Method of and Means for Regulating Electric Currents, Dynamo- machines, and Electro-motors.
Year: 1888

page_text: Date of Application, 22nd Dec., 1888
Complete Specification Left, 23rd Sept., 1889-Accepted, 9th Nov., 1889
PROVISIONAL SPECIFICATION.
Method of and Means for Regulating Electric Currents, Dynamo-
machines, and Electro-motors.
I, WILHELM FRIEDRICH LAHMEYER, Electrical Engineer, of 37, Rue Phillippe-le-
Bon, Bruxelles, Belgium, do hereby declare the nature of my invention to be as
follows:-
This invention relates to the regulation of electric currents and chiefly consists
in replacing the variable resistances, hitherto employed for that purpose, by the
counter electro-motive force produced by a freely revolving armature introduced into
or otherwise connected with the (magnetic) circuit.
Supposing the case of a series-wound electro-motor, to be regulated for constant
speed when the load varies, but the driving current remains constant, we branch
from the circuit containing the field coils and the working armature a shunt
circuit containing a regulating armature and a second field winding acting opposite to
the first. The current supplied to the motor divides itself between these two branches
in the inverse ratio of their resistances, which for each branch is ascertained by
totalising the resistances of field wire, armature wire and the value of the counter
It is easy to see,
electro-motive force produced by the corresponding armature.
that any increase of the load on the working armature will cause its counter electro-
motive force to decrease and that consequently the current in the main branch will
increase at the expense of the current in the regulating branch.
It is only necessary to find out the exact dimensions which must be given to the
wires in both branches for an exact regulation, i.e. in order that the increase of
current thus sent into the working-armature will be sufficient to keep its speed
constant when the load increases.
The regulating armature is preferably made smaller than the working armature,
in which case the two armatures should be placed in parallel in the magnetic field ;
that is to say, so that the lines of force will cross both armatures in the same
direction, whereas, when the two armatures are placed in series in the magnetic
field, that is so as to form part of the same magnetic circuit, the armatures should
be nearly equal.
The field magnets of the two armatures may be combined in this manner in a single
frame, or they may be mounted in separate frames.
The field of the regulating armature need not be obtained in the same manner as
the field of the working armatúre, that is by two coils acting opposite to each other;
it may, for instance, be produced by only one coil receiving the entire current before
it branches off, or by one coil separately excited, or by a permanent magnet.
A regulating armature may also replace the variable resistance used in the case,
where the field of a dynamo is regulated by varying a magnetic shunt branched on
the field of the dynamo:
The regulating arinature may be simply placed in a shunt taken off the circuit
containing the working armature and the fields, (that is to say parallel to that circuit)
which in this case will carry no counter windings. The shunt containing the regu-
lating armature may also be taken off the brushes of the working armature.
In the above cases, we have always assumed the main current to be constant, but
we can obtain a constant speed even when the intensity of the current varies con-
siderably. For this purpose the working armature is provided with a centrifugal
speed governor which controls a brake mechanism acting on the regulating armature
in such a manner that when the working armature (hereinafter called W) runs
too fast, the brake retards the regulating armature (hereinafter called R) which
consequently admits more current to its branch at the expense of the branch of W,

page_text: the result being the required diminution of speed of W. This method of regulation
may, of course, be varied; for instance the brake action may be reversed, so that
when W runs too fast, R will also be accelerated, and admit less current to its
branch, which in this case would comprise a shunt exciting coil of W, so that the
said reduction of current will weaken the field of W.
Or, with the same brake action, R. may comprise in its branch an exciting coil,
whereas another branch connected in parallel comprises a de-magnetizing coil, so that
an acceleration of W, by causing an acceleration of R, diminishes the exciting
current and increases the de-magnetizing current so as to weaken the field of W.
The new method of regulation is applicable also to motors working in parallel. For
this purpose we may for instance place R in circuit with the exciting coils of the
motor.
This inventiou may also be applied to the regulation of dynamos, either for constant
current or for constant electro-motive force. In the first case we place R in a branch.
with de-magnetizing field coils, W being in a parallel branch with exciting field coils
while an electro-magnet acting on a brake mechanism of R is in the main circuit.
If the current in the main becomes too strong, the brake will retard the motion of R,
and more current will pass through the de-magnetizing than through the exciting
branch, in consequence of which the magnetic field, and therefore also the main
current, will be reduced.
To regulate a dynamo for constant e. m. f., we may insert R into the exciting
shunt, while the electro magnet which operates the brake is situated in a branch
taken off tho dynamo terminals in such a manner, that the attraction of its armature
slackens the brake.
We may, of course, apply our method to the shunt of a compound wound dynamo,
so as to render it independent of variations of speed.
In applying our system to the regulation of a continuous current transformer (or
the combination of a dynamo with an electro-motor) we may regulate the motor for
constant speed and cause it to drive a constant current dynamo or a shunt dynamo for
equal tension or a compound dynamo, or we may lead the current from the dynamo
through the coil of an electro magnet adapted to regulate the variable speed of the
motor, so that it drives the dynamo at such a speed, as to give always the desired
tension or current.
Our method may be adapted also to continuous current transformers having but
one armature carrying the windings and collectors of the electro-motor as well as
of the dynamo.
Another important application of our invention consists in keeping the electro-
motive-force constant at the terminals of mains run from a central station. For
this purpose, we may, for instance, insert a motor into one of the mains, the
latter being divided into two branches, one of which contains the field coils and
a large but constant resistance, while the other contains the regulating armature
and de-magnetizing coils. Two small extra wires connect the main terminals with
an electro-magnet actuating our ordinary brake. mechanism. The latter is so
arranged, as to retard the armature when the electro-motive-force at the terminals
is too low. Or we excite the field by a shunt taken from the mains and insert
into one of the mains the regulating armature and the de-magnetizing coils. In
this case the motor must be driven at a constant speed by an independent motive
power on which it reacts. We may also dispense with the exciting coils shunted
on the mains, and retain only the de-magnetizing coil, but then the machine will
absorb mechanical power and therefore act as a dynamo. Or the machine may be
arranged so as to act as a motor when the current is weak, and when this current
increases beyond a certain limit, the direct winding obtains the preponderance and
the machine acts as a dynamo.
In all the arrangements for regulating current and electro-motive-force described
above, where mechanical brakes are employed, we may use equally well a magnetic
brake consisting of a large metallic disc keyed on the motor shaft and influenced by
'the two magnetic poles N and .S of a separately excited electro-magnet.

page_text: But when the speed of the motor has to be regulated, the current led to its field
must vary, and this may be obtained by causing a centrifugal regulator to produce
variations cither in the e. m. f. or in the resistance of the field current.
We may
also simply cause the shaft of the working motor to drive a dynamo, the current of
which feeds a coil wound on the field of the motor.
or in
The heretofore described methods and arrangements or combinations are applicable
also for regulating alternating currents, either in dynamos and motors
conductors. In this case the regulating motor or the regulating armature may
be fed either with a constant current, or in certain conditions, with alternating
currents.
Dated this 22nd day of December 1888.
FAIRFAX & WETTER,
433, Strand, London, Agents.
COMPLETE SPECIFICATION.
Method of and Means for Regulating Electric Currents, Dynamo-:
machines, and Electro-motors.
I, WILHELM FRIEDRICH LAHMEYER, Electrical Engineer, of Aix-la-Chapelle, in
the German Empire, 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 :-
Variable metallic resistances are frequently employed for regulating the
electro-motive force or tension and the current produced in conducting circuits by
dynamo-electric machines, as well as for regulating the number of revolutions of
electro-motors.
My invention has for its object to replace these variable regulating resistances
by a variable electro-motive force (or, according to circumstances, by a counter
electro-motive force).
This electro-motive force is produced in a special induced conductor (or armature),
and by adopting suitable arrangements and establishing electric circuits, always on
the same principle, I produce an automatic variation of the said electro-motive
force corresponding to the requirements of the most important cases of the said
regulation.
By this new method I obtain in many cases, where hitherto the regulation was only
possible in a very imperfect manner, a high degree of regularity, and consequently
remove some technical difficulties which have previously existed. An important
difficulty of this kind has hitherto been found in the regulation of motors arranged
in series, and consequently receiving a constant current, and also in the regulation'
necessary for placing dynamos in series. The regulating apparatus on this system
can be easily applied for attaining these objects.
Considering first the case of motors arranged in series, that is to say, a motor
which always makes the same number of revolutions, whatever the load may be, as
long as the current supplied to it remains constant, the product of the driving
effort of the motor, with its speed of rotation, constitutes its dynamic effect, which
it produces externally in the form designated by the name:-horse-power. Having
imposed the condition, that the number of revolutions shall be constant, it is
necessary that the driving effort of the motor shall be rendered variable in propor-
tion to the external load. For every motor the said driving effort is equal to the
product of a constant with the current in the coil and with the number of lines
of force which intersect the said coil. If the motor is placed in a derived circuit;
that is, if it receives a constant electro-motive force at the terminals, the variation
of the current in the coil which naturally corresponds to the variation of the
external load, provides a relatively easy means of obtaining a constant number of
revolutions. But in the case which is now supposed, that is to say, in the series
arrangement, the current that passes through the induced conductor coil is fixed.
"

page_text: The only means of regulation which remains consists in varying the number of
available lines of force, that is to say, the useful magnetism, and consequently the
electro-motive force at the terminals of the motor, in a manner corresponding to
the variations of the external load. This may be obtained by reducing the number
of ampère-turns of the exciting coil on the field-magnets.
This regulation may be effected by a centrifugal governor, in the following
manner :-
A regulating resistance is interposed parallel to the coils of the electro-magnets,
and connected with the centrifugal governor in such a manner that when the number
of revolutions increases, the resistance decreases; and vice versa. By this method
is withdrawn from the electro-magnets an amount of current corresponding to
requirements; which current then passes through the resistance placed in the shunt.
The reverse action takes place when the number of revolutions decreases.
The following arrangement would produce the same effect. The winding (in series)
of the electro-magnets is divided into a certain number of sections, and the different
sections are connected with the centrifugal governor by conducting wires in such a
manner that when the number of revolutions decreases, the number of convolutions
of the electro-magnets which are traversed by the current increases; and vice versa.
These two, and other analogous contrivances are applied in many ways, but all have
the following drawback. The necessary variation of the effective length of the
exciting coils, from the unloaded condition up to the fully loaded state, is very
extensive in good motors of large size, this variation reaches the ratio of 1 to 10.
It would therefore be necessary to employ an enormous number of contacts for
avoiding a too abrupt regulation of speed. Such a long series of contacts along
which the lever actuated by the centrifugal governor would have to travel, would
require a long range of oscillation of the governor from its middle position; that is
to say, a great variation of its speed. For these reasons, the number of revolutions
could not be exactly regulated in this manner, and the practical use of these motors
has been very small.
My invention solves the difficulty by the application of the resistance provided by
the counter electro-motive force of an induced conductor revolving (so to say) free ;
which resistance varies continuously, that is, without any sudden changes or leaps.
The motor has therefore two armatures or induced conductors, one of which serves to
perform external work, while the other serves only for regulation. The arrangement
of the circuits may be greatly modified, but the following is a good type:-The
working armature is placed in series with the winding of the field-magnets.
Parallel to this circuit there is a shunt comprising the regulating armature and, in
series with the latter, a second winding of the field-magnets acting opposite to the
first. The two field-windings have therefore a differential action. The first may be
called the "exciting coil" and the second "counter coil."
In all the figures the letters of reference are used as follows :-
A designates the working armature.
e shows the exciting coils of the field-magnets.
L is the regulating armature.
y the coils of the field-magnets acting opposite to e (counter-windings).
M
e,
and Mg indicate the respective number of convolutions of e and of 9.
Je and Jg show the corresponding intensities of current ; and
J shows the undivided main current.
Fig. 1 is a diagram of an electro-motor with two armatures, as mentioned above.
The two armatures are placed one behind the other in the same electric circuit, so as
to be intersected by the same lines of force.
e
and
L
9.
and goes
The current entering at 1 is divided into two branches e A
out at I I. The amount of current in the two branches is inversely proportional to
the resistances encountered and the latter are composed of the resistance of the field
coils, the resistance of the induced conductors and of the counter-electro-motive
force developed in the respective armatures. The two armatures may run unloaded
and the current intensities may be Je, and J g. In this case the effective number

page_text: of convolutions will be Me x Je
-
e,
-
}
Mg, x Jg. The coils e and y are naturally,
so calculated that the number of ampère-turns of the first preponderates already
under this first supposition, and consequently the said difference will be positive.
If the working armaturo or induced conductor is now loaded, its counter-
electro-motive force will commence to fall, and the branch e Ae will immediately.
absorb more current. Supposing the new intensities to be J¹ e, and J¹g, it is evident
that the number of effective ampère-turns, M
× J'e
Mg, xg, will be'
greater than before, for two reasons; namely, because Je has become greater, and
because Jg has become smaller. The opposite occurs, if the load of A is diminished.
It is clear, therefore, that by means of a suitable calculation of the coils of the two
branches, I am enabled to "compound" the motor in such a manner, that whatever
the load of A may be, it will, by modifying the distribution of the intensity J,
produce as the differential action of the two windings, exactly the number of effective
ampère-turns which is required for the motor to make a given number of revolutions
under the said load. At the same time the regulation will be assisted by the fact, that
the displacement of current, as a whole, will produce a slight increase of the intensity
in the working armature, when the load increases.
The number of revolutions of a motor, well compounded in this manner, varies
therefore between the unloaded condition and the full working condition only in a
manner almost imperceptible and only sufficient to effect the change in the dis-'
tribution of the current which is necessary for its regulation.
When the working armature is loaded, the regulating armature behaves in such a
manner, that it will automatically tend to increase the speed of rotation, so as to
obtain the diminution of current which is required in its circuit. In other respects,
the amount of this speed is indifferent and does not require any attention, except as
regards its mechanical realization.
As the insertion of the two armatures in the magnetic circuit one behind the other
(in series) requires almost equal dimensions for the same, while by itself the regulating
armature may be very small in comparison with the working armature, it is preferable,,
to arrange the two armatures parallel to each other as regards the magnetic field.
Fig. 2 shows this kind of arrangement. It is, of course, immaterial in principle,"
that there is hero shown a magnetic system with a single branch field magnet, instead
of which any of the numerous varieties of form of the different types of dynamo-
machines may be employed. The two branches in this case are A e and y L,
and the mode of action is exactly like that which has been described in reference
to Fig. 1.
It is by no means necessary, either from an electrical point of view, or mechanically,
to construct the magnetic frames of the two armatures of a single piece. On the
contrary, I may give to the small armature a separate magnetic field, and consequently
construct it also as a separate motor. Fig. 3 represents this case. The magnetic field
of the regulating motor is produced in a manner corresponding to that of the working
motor, by an exciting coil e¹ and a counter coil g'. The two branches are in this
case I e A el II, and I g Lg' I I. The method of electric action differs in nothing
from those that have been described above.
It is clear that the magnetic field of the regulating motor need not be produced in
the same manner, as that of the working motor; that is, by means of two coils acting
differentially. As the speed of rotation of this armature may be chosen at will, it is
always possible to obtain the counter electro-motive force necessary for regulation, by
modifying the said speed, whether its field varies with that of the working motor in
the manner described, or otherwise; or whether the said field remains constant.
Consequently, I may also excite the magnetic field of the regulating motor in a
different manner; I may, for instance, omit the coil g'; or I may also employ
the undivided main current for exciting. Fig. 4 represents this case applied to
the machine shown in Fig. 3. The two branches are I e AII, and Ig III; the
point II being situated in front of the undivided winding e¹ of the field magnet of the
regulating motor.
may also take the exciting current from a third source, or employ a frame formed

page_text: of permanent magnets. In all these arrangements, the variation in the number of
revolutions will be much greater than in the arrangement described first; for which
reason the latter is generally preferable from a mechanical point of view.
In the diagrams of machines the field magnets of which are divided into two
branches, I represent, for the sake of clearness, each branch as carrying one of
the coils e and 9.
Of course, it is better in practice, to distribute each winding or coil over the two
branches, so that each branch carries one half of the winding.
In the case of a dynamo, where the magnetism is varied by varying the ampère-
turns of a magnetic shunt (see Strecker, Fortschritte, 1887, No. 2225, page 413), the
regulation may be effected by means of my regulating armature. Fig. 5 is a
diagram illustrating this arrangement. C is the principal branch of the field magnet
excited by the coil S placed in the undivided circuit.
The branch D, when magnetized, constitutes a magnetic shunt that weakens the
field of the armature. If this branch is magnetized more strongly, it will produce a
greater number of lines of force, which will be concentrated in the field of the
armature. After having traversed the coil S, the current will be divided at 1 into
two branches, one part flowing into the working armature A, (or inductor) and the
exciting coil e; while the other flows into the regulating armature L, and the counter
coil g. The two coils surround the branch D. e tends to magnetise it in the manner
indicated by the letters n and s (representing north and south polarity), while g has a
de-magnetising effect. Any increase of the working load will cause the current in e
to increase at the expense of the current in g, the result being the desired strengthening
of the armature-field. The conditions of regulation, that tend to maintain a constant
number of revolutions are thus established, just as in the previous cases. As in the
latter, I may also give to the small armature a separate frame and thus convert it into
a separate motor.
The construction represented by Fig. 5 may be modified by winding the coils e and y
directly on the poles of the field, in which the regulating armature revolves, and
omitting the branch D. But in this case, care must be taken, that the magnetization
by the regulating coils, when at its minimum, is of the same kind as that of the
armature field; in order that when the current in the coil e increases, the magnetism
of this branch will not pass through zero.
Supposing now, that in all the arrangements described above, the coil g is omitted;
so that only the regulating armature is placed parallel to the circuit, that contains
the other coile and the working. armature; certain conditions are still fulfilled
which render the motor capable of proportioning its magnetism (the intensity of
its magnetic field) to the external load. In this case, the speed of the regulating
armature will be sensibly increased by loading the working armature. In consequence
of this, the latter armature and coil e absorb a greater portion of the current,
which is the condition necessary for a greater output of work. In this case, the
regulating armature acts as a variable regulating resistance interposed in parallel.
In each of the devices described, the connection may be modified. The method,
that has been described and which consists in placing the regulating armature in
a branch parallel to that which contains the working armature and the coil of the
field magnet, corresponds to what is called the long shunt of compound wound
dynamos. With this method, I may establish also the corresponding short shunt.
In this shunt, the branch of the field magnet belonging to the regulating armature,
with or without exciting coils, is directly placed in a magnetic circuit parallel to that
of the working armature, the exciting coils of the field magnets thus receiving the
undivided current. However, it follows from the variation of speed of the two
armatures, and consequently from the variation of the intensities of current passing.
through their branches, that the conditions necessary for the regulation are fulfilled,
although between narrower limits. With these motors I may also employ an ordinary
shunt, either long or short. In this case, the electro-motive force increasing in
consequence of the regulating action of the small armature, will be equally beneficial
to the shunt, for which reason this arrangement may be recommended.

page_text: In the preceding arrangements this shunt is preferably connected at I and II and
surrounds the branches of the field magnets in the sense of e.
Fig. 6 is a diagram showing an arrangement of circuits, which comprises; this kind
of shunt and from which the coil g is omitted.
This arrangement corresponds to Fig. 3, in which the coils g and g¹ are omitted,
inasmuch as the shunt n is connected at I and I I. The circuit of the regulating
armature is likewise joined at I and II and consequently placed parallel to the
circuit containing the working armature and the coil e. Tho distribution of the
current to the branch I L II, and Ie A e e¹ II is affected by the regulation of
the magnetism aided by the action of the shunt. The shunt could also be applied
directly parallel to the armature A, that is to say as a short shunt. The use of the
shunt simultaneously with counter coils is also admissible in all arrangements that
havo been just described.
The arrangements hitherto described are based on the principle of the application of
an armature revolving without external load and serving as a variable resistance for
regulating the number of revolutions of the working armature of an electro-motor,
while, owing to the method of placing it in circuit, the speed of the regulating
armature is automatically controlled according to requirements. The condition ot
this method was that the strength of the undivided current supplied to the motor
should remain constant.
..
If the
This condition. may, however, be avoided within wide limits, if the speed of the
small armature is regulated by means of a centrifugal governor actuated by the
working armature. Fig. 7 represents a combination of mechanism designed for this
purpose. The shaft of the working armature carries a centrifugal governor R. The
latter acts on the shaft of the regulating armature by means of a lever mechanisin
and a brake block C, pressing on the pulley B, in the following manner.
number of revolutions is exactly as required, the block C exerts on Ba certain
medium pressure; as soon as the speed increases a little, this pressure increases
immediately, owing to the friction exerted by the governor; but the least retarda-
tion causes the pressure to decrease. If the pressure grows stronger, the speed of
the regulating armature decreases, and it increases whenever the pressure. decreases.
The special arrangement of mechanism is, of course, subordinate and capable of many
modifications; the only essential condition being, that a rise of the governor shall
correspond to a tightening of the brake on the shaft of the regulating armature,
and vice versa.
It follows, that every time this device is employed in any of the combinations.
described above, the rising of the governor always causes a diminution of the
number of ampère-turns of the exciting coil, or a diminution of the strength of
current in the working armature, or a diminution of both; that is to say, a
diminution of the cause of the excessive speed of the working shaft. On the
other band, and inversely, the fall of the governor, produced by insufficient
speed, causes also the pressure of C to decrease and consequently the regulating
armature to run faster, the effect of which on the electrical conditions is such, that.
the speed of the working armature increases also.
The fact, that the governor does not. abandon its medium position, and that the
least modification of pressure produces a large regulation, thus assures most accurately
a constant number of revolutions.
It will be evident now, that this system offers decided advantages over the
arrangement described at the beginning, and in which the regulator acts on a
variable resistance having a long series of contacts, which require a very long
range of action.
In fact, a motor regulated in this manner may maintain the
number of its revolutions absolutely constant, better even than the best steam
engines, and that just because the regulator never leaves its medium position and
because the least change of pressure produces immediate regulation.
In this new arrangement, when the centrifugal governor acts on the regulating
device, it is no longer necessary to establish a circuit connection which already
tends to produce regulation by itself. On the contrary, the new regulating armature

page_text: 氧
•
1
may be applied in every case, where a variable resistance, controlled by an automatic
mechanism or by hand, would produce the required regulation of speed.
Fig. 8 illustrates this circuit connection applied to the case of two distinct
magnetic frames. The undivided current passes through the working armature A,
after which it is split into two branches at 1. One branch is formed by the
direct windings of the field-magnets I e e¹ I I. Parallel with this branch is the
conductor ILI I, containing the armature. The braking of this latter armature
increases its current by a quantity which is taken away from the exciting current
at e and e, the result being the required regulation. If the two armatures had
but a single frame of the type illustrated by Fig. 2, it would only be necessary
to omit from the diagram 8 the winding e. The mode of action would remain
the same.
Also in this method, which consists in placing the regulating armature in
a shunt taken directly off the field-magnet coils, may interpose in this branch
magnetic coils acting contrary to e and e¹.
I may also cause the governor to act on the armature in such a manner, that an
"excessive speed of rotation releases the brake-pulley B, while an insufficient speed
increases the pressure on the brake-pulloy. It would only be necessary for this
purpose to replace the brake-blocks by a metallic band fixed to the lever and
adapted to be stretched, when the latter rises. Other mechanical arrangements may,
of course, be adopted. In this case, the small armature should either be interposed
in a branch at the same time with an exciting coil, or it should be interposed in such
a manner, that, when the brake acts, it takes away a certain quantity of current from
a de-magnetising coil of the field-magnets.
As the regulating armature requires no separate frame, and as in case such a frame
is used, the exciting coil may vary greatly, the diagram need not show by what means
the said frame is excited.
Supposing & Fig. 9 to be a direct exciting coil of the field magnets, na shunt coil
having a magnetising effect in the same sense or direction, and in the circuit of which
is interposed the exciting armature L, such a motor will work in the following
manner An excessive speed of the working armature A lifts the brake away
from L; consequently L turns more quickly, the current in the shunt In LII
decreases at the same time with the number of lines of force acting on A, which
is the effect to be attained.
The coil d may also be omitted and the machine constructed as a simple shunt
wound machine.
Fig. 10 represents an arrangement in which the motor, when acted upon by the
brake, abstracts current from a de-magnetising counter coil made to conduct it to an
exciting coil interposed in its circuit. The designations are the same as those
which have been applied hitherto. The winding e may be omitted, as is also the
case with n or d.
All the preceding considerations are based on the supposition of a series arrange-
ment; but a regulating armature with automatic brake may, of course, be also applied
for short circuiting a motor working in parallel. For, as explained above, the said
armature is applicable, wherever a variable regulating resistance might be employed.
Consequently, I may place the regulating armature of a shunt wound motor,
adapted to work in derivation, in the shunt circuit. Fig. 11 illustrates this arrange-
ment, which corresponds to that of Fig. 9, except that the direct winding (in series)
is omitted, and that the extent of the regulation, and therefore the variation of the
number of revolutions of L, is much smaller.
The application of the brake is the same, as in the case of Figs. 9 and 10; that is
to say, when A runs too slow, the speed of L is also retarded in such a manner,
that n receives more current. In the same manner, the arrangement represented by
Fig. S is suitable for the interpolation of motors in derivation. The windings are
then calculated for the least range of regulation. If A runs too fast, the governor
applies or tightens the brake of L, so that a portion of the current is withdrawn from
the winding of the field-magnets.
It is evident, that in all these applications the method of arranging the mechanical

page_text: organs, as well as the manner of connecting the governor and the brake, is quite
immaterial. Instead of a brake with friction blocks or shoes, 1 may employ a brake
band, or other form of brake.
To provide, that the working armature shall make a given number of revolutions,
I employ the screw-nut m of the rod h. By tightening this nut, the brake is caused
to act on the regulating motor. For the same purpose, I may also modify the
pressure of the brushes of. this motor; for instance, in the case. of motors without a
centrifugal regulator, the position of the brushes of the regulating armature is fixed
before starting, according to the number of revolutions of the working armature. As
the current passing through these brushes is only insignificant, no sparks are
produced, and the pressure of the brushes is not subject to rapid variations from
wear and tear.
The next point to consider is the application of a regulating motor, or in other
words, of a regulating armature to the regulation of dynamos generating current.
The most important result, that may be attained by this regulation, is the exact
regulation of a dynamo for constant current. Here again is employed a brake
mechanism adapted to its purpose and acting automatically on the regulating arma-
ture. This brake is actuated on one hand by a spring, a weight, or other mechanical
device, and on the other hand by a coil serving as conductor for the current which is
to be kept constant, and the effect of which is opposite to that of the mechanical
device. According to the circuit connection, the brake is tightened either by the
spring or by the coil.
Fig. 12 represents a simple arrangement suitable for the first case. S is the coil of
the main current; F, the spring which constitutes the opposing force; H, is a lever,
and a link connecting the core with the spring. The regulating motor is applied
to the side of the dynamo in such a manner, that the solenoid S is situated close to
the axle bearing of the dynamo. The regulation is rendered accurately adjustable, by
means of the screw-nut m. In as much as there occurs no displacement of the core
in the bobbin, because the brake is always applied (although with variable pressure),
1 may substitute for the feeble attraction which is produced between a solenoid
and its core the stronger attraction between an electro-magnet and its armature.
Fig. 12" shows the most appropriate construction for an electro-magnet of this
kind. The core K of the coil S is movable, and the counter effort tends to lift it.
In order to enlarge the region of strong attraction, the core is reduced conically
towards the bottom, and the iron base G of the bobbin has a conical recess to corre-
spond. This base G is connected with the cover F by the jacket M which surrounds
the hobbin, and is provided with ventilating holes . The cover has an upward
extension of iron which surrounds the movable core for a part of its length, so as
to leave only very little clearance space between the two iron parts. The lines of
force will therefore pass through iron along their entire course, with the exception of
this very short distance and of that which exists at the lower extremity of the core
(between this core and the iron base). The resistance of the former is exceedingly
small, owing to the arrangement of the cylinder Z which is only about 1 m from the
core and has a large inner surface. The only magnetic resistance of any importance
is therefore due to the layer of air situated at the lower extremity of the core.
Consequently, the coil with a comparatively small number of ampère-turns, produces
a large number of lines of force, and the attraction between the core K and the
extended base G is the greater, as the resistance of the intermediate air layer which
varies with the displacement of the cores, constitutes the only notable resistance of
the whole magnetic field. The attraction of a fixed electro-magnet on a movable
armature is known to be proportional to the variation, which the total magnetic
resistance of the field experiences, when the armature moves a unit of length in the
direction of the attractive force.
•
It follows, that the practical value of the cylindrical extension Z is very great; and
such an electro-magnet acts so energetically, that even, when excited by weak-tension
coils, it produces powerful attractions..

page_text: Fig. 13 shows an arrangement of circuits, which, with the construction above
described, answers well the requirements of a dynamo for producing a constant
current, and it relates to the case, where the regulating armature has a separate
magnetic frame. The current produced in the armature A divides itself at I into two
branches, in order to pass into the exciting coils of the two frames; one branch
passing through e and e, while the other flows into the counter coils g and gl and the
regulating armature L, and then into the external circuit. The latter comprises
before the armature A, the regulating coil S, which therefore receives the undivided
current. If this current is stronger, than it should be, it follows from our description
of the preceding figures, that the solenoid S attracts the brake, thereby abstracting
current from the exciting coils for the benefit of the counter coils. As a result, the
intensity and the tension of the current supplied by the machine will diminish.
When the current is too weak, the contrary takes place, owing to the slackening
of the brake.
-
=
The following example will clearly show the sensitiveness of the regulation.
Supposing the current supplied in S to be 20 ampères, the force of attraction of the
bobbin on the core will be 1,9000 grammes. In the opposite sense, the spring acts
with a force, which, when reduced to the leverage at which the pin C of the con-
necting rod acts on the brake lever, is equal to 1,820 grammes. Consequently,
1,900 1,820 80 grammes act as an average pressure at the joint C, which
pressure applies the brake-block with a force that is inversely proportional to the
leverage of the brake-block. If the current of the bobbin would increase up to 21
amperes, the attraction of the bobbin would become about 1,980 grammes. The force
of the spring would remain the same, in as much as the position of the lever
remains unchanged. Consequently, the resultant effort at the joint C would now be
1,980 1,820 ==== 160 grammes. The pressure of the brake would therefore have
been doubled. It is clear now, that very minute variations of the current to be
maintained constant produce immediately important variations in the regulating
pressure of the brake, that therefore the regulating action is extremely sensitive,
and that great variations both in the load and in the speed of rotation remain
-
without effect.
It is hardly necessary to state, that also in these applications I may suppress the
counter windings g and gl, and produce the regulation solely by the changes of the
current in e and e. Furthermore, as has been already mentioned with regard to the
regulation of motors, the armature L may be mounted on the same magnetic frame;
in which case the windings e¹ and g must be omitted from the diagram. Finally,
nearly all the modifications of the circuit which have been indicated in that part of
the specification which relates to motors, may be applied here with others in
addition.
For regulating a dynamo for constant potential by means of a regulating armature,
the best way consists in taking a shunt wound dynamo and inserting the regulating
armature into the shunt at the place where ordinarily the regulating resistance would
be inserted. Fig. 14 shows this arrangement. The brake would be actuated by a
tension bobbin S, placed in derivation off the terminals, with a counter spring; and
that in such a manner, that an insufficient tension at the two ends (of the bobbin),
that is, an insufficient current, applies the brake more strongly. The effect of this
is to produce the desired increase of current in the derived circuit n. In this
arrangement, care should be taken to construct the tension bobbin S according
to the model electro-magnet shown by Fig 12, in order to obtain the most
sensitive regulation.
"
This automatic regulating device may, of course, be employed equally well in
the shunt of compound-wound dynamos, in order to render them independent of
variations of speed.
As the new principle of the regulating armature or motor is adapted to maintain
constant both the speed of motors and the electric factors of dynamo-machines, it
follows that a method of regulating the combination of a dynamo and a. motor,

page_text: that is, a motor dynamo or of a constant current transformer, has been obtained
at the same time.
For this purpose, I may choose between two modes of regulation.
Firstly, regulate the motor inserted in series or in parallel, independently of the
dynamo and for a constant number of revolutions, and I cause it to drive a dynamo
working either with constant current or with constant electro-motive force. Thus a
motor, regulated by this method for a constant number of revolutions, and for
working in series, when connected directly with a compound dynamo, constitutes a
specially recommendable continuous current transformer."
Secondly, I obtain the direct regulation of the speed of the motor, and consequently
of the dynamo which is connected with it (either directly or indirectly by a belt) by
means of a bobbin traversed by the current of a dynamo, one of whose characteristics
(namely the electro-motive force or the current) is to be maintained constant, in the
manner indicated by Fig. 12 and the following.
Thus, I may employ a tension bobbin in derivation off the terminals of a dynamo
with constant electro-motive force, or a bobbin. traversed by the main current of a
constant current dynamo, for acting on the brake-motor, to reduce the number of
revolutions of the working armature in such a manner, that the current traversing the
said armature remains as constant as possible. This constitutes a new principle which
is render al practicable by this new method of regulation.
It is known, that motor-dynamos adapted to be arranged in parallel, may be
constructed with a single armature comprising at the same time the winding of
the motor with its collector and the winding of the dynamo with its collector.
This case is illustrated in Fig. 15, by the concentric arrangement of the collectors A
of the motor and D of the dynamo. The same magnetic frame acts therefore on
both windings.
For magnetising this frame, an exciting shunt (n) taken off the terminals I and I I
of the motor, is employed. Into this shunt is inserted, according to the arrangement
of Fig. 14, both the field winding (n) and the armature L of the regulating motor.
That of the two brakes of this armature, which is here necessary, is actuated by the
bobbin S placed in derivation of the main conductors of the dynamo. The circuit
connections are capable of numerous modifications without departing from: the
principle. The frame, may for instance, be provided with a direct winding: (in
series).
As continuous current transformers have the object of surmounting long distances,
a series arrangement is certainly most suitable for them. For this reason, the case
hereafter described has special importance.
A shunt wound dynamo is adapted to be driven, either direct or by means of a belt,
by one of my motors adapted to work in series. The motor is subjected to a
regulating brake actuated by a bobbin placed in derivation off the main conductors
of the dynamo. The motor, and consequently the dynamo, modify therefore their
number of revolutions in such a manner, that the electro-motive force developed by
the dynamo remains constant.
In dealing with a compound wound dynamo, the smaller the variation of the
number of revolutions, the more perfect is the effect of the compound winding.
Fig. 16 represents this case with a shunt n of the dynamo. The motor is inserted
in a circuit, in which the intensity of the current is as constant as possible, therefore
in series. I have adapted the winding of the type shown in Fig. 8 and the following
figures. Of course, any other winding may be adopted which is appropriate for that
circuit connection. The bobbin S is placed in derivation off the main conductors or off
the dynamo-terminals, and it acts on the brake of the regulating armature L in such
a manner, that the brake is applied as soon as the dynamo gives an excessive electro-
motive force. This tightening of the brake produces a decrease of speed, and
consequently a diminution of the electro-motive force of the dynamo.
Having seen, that this method of regulation requires not even a constant current in
the series circuit in- which the motors are interposed, but counteracts in a great

page_text: measure ther variations of this current, it is easy to understand what accuracy of
regulation is obtained if I supply to the series circuit a constant current, in choosing
as a generator.a constant current dynamo regulated by this method. In such a
system of distribution of current. provision is made to obtain very nearly the same
tension at all second pairs of terminals of the different motor dynamos, and they are
all connected with the same network of conductors directly, or by means of tension
regulators acting at a distance.
In this manner they serve each other as a mutual reserve, so that the stoppage
of some of them entails no sensible variation in the tension of the network.
According to the load sustained by the network, a greater or smaller number of
continuous current transformers are interposed. In the case of motor dynamos, I
may adopt a great number of variations, as regards the winding and placing in
circuit, corresponding to those indicated for the dynamos and the motors, by pro-
ceeding on the same principle.
The regulating resistance usually employed in electric distributions by central
stations, for maintaining a current constant at a distance on a long line, may likewise
be replaced by a regulating motor on my principle.
Fig. 17 shows an arrangement designed for this purpose. A and B are the main
conductors, in which the difference of potential remains constant. At I and II the
motor is inserted into the line of which the terminal tension is to be maintained
constant. The branch 1 Re II comprises the exciting field coil e and a strong and
invariable resistance R placed outside the motor. This resistance may be omitted,
if that of winding e is sufficiently large. The branch I LII contains the regulating
armature and the demagnetising coils y of the field. Land g have comparatively
weak resistances. The bobbin S is subjected to the influence of the tension at a
distance through special line wires ff. The bobbin Sacts in such a manner upon my
brake systein already described, that as soon as the tension at a distance is less than
the normal tension, the brake of the motor will be tightened, and vice versa.
The
regulation by the motor is, as usual in such cases, tied to a minium limit of tension in
the line. This limit may be determined. Supposing, for example, that it is 15 of
the maximum intensity, the pressure on the brake is a minimum, when the tension in
the line amounts to 1 of its maximum. It follows that the subdivision of the
current will then be quite in favour of the branch I Re I I. The motor receives
therefore many lines of force, and L develops a strong counter-electro-motive force.
As Reconstitutes likewise a high resistance, the motor is in such a condition as to
absorb the highest tension possible. That is just, what was necessary to obtain,
because, owing to the feebleness of the current in the line F, the loss of electro-
motive force is maintained quite insignificant. If now, the intensity in F F increases,
owing to the interposition of several brakes at different stations, the electro-motive
force reigning there begins to decrease. But it follows also, that the pressure on
the brake increases, and that the current in the motor is divided more in favour
of the branch Ig LII. Consequently, the number of lines of force and the counter-
electro-motive force of the motor diminish in such a manner, that (as now required)
the motor absorbs less electro-motive force. When in the intensity of the current
is at its maximum, mg Jy is almost equal to me J e. The number of lines of
force is therefore almost negligeable, in such a manner, that the armature is nearly or
completely at rest The tension at different points cannot, therefore, differ sensibly
from the normal, as long as the tension at A and at B is kept constant.
J
The method of action of the motor, as represented by Fig. 17 constitutes what
may be called a repairing regulation."
"
With the arrangement of Fig. 18 the same object is reached by a regulation
having the character of " prevention."
This figure represents a compound wound motor, which (owing to this method of
winding) may be regulated without the use of a brake or of a distance tension hobbin.
The letters A B E FL correspond with those of Fig. 17.
The armature L. and a demagnetising coil y are arranged in series on one of the

page_text: external circuits. The winding e serves to excite the electro-magnets, and is placed
in derivation on the main conductors A-B. The motor is brought to a constant
number of revolutions by means of belt driving gear r.
The method of action is simply as follows :-A stronger current at F, and there-
fore at g, diminishes the number of lines of force, and, consequently, the counter-
electro-motive force of the motor. Consequently, if the current increases, the motor
absorbs by itself less tension, as is necessary for maintaining the tension constant at
a distance. By suitably calculating the windings e and g and that of L, this latter
condition may be exactly fulfilled. The current of the outer circuit actuates the
motor, and the latter communicates its force to the shafting by means of the driving
belt. If, as shown on the drawing, this shafting drives the dynamo, the consump
tion of electro-motive force of the motor benefits again the dynamo. The motor
greatly resembles. a compound dynamo, as regards its mode of action, and it may
therefore be compounded exactly like the latter. A regulator may be interposed in
the shunt e, so as to counteract the effects of the variation of temperature on the
resistance of the external circuit.
The advantage which this method of regulation offers, namely, that the regulation
is no longer tied to a minimum intensity of current, is of great importance. The
compounding of the motor has, in fact, the following effect: If a single lamp
burns at a distant place of consumption, the action of the bobbin g may be taken as
equal to zero. At this moment, consequently, there are m-e* J-e ampère-turns
acting in a magnetic sense, and the winding should be calculated in such a manner,.
that in this case the motor opposes to the current a counter-electro-motive force
exactly equal to the constant loss of electro-motive force, which must be assumed
between A and B at the distance in question (at the place of consumption
mentioned above). This affords, therefore, an easy means of calculating the
winding e. On the other hand, in the case, where the current has its maximum
intensity, it is necessary that the motor should not oppose any counter-electro
motive force; or in other words, no lines of force should be produce:l.
this case we must therefore have mg. Jg Me. Je, which equation serves immediately
to ascertain the value of m g. In order to obtain a perfect compounding for all
intermediate values of intensity, the arrangements may be so.chosen, that the magnetic
range of the motor falls (as in the case of the compound dynamos) into the rising
and almost rectilinear part of the curve of magnetization.
-
In
If now the allowable maximum intensity of the current is exceeded, the following
will happen: The sum of the ampère-turns me. Je = mg. Jg bocomes negative, but
it follows also from this, that the direction of the electro-motive force is reversed,.
consequently, the motor now produces a tension which-as is necessary at this.
moment will be added to that of the distant current. For a stronger current, than
that which is determined by the equation m g. J g = me. Je, the motor acts therefore.
like a dynamo machine. The windings may also be calculated in such a manner, that.
this effect is produced for a weaker J g, than the maximum intensity of the distant.
current. In this way the dimension and action of the motor are limited. This will
be reduced as much as possible, if in this equation a value of Jg equal to half this.
maximuni intensity, be chosen. In this manner, the motor will still act with good
effect, even when the current is weaker.
Finally, the action of e may be completely suppressed. In this case, the winding
of the external circuit will act alone, and the machine will act from the beginning as
a dynamo. It constantly supplies the electro-motive force which is lost in the line..
The main conductors A B have therefore the same tension, as the distant consuming
stations. This again constitutes an arrangement new in principle. The winding of
the machine that regulates the tension at a distance should then bo simply calculat
in such a manner, that for the maximum intensity of current it gives at the terminals
a tension (that is, a number of volts) exactly equal to that which is lost in the line at.
this moment.
Fig. 19 represents this arrangement. The winding of the external. circuit is.
designated with d; the armature with L.. Externally the winding is similar to the-

page_text: direct winding (in series) of dynamos. The mode of action is lowever, quite different.
The current has a different source, and in this machine the tension increases only in
proportion to the intensity.
Besides the described methods of putting in circuit and of winding dynamos or
motors, that regulate the tension at a distance, others may easily be employed in
conformity with what has already been described, and without departing from the
principle.
If a considerable number of these motors are required in a central station, their
shafts may be directly coupled together, so as to require only one pair of driving
pulleys. As these motors absorb but little power, a great number of them may be
coupled together, so as to obtain a driving shaft of considerable length; the driving
pulleys being preferably mounted in the middle of the shaft, between two of the motors.
The external circuits are arranged in such a manner, that their charge and their loss
of electro-motive force are approximately equal; and to each group of equal regulating
machines such a machine is added as a reserve.
Instead of the mechanical brake for the regulating motor, a magnetic brake may be
employed.
Fig. 13 shows a simple arrangement for this purpose, applicable for regulating
after the manner of Fig. 12. K is a thick metallic disc fixed on the shaft a of the
regulating motor. On this disc act two poles of a separate electro-magnet frame with
differential winding. S represents an exciting coil supposed to be arranged in circuit
exactly like the bobbin S in Fig. 13. g represents a demagnetising coil acting with
constant current, for which purpose it is connected with a source of constant electro-
motive force, such as an accumulator or a separate sinall dynamo, or a pair of electric
light mains with constant current.. Each of the coils y and S is shown as being
wound on a separate magnet core; but in practice they would preferably be wound
one over the other, each on both magnet cores. Supposing, that the influence of the
coil S prevails, the lines of force will act on the metallic disc K and produce eddy
currents which are the cause of the retardation or brake action.
If the disc K is of iron, the number of lines of force and the brake action is already
very considerable with a small differential action of the coils. Consequently, a slight
increase of current in S will cause a corresponding rapid increase of the brake action,
and thus will have exactly the same effect as the mechanical brake of Fig. 12.
To avoid a brake action, in case the current in S should become too weak, and thus
allow the influence of the coil g to prevail, I provide, in the well-known manner, an
automatic appliance, for opening the circuit of g, as soon as the magnetism of the
magnet frame falls to zero or is reversed.
In all the other appliances described above for regulating the electro-motive force
or the current, the friction brake may be replaced by the described magnetic brake,
with a suitable modification as regards the arrangement of circuits. For regulating
the electro-motive force, the coil S would simply be replaced by a tension bobbin.
For maintaining constant the number of, revolutions of a motor, such a differential
winding of the brake frame cannot be employed. In this case the frame receives only
one winding connected with a separate source of electro-motive force, the centrifugal
governor being. adapted to change either this electro-motive force or the resistance
of its circuit. I may employ, for instance, a galvanic element, the plates of which
are immersed or lifted out by the motion of the governor:
'
A variable electro-motive force may, however, he produced by a separate dynamo,
which receives motion from the shaft of the working motor, or the armature of which
is mounted on the same shaft as the working armature. In such a case, that is where
a regulating dynamio is driven by the shaft of the working armature, the regulating
motor may, however, be entirely dispensed with the current of the regulating dynamo
being led directly around the magnet cores of the working motor.
'
Fig. 21 represents such a case for arrangement in series. The armature R of the
small regulating dynamo is driven from the working armature A by means of belti
pulleys. If the two armaturès are arranged for the same number of revolutions,
they may be mounted on the same shaft. The frame of.. the. motor. has a magnetising

page_text: oile, which is situated with its armature in series between the terminals I and I
at is, directly in the series circuit.. g is a demagnetising coil fed by the regulating
ynamo. The latter may be shunt wound, or compound wound, or series wound, as-
hown by the drawing. In the latter case the armature and the field coils d'aré
ituated in the same circuit as the coil g. If now the armature A runs too rapidly;
he counter coil g at once receives a stronger current, because R also runs more
[uickly than usual. This again tends to diminish the excessive speed, as explained
a connection with previous figures. Insufficient speed produces the opposite effect.
In the case of a motor intended for working in parallel, the field coil fed by such a
egulating dynamo must act in the same sense as the shunt winding of the same, in
rder to ensure, that a fall of speed will reduce the magnetism, which is necessary in
his case.
:
In a similar manner to that already described, 1 may regulate alternate current
notors, dynamos and conduits. In this case, the regulating armature inay be fed by
continuous current, as is the. case in exciting the magnets of alternate current
lynamos, or under certain conditions, by alternating currents.
Having now particularly described and ascertained the nature of my said Inven-
ion, and in what manner the same is to be performed, I declare that, what I
laim is :
1. In apparatus for regulating electric currents or electro-motive force, or the
peed of revolution of electro-motors, the use of a separate armature or a separate
lynamo machine instead of the variable metallic resistances usually employed; so
hat the change of electro-motive force of the said armature or machine produces in
he manner substantially as described, the regulation that is usually produced by the
variation of the regulating resistance.
2. The combination with a regulating armature, of a brake device, the effective
pressure of which is produced either by
(a) The differential effect on a movable iron body of the attraction of an electric
bobbin with or without iron core, on the one hand; and a spring, the weight
of a body, or other suitable mechanical opposing force, on the other hand;
so that the regulation of the electro-motive force of the armature serves by
regulating its speed, to keep the current of the bobbin constant ; or,
(b) By the differential effect of a centrifugal governor connected with the shaft
of the working armature of an electro-motor on the one hand, and a spring,
weight of a body, or other suitable mechanical force, on the other hand; so
that the regulation of the electro-motive force of the armature (by its brake-
action on the same), serves to maintain a constant number of revolutions of
the working armature; or
(c) By a magnetic or electric appliance comprising a strong metallic (preferably
iron) disc K mounted on the shaft of the regulating motor and influenced by
the poles N and S of a suitably excited magnet frame.
3. For regulating, in the manner described, the number of revolutions of electro-
motors or motor-dynamos, adapted to work in series and in parallel ; for regulating,
n the manner described, the current of constant current dynamos, or the electro-
motive force of constant tension dynamos; and for regulating the loss of tension in
ong distance conduits, in the manner described by claims (1) and (2); the special
methods of connecting in circuit, and the arrangements which are represented by
Figs. 1 to 12, and from 13 to 19, aud described in the specification.
4. For obtaining a sensitive differential effect between an electric coil and a
mechanical force, the arrangement of bobbin S as represented in Fig. 12ª, so that
the interior of the bobbin contains an axially movable core, which the counter electro
motive force tends to draw out of the bobbin, one end of the core extending beyond
the bobbin and being closely surrounded by an iron cylinder Z which is connected
by iron to an iron base or plate situated in front of the opposite end of the iron
core; substantially as described.

page_text: 5. A dynamo machine driven by mechanical power and arranged in a main circuit
in the manner described with reference to Fig. 19; so that the electro-motive force
produced by the said dynamo is always approximately equal or proportional to that
which is absorbed in the said circuit.
6. In an electro-motor, the application of a regulating dynamo, driven from its
axle either direct, or by intermediate gear; the said dynamo serving to feed a
special field winding of the motor, for regulating its speed of rotation; and the
special arrangement of circuits as described with reference to Fig. 21.
7. The regulation of alternating currents in dynamos, motors and main conductors,
the application of a regulating motor or of a regulating armature arranged in the
manner mentioned in one of the claims 1, 2, 3 and 5; and fed either by a continuous
current or, under certain conditions, by alternating currents.
Dated this 21st day of September 1990.
W. F. LAHMEYER.
By Fairfax & Wetter,
433, Strand, London, Agents.
W. F. LAHMEYER.
By Fairfax & Wetter,
433, Strand, London, Agents.