Improvements in Electricity Meters.
Year: 1889

page_text: Date of Application, 13th Mar., 1889
Complete Specification Left, 10th Jan., 1890-Accepted, 15th Feb.,
1890
PROVISIONAL SPECIFICATION.
Improvements in Electricity Meters.
.
I, GEORGE HOOKHAM of No. 7 & $ New Bartholomew Street Birmingham,
Manufacturer do hereby declare the nature of this invention to be as follows:-
My electricity meter constructed according to this invention consists essentially
of two parts the first may be a pendulum vibrating (at least when no current to
be metered is passing) isochronously, the 2nd a moving part whose position is
alternately and at regular or arranged periods first displaced by the current passing
& then restored to zero directly or indirectly by the action of the pendulum. The
part last mentioned has its movement recorded by a counting apparatus; and
obviously, if the product of the number of oscillations (or movements) of this second
part in a given time into the average space through which it moves at each
oscillation is proportional to the current passing, the record will represent the time
integral of the current & if the E.M.F. is constant, will be a measure of the electrical
energy passing in a given time.
I employ a magnetic core which is attracted in one direction by the current to
be metered, & it is so arranged either by the nature or mode of application of the
force opposing the action of this current, or by the fashioning of the conductor
carrying the current, that the movements of this core under the action of the
current are proportional or approximately proportional to the current passing at
any time At regular, or arranged intervals the position of this core is restored to
zero by the action of a current either neutralizing the action of the first or over-
powering it. I prefer to make the first current act continuously & the second at
stated intervals. The reciprocating motions of this part of the meter are commu-
nicated to a counting apparatus & preferably by means of what is known as
"silent feed acting on a wheel. For the paul of the silent feed I prefer
to use bristles, hairs, or such-like natural products placed at an angle may
neutralize the action of the current to be metered by a similar & opposite current
acting at intervals on the same part of the magnetic core: but I prefer a
shunt"
solenoid acting on another part of the core, in an opposite direction and over-
powering the current to be metered.
(
"
il
dash-pot or other damping
The motions in each direction may be modified by a
device.
The pendulum (or its equivalent) controlling the frequency of the intervals at
which the action of the current to be metered is neutralized or overpowered may
be the pendulum of an ordinary clock wound up at stated periods in the usual
way or the energy required to maintain its motion may be supplied from an
electrical source, preferably by the intervention of a gravity-escapement. Contact
is made by means of combs of platinum or other unoxidable material, which may
engage with a rotating cylinder (so as to continually present fresh surfaces) & then
may for greater certainty be supplemented by mercury contacts under alcohol in
closed vessels, actuated either by gravity or magnetism. The intervals at which the
neutralizing or overpowering coil, comes into play. need not coincide with the time
of vibration of the pendulum, but may take place at intervals of several or many
minutes.
If it is found not easy to make the motions of the core above-mentioned
proportional to the current passing, & especially if there is relatively a defect of
movement with the larger currents, the oscillations of the clock-pendulum may be
accelerated by the attraction of a solenoid (carrying the current to be metered) to
iron or steel attached to the pendulum, or the error may be corrected or approxi-
mately corrected, by placing the solenoid (permanently attracting the core) in shunt

page_text: with a conductor whose resistance is relatively greater or less with an increase of
temperature than that of the metal composing the aforesaid solenoid.
In another forut, instead of, as in the last described form, utilizing a slow oscillation
of the core, I may make & break the current (to be metered aid) displacing the
core & make the kich of the core proportional to the current, as in the ballistic
galvanometer, & measure the amplitude and frequency of the kich.”
3.
In yet another form of the apparatus I may cause the clock pendulum to be
deffected under the influence of the current, so that its mean position is no longer
vertical & by a special counting apparatus integrate this deflection; or I may
deflect the actuating arm of the counting apparatus so that its movements under
the influence of the clock pendulum are proportional to the current,
I do not confine myself to the special methods above indicated, as there are other
ways of arranging the relative action of the continuously moving part, & the part
acted upon by the current to be metered. For instance I may slowly rotate a dise
under the influence of the former & press against its face a second disc whose
distance from the centre of the first disc, or whose angle of application is so varied
by the current to be metered that its rotations are a measure of this current.
Dated this 12th day of March 1889.
GEORGE HOOKHAM.
COMPLETE SPECIFICATION.
Improvements in Electricity Meters.
I GEORGE HOOKHAM of Nos. 7 and 8 New Bartholomew Street Birmingham in the
County of Warwick Manufacturer do hereby declare the nature of my invention
and the manner in which the same is to be performed to be particularly described
and ascertained in and by the following statement:―
My improvements in electricity meters consist essentially of two parts the first part
is a pendulum vibrating (at least when no current to be metered is passing)
isochronously the second part is a moving part whose position is alternately and at
regular or arranged periods first displaced by the current passing and afterwards
restored to zero directly or indirectly by the action of the pendulum. The part last
mentioned has itsmovements recorded bya counting apparatus and if the product of the
number of oscillations (or movements) of this serond part in a given time is multiplied
into the average space through which it moves at each oscillation the said product is
proportional to the current passing and the record will represent the time integral of
the current and if the electro motive force is constant the said record will be a measure
of the electrical energy pussing in a given time.
I employ a magnetic core or fine wire solenoid which is attached in one direction
by the current to be metered and the said core is so arranged that its movements under
the action of the current are proportional or approximately proportional to the
current passing at any time. A regular or arranged intervals the position of this
core is restored to zero by the action of a current either neutralizing the action of the
first or overpowering it. I prefer to make the first current act continuously and
the second at stated intervals. Or in place of the electrical restoration of the core
to its normal position the restoration may be effected mechanically.
The reciprocating motions of this part of the meter are communicated to a counting
apparatus and preferably by means of whatis known as a "silent feed"acting ona wheel.
For the pawl" of the silent feed "I prefer to use bristles hairs glass fibres or such
like natural or artificial products placed at an angle. I may neutralize the action of
the current to be metered by a similar and opposite current acting at intervals on the
same part of the magnetic core but I prefer a shunt solenoid acting on another part
of the core or on a separate core in an opposite direction and overpowering the current
to be metered.
The motions in each direction may be modified by a
device.
"
dash-pot" or other damping
The pendulum (or its equivalent) controlling the frequency of the intervals at

page_text: which the action of the current to be metered is neutralized or overpowered may be
the pendulum of an ordinary clock wound up at stated periods in the usual way
or the energy required to maintain its motion may be supplied from an electrical
source.
The intervals at which the neutralizing or overpowering coil comes into play need
not coincide with the time of vibration of the pendulum but may take place at
intervals of several or many minutes.
If it is found not easy to make the motions of the core above-mentioned proportional
to the current passing and especially if there is relatively a defeet of movement with
the larger currents the oscillations of the clock pendulum may be accelerated by a
solenoid (carrying the current to be metered) attracting a mass of iron or steel attached
to the pendulum.
In another form of the apparatus I may deflect the actuating arm of the counting
apparatus so that its movements under the influence of the clock pendulum are pro-
portioned to the current.
I will now proceed to describe with reference to the accompanying Drawing the
manner in which my invention is to be performed.
Figure 1 is a diagram illustrating one arrangement of the pendulum and solenoid
apparatus.
is a pulley freely movable about its centre o; b is a flexible band preferably a
piece of fine watch spring from which hangs an iron core e; d is a solenoid wound
with thick wire carrying the current to be metered the said core and solenoid being
about the same length.
When no current is passing through the solenoid about one half of the core is
situated in the solenoid. is a weight attached by an arm rigidly to the pulley a
and taking up a position (when no current is passing) at an angle of about twenty
degrees to the vertical; is a curved iron core also attached to the pulley and
balanced by a weight g. h is a curved solenoid attached to the frame work of the
instrument wound with a large number of turns of fine wire and forming a shunt to
the current to be metered. is the first wheel of a counting train free to move
about the same axial line.as the pulley but independently of the pulley . j is a
camel's hair pencil ont obliquely as shown and attached to the arm carrying the
weight 6. kis a similar pencil attached to the frame of the machine.
The action of the machine is as follows:-
If the core is sufficiently long (say from two to three times the diameter of the
pulley) the angular motion of the pulley will be approximately proportional to the
current circulating in the solenoid d through an angle of about forty five degrees.
As soon as a current passes through the solenoid the arm c is deflected carrying with
it the brush which urges forward the first wheel of the counting train. The core f
is now partly withdrawn from the solenoid in which I will suppose that no current
is passing. At stated intervals (say of one minute) a contact actuated by ordinary
clockwork completes the shunt current through the fine coil solenoid 4. This is suffi-
ciently powerful under all circumstances and of sufficient duration to completely over-
power the influence of the current in the solenoid acting on the core e and to restore
the weight e to the zero position the circuit being afterwards broken by the clock.
is convenient but not essential to modify the motions of the pulley a by a dash pot
(not shown) which is most conveniently attached to the core c. The fixed brush k
prevents the return of the wheel with the brush i.
Th
For alternating currents the cores e and f must he composed of fine iron wires in
all cases where iron is used in the core.
I do not confine myself to the special method illustrated of making the motions of
the weight e proportional to the current. Several of the methods in common use for
volt-meters and (so called) ammeters being applicable for the purpose. Nor do I
confine myself to the special method of restoring the weight e to the zero position.
In some cases I accomplish this mechanically by an arm or cam driven by clock-
work coming in contact with the weight eat stated intervals and moving it back
o zero,

page_text: I will now describe an arrangement in which the army of the counter is actuated
directly by the pendulum. This arrangement is illustrated by the diagrum Figure 2.
abcde represent parts similar to those marked with the same letiers as in Figure 1.
y is the arm actuating the counter of which the first wheel is driven by the brush j.
is the bob of a pendulum driven by clock work carrying in its rod pin 7
projecting say two inches backwards the whole being so arranged that when no
current is passing through the solenoid the end of the pin 7 just touches the arm g
when the pendulum is at the end of its swing to the left.
It will be found that in the arrangement described at Figure J the distance to which
the core is drawn into the solenoid is over a certain range proportional to the
current in the said solenoid and if the proportions shown in Figure 2 are observed
the motions of the army resting by its own weight on the arm will follow the same
law. Consequently as the core is drawn into the solenoid & the army moves to the
right to an extent proportional to the current in the solenoid and is at each swing of
the pendulum restored to zero so that the rotation of the first wheel i will register the
product of the time multiplied into the current.
In this arrangement it is not necessary that the movements of the core c be
proportional to The current. If for instance there is excess or defect of movement
with large currents the movements of the arm g may still be made proportional to the
current by altering the distance between the centre on which the arm turns and
the centre on which the arm f turns. Or that part of the arm g on which the arm f.
works may be curved.
In this way the motions of the arm g may be made proportional to the current even
though the motions of the core a vary greatly from proportionality. Or the rising
and falling core may raise and lower a cam which should similarly make the
movements of the army proportional to the current.
Where the motion of the actuating arm carrying the advance brush is from any
cause not proportional to the current that is when there is excess or defect of motion
under the influence of large currents the required correction may be effected by the
use of a magnetic bob to the pendulum the oscillation of which is accelerated or
retarded by means of a solenoid conducting the current to be measured.
"
In all cases in place of the iron cores représented at ‹ in both Figures of the drawing
fine wire solenoids may be substituted the current being conveyed to such solenoids
by long fine helically wound wires so as not to interfere with the motions of the core.
Such solenoids possess the advantage over iron cores that they are not subject to
the effects of residual magnetism. "In this arrangement the instrument becomes a
meter of electrical energy.
To avoid temperature errors the fine wire should generally be German silver.
Although I have only described and represented my invention as carried into effect
by the use of an oscillating gravity pendulum yet I wish it to be understood that
isochronous vibrations obtained by the use of a spring balance or tortion balance or
other device by which isochronous vibrations or intervals may be obtained may be
substituted for a gravity pendulum I prefer however a gravity pendulum.
Having now particularly described and ascertained the nature of my invention
and the manner in which the same is to be performed I declare that I claim as my
invention of "Improvements in electricity meters"
First The arrangement and combination of parts substantially as hereinbefore
described and illustrated by the accompanying Drawing consisting essentially of an
isochronous pendulum or its equivalent and a moving part first displaced from its
normal position by the action of the passing current to be measured and afterwards
restored directly or indirectly to its normal position by the said pendulum or its
equivalent the said arrangement and combination being used in conjunction with
registering or recording mechanism.
Secondly Producing the advance motion and preventing the return motion of the
registering or recording mechanism of electricity meters by the employment of camel
hair brushes or other brushes made of natural or artificial fibres arranged so as to

page_text: act in the manner herein before described and illustrated in the accompanying
Drawing.
Thirdly Correcting the irregularities of electricity meters caused by excess or
defect of the motions communicated to the recording apparatus by the use of a
pendulum having a magnetic bob operated upon by a solenoid substantially as herein-
before described and illustrated in the accompanying Drawing.
Dated this Tenth day of January 1890.
W. T. WHITEMAN,
Agent for the Applicant.