Improvements in Apparatus for Metering Electric Energy.
Year: 1889

page_text: Date of Application, 26th Feb., 1889
Complete Specification Left, 6th Dec., 1889-Accepted, 18th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Metering Electric Energy.
We WILLIAM HARDING SCOTT Electrical Engineer & LAURENCE PARIS & SCOTT
Limited Electrical Engineers all of Gothic Works King Street Norwich do hereby
declare the nature of this invention to be as follows:-
The object of the invention is to provide an efficient & simple apparatus or device
suitable for metering electricity.
:
The apparatus consists of a timing arrangement like a clock in which a wheel
revolving at a certain speed makes & breaks periodically in any convenient way a
high resistance circuit which is in shunt to the mains. In this high resistance circuit
is a small electromagnet which by means of its armature a ratchet wheel & pawl
can wind up the spring which keeps the clock going as fast as it runs down.
In the same circuit but not necessarily in series with the small electromagnet is a
coil or coils of fine wire the current in which is acted upon & acts upon the service
or working current which flows in a coil or coils of conductor of large sectional area
& which we will call the series coil or coils.
Either the shunt or the series coil or coils are moveable & the shunt current being
alternately made & broken there is a tendency when any current flows in the series
coil for the moveable or suspended coil to vibrate. This vibratory motion is caused
by means of a ratchet wheel which is operated to wind up a coiled spring until its
tension balances the attractive force between the shunt & the series currents flowing at
the time. The movement of the ratchet wheel is conveyed to the train of indicating
wheels.
At fixed intervals of time the shunt current is caused for a time to cease being
made & broken by a cam or other convenient arrangement which is made to revolve
very slowly by the clockwork arrangement lifting the contact by which the circuit is
made & broken out of gear or by breaking the circuit in another place; the same
cam may be also used to raise or release a catch which holds the other end of the
coiled spring so that it uncoils.
If now the free end of the coiled spring be again locked by the cam letting back
the catch & the contact be again put gear or the shunt circuit completed so that
the moveable coil has a tendency to vibrate the coiled spring will again be wound
up an amount in proportion to the currents in the coils.
This being done at certain intervals of time which are regulated by the clock
arrangement the indicating train of wheels will integrate the amount of electricity
flowing at different times.
.For alternating currents the small electromagnet coils & the acting shunt coils may
be in parallel to one another so that the varying self-induction due to varying number
of alternations may have less effect on the acting shunt coils.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Metering Electric Energy.
We, WILLIAM HARDING SCOTT Electrical Engineer and LAURENCE PARIS and
SCOTT Limited Electrical Engineers all of Gothic Works King Street, Norwich 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:-
This Invention relates to apparatus of the class described in our application for Letters
Patent dated 15th November 1888 No. 16,623 and consists in an improved combina-
tion and arrangement of parts operating as hereinafter described. The apparatus
comprises a timing arrangement which makes and breaks periodically in any
convenient way a high resistance circuit which is in shunt to the mains. In this
high resistance circuit is an electro-magnet in proximity to a coil which is hereinafter
referred to as the series coil.
Either the shunt or the series coil or coils are noveable and the shunt current being
alternately made and broken there is a tendency when any current flows in the series
coil for the moveable or suspended coil to vibrate. This vibratory motion is caused
by means of a pawl and ratchet arrangement to wind up a spring until the resistance
of the spring balances the attractive force between the shunt and the series-currents
flowing at the time. The movement of the ratchet-wheel is directly transmitted to
the train of indicating wheels.
And in order that the said Invention may be fully understood we shall now proceed
to more particularly describe the same and for that purpose shall refer to the several
figures on the annexed Sheets of drawings, the same letters of reference indicating
corresponding parts in all the figures.
Figures 1, 2, 3 and 4 of the accompanying Drawings represent in front view, opposite
side views and end view or plan respectively an arrangement of apparatus for motering
continuous currents according to our present Invention. This apparatus is provided
with a timing-arrangement and a wattineter or Electro dynamometer arrangement in
which a shunt current which is constant with constant electro-motive force and varies
with varying electro motive force acts upon and is acted upon by a series current.
There is also an integrating arrangement which is acted upon by the wattmeter or
electro dynamometer arrangement so as periodically to register its indication by moving
a train of wheels in the usual way.
For use with continuous currents we prefer to use iron or other magnetic metal for
concentrating the effect of either the shunt or the series current, but for alternating
currents the iron may be absent.
The following will explain with the Drawings the arrangement and working of
the apparatus for continuous currents, 1 is an electro-magnet wound with a fine
wire coil which is of high resistance and which is placed in shunt to the mains,
2 is a coil of conductor with a very few turns and having its carrier suspended
by the pivots 3, 3, and hanging in a very intense magnetic field when the electro-
magnet (1,) is excited.
The conductor of the coil 2, is electrically connected to the terminal 4, 4, by
the flexible copper strip connection 5, 5, as shewn. These may for large currents
be replaced by mercury cups.
When a current flows in the coil 2 and the electro-magnet 1 is excited by the shunt
current, the coil 2 will have a tendency to move and the force of this tendency with
constant electro motive force for the shunt circuit will be in proportion to the current
in the Coil 2.
:-
We prefer in order to simplify the clock movement to make and break the high
resistance shunt circuit entirely by the clock or timing arrangement as follows:-
The magnet (1,) attracts when excited the rod of iron 6, on the pendulum 7
moving the pendulum so that the shunt circuit is broken at the point 8. The
pendulum 7 then falls back, is again attracted and so begins to swing. The contacts

page_text: at 8 are preferably of platinam on springs, so that the pendulum can get an effective
swing and also so that there is a rubbing action which keeps the contacts in order and
at the same time there is a quick make and break which minimises the effects of
sparking.
The bob of the pendulum 7, is made very heavy, so that effects of the magnetic
pull and the contact springs in altering its time may be as small as possible. It is
also hung so that the contacts at 8 are just touching when the pendulum is stationary
and hanging in a vertical position, the pendulum is therefore self-starting.
The swings of the pendulum are caused by the pawl 74, attached to the lever 7B,
operated by the pendulum, to give motion to the ratchet-wheel 9, which is on a spindle
carrying a pinion in gear with the toothed-wheel 10, on the spindle of which are the
cams 11 and 12.
The suspended coil 2, and with it the frame 13, will when a current flows
in it have a tendency to vibrate because of the alternate magnetisation and
demagnetisation of the electro-magnet 1. These vibrations are made by means
of the pawl 14, to rotate a fine toothed ratchet-wheel 15, fixed to the spindle 16,
to which also one end of the coiled spring 17 is fastened, the other end of this
spring being fastened to the toothed wheel 18, which revolves freely on the
spindle 16. This toothed wheel can be locked by the catch 19, on the lever 20,
which catch is released periodically by the cam 11 worked by the timing arrangement
and acting on the said lever. It will now be seen that as the ratchet wheel 15 is
rotated it winds up the spring 17 and the spindle 16 being connected to the indicating
train of wheels these are also rotated to a corresponding extent. The frame 13 being
caused to vibrate gives motion of rotation to the ratchet wheel 15 until the resistance
of the spring 17 exactly balances the force exercised by the current in the coil 2.
This force is in proportion to the current in the coil 2 providing there is constant
electro motive force at the terminals of the shunt coil and as the resistance of the coil
spring 17 increases in proportion to the amount to which it is wound up the spindle 16
and the indicating train of wheels will be rotated an amount in proportion to the
current in the coil 2.
If now the catch 19 be raised by the timing arrangement the toothed wheel 18 to
which the other end of the spring is attached will revolve and take up a position in
which there is no tension in the spring 17 and the catch 19 being again let down by
the working round of the cam 11 by the timing arrangement the ratchet wheel 15 is
again rotated and the spring wound up in proportion to the current in the coil 2.
During the time that the toothed wheel 18 is free owing to the catch 19 being raised
it is necessary that the frame 13 should not vibrate and act on the ratchet wheel 15
the lever 20 is consequently prolonged so that when it is raised to release the wheel 18
it catches a projection 22 on the frame 13 and prevents the frame from vibrating
The prolongation of the lever 20 we may make of a piece of steel spring so that it
may not jamb the clock work if it should catch under the projection 22 instead of at
its side.
The projection 22 we also prefer to pivot at the point 21 so that it will be rigid
sideways but not in an upward direction.
In order that the toothed wheel 18 shall not run down too quickly a governor
brake 23 is provided. This governor may be like the governor of an astronomical
clock in which a slight increase of speed effects a great increase in the friction between
suitably arranged surfaces.
This brake is driven by the pinion 24 on a spindle 26 supported by the end of
the lever 25 by which the pinion can be raised clear of the toothed wheel by the
cam 12 when the toothed wheel has run down as far as it would with the friction of
the spindle 26. The object of this is to enable the toothed wheel to move with the
least possible friction and so take up a position in which there is the least possible
tension of the spring thus greatly increasing the range of the instrument.
In the foregoing we have referred to the apparatus as integrating the different
amounts of current flowing in the coil 2 with constant electro motive force at the
terminal of the shunt coil but it is obvious that this same apparatus will as long as

page_text: the iron in the electro magnet is far from saturation integrate the watts in the circuit
although with this form of the apparatus the range of electro motive force through which
it will meter correctly is somewhat limited as a large variation will alter the time of
the pendulum. The range of electro motive force is however quite sufficient for
nearly all electric light and power purposes where the electro motive force is
supposed to be constant.
For use with alternating. currents the arrangements are somewhat altered. In
this case we prefer to use flat stationary coils of thick conductor for the series coils
see 27, Figure 5 with the shunt coil or coils 28, suspended on a pivotted frame to
which is attached a pawl 14 as in figure 1. For operating the pendulum we use
3 shunt coils 29, which may all be in series with one another and with the shunt coil
or coils 28, that move the pawl 14 one of these three coils is fixed on to the pendulum
the other two being stationary. The pendulum will make and break the shunt
circuit as in the continuous current arrangements and in all other respects the
apparatus is the same and it is obvious that the shunt and series circuits may be
arranged in a great variety of ways either the one or the other being suspended on
the vibrating frame and the pendulum may be worked by a separate smaller
magnet.
Having now particularly described and ascertained the nature of this Inven-
tion and in what manner the same is to be performed we declare that what we
claim is.
First In combination with electric meters a wattmeter or electro dynamo meter
arrangement in which the force produced being proportional to the current flowing
in the series coil or to the watts between terminals is caused to wind up a ratchet
wheel against the force of a coiled spring the other end of which spring is fastened
to a toothed wheel which is free on the same spindle so that the spring can be
periodically let down and locked again in any position it may take up substantially
as herein before described.
Second-The arrangement and combination of parts constituting the apparatus
for metering electric currents substantially as herein before described and illustrated
in Figures 1 to 4 of the accompanying drawings.
Third The arrangement and combination of parts constituting the apparatus
for metering electric currents substantially as herein before described and illustrated
in Figure 5 of the accompanying drawings,
Dated this 3rd day of December 1889.