Year: 1888

page_text: Date of Application, 9th Mar.,
1888
Complete Specification Left, 29th Nov., 1888
Complete Specification Accepted, 22nd Jan., 1889
I, ALEXANDER SIEMENS of No. 12 Queen Anne's Gate, Westminster, Civil Engineer
do hereby declare the nature of this invention to be as follows:-
My invention relates to a volt indicator or instrument for shewing by a pointer on
a dial, the number of volts in the current produced by an electric machine. For this
purpose, I fix on a spindle a radial arm carrying at its end an iron core bent to an arc
of the circle in which it is free to move round the axis of the spindle, into or out of
the middle of a solenoid coil which is wound on a tube of corresponding circular
curvature. The spindle carries an index pointing to divisions on a dial, or this index
may be on another spindle connected by gearing to the former. When a current
passes through the solenoid coil, the bent core is attracted more or less inwards in
opposition to a spring and the index points to a division on the dial indicating the
number of volts in the current which excites the solenoid. In order that the
instrument may be accurately balanced, which is important especially on shipboard, I
prefer to use two solenoids and their cores and springs arranged symmetrically on each
side of the spindle.
A
1 1000
ABEL & IMRAY,
Agents for the Applicant.

page_text: A Volt Indicator.
I, ALEXANDER SIEMENS of 12 Queen Anno's Gate Westminster, Civil Engineer do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascortained in and by the following
statement:
My invention relates to the construction of a volt indicator or instrument for
shewing by means of a pointer on a graduated dial the difference of potential,
measured in volts, which exists between any two points in a circuit traversed by an
electric current. For this purpose I construct the instrument as I will describe
referring to the accompanying drawings. Fig. 1 is a front view with most of the
dial broken away to show the interior. Fig. 2 is a vertical section. Within a casing
are fixed two solenoids C and D, through the coils of which passes the current due to
the difference of potential at the ends of the leads which are connected to the
instrument at T T. On a spindle H pivotted midway between the solenoids C, D
is fixed a bar of non-magnetic material forming two radial arms A A; to these are
attached pieces of iron B B which are bent to circular curvature and which enter the
hollow central spaces of the solenoids CD. On the spindle H is fixed a toothed
wheel F gearing with a pinion G on the axis of which is fixed the index N. Each of
two springs E E is fixed at one end adjustably to a stud K and is hooked at the other
end to a knife edged pin on the wheel F. According as the difference of potential at
the terminals of the instrument, and consequently the current through the solenoids
is greater or less the iron ares B are drawn more or less into the solenoids, and the
index M is thus moved over a greater or less number of degrees on the dial, indicating
by its position at any moment the difference of potential between the points to which
the instrument is connected.
I am aware that volt meters have been proposed having a single iron are mounted
on a radial arm acting in combination with a solenoid, also that in a differential
indicator for a three wire circuit consisting of two iron arcs acting in combination
with two solenoids on separate circuits, it has been proposed to cut out the one circuit
and solenoid, so that the second solenoid and its iron arc may serve to indicate in
amperes, the current flowing through the other circuit and I do not claim such
arrangements.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed I declare that what 1
claim is :-
A volt indicator wherein two iron arcs mounted on radial arms and entering the
hollow central spaces of solenoids move, in opposition to springs, an index pointing to
graduations on a dial so as to indicate the difference of potential, measured in volts,
between the two points of an electrical circuit to which the instrument is connected
substantially as herein described with reference to the accompanying drawings.
Dated this 29th day of November 1888.