IMPROVEMENTS IN ELECTRIC METERS
Year: 1885

page_text: I JAMES EDWARD HENRY GORDON of 28 Collingham Place Kensington in the
County of Middlesex Electrical Engineer do hereby declare the nature of my
invention for "IMPROVEMENTS IN ELECTRIC METERS and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
In the Specification of a Patent granted to me No 2922 in the year 1883
I described a new electric meter. The meter which is the subject of my present
invention is on the same general principle as the former but contains numerous
important modifications and improvements.
The annexed drawings show the meter in its completed form as arranged for
alternating currents. When the instrument is used for direct currents certain
modifications have to be made which will be indicated in their proper places. It
must be noted that the instrument measures current hours" but as the electro
motive force which each instrument is used ab is constant, the commercial units are
proportional to the "current bours" and by suitably proportioning the cog wheels
the dials are made to indicate direct in commercial units, each instrument after
being adjusted being marked "Right at volts."
DESCRIPTION OF THE DRAWINGS..
Figure 1 is a back elevation, Figure 2 a front elevation and Figure 3 an end
view partly in section of the meter. Figure 4 is a plan view partly in section of
the upper part of the meter and Figure 5 a plan view partly in section of the
lower part.
The current to be measured passes through two or more by preference through
three solenoids (a) as shewn which draw into them the corresponding number of
cores (b). The object of having two three or more solenoids is to diminish the
self induction when alternating currents are used as the connections are so made
that the currents in the adjacent wires of neighbouring coils are in opposite
directions and so assist each other by their mutual induction. The two three or
more coils may be connected in series or parallel as best suits the current to be
measured and the wire wound on them. With direct currents this two three or
more coil arrangement would have no particular advantage over a single coil of
larger size.
The cores (b) consist of thin sheet iron either forming a split tube or preferably
wound into a roll so that a cross section of the core would form a spiral a sheet of

page_text: '
paper or other insulator being laid on the iron sheet before rolling so as to insulate
neighbouring convolutions from each other.
With direct currents a solid core may be used.
The cores are attached to a light frame and suspended by a cord to a pulley
wheel (c) fixed on a spindle (d) on the same spindle is another pulley (e) from the
edge of which a weight (f) is suspended which just balances the cores when no
current is passing.
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From the pulley wheel (c) a cord also goes up to the short end of a lever (/) to
the long end of which a counterweight (i) is fixed. At the short end of the lever
is the segment () of a pulley in the groove of which the cord lies. A guard (1)
protects it from being thrown out of the groove by any sudden jerk.
As the counterweight is more raised it gets more leverage (as in an ordinary
postal balance) and therefore the position in which the cores rest indicates the
strength of the current.
On the same spindle (d) which carries the pulleys is the .snail disc (m) already
mentioned in the Specification of my former Patent No 2922 53. The curvature of
its edge is such that the distance measured vertically downwards from a certain
point above it to its upper edge is always proportional to the deflecting current.
The method of drawing the curve is to fix on the spindle a circular disc faced
with paper and then to mark on it radial lines in the positions which successively
come into the vertical line with successive increments of current in the solenoids.
Distances proportional to the successive currents are then measured on these
lines from the edge towards the centre. The spiral line drawn through the points
thus obtained gives the shape of the edge of the snail disc.
The train of wheels (n) causes the arm (o) to fall at uniform intervals of time
from its zero position to the edge of the snail disc. It will thus have a short fall
when the disc is but slightly deflected and a long one when it is much deflected.
Immediately after the fall the wheel work raises the arm to its zero position and
throughout its upward journey a catch on the arm engages with the teeth of a
ratchet wheel (p) and moves the train of counting wheels (9) by an amount
corresponding with the length of rise that is with the amount of current passing
at the moment of fall.
The wheel work n is actuated by a vibrating iron bar (r) welded. on to an iron
block (s). It is kept in vibration by means of a small electro-magnet (t) wound
with a fine wire of high resistance and connected across from the positive to the
negative main. The alternations of the current in the magnet keep the rod in
vibration like a tuning fork.
When the meter is used for direct currents a make and break arrangement like
that of an electric bell must be added.
The core of the magnet is screwed and passes through the iron block and ends
in a square head at (u). By means of a key the distance of the pole from the
vibrating rod can be varied and the amplitude of vibration adjusted.
At the top of the vibrating rod is a catch (v) which engages the fine teeth of a
ratchet wheel (w) preferably constructed of hard steel. A second catch (x)
prevents the wheel from revolving the wrong way. As long as the current from
the mains goes through the magnet (t) the ratchet-wheel (w) revolves at a steady
and uniform rate. By means of the train of cog wheels (n) it causes the brass
disc (y) to move at a steady but much slower rate. I preferably adjust my meters
so that this latter brass disc (y) revolves exactly once per minute but this is not
the only useful speed. In the disc (y) is a notch () and once in each revolution
the lever o falls into this notch and allows the arm (o) to fall until stopped by the
snail disc (m).
When no current is passing through the solenoids the arm (o) would still be
released each minute but would fall no distance and therefore nothing would be
indicated on the counter. As however it would cause unnecessary wear of the
wheel work to keep it running for instance all day in summer time when no
lamps are burning the following arrangement is adopted. The feeble current which

page_text: works the vibrator passes on its way through the springs (b¹) (c¹) which are so set
that they tend to keep the magnet circuit closed. When no current is passing
through the solenoids the counterweight (i) lifts the spring (6') out of contact
with (c) and so stops the wheel work. The instant that a current capable of
drawing in the cores ever so little passes in the solenoids the lifting of the counter-
weight allows the springs to come together and the wheel work starts.
The first adjustment of the meter is made by varying the ratio of the two
wheels (d) (c) For instance if a meter constructed to work at 100 volts is
wanted to work in a district where the electro motive force is 120 volts the ratio
of these two wheels would have to be altered,
A fine adjustment can further be made by slightly altering the speed of the
wheel work by means of the key at (u).
An escapement wheel might be added to the wheelwork but I prefer not to
use one.
The whole apparatus is enclosed in a wooden case (fl) A cover is placed over
the key place (u) and secured by nuts fastened inside the case.
The case is closed by a locked door the key of which would be kept by an
appointed officer.
A small glass window in the door enables the consumer to see the dials.
In certain systems of electric lighting each house supplied by two currents
brought by two systems of mains part of the lamps being on one system and part
on the other.
To avoid the necessity of having two meters the following addition (not shown
in the drawings) may be made to the meter described above."
The height of the case may be increased and a second set of solenoids and cores
nay be placed vertically under the first. The cores will be connected to the upper
cores by rods cords &c.
If currents are sent through both sets of solenoids the deflection of the snail
disc will be proportional to the sum of the two pulls and the meter will register
according to the sum of the two currents.
The meter from which the drawings have been made is suitable for about 60
to 70 lamps i.e. for a current of 50 to 60 amperes working at an electro motive
force of 100 to 120 volts.
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
(1). The use in meters intended for alternating currents of two three or more
coils instead of one larger one such coils being connected as described herein for
the diminution of self induction,
(2). The method of driving the wheel work of meters by means of a vibrating
rod or tuning fork such rod being kept in vibration by the current substantially as
herein 'described.
(3). The method of stopping the wheel work of meters when no current is
passing substantially as herein described.
(4). The use of two sets of coils in the same meter so as to make one meter
record two currents substantially as herein described.
(5). The general construction of the meter substantially as herein before described
and illustrated in the drawings annexed.
Dated this 25th day of February 1885.
CARPMAEL & Co.,
Agents for the Applicant.