Electric Currents.
Year: 1886

page_text: Date of Application, 23rd Nov., 1886.
Specification Accepted, 14th Jan., 1887.
Electric Currents.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, 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:-
My present invention relates to a means for regulating or controlling the flow of an
electric current and is applicable among other things to controlling the flow of current
in the field magnet coils of a dynamo electric machine or motor, or other apparatus of
a similar nature, so as to vary the power or efficiency of said machine.
The object of the invention is to provide a suitable means for varying the resistance
in an electric circuit without employing operating contacts which are objectionable on
account of sparking and friction of the parts, and further to provide an adjustable
resistance or rheostat by which gradual or smooth changes in resistance may be
effected so as to avoid sudden fluctuations in the power or force of the electric
current.
My invention consists essentially of an adjustable rheostat composed of an electric
conductor whose resistance is variable by changes of temperature combined with
means independent of the current to be adjusted and flowing in said conductor, for
varying the temperature of the same so as to vary its specific resistance with a given
current.
My invention consists further in the combination with the field magnet coils for a
dynamo machine or motor of an electric conductor whose resistance is variable by
changes of temperature and is properly connected to said coils so as to be effective
in varying the flow of current in the same, and suitable means manually or automati-
cally controlled, for varying the temperature of said conductor, as for instance by
varying its exposure to a cooling or heating influence..

page_text: My invention consists further in the combination with a conductor whose resistance
is variable by changes of temperature, of an enclosing case formed of suitable material
that is a non-conductor of heat so as to limit the loss of licat by radiation or convec-
tion, and means for varying the changes of temperature produced in said conductor by
external influence.
I have herein shown my invention applied to controlling the potential of a dynamo
so as to compensate for fluctuations of the driving speed.
In the application of my invention to a dynamo machine or motor, when the
invention is applied in its most complete form, four different parts are employed, in
combination, to wit:-
First; a controller magnet connected to the electric circuit so as to be sensitive to
changes of electrical conditions thereon.
Second; a motor device consisting of either a motor electro magnet, or a mechanical
motor controlled by said magnet, which device is controlled in its action by the
controller magnet.
Third; a variable resistance connected to the dynamo machine in such way as to
control the generating capacity of the same and composed of a material whose
resistance varies with changes of temperature.
Fourth; suitable means for governing the temperature of said resistance coil; said
means being operated by the motor device mentioned.
The controller magnet of my invention, when used with a dynamo supplying lamps
or other devices in multiple arc, is properly connected to the mains so as to be sensitive
to small variations in the difference of potential between said mains. I prefer to make
such controller magnet act as an electric relay to throw into. and out action the motor
magnet, though it may be employed to operate a device that acts mechanically to
throw into action a mechanical power acting on the devices for varying the temperature
of the conductor whose resistance varies with change of temperature.
The adjustable resistance is preferably placed in the circuit with the field coils of
the machine where such coils are in a derived circuit to the work.
In the accompanying drawings
÷-
Fig. 1, is a diagram illustrating such an application of the invention.
Fig. 2, illustrates a modification in the arrangement of the resistances and the means
for controlling the external heating or cooling influence.
Fig's. 3, 4 and 5, illustrate modifications in the details of the device.
Fig's. 6 and 7, show an adjustable rheostat applied in other ways to varying the
flow of current in a coil.
Fig's. 8 and 9, show modifications in the means for varying the temperature of a
conductor.
Fig. 10, is a diagram illustrating the invention as applied to an ordinary shunt
wound dynamo machine.
Fig. 11, illustrates the preferred way of mounting the adjustablo resistance coil so
as to expose it more thoroughly to the effects of the cooling action of air.
Fig. 12, shows a controller magnet adapted more especially for use with certain
kinds of compound wound dynamo machines.
Fig. 13, illustrates the manner of controlling the mechanical motor such as a clock-
work or wheel-work when such is employed in place of the motor magnet of Fig. 10.
Referring to Fig. 1, A, indicates the armature of a dynamo machine of any
construction, and S, the field magnet coil of the machino, placed in derived circuit to
the work in a manner well known in the art. The working resistances fed from mains
leading from the armature are indicated at L, L.
At R, is indicated a variable resistance or rheostat of the usual kind, which is
placed in the circuit with the coils S, S, and which may be operated by hand so as to
vary the excitation of the field magnet by introducing more or less resistance into
the circuit of the coils. This variable resistance may be used or not as desired and
may be omitted where the variations to be produced in the field magnetism are small.
V. indicates a strip or coil of platinum, or platino iridium, or other suitable material

page_text: whose resistance varies with changes in its temperature and which is placed in the
circuit of the coils S, as indicated.
Around the coil D, is an upright tube T, of any desired material such for instance
as metal covered or lined with a non-conductor of heat, and which tube serves to
prevent the lateral escape of heat from the coils V, This tube or casing might be
made from earthenware, glass, or other similar material. At its bottom is an opening
for the entrance of air, and at or near the top is another opening for the exit of air
heated by the coil V, when the latter carries an electric current. A valve W, controls
the passage of air through the tube or casing T.
The coil V, is made of wire sufficiently fine to cause the coil to be considerably
heated by the normal current passing through it.
When the valve W, is closed the heated air is retained in the casing and the coil
accumulates heat so as to considerably increase its resistance to the electric current,
but when the valve is opened the air is permitted to circulate upward through the
casing T, and the coil is made cooler, thus lowering its resistance.
The position of the valve determines the circulation of the cooling current of air
and determines therefore the specific resistance of the coil to a given current.
The valve W, may be operated by any desired means. In the present instance it is
shown as moved in one direction, that is to open the passage for the escape of air, by
the influence of an adjustable retracting weight ✗, and in the other direction, to
prevent the escape of air, by the operation of an electro magnet C, whose movable
core is attached to the lever carrying the valve, and whose coils are placed in a derived
circuit to the group of working resistances L, L, such as incandescent lights. The
valve might be operated by hand.
The retracter X, is to be so adjusted as to open the valve when, through a lowering
of the difference of potential between the mains supplying the lights L, the magnet C,
is energized below normal. This will permit the wire V, to be cooled so as to lower
its resistance, and allow current to flow in greater amount through the field coils S, S,
thus increasing the strength of the field magnets and, through the reaction of the
same on the armature, raising the difference of potential on the mains towards
normal.
If the difference of potential rises above normal the magnet C, closes, or tends to
close, the valve W, upon which the heat of wire V, increases inasmuch as the circula-
tion of the cooling current of air through the casing T, is restricted and the resistance
in the circuit to the coils S, increases, thus cutting down the field magnetism .and
lowering the potential on the mains connected with the armature.
In practice a slight oscillation of the valve W, takes place, which keeps the coil V.
at a proper temperature to maintain a flow of current in the coils S, adapted to the
particular conditions.
It is obvious that the resistance of the coil or conductor V, should be a consider-
able fraction of the total resistance in the derived circuit including said coil and the
coil S.
The arrangement described is particularly useful in counteracting accidental small
variations of potential on the mains arising from small changes of speed in the driving
power applied to the armature shaft of the machine.
When the dynamo is compound wound so as to give a constant potential at constant
speed, the adjustable resistance R, may be dispensed with, the rheostat V, used alone
being adapted to counteract the effects of small variations of the driving power.
When the dynamo is compound wound in the proper way to give an increase of
volts or potential as the load is increased, which is often the case in machines which
compensate automatically for changes in the volts, or drop occurring on the supply
mains when of considerable length, the magnet C, instead of having a simple coil in
derived circuit should have an additional coarse wire coil of a very few turns, as
indicated at D, Fig. 2, placed in the main or supply circuit leading to the working
resistances, and properly wound or connected so as to tend to oppose or counteract
the magnetizing influence of the coil (.

page_text: The magnetizing influences of the two coils should be so adjusted with relation to
one another that upon an increase of current due to increase of load or number of
lights, the increase of current in the coils D, will be just sufficent to counteract the
corresponding increase of effective current in the coils C, that is due to the normal
increase of potential on the mains provided for purposely in the compound windings
of the machine itself.
Any valve may be used in place of the valve W, Fig. 1, as for instance, a damper
valve such as indicated in Fig. 3.
In Fig. 4, a manual device for controlling the flow of the cooling current of air in
the tube or casing. T, is shown. This device consists simply of a screw Y; passing
through a movable support for the tube T, and bearing against a suitable base plate
whose end at W, serves to close the lower end of the tube T, when the latter rests on
the base. By turning the screw the tube is raised from the base and air is allowed to
enter to greater or less amount at the base of the tube.
If a very accurate regulation is not required the coil V, may itself be made the
magnet coil for moving the valve W, in the direction to shut off the flow of air
through the tube. Such a construction is indicated in Fig. 5, where the movable
magnet core attached to the lever carrying valve W, is arranged within the coil V, so
as to be drawn down by the action of current in said coils.
In Fig. 6, the adjustable resistance coil V, is shown placed in a shunt around a
set of coils M, so that as the resistance of said coil increases, more current will be
made to flow in the coils M, while on a decrease of such resistance due to opening of
the valve W, the flow of current in the coils M, will be diminished. This arrangement
is suitable for application to the field magnet coils of an ordinary direct current
dynamo whose field is maintained by the current on the main circuit."
In Fig. 7, the coils are shown arranged in direct circuit with a set of coils S, and
with a source of current D, P. Any other means external to or independent of the
current which flows in the coils V, may be used for varying or controlling the
temperature of said coil or conductor."
A simple device for the purpose, which dispenses with the use of a surrounding
tube or casing, is indicated in Fig. 8, it consists simply of a tube or nozzle T¹, which
directs a cooling or heating fluid or gas upon the coils.
The extent to which the temperature of the coil V, is varied by such gas or fluid
may be determined by moving the tube or nozzle T¹, so as to vary the extent to
which the coils are immersed in the stream of fluid or may be determined by the
agency of a cock or valve in the tube or nozzle.
In the particular instances shown the latter device is indicated, and the movement
imparted to such device is secured by the operation of an electro magnet C, whose
armature is connected with the valve to move the same in one direction, while a
spring X, serves to move said valve in the opposite direction.
If the tube T', convey a gas or fluid whose temperature where it immerses the
coils is less than the temperature of the coils themselves as developed by the current
in them, the movement of the valve to cut off the flow of the fluid would obviously
result in an increase of temperature in the coils V, and an increase of resistance in
the circuit to the coils S.
:
In Fig. 9, I have illustrated the employment of a flame as the external means for
varying the temperature of the coils V. The flame may be regulated by a valve or
cock U, which can be turned to lower the flame so as to permit the coil V, to cool,
thus lowering its specific resistance, or may be turned to increase the flame thus
increasing the temperature of the coils V, and causing them to oppose a greater
resistance to the flow of current in the circuit in which they are included.
It is obvious that by a proper and obvious re-arrangement of the parts a material
such as carbon whose resistance falls with an increase of its temperature might be
used in place of that mentioned.
Referring to Fig. 10, the parts of any shunt wound dynamo are indicated as
follows:-

page_text: F, indicates the coils of a field magnet placed in derived circuit to the work con-
sisting of electric lamps or other devices E, E, fed in multiple arc from the.
mains () b.
A, is the armature of the machine. K, the commutator cylinder, and B, B, the
brushes connected to the mains and to the circuit of coils F, as indicated.
In the circuit of coils F, is included the adjustable resistance composed of a coil or
conductor whose resistance changes with changes of temperature. Such a coil is
indicated at R, and forms a considerable fraction of the total resistance in the branch
or derived circuit including F and R.
T, indicates an enclosing tube or chimney surrounding the resistance R, and
preferably lined with a non-conductor of heat, such as plaster, asbestos, clay, or a
mixture of such materials, or otherwise constructed so as io guard against lateral
escape and conduction of heat. This case is formed with a number of openings at
its bottom through which air may enter, and at its top has an opening controlled by a
suitable valve V, operated by the motor device of my invention.
In the present instance the motor device is shown as composed of an electro
magnet M, whose armature is carried by a lever L', pivoted at P¹, and having a
suitable retracting spring Z.
The valve controls the draught of air through the chimney T, produced by the.
heat developed in the coil R, and according to the draught, determines the temperature
that the coil R, shall attain by the agency of the heating effects of current passing
through it.
If the conductor R, is of carbon, which decreases in resistance with an increase of
temperature, the valve should be arranged so as to close the opening at the top of
chimney T, when a decrease of resistance is required instead of opening it as would be
required if the conductor R, is formed from a metal, such as platinum, so as to require
to be cooled to produce a similar effect.
In the description which follows it is assumed that iron or other substance is
employed for the conductor R, which increases in resistance considerably with an
increase of temperature. If a material having the opposite characteristic is used it
would only be necessary to reverse the cycle of operations at some one of its stages
as is obvious.
The magnet M, is preferably energized from the mains a, b, as indicated, and under
such conditions of use would naturally be of considerable resistance. At the same
time, however, it will be understood that such magnet might be energized by current
from any source separate from that supplying current to the mains a, b.
The circuit of the electro magnet M, is controlled by contacts operated by the
controller magnet C, of my invention.
The controller contacts are formed of a stop or contact D, as shown, and a contact
screw S, preferably made adjustable and mounted on the lever L, which carries the
armature N, of the electro magnet C. The contact D, is connected to one of the
inains as for instance a, and the contact S, is connected through the electro magnet M,
with the other main b.
I prefer to employ in conjunction with these devices a condenser G, for preventing
spark at the contact D, on the opening of the circuit of magnet M. The two poles of
the condenser are connected respectively to the upper and lower contacts or to their
running connecting wires, as indicated in the figure.
The electro magnet C, is also connected in one of the branches between the
máins a, b, so that it will feel any changes in the conditions of potential between the
mains a, b.
The armature lever L, is mounted on knife-edge bearings, indicated at P, and is
supported on a pillar J. The pull of the magnet is counterbalanced by a variable
weight W, which is hung so as to avoid friction on the bearings of the lever and
which is preferable to a retractile spring, on account of its constancy. It is desirable
to provide also a rider weight W₁, which can be moved to effect small adjustments of
counterpoise.

page_text: Assuming an adjustment to be made so that there will be a balance when the electro
magnet C, is energized to normal amount, and that the screw S, is set so as to act in
conjunction with the back stop X, of the lever to permit a small play at the controller
contacts, it will be evident that any very slight variation in the difference of potential
between the mains a, b, will cause an increase or decrease of power of the magnet C,
which will be attended by a closing or opening of the contact at D.
By the action of the controller contacts D, S, the magnet M, is thrown into or out
of action, and from this there results a change of resistance through a closing or
opening of the valve V, with a consequent heating or cooling of the resistance R, as
the cooling draught of air is cut off or re-established by the operation of the valve.
An increase in the temperature of the resistance R, produced by closing the valve,
results in introducing greater resistance to the flow of current in the field circuit
including coils F, and therefore diminishes the power of the field magnet of the
machine, while conversely the lowering of the temperature of R, through the establish-
ment of the cooling air draught results in greater power of the field magnet. These
changes in the field magnet, as is well understood in the art, change the generating
capacity of the machine and the difference of potential between the two mains
a and b
In practice there is a vibration of the parts resulting in the maintaining of such a
temperature in the coil R, through vibration of the valve, as to secure a constant
electro-motive force or constant difference of potential between the mains a, b.
In the normal action of the device a frequent closure and opening of the contacts
at D, takes place, which, as is obvious, are accompanied by movements of the valve V.
If an increase of the speed of the armature A, should occur, there will be a tem-
porary increase in the electro motive force since the increased power of magnet C
resulting from such action would close the contact D, and keep it closed. Valve V,
would therefore be kept closed and the resistance R, would increase by increase of
temperature thus cutting down the field F, and restoring the potential to normal, after
which the vibratory actions just described would be resumed.
A diminution of speed would give temporarily a low potential since the power of C,
would decrease allowing the contacts D, S, to remain open until, through the continual
opening of the valve V, and the cooling of the resistance R, the strength of the field
magnet is increased so as to raise the potential of the mains to normal whereupon the
vibratory state is again resumed. The coils of controller magnet C, must of course
be of such high resistance as to prevent injurious heating during use.
It will be obvious that the valve V, may be made to close through the action of the
spring Z, and the magnet M, made to act so as to tend to close the valve. In this case
the contacts of the controller magnet must be reversed in position so that the
magnet M, will be thrown into action when its power decreases.
It is likewise obvious that the same effect produced by retracter Z, could be pro-
duced by the employment of a second magnet thrown into action when the magnet M,
is cut out.
The magnet M, and its retracter are simply typical of any motor devices controllable
by the operation of sensitive magnet such as the controller magnet C, and whose
function is to do the heavier work demanding a large range of movement of the
parts.
I prefer to mount the resistance coil R, in the manner indicated in Fig. 1, so as to
expose all its parts more effectively to the action of the current of air or gas that
effects its temperature. This result is secured by mounting the coil of the tapering
frame as indicated so that its successive turns will be displaced laterally and will not
shield one another from the current. The frame is preferably constructed of tapering
wings formed of a non-conductor such as mica and supported at their inner edges in a
metal or plaster stem. At the outer edges of the wings suitable notches are cut for
the reception of the iron or platinum wire making up the coil.
In applying my regulator to the shunt field coil of a compound wound dynamo
wound to give a constant difference of potential, no modifications are necessary, but
where the dynamo machine is wound so as to give an increase of potential as its

page_text: terminals when the load is increased, as is the case with machines which are properly
wound to compensate for a drop of potential in the mains on an increase of load, the
controller magnet C, should be wound additionally with a coil C", in the main circuit
of the machine or a portion of such main circuit. The main circuit coil wound consist
of a few turns of coarse wire as indicated at Fig. 12, placed in the main a, a, leading
from the armature of the dynamo.
The coils C, C, thus applied should be wound differentially. As it is very difficult
to determine the exact magnetic effect required of the coils C₁, it is preferable to shunt
such coils with a wire V2, whose effective conducting length may be varied so as to
determine the effective action of the coils C¹.
The coils C, Fig. 12, are connected after the manner indicated in Fig. 1, so as to be
sensitive to changes in the difference of potential, and the magnetic effects of such
coil are opposed by the action of the coils C¹.
In order to produce the proper operation of the regulator, it is obvious that the
resultant of the effects of the two coils must be such that the armature N, operating
the controller contacts will vibrate during the existence of the normal difference of
potential of either light load or little current in the mains, or heavy load or maximum
current in the mains.
It is of course not essential that the windings C, C, be upon the same coro as all
that is necessary is that they should oppose each others actions so far as the controller
lever L, is concerned.
In Fig. 13, one of the numerous motor devices which may be used in place of the
motor magnet M, Fig. 1, is illustrated. The controller lever L, instead of operating
on controller contacts moves the wheel 2, consisting of a friction roller or clutch, in
such way as to bring it into or out of contact with two other rollers 1, 3, simultaneously.
One of the rollers, as for instance 1, is revolved continuously by any suitable power,
and the other 3, is maintained on a shaft from which extends an arm L', carrying the
valve V.
The counterpoise Z, attached to the lever, tends to open the valve, while the roller 2,
when driven by the roller 1, revolving in the direction of the arrow, turns the wheel 3,
in a direction to close the valve. The results effected are obviously the same as those
secured by the arrangements shown.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, as communicated to me by my
foreign Correspondent I declare that what I claim is:
1. An adjustable rheostat consisting essentially of a conductor of electricity carry-
ing an electric current combined with means independent of the heating effects of such
current, for varying the temperature of said conductor so as to vary its specific
resistance, as and for the purpose described.
2. The combination with an electric conductor whose resistance varies with changes
of temperature, of a surrounding tubo or casing, and a valve controlling the passage
of a cooling current through such casing.
3. The combination with a magnet coil, of an artificial resistance connected with
the circuit of the same and consisting of a material whose resistance varies with
changes of temperature, and means for varying the temperature of said material so as
to vary its specific resistance to the current flowing through it.
4. The combination with a dynamo electric machine, of a resistance coil whose
resistance varies by changes of temperature, connected with the field magnets of said
machine, and means independent of the current flowing in the coils for controlling its
temperature, as and for the purpose set forth.
5. The combination with a dynamo machine having derived circuit field coils, of a
resistance coil placed in said circuit and composed of a material whose resistance
varies with changes of temperature, an enclosing case for said coil, and a valve
controlling the passages to said case, as and for the purpose described.
6. The combination with field magnet coils in a derived circuit to the work, of a
coil V, in circuit with the field magnet coils, a surrounding casing T, for said coils, a

page_text: valve W, and an electro magnet C, placed in derived circuit to the work and controlling
the valve.
7. The combination in an electric regulator with the controller magnet C, connected
in a circuit or branch uniting mains that supply devices in multiple arc, of a main
circuit coil D, said coils C, D, being differentially round, as and for the purpose
described.
8. In an electric regulator the combination, substantially as described, of a field
magnet coil upon whose degree of excitation the action of the machine depends, an
artificial resistance connected to the same and formed of a material whose specific
resistance varies with changes of temperature, controlling devices external to the coil
for governing or controlling the temperature thereof, motor devices such as an electro
.magnet or a mechanical motor for controlling such controlling devices, and a
controller magnet governing the controller devices, as and for the purpose described.
9. The combination with the mains a, b, supplying devices in multiple arc, of an
electro magnet connected in a circuit from one main to the other, an armature lever L,
balanced on knife-edges, controlling contacts governed by the same, a motor magnet
or magnets governed by said controlling contacts, and an artificial resistance whose
temperature is controlled by the operation of the motor devices, as and for the purpose
described.
10. The electric conductor R, formed of material whose resistance varies with
changes of temperature and placed in the path of a cooling current by which its
temperature may be governed, in combination with a tapered frame on which the
conductor is wound, as and for the purpose described.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, 2
Agents for the Applicant.