Improvements in Alternate Current Electro Dynamic Machines.
Year: 1892

page_text: Date of Application, 28th July, 1892
Complete Specification Left, 27th Apr., 1893-Accepted, 27th May, 1893
PROVISIONAL SPECIFICATION.
Improvements in Alternate Current Electro Dynamic Machines.
We, MAURICE HUTIN, of No. 46 Rue Canmartin, Paris, Engineer, and
MAURICE LEBLANC, of No. 63 Allee du Jardin Anglais, Le Raincy, Scine &
Oise, France, Engineer, do hereby declare the nature of this invention to be as
follows
:-
The synchronous motion of two moving objects is a true condition of mechanical
equilibrium. It is a natural law that a state of equilibrium is only attained after
a certain number of oscillations to either side of that condition.
From this results the great difficulty of causing alternate current electro
dynamic machines to work synchronously although it is known that theoretically
this can be done.
Such synchronism cannot be attained by a simple operation of causing the two
machines to work at the speed corresponding to synchronism; it is necessary during
a certain length of time to arrange that they differ to such a slight extent from
that speed, that the said oscillations can be gradually extinguished; hence the
difficulty of starting.
On the other hand all disturbing causes, of which there are always various
kinds, will affect the equilibrium, which cannot be re-established until further
oscillations have taken place whereby the working is rendered very unstable.
If the disturbing cause is periodical, such for instance as the passage of a belt-
joint, and if the period is more or less equal to the duration of the natural
oscillations of the armature; the synchronous motion will never be obtained.
Owing to the above causes, there exist in reality no alternate current inachines
that entirely fulfil the conditions of absolute synchronism.
Our present invention has for its object to render comparatively easy the
attainment of synchronism in alternate current machines, and to insure the con-
tinuation of such condition no matter what disturbing causes may occur.
The principle of action is as follows:-
Assuming an electro dynamic machine composed of a gramme ring turning
between two magnetic inducing poles, the current being sent into the ring at two
diametrically opposite points by means of two contact rings and two fixed contact
brushes, the field magnets being excited by a continuous current passing through
their ordinary winding. The field magnets are provided according to this
invention with a second winding with closed circuit.
If now an alternating current of constant intensity be sent into the gramme
ring, and a gradually increasing speed be imparted thereto there will be produced
in the said closed circuit of the field magnets induced currents that will generate
a couple acting on the ring.
The value of this couple will be a function of the speed; for a speed of zero
the couple is zero; it grows with the speed and attains its maximum for a speed
which is below that of synchronism, but very near it; it vanishes again when
synchronisin is attained, or rather, for a speed exceedingly near synchronism it
appears with the opposite sign when that point is passed, and passes over a new
inaximum value the inverse of the previous one for a speed very slightly above
that of synchronism, and then it gradually diminishes as the speed further
increases.
It follows from this that when the speed of the machine is sufficiently near
synchronism the said couple will tend with energy to produce the synchronous

page_text: motion, and when once this is attained it tends constantly to maintain it, in
correcting the deviations that may occur in the one or the other direction.
The same action will take place if the gramme ring has two circuits, the
entrances of which are on two diameters at right angles to each other, and which
have currents passing through them that are of shifted phase so that the ring
will produce a rotating magnetic field.
The action of the currents of the closed circuit on each of these circuits will be
of the same order and in the same direction, so that the synchronising effect will
not be modified.
When the synchronous motion is attained, the ring will turn at the same speed
as the magnetic field and in the contrary direction, so that the field will remain
stationary in space. Its polar line will occupy a position forming a certain angle
with the polar line of the inducing magnetic field, which angle will be a junction
of the resisting couple to which the machine is subject when working as receiver
or motor. If this couple varies, the said angle will assume a different value, the
polar line assuming a new position in which it will become fixed after some
oscillations. The presence of the closed circuit will limit these oscillations and
will deaden them very quickly so that the synchronism will be maintained.
But in order that the deadening action may be energetic and regular, it is
evidently necessary that the closed circuit shall always be intersected by the
magnetic current emanating from the armature, whatever may be the position of
the polar line of the latter.
The closed circuit must therefore surround the armature so that all displacements
of the polar line of the latter shall give rise to an induction.
In order to give to this closed circuit the greatest possible efficacy, it is necessary
that the slightest displacement of the polar line will generate therein the greatest
possible amount of energy.
This requires on the one hand that the inductive action, or more correctly the
mutual induction between the closed circuit and the armature, shall be as great as
possible, and on the other hand that its resistance shall be as small as possible.
It is particularly necessary that the mutual induction shall be very great
relatively to the resistance.
One is led on this account to impart to the closed circuit generally speaking the
armature formed of a large mass of copper.
However, if this form is preferable, it is not strictly indispensable, and provided
that the circuit preserves the essential qualities above stated, it can be modified
according to requirements.
We may introduce into the same temporarily or permanently accessory appliances
such as condensers, resistances or sources of electro motive force, which may in
certain cases either serve to facilitate the starting of the machine or for contributing
to the regulation of the speed thereof.
The following may be given as examples of the manner of practically carrying
out our invention.
Assuming a construction of machine in which both the revolving armature and
the field magnets are of ring form; the latter are provided firstly with a winding
in sections forming a circuit into which a continuous current is sent, and secondly
with another winding in sections which are placed intermediately between those of
the first, and which form the closed circuit.
The armature has also two circuits into which are sent two currents of shifted
phase and that produce a revolving magnetic field.
By virtue of this arrangement and of the motor-couple generated by the closed
circuit, the machine will start and will arrive at a speed very near that of
syuchronism.
This approach may be made as near as may be desired by arranging suitably the
closed circuit, and in particular by forming it of a large mass of copper as before
stated. Under these conditions the synchronism will be produced rapidly and with
certainty; the machine then works as before described.

page_text: The above arrangement may be reversed; the currents of shifted phase may be
sent into the fixed circuits, and the circuits of the armature may be arranged as
previously described with reference to the fixed circuits. The closed circuit
may, as already stated, have variable resistances introduced into it for facilitating
starting.
In the above described arrangement the closed circuit surrounds the moving
armature, but it does not satisfy the conditions as to relative resistance and induc-
tion above stated.
In consequence hereof one would be led to impart to it the form of a simple
copper cylinder surrounding the armature. This arrangement would however have
the disadvantage of increasing the distance between the iron of the armature and
that of the field magnets to a detrimental degree.
It is therefore proposed to adopt the following arrangement which is substantially
equivalent to the above.
The fixed circuits are arranged on a ring formed of sheet iron plates placed side
by side, but insulated from each other.
The circuit which receives the continuous current, is formed of wires coiled in
grooves cut in these plates so as to form a series of alternating poles.
The closed circuit is formed of two annular bronze cheeks placed on each side of
the wrought iron ring and tied together by bolts passing through holes in the
wrought iron ring but insulated therefrom, the bolts serving to establish electrical
connection between the checks. These must be brought as near as possible to the
rotary armature in order to intersect the inagnetic current flowing therefrom. The
continuous electric current may be supplied either by a small dynamo arranged on
the shaft of the armature, or from any other source.
The rotary armature is made to present the same number of poles as the fixed
ring. When the machine is one with revolving magnetic field the said poles are
constituted by means of two or more juxtaposed or superposed circuits, according to
the ordinary method, and which receive a corresponding number of alternating
currents with shifted phase.
But according to the principle first above stated, the deadening action of the
inducing circuit does not require a rotary magnetic field for its production; it also
takes place under the action of a simple alternating current.
If therefore there is
only a single current available there may be placed on the armature of the machine
a single circuit so arranged as to give a number of poles equal to the number of
inducing poles. In this case the machine will not start of itself; it is necessary
to start it by extraneously imparting to it a speed equal to synchronism or very
near it.
But with the presence of the closed deadening circuit, it suffices that the machine
be made to pass through the condition of synchronism in order for it to remain
there.
The simplest way will therefore be to start it at any speed higher than
synchronism and then allow it to slow down by itself till the required speed is
obtained. The machine then becomes an ordinary alternating current machine
only differing in form from those now in use.
The method of synchronisation above described may be applied generally to all
machines, whether generators or receivers, in preserving the essential features above
set forth, and only modifying the arrangements for adapting the deadening circuit
to the forms of machines to be synchronized.
The application of the deadening circuit to alternate current machines with fixed
magnetic field has another effect besides insuring synchronism.
This effect consists in diminishing or suppressing the "Foucault" currents
produced in the polar pieces and the inducing cores, as also the parasite currents
which may be generated in the inducing circuit in consequence of the variations of
magnetic current caused by the passage of the alternating current in the induced
armature. The said circuit serves the purpose of a magnetic screen, and its presence

page_text: considerably improves the yield of the machines and suppresses the unpleasant noise
which is generally produced thereby.
Dated this 28th dox of July 1892
ABEL & IMRAY,
Agents for the Applicants.
Improvements in Alternate Current Electro Dynamic Machines.
We, MAURICE HUTIN of No. 46 Rue Canmartin Paris, Engineer, and MAURICE
LEBLANC of No. 63 Allee du Jardin, Anglais, Le Raincy, Seine and Oise,
France, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:-
The synchronous motion of two moving objects is a true condition of mechanical
equilibrium. It is a natural law that a state of equilibrium is only attained after a
certain number of oscillations to either side of that condition.
From this results the great difficulty of causing alternate current electro dynamic
machines to work synchronously although it is known that theoretically this can be
done.
Such synchronism cannot be attained by a simple operation of causing the two
machines to work at the speed corresponding to synchronism; it is necessary
during a certain length of time to arrange that they differ to such a slight extent
from that speed, that the said oscillations can be gradually extinguished; hence
the difficulty of starting.
On the other hand all disturbing causes, of which there are always various kinds,
will affect the equilibrium, which cannot be re-established until further oscillations
have taken place whereby the working is rendered very unstable.
If the disturbing cause is periodical, such for instance as the passage of a belt-
joint, and if the period is more or less equal to the deviation of the natural
oscillations of the armature, the synchronous motion will never be obtained.
Owing to the above causes, there exist in reality no alternate current machines
that entirely fulfil the conditions of absolute synchronism.
Our present invention has for its object to render comparatively easy the
attainment of synchronism in alternate current machines, and to insure the
continuation of such condition no matter what disturbing causes may occur.
The principle of action is as follows:-
Assuming an electro dynamic machine (Figure 1 of the accompanying drawings)
composed of a gramme ring O turning between two magnetic inducing poles N
and S the current being sent into the ring at two diametrically opposite points a
and by means of two contact rings and two fixed contact brushes A. B while the
field magnets are excited by a continuous current passing through their ordinary
winding. The field magnets are provided according to this invention with a second
winding C. D. E with closed circuit.
If now an alternating current of constant intensity be sent into the gramme
ring O and a gradually increasing speed be imparted thereto there will be produced
in the said closed circuit C. D. E. of the field magnets induced currents that will
generate a couple acting on the ring O.
The value of this couple will be a function of the speed. It may be represented
by a curve such as that indicated at Figure 2; for a speed of zero the couple is
zero; it grows with the speed and attains its maximum A for a speed which is
below that of synchronism, but very near it; it vanishes again when synchronism
is attained, or rather, for a speed exceedingly near synchronism; it appears with
the opposite sign when that point is passed and passes over to a new maximuin

page_text: value A the inverse of the previous one for a speed very slightly above that of
synchronism, and then it gradually diminishes as the speed further increases.
It follows from this that when the speed of the machine is sufficiently near
synchronism or when it attains the point A the said couple will tend with energy
to produce the synchronous motion, and when once this is attained it tends
constantly to maintain it, in correcting the deviations that may occur in the one or
the other direction. Consequently it perform the function of a corrector and
deadener.
The same action will take place if the gramme ring has two circnts, the
entrances of which are on two diameters at right angles to each other, and which
have currents passing through them that are of shifted phase so that the ring O
will produce a rotating magnetic field.
The action of the currents of the closed circuit C. D. E. on each of these circuits
will be of the same order and in the same direction so that the synchronizing effect
will not be modified.
When the synchronous motion is attained, the ring will turn at the same speed
as the magnetic field and in the contrary direction, so that the field will remain
stationary in space. Its polar line will occupy a position sn Figure 3 forming a
certain angle I with the polar line N S of the inducing magnetic field, which angle
will be a function of the resisting couple to which the machine is subject when
working as receiver or motor. If this couple varies, the said angle I will assume
a different value, the polar line sn assuming a new position in which it will become
fixed after some oscillations. The presence of the closed circuit C. D. E. will
limit these oscillations and will deaden them very quickly so that the synchronism
will be maintained.
But in order that the deadening action may be energetic and regular, it is
evidently necessary that the closed circuit C. D. E. shall always be intersected by
the magnetic current emanating from the armature whatever may be the position
of the polar lines of the latter.
The closed circuit must therefore surround the armature so that all displacements
of the polar line of the latter shall give rise to an induction.
In order to give to this closed circuit the greatest possible efficacy, it is necessary
that the slightest displacement of the polar line will generate therein the greatest
possible amount of energy.
This requires on the one hand that the inductive action or more correctly the
mutual induction between the closed circuit and the armature, shall be as great as
possible, and on the other hand that its resistance shall be as small as possible.
It is particularly necessary that the mutual induction shall be very great relatively
to the resistance.
One is led on this account, to impart to the closed circuit generally speaking
the form of a conductor closed in itself surrounding the armature formed of a large
mass of copper.
However, though this form is preferable, it is not strictly indispensable, and
provided that the circuit preserves the essential qualities above stated, it can be
modified according to requirements.
We may introduce into the same temporarily or permanently accessory appliances
such as condensers, resistances or sources of electromotive force, which may in
certain cases either serve to facilitate the starting of the machine or for contributing
to the regulation of the speed thereof.
The following may be given as examples of the manner of practically carrying
out our invention.
Assuming a construction of machine in which both the revolving armature and
the fixed field magnets are of ring form shewn diagrammatically at Fig. 4, the
latter are provided firstly with a winding in sections forming a circuit A into which
a continuous current is sent, and secondly with another winding B, in sections
which are placed intermediately between those of the first, and which form the
closed circuit.

page_text: The armature has also two circuits ab into which are sent two currents of shifted
phase and that produce a revolving magnetic field.
By virtue of this arrangement and of the motor couple generated by the closed
circuit B the machine will start and will arrive at a speed very near that of
synchronism.
This approach may be made as near as may be desired by arranging suitably the
closed circuit B and in particular by forming it of a large mass of copper as
before stated. Under these conditions the synchronism will be produced rapidly
and with certainty; the machine then works as before described with reference to
Fig. 3.
The circuit A performs the function of inductor with fixed polarity, and the
circuit B performs the function of deadener and maintains the synchronism,
whatever may be the variations in the work performed.
The above arrangement may be reversed; the currents of shifted phase may be
sent into the fixed circuits A and B and the circuits a and b of the armature may
be arranged as previously described with reference to the fixed circuits. The
closed circuit may, as already stated, have variable resistances introduced into it
for facilitating starting.
In the above described arrangement (Fig. 4) the closed circuit surrounds the
moving armature, but it does not satisfy the conditions as to relative resistance and
induction above stated.
In consequence hereof one would be led to impart to it the form of a simple
copper cylinder surrounding the armature. This arrangement would however have
the disadvantage of increasing the distance between the iron of the armature and
that of the field magnets to a detrimental degree.
It is therefore proposed to adopt the arrangement shewn at Figs. 5 and 6 which
is substantially equivalent to the above.
The fixed circuits are arranged on a ring formed of sheet iron plates A placed
side by side but insulated from each other.
The circuit which receives the continuous current, is formed of wires B C, C D
coiled in grooves cut in these plates so as to form a series of alternating poles.
The closed circuit is formed of two annular bronze checks M M placed on each
side of the wrought iron ring and tied together by bolts F P, passing through holes
in the wrought iron ring but insulated therefrom, the bolts serving to establish
electrical connection between the cheeks. These must be brought as near as
possible to the rotary armature in order to intersect the magnetic current flowing
therefrom. The continuous electric current may be supplied either by a small
dynamo D arranged on the shaft of the armature, or from any other source.
The rotary armature is made to present the same number of poles as the fixed
ring. When the machine is one with revolving magnetic field, the said poles are
constituted by means of two or more juxtaposed or superposed circuits, according to
the ordinary method, and which receive (Figs. 5 and 6) a corresponding number of
alternating currents with shifted phases. The machine will then act as described
with reference to Fig. 4.
But according to the principle first above stated, the deadening action of the
inducing circuit does not require a rotary magnetic field for its production; it also
takes place under the action of a single alternating current. If therefore there is
only a single current available there may be placed on the armature of the machine
a single circuit so arranged as to give a number of poles equal to the number of
inducing poles as shewn at Figs. 5 and 7. In this case the machine will not start
of itself; it is necessary to start it by extraneously imparting to it a speed equal to
synchronism or very near it.
But with the presence of the closed deadening circuit, it suffices that the machine
be made to pass through the condition of synchronism in order for it to remain
there.
The simplest way will therefore be to start it at any speed higher than
synchronism and then allow it to slow down by itself till the required speed is

page_text: obtained. The machine then becomes an ordinary alternating current machine
only differing in form from those now in use.
The method of synchronisation above described may be applied generally to all
machines, whether generators or receivers, in preserving the essential features
above set forth, and only modifying the arrangements for adapting the deading
circuit to the forms of machines to be synchronised.
We show by way of example at Figs. 8 and 9 the application of the invention to
a machine of the type with multiple lateral inductors.
It is to be understood that the invention is not limited to the arrangement
shewn as already stated, we can reverse the mode of application, and place the
deadening circuit on the moveable part of the machine instead of on the fixed
part.
We can also arrange this circuit in a variety of ways, and divide it into several
circuits, provided it fulfils the above mentioned essential conditions.
The application of the deadening circuit to alternate current machines with fixed
magnetic field has another effect besides insuring synchronism.
This effect consists in diminishing or suppressing the Foucault currents produced
in the polar pieces and the inducing cores, as also the parasite currents which may
be generated in the inducing circuit in consequence of the variations of magnetic
current caused by the passage of the alternating current in the induced armature.
The said circuit serves the purpose of a magnetic screen, and its presence con-
siderably improves the yield of the machines and suppresses the unpleasant noise
which is generally produced thereby.
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. In alternate current electrodynamic machines, having a constant inducing
field, and of which the induced armature may have one or more circuits traverseil
either by a single alternating current, or by several currents with shifted phases,
producing synchronous motion by combining with the inducing circuit traversed by
a continuous current, one or more special closed deadening circuits, with or without
the introduction into the said circuit or circuits of any appliances for facilitating
the starting or for regulating the deadening action, the said inducing circuit
through which passes the continuous current, and the said deadening circuit or
circuits being placed either on the fixed or on the movable part of the machine
substantially as described.
2. The various arrangements herein described for the application of the method
of construction referred to in the preceding claim to the two varieties of electro
dynamic machines above referred to, of whatever type, which arrangements fulfil
the condition that the deadening circuits shall always be intersected by the whole
of the magnetic currents proceeding from the induced part, it being understood
that these circuits, combined with the inducing circuit can be placed with the same
either on the fixed or the moveable part of the machine either surrounding the
induced armature or being surrounded thereby substantially as described.
3. In electrodynamic machines constructed and operating as set forth in the
preceding claims, the arrangement wherein the closed circuit is constituted by a
system of cheeks of non magnetic metal placed at the sides of the inductor and
connected by bolts of non magnetic metal passing through but insulated from the
polar pieces of the said inductors, the said cheeks being placed as near as possible
to their polar surface substantially as described.
4. The application of the above described deadening circuit to alternate current
machines with fixed magnetic field, whether working synchronously or not, with a
view to the suppression of Foucault currents produced in the polar pieces and the
inducing cores, as also the parasite currents that may occur in the inducing circuit.
in consequence of the variations of magnetic current caused by the passage of
the alternating current in the induced armature, whereby the yield of the machines

page_text: is considerably increased and the noise produced thereby is prevented substantially
as described.
וי
ABEL & IMRAY,
Agents for the Applicants.