the electromagnets J J, the condition of the
system is analogous to that of a machine with continuous currents, the inductors
and ring of which are traversed by one and the same alternating current.
It will consequently be started in motion and will give a motor couple which will
depend upon the intensity of the current which it receives. Consequently it
solves the problem which we have stated above, and the system thus obtained will
both be free from sparking due to variations of the flux, in consequence of our
method of commutation, and will only have a negligible self induction if the
number of windings of the bobbins J J is small relatively to that of the
bobbins I I.
The ring being closed in itself, the size of the wires which cover it need not be
of any fixed size, but may be chosen so as to facilitate the construction of the
apparatus.

page_text: PRACTICAL APPLICATIONS OF THE ABOVE DESCRIBED METHOD OF
CONSTRUCTION.
We have not considered in the above the losses of energy in the iron due to
hysteresis and the Foucault currents when alternating currents are employed.
These losses are proportionate to the intensity of the total magnetic flux and to the
frequency of the current. It would therefore be advantageous, in a motor of a given
power, to employ magnetic fluxes of small intensity, which shall be passed through
several times by the induced circuit.
This will cause multipolar machines to be mostly employed in practice.
In the foregoing, for facility of explanation, we have assumed that the machine
was bi-polar, but it is evident that what we have stated is equally applicable to a
multipolar machine, as this can always be considered as consisting of two or more
superposed bi-polar machines.
The machine shewn at Figs. 5, 6 and 7 respectively in longitudinal section, cross
section and end view, and in diagrammatic view of the circuits at Fig. 8, is a
machine with four poles. The inducing system is constituted by a ring R R formed
of layers of sheet iron cut to the shape shewn, fixed together with interposed layers
of insulating material. The ring has, on the one hand, four projections A'A'A³ A
having polar extensions, and on each of which is mounted a bobbin a¹ a² a² aª ;
these projections correspond to the electro magnets II of Fig. 4. On the other
hand, the ring has four other smaller projections B1 B2 B3 B', also carrying
bobbins 163, which constitute electro-magnets analogous to those shewn
at J J Fig. 4.
The bobbins b₁₁.. should, as above stated, have less convolutions than those
of a¹ a²... The eight bobbins are grouped in series and are traversed by the
actuating alternating current.
The parts D D D³ D' are plates of copper forming magnetic screens for
obtaining a perfect commutation; these pieces correspond to those shewn at a abb
Fig. 2.
The ring E E constitutes an armature formed of sheet metal fixed side by side
with the interposition of insulating material such as paper. On this armature are
coiled bobbins which we will assume to be 12 in number.
The coiling is effected according to the method which we have described with
reference to Fig. 1. The diagram of the whole at Fig. 8 shews clearly the different
groupings.
The plates of the collector which are at diametrically opposite points are
connected with each other; they are 24 in number.
The entering wire of the first bobbin is connected to the plate of the collector ;
the winding is first made at 6¹ and continued at b₁₁; the leaving wire of this first
bobbin is attached to the plate 3 of the collector; the entering wire of the third
bobbin is connected to the plate 3, the plates 3¹ and 3 being connected, the leaving
wire of 6 is consequently connected to the entering wire of 63. The winding is
then continued in 6, connected to the plate 5' of the collector, which is connected
through plate 5 with the entering wire of 65, and so on, to the leaving wire of bu
which may be connected to the plate 1' of the collector, but which for facility of
construction is connected directly to the plate 1, which is next to it.
We have thus constituted a first winding of all the bobbins of uneven number.
The grouping of the bobbins of even number is effected in an analogous manner,
and is indicated at Fig. 8.
It must be observed that for facilitating the reading of the diagram, we have
shewn the bobbins placed side by side; in actual construction the two windings
would be advantageously superposed, and juxtaposed as far as possible along their
whole length; this arrangement however, though advantageous, is not obsolutely
necessary.

page_text: Also, for facilitating the reading we have provided the armature with a Gramme
winding, but a Siemens, Desroziers, or other winding which can be applied to a
continuous current machine is also applicable. The same observation also holds
good for the windings of the field magnets.
It may be of advantage to employ a Gramm-Paccinotti armature in order to
render the space between armature and field magnets as small as possible.
We provide two brushes at an angle of 90° on the collector; two brushes are
sufficient as the diametrically opposite plates are connected, as above stated.
The brushes are arranged as described with reference to Fig. 3.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is
1. In an alternate current motor, the use of an armature of the Gramme or
Siemens kind in which the sections are coiled with two definite groups, namely:
a. The sections of even number, which are all connected together so as to give
on the armature a continuous winding in the same direction, the points of
contact of the successive sections being connected to the even numbered.
plates of a Gramme collector.
b. The sections of odd number also connected together so as to form a continuous
winding in the same direction, the points of contact of the successive
sections being connected to the plates of odd number of the collector, and
the brushes resting on the collector being made of a width such that they
can never short circuit a section, while the brushes of opposite sign are
connected with each other by a conductor of small resistance, substantially
as and for the purposes described.
2. The use in an alternate current motor of the kind referred to in the first claim,
of conducting screens covering the whole of the space not covered by the magnetic
poles, for the purpose of preventing the passage of lives of force beyond the
armature at those parts, substantially as described.
3. In an alternate current motor of the kind referred to in the first claim, the
use of supplemental poles placed in a plane bisecting the angle formed by the axial
ines of two consecutive poles of the machine, such supplemental poles being
provided with a winding in which circulates the same alternating current that
circulates in the winding of the main poles, substantially as and for the purposes
Jescribed.
Dated this 20th day of March 1894.
ABEL & IMRAY,
Agents for Applicants.