Year: 1888

page_text: Date of Application, 7th July, 1888
Complete Specification Left, 25th Mar., 1889
Complete Specification Accepted, 11th May, 1889
CARL PIEPER,
Agent for Applicants.

page_text: COMPLETE SPECIFICATION.
An Improvement in Electric Current and Tension Meters.
We, MICHAEL VON DOLIVO-DOBROWOLSKY. Engineer, and the Company "ALLGEMEINE
ELECTRICITÄTSGESELLSCHAFT," both of 26 Schlegelstrasse, Berlin N., Prussia, 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:-
Our invention relates to electric current and tension-meters, and the improvement
consists in the combination, with a solenoid, of an axlo being vertical to or forming
an angle with the axis of the solenoid and carrying one or more bunches or pencils
of thin wires of soft iron and a pointer, the said axle having connected to it a weight
or a spring, which normally maintains the axle in such position that a current
passing through the solenoid and magnetizing the wires of the bunch or bunches,
will cause the axle to turn, while, in the measure as its angle of rotation becomes
greater, the resistance presented by the said weight or spring increases relatively to
the rotative power of the magnetism induced. The quantity or tension of the
current thus measured by the latter, is indicated by the pointer on a graduated arc.
In the annexed drawing Fig. 1 represents in sectional elevation an apparatus
carried out according to our invention. a is the solenoid; b is the axle, preferably
mounted on centres; c c are two bunches of thin wires of soft iron, fixed to the axle b
so as to project therefrom in opposite directions; d is a pointer indicating the angle
of rotation of the axle on the graduated arc f, and e a weight secured to the axle and
forming together with the pointer da counter-weight, adapted to balance the rotating
force acting on the rotative system. This weight may be replaced by a spring.
Whenever a current passes through the solenoid, each of the said wires becomes a
magnet and tends to place itself parallel to the axis of the solenoid, the axle band the
parts carried thereby being, in consequence, subject to rotation, until the momentum
of the gravitating force of the counterweight becomes equal to the momentum of the
acting magnetic forces.
The object of dividing into thin wires the mass of iron employed is, firstly, to
make the indications of the instrument independent of remanent magnetism, as, with
the said arrangement, the mass of iron may be made so small, relatively to the solenoid,
that even extremely weak currents flowing through the latter, will operate to produce
a magnetic saturation of the system of wires, and that consequently the magnetic
state of the said system will be uniform for different positions of the same, corre-
sponding to currents of different strength or tension, this being of the greatest
importance for the permanent correctness of the apparatus. The second object is to
afford the possibility of regulating at will the angle of oscillation of the instrument
for any determinate portion of the range of motion of the pointer, by altering the
number, size or arrangement of the wires, as we shall proceed to explain.
Supposing two wires c¹, Fig. 2, be fixed to the axle 6 in opposite directions and in
the position shown in the said figure, then the magnetic forces induced by the
solenoid, will act on the ends of the wires in the direction of the arrows x x and

page_text: turn the axle with the wires, so as to make the pointer d oscillate to the right until
equilibrium between the acting forces and the counterweight is attained. But, if
previous thereto the wires should come into the vertical position, the momentum of
the magnetic forces would be zero, and small alterations in the strength or tension
of the current would either not he indicated at all, or only by inconsiderable oscil-
lations of the pointer.
If, however, an additional wire, c², is fixed to the axle 6 in the position shown, this
wire will at first counteract the required rotation; but, when the wire c' is in the
vertical position, it will be the very agent by which the said rotation is obtained, as
shown by Fig. 3. In like manner a number of wires forming a bunch, may be
employed to produce the described result.
Having now particularly described and ascertained the nature of our said Inven-
tion, and in what manner the same is to be performed we declare that what we
claim is:
In an electric current and tension meter, the combination of a solenoid, an axle
being vertical to, or forming an angle with the axis of the solenoid and carrying one
or more bunches or pencils of thin wires of soft iron and a pointer, a weight or
spring connected to the axle, and a graduated arc, substantially as and for the purpose
described.
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