IMPROVE. MENTS IN THE METHOD OF MEASURING ELECTRIC CURRENTS
Year: 1884

page_text: ARTHUR WRIGHT (Electrical Engineer) of 180 Belsize Road South Hampstead
London Middlesex do hereby declare the nature of my invention for IMPROVE.
MENTS IN THE METHOD OF MEASURING ELECTRIC CURRENTS to be as follows:-
The pole pieces of one or two bars of iron, magnetised either by one or two coils,
through which the whole or part of the current to be measured passes; repel the
pole pieces of like polarity against an opposing force such as gravity.
The amount of motion consequent on this repulsion, forming the measure of the
current required.
'
The following are some of the forms by which the above principle can be applied
in practice.
.
One form consists of two equal parallel bars of iron, lying close to each other,
one of which is pivoted so as to be capable of rotating on its axis. These bars
are magnetised by the current, to be measured, passing through a coil of wire
surrounding both. The ends of the bars project on each side of the coil and are
turned down at right angles to the bars' length; these ends constitute a pair of
like pole pieces at each end of the coil and are kept parallel and close to each other
by some constant force such as their own weight or by springs. On a current
being sent through the coil, the two bars are magnetised and the like pole pieces
repel each other, causing the pivoted bar to rotate through a certain angle against
the opposing force; so as to separate the pole-pieces, the amount of this rotation
forming a definite measure of the strength of the current passing through the coil.
In another form each of the above bars has its own magnetising coil and the pole
pieces of the pivoted bar, touch or approach very closely the ends of the fixed bar's
pole pieces, when no current passes; but are repelled by them, when a current does
pass, through a certain angle, dependent on the strength of the current.
In a third form, only one coil and one bar are used, a projecting part of the
latter at one end of the coil is split into two parts so as to form two like pole pieces,
one of which is delicately hinged against the other. The current magnetising the
bar causes these similarly magnetised pole-pieces to repel each other; the angular
movement of the hinged one against an opposing force, forming a measure of the
current passing.
Dated this 31st day of March 1884

page_text: I, ARTHUR WRIGHT Electrical Engineer Regent Foundry North Road Brighton
Sussex do hereby declare the nature of my invention for IMPROVEMENTS IN THE
METHOD OF MEASURING ELECTRIC CURRENTS and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:
The pole-pieces of one or more bars of iron, magnetised either by one or more
coils of wire, through which the whole or part of the current to be measured passes,
repel moveable pole-pieces of like polarity against a counterbalancing force. The
amount of motion consequent upon this repulsion constitutes a definite measure of
the strength of the current passing.
The following are some of the forms by which the above invention can be applied
in practice for the purpose of measuring either the quantity, or pressure or energy
of an electric current.
One form has two equal and parallel bars of soft iron, lying close to each other,
one being so pivoted as to be capable of rotating on its axis. These bars are
magnetised by causing the current to be measured to pass through a coil of wire
surrounding both. The ends of the bars project on each side of the coil and are
turned down at right angles to the bars' length, these end pieces constitute a pair
of similar pole-pieces at each end of the coil, which, by reason of their own weight or
other counterbalancing force, tend to keep parallel and close to one another. On a
current being sent through the coil, the two bars and their respective pole pieces are
similarly magnetised and the contiguous pole pieces, being of like polarity, repel
each other, causing the pivoted bar and its pole-pieces to turn through a certain
angle so as to separate the similar pole pieces until the repulsion is balanced by the
counterbalancing force. The amount of this rotation measured by an index on a
dial forms a definite and constant measure of the strength of the current passing
through the coil.
:
In a second form each of the above bars has its own magnetising coil and the
pole pieces of the pivoted bar are so arranged as to approach very closely to those
of like polarity of the fixed bar, but on a current passing, the moveable bar rotates
with its pole pieces through a certain angle until the magnetic repulsion of the
similar poles is balanced by the counterbalancing force.
In a third form only one. coil and one bar are used, a part of the latter projects
beyond the coil and is split into two parts so as to form two like pole-pieces, one of
which is delicately hinged against the other part. On the current passing round
the bar, these similarly magnetised pole pieces, repel each other, and the angular
movement of the hinged one against an opposing force, forms a definite measure of
the current passing.
In another form instead of measuring the angle through which the repelled pole
pieces have moved, the amount of an opposing force requisite to bring them back
to a certain zero position is measured by any suitable means, such as the torsion of
a wire and this is taken as a measure of the bar's magnetism and therefore of the
strength of the current passing.
The methods of winding and connecting up the coils of the above instrument,
when it is intended for the measurement of electric quantity or pressure or energy,
are the well known ones adopted in many of the existing ammeters, voltmeters or
ergmeters. For a counterbalancing force I pefer to use gravity, such as the weight
of the pole pieces, because of its constancy.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The determining the strength of a current of electricity, by causing it to pass
round one or more electromagnets with multiple and moveable pole pieces and then
measuring the amount of repulsion between the pole-pieces of like polarity, either
by determining the separation of the pole-pieces against a counterbalancing force,
consequent upon the said repulsion; or by determining the strength of an opposing
force necessary to, bring the moveable pole pieces back to a certain position.
Dated this 28th day of December 1884.
ARTHUR WRIGHT.