Improvements in the Method of and Devices for Regulating Currents Generated by Shunt Wound Dynamo-electric Machines.
Year: 1889

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[Communicated from abroad by ERNEST P. CLARK, of the City, County, and State of
New York, United States of America, Electrician.]
Improvements in the Method of and Devices for Regulating Currents
Generated by Shunt Wound Dynamo-electric Machines.
I, WILLIAM EDWIN HEYS of 70 Market Street Manchester in the County of
Lancaster, Patent Agent, 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 :—
This Invention relates to the automatic regulation of dynamo electric machines.
It is designed for the regulation of a constant current, shunt wound machine, and
consists of a small electro motor having its field magnet in the main circuit of the
dynamo, and its armature in the shunt circuit which also includes the field coils of
the dynamo. The counter E.M.F. of this motor is the regulating power.
In this apparatus, the actions are practically instantaneous, but are found in practice
not to be sufficient in range to meet all the requirements of perfect regulation, and
for this reason another piece of apparatus is combined with the motor to assist
its action.
This consists of a variable resistance arranged as a shunt to the field coils of
the motor and operated by an electro magnet or solenoid located in the main
circuit.
Referring to the accompanying drawings; the figure represents a diagrammatical
view of a generator, the regulating mechanism and the circuits.
A represents the generator and B the regulating motor. The field magnets of
the motor B are in the main circuit of the generator A, while the armature of the
motor is in the shunt circuit with the field of the generator. The armature of the
motor is wound with a large number of turns of fine wire in order to obtain a large
counter E.M.F. The main circuit also includes a solenoid C, and this solenoid
controls a variable resistance D in a shunt to the field coils of the motor.
The action is as follows: A sudden increase of current from the dynamo from
any cause increases the power of the field magnets of the motor and this increases
the counter E.M.F. of its armature, (as the motor always runs at a certain
unvarying speed) which reduces the current flowing through it and the field coils
of the dynamo. This at once reduces the power of the dynamo to generate current
and thus tends to restore the normal strength of current. A reduction of current.
strength in the main circuit operates in exactly the opposite way, and increases the
capacity of the generating dynamo.
These actions are practically instantaneous, but are found in practice not to be
sufficient in range to meet all the requirements of perfect regulation, and for this
reason another piece of apparatus is added to assist the action of the motor, consisting
of a variable resistance arranged as a shunt to its field coils and operated by an
electro magnet or solenoid located in the main circuit; and so arranged as to increase
the resistance of the variable shunt when the current in the main circuit increases,-
thus sending more of it through the field coils of the motor, increasing their
magnetising power and consequently the counter E.M.F. of the motor, and to
decrease the variable shunt when the current in the main decreases, thus shunting
more of the current from the field coils of the motor and decreasing its
counter E.M.F.
With this apparatus as described, the result would be that when the dynamo was
generating the proper current strength with a certain E.M.F., the motor would
run at a certain fixed speed, but if the E.M.F. of the dynamo were reduced
materially from this point, there would no longer be sufficient current sent through
its field coils and through the armature of the motor to produce enough rotary effort

page_text: to maintain the speed of the motor. Consequently the speed of the motor would
decrease, and its counter E.M.F. decreasing as its speed decreased would allow
an increased current to flow through its armature coils and the field coils of
the dynamo. A balance would be quickly reached again, owing to the increasing
power of the field magnet of the motor, but it would now be running at a reduced
speed and the, current in the main circuit would be greater than is required. The
opposite action will take place if the E.M.F. of the dynamo were increased. The
motor in this case running too fast and the current in the main circuit becoming too
small, in place of which, the object of this apparatus is to maintain a constant
strength of current in the main circuit, while the E.M.F. rises or falls through a
long range of values to suit the varying resistance in the main circuit, as the number
of lamps or other translating devices is varied. To accomplish this it is found only
to be necessary that the motor should run at a certain constant unvarying speed.
This is best accomplished by the use of a belt or other equivalent device to connect
the motor shaft with the dynamo shaft or with some other revolving shaft or pulley
having a uniform speed. The action of the belt is thus to accelerate the velocity of
the motor when the E.M.F. of the dynamo is low, and to retard it when the E.M.F.
is high.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad, I declare that what I claim is :-
(1) A regulator for a shunt wound dynamo, consisting of an electro motor whose
armature is maintained at a constant speed and is included in the field magnet
circuit of the dynamo, for the purpose of varying the counter E.M.F. of the motor
as the main current varies in strength.
(2) A regulator for shunt wound dynamo electric machines, having its armature
included in the field magnet circuit of the dynamo and its field magnet coils
included in the main circuit, a variable resistance arranged as a shunt to the field
magnet coils of the regulator, and an electro magnet in the main circuit arranged
to control said variable resistance for the purpose of magnifying the variations in
magnetic strength of the regulator field magnets caused by changes in strength of
the current in the main circuit.
(3) The combination of a dynamo electric machine having the field magnet coils
in shunt or derived circuit, an electro motor maintained at a certain unvarying speed
and having its armature in circuit with the field magnet coils of the dynamo and its
field magnet coils in circuit with the lamps or other translating devices, a variable
resistance arranged as a shunt to the field magnet coils of the regulator motor, an
electro magnet or solenoid located in the main circuit controlling said variable
resistance and so arranged as to intensify the variations in magnetism of the field
magnets of the regulator caused by variation in the main current; for the purpose
of maintaining a constant strength of current in the main or working circuit
notwithstanding variations in potential or a varying speed of the dynamo.
(4) A regulator for a shunt wound dynamo consisting of an electro motor whose
armature is included in the field magnet circuit of the dynamo, and whose field
magnet coils are arranged so that the full current on the main circuit of the dynamo
will pass through them, for the purpose of varying the counter electro motive force
of the motor as the main current varies in strength.
(5) The herein before described method of regulating the current generated by a
constant current shunt-wound machine by means of a motor having its field coils
in the main circuit and its armature in the field circuit of the dynamo, a variable
resistance in a shunt to the motor field coils, and an electro magnet in the main
circuit; all arranged and operated and operating substantially as set forth.
Dated this 3rd day of June A D 1889
WILLIAM E. HEYS.