IMPROVEMENTS IN ELECTRIC METERS D
Year: 1883

page_text: LETTERS PATENT to Reginald Belfield of Lyndally Palace Road Tulse Hill
Park in the County of Surrey for an Invention of "IMPROVEMENTS IN
ELECTRIC METERS
D
PROVISIONAL SPECIFICATION left by the said Reginald Bolfield at the
Office of the Commissioners of Patents on the 1st November 1883.
REGINALD BELFIELD of Lyndally Palace Road Tulse Hill Park in the County
of Surrey "IMPROVEMENTS IN ELECTRIC METERS
"
This invention has for its object improvements in electric meters.
For the purpose of measuring electric potential and especially the potential of
rapidly alternating currents I employ an instrument in some respects similar to a
Thomson electrometer. It has four double quadrants mounted upon an insulating
base and connected together in pairs; the opposite quadrants forming a pair. In
proximity to these and between the upper and lower surfaces of the double quadrants
a needle is suspended by a wire. The form of the needle is approximately that of
one pair of quadrants.
The needle can be set to a zero point by a capstan head at the upper end of the
suspending wire and in connection with the head there is a pointer which indicates
upon a scale the distance through which the head is moved and consequently the
torsion required to bring the needle to the zero. When the instrument is applied
to the measurement of the potential of a generator yielding alternating currents
such as commonly employed in electric lighting, one terminal of the machine is
connected with one pair of quadrants and the other terminal with the other pair;
also one terminal is connected with the needle through the suspending wire.
Under theso conditions the needle and one pair of quadrants are similarly
electrified and the needle is repelled by these quadrants but attracted by the other
pair. This causes the needle to leave the zero point. The needle is brought back
by turning the capstan head and the amount of this movement is read upon the
scale which may be so graduated as to admit of the potential being read off directly
in Volts.

page_text: The case of the instrument is suitably glazed to admit of the ready observation
of the position of the needle and its suspension between the quadrants.
There are guides in connection with the axis of the needle which serve to retain
the needle approximately parallel to the quadrants. The needle can be lifted and
nipped by the guides to hold it safely whilst the instrument is carried from place
to place.
In another arrangement I employ two discs one fixed and the other suspended
over it. The discs are connected with the terminals of the machine and the
attraction is measured to ascertain the olectro-motive force.
For the purpose of measuring electric currents I employ an instrument consisting
of a wheel or drum mounted upon axes, and free to revolve. It is placed between
a pair of coils of insulated wire or copper strip concentric with the axes and the
current to be measured circulates in these coils and also in the wheel or drum.
The wheel or drum consists of radial arms fixed upon the axes; each axis has
one set of arms and these are connected with the arms of the other set by
connections which run parallel to the axes, or it may be by a cylindrical conductor.
The current to be measured is caused to pass through the coils one direction in
one coil and in the opposite direction in the other coil. The same current or
another portion of the main current also flows through the wheel. The axes
serve as conductors which lead the current to and from the wheel; the current
divides between spokes and so passes from one axis to the other, I mount a fly
upon one of the axes of the wheel or drum, and the vanes of this fly I cause to
dip into a trough containing mercury or other liquid. I also connect the axis
with a train of wheels similar to the counter of a gas meter the current flowing
through the wheel or drum and the coils causes the rotation of the former and
the revolutions are counted by the wheelwork. The number indicated gives
directly the quantity of current which has passed through the meter. I modify
this apparatus also in such a manner as to convert it into an ampère meter,
suitable to be used with a continuous or alternating current machine. For this
purpose I mount upon the axis a wheel or drum with a suitably curved arm and
over this I pass a cord, from which a weight is suspended or a spring is fastened.
By suitably forming the arm the deflection of the axis can be made proportional
to the electric current by which it is produced.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent and of
an Order of the Lord Chancellor filed by the said Reginald Belfield in the
Patent Office on the 21st May 1884.
REGINALD BELFIELD of Lyndally Palace Road Tulse Hill Park in the County
of Surrey. "IMPROVEMENTS IN ELECTRIC METERS
"
This Invention has for its object improvements in electric meters.
For the purpose of measuring electric potential and especially the potential of
rapidly alternating currents I employ an instrument in some respects similar to a
Thomson electrometer. It has four double quadrants mounted upon an insulating
base and connected together in pairs; the opposite quadrants forming a pair. In
proximity to these and between the upper and lower surfaces of the double quadrants
a needle is suspended by a wire. The form of the needle is approximately that of
one pair of quadrants.
The needle can be set to a zero point by a capstan head at the upper end of the
suspending wire, and in connection with the head there is a pointer which indicates
upon a scale the distance through which the head is moved, and consequently the
torsion required, to bring the needle to the zero. When the instrument is applied
to the measurement of the potential of a generator yielding alternating currents
such as commonly employed in electric lighting, one terminal of the machine is
connected with one pair of quadrants and the other terminal with the other pair,
also one terminal is connected with the needle through the suspending wire;
Under these conditions the needle and one pair of quadrants are similarly
electrified and the needle is repelled by these quadrants but attracted by the
other pair. This causes the needle to leave the zero point. The needle is brought
back by turning the capstan head, and the amount of this movement is read upon
the scale which may be so graduated as to admit of the potential being read off
directly in Volts.
The case of the instrument is suitably glazed to admit of the ready observation
of the position of the needle and its suspension between the quadrants.
There are guides in connection with the axis of the needle which serve to retain
the needle approximately parallel to the quadrants. The needle can be lifted and
nipped by the guides to hold it safely whilst the instrument is carried from placo
to place.
Figure 1 represents a saction of my volt meter.
Figure 2 a plan of the same, and Figure 3 a plan of the head. Figurē 4 an
enlarged section of the head. Figure 5 shews a method of double suspension;
while Figure 6 shows a fibre suspension with a spring adjustment. Figure 7 a
diagram of the connections.
In the above figures A is the needle made of a very light metal such as
aluminium following somewhat the shape of a pair of opposite quadrants as may
be seen in Figure 2, the needle may be corrugated to give it stiffness, it is fastened
as may be seen to a piece of metal wire B which passes through it and is also
fastened to the thin wire C the upper end of which is fastened to the head of the
instrument of which moro hereafter.
The quadrants D eight in number are of brass or other metal they are fastened
together in pairs by means of the pillars E and when they are together they form
a sort of round box in which the needle is free to move. These quadrants may be
fixed or made to slide on guides in a radial direction so that they may have less
action on the needle. Fshews the wire connection to the head it is enclosed in
the ebonite tube G as may be seen. H is a metal case made to slide over the
instrument and thus protect it. This case is glazed as may be seen so as to allow ;

page_text: the pointer needle L (which is fixed to C, and shows all the movements of A) and
also the needle to be seen to ascertain if the needle be properly hung and to
observe its motions. The glasses at the sido of the case are so arranged as shewn
in Figure 2 that one can see through the instrument. M. N. shows an insulating
cover put over the quadrants. N is a ring fitting closely to their sides and M is a
disc of insulating material which is screwed on as shewn. O is an insulating collar
in which works it is kept in placo by a ring nut 'screwed on as shown. P is
another collar but made to slide up and down. When it is down the end of B just
enters the hole and so keeps the needle from touching the quadrants, it is raised
and lowered by the spring Q which is worked by the screw R. When it is raised
the needle is held so that a jar in travelling will not affect it. In Figure 4 the
wire F is attached to the metal collar S which is fixed to the insulation T both
being fixed by nuts screwed over them as shown. In S works the collar of V which
is screwed to the head Z and has a little winch to wind up B. W is a cap over Z
and has a pointer Y attached to it while X is a disc divided off and shews through
what angle W has turned; thus turning W twists the wire and we can read off
on X the amount of torsion given. On referring to Figure 7 we see that each pair
of opposite quadrants are connected and that the needle is connected to one pair,
and if we put ono pole of a machine to one pair and the other pole to the other
pair and needle the first pair will attract the needle and the other pair will repel
it. This will occur however the current may alternate for the needle will always
be of the same difference of potential relatively to the first pair, while of the same
potential as the second pair, thus it will tend to turn towards the first pair with a
strength proportional to the square of the electro motive force.
Having got this deflection all we have to do is to turn the head W in the
opposite direction till the needle is brought back to its first position when no
current is flowing this being caused by the torsion of the wire C being equal to the
attraction and repulsion of the quadrants on the needle. As the torsion of the
wire is proportional to the angle gone over while that of the needle is proportional
to the square of the electro motive force it follows that the angle over which the
pointer bas moved is proportional to the square of the electro motive force so that
when the constant of the instrument is found by the deflection given by a known
electro motive force any other electro motive force can be measured by it.
In Figure 5 we see a method of double suspension the distance between the
filament (silk or metal) being altered by the screw A¹ while the needle can be
raised or lowered by B¹. Figure 5 also shews the needle fixed by a bottom
suspension to the collar P. Figuro G shews a filament suspension having a spring
to give the necessary tension. The connections with the needle can also be made
by having P of metal its hollow cup filled with a conducting liquid and a piece of
wire from the needle dipping into it.
If wo take the lines upward from left to right to represent insulation and
downwards to represent metal we see that the case of the instrument is perfectly
insulated so that no danger can arise when working it with high electro motive
forces.
The instrument is provided as shown with levelling screws and the necessary
terminals for making connections.
In another arrangement I employ two discs one fixed and the other suspended
over it. The discs are connected with the terminals of the machine and the
attraction is measured to ascertain the electro motive force.
Figures 8 and 9 shew this form of Volt meter, in which there are two discs of
metal A and B with a piece of insulation C between them. A and C are fastened
to the base while B is suspended from an arm D pivoted at C so that by turning
the handle C which is attached to it by means of the spring a torsion is given
to the spring until it is able to overcome the attraction between the plates the
amount of torsion being shown by the pointer F.
For the purpose of measuring electric currents, I employ an instrument con-
Bisting of a wheel or drum mounted upon axes, and free to revolve. It is placed

page_text: between a pair of coils of insulated wire or copper strip concentric with the axes
and the current to be measured circulates in these coils and also in the wheel or
drum.
The wheel or drum consists of radial arms fixed upon the axes; each axis has
one set of arms and these are connected with the arms of the other set by
connections which run parallel to the axes or it may be by a cylindrical conductor.
The current to be measured is caused to pass through the coils one direction in
one coil and in the opposite direction in the other coil. The same current (or
another portion of the main current) also flows through the wheel. The axes
serve as conductors which lead the current to and from the wheel; the current
divides between spokes and so passes from one axis to the other. I mount a fly
upon one of the axes of the wheel or drum, and the vanes of this fly I cause to dip
into a trough containing mercury or other liquid. I also connect the axis with a
train of wheels similar to the counter of a gas meter the current flowing through
the wheel or drum and the coils causes the rotation of the former and the
revolutions are counted by the wheelwork. The number indicated gives directly
the quantity of current which has passed through tho meter.
Figures 10 and 11 shew my current meter. A and B are coils of insulated wire
or copper tape. C is a drum or cage of metal free to revolve. At D and E on its
axis are small wheels dipping in troughs of conducting liquid. F is a fly, the
paddles of which are immersed in a liquid this fly can be mounted either on the
shaft or on a pinion driven off the shaft. G H represent an ordinary train of
wheels to show the number of revolutions C has made.
Now the current circulates round the coils, and from one end of C to the other,
thus the currents in C flow at right angles to those in the coils. These coils are
arranged so as to cause the electricity to flow through them in opposite directions,
C will thus revolve in one direction never mind how the current alternates and the
speed of revolution will be proportional to the square of the current flowing. Now
the friction of F on the liquid will be as the square of the speed, these two acting
one on the other will cause the whole system to revolve proportionally to the
amount of current flowing and thus give a register on the train of wheels.
Instead of the wheels D E I sometimes use brushes making contact with the
axis and sometimes make F to make contact.
I modify this apparatus also in such a manner as to convert it into an ampèro
meter, suitable to be used with a continuous or alternating current machine. For
this purpose I mount upon the axis a wheel or drum or a suitably curved arm and
over this I pass a cord, from which a weight is suspended or a spring fastened.
By suitably forming the arm the deflection of the axis can be made proportional
to the electric current by which it is produced.
To make the ammeter I dispense with F and the train of wheels and put in
their place a wheel K Figure 12 having a spring attached to it; the amount by
which the current is able to overcome the spring is shewn by the pointer in the
same reading according to the square of the current.
Figure 13 shews an arm attached to the axis in place of the wheel and having a
cord with a weight attached to it the arm being shaped so that the readings giveu
are proportional to the strength of the current.
Having thus described the nature of my said invention and the manner of
performing the same I would have it understood that I claim :-
First. The construction of an electric volt meter by which a rapidly alternating
or other electro motive force may be measured by means of a needle and quadrants
substantially as herein described.
Second. The construction of an electric volt meter by which a rapidly alternating
or other electro motive force is measured by the mutual attraction of two plates
separated by insulating material substantially as described.
Third. The construction of an electric current meter consisting of a wheel or
drum revolving between coils and actuating a counting train substantially as
described.

page_text: Fourth. The construction of an electric ampère meter suitable to be used with a
continuous or alternating current machine and consisting of a wheel or drum pin
to turn between coils and thereby to strain a spring or lift a weight at a varying
loverage substantially as described.
In witness whereof I the said Reginald Belfield have hereunto set my hand
and seal this thirtieth day of March in the year of our Lord One thousand eight
hundred and eighty four.
REGINALD BELFIELD. (LS)