Improvements in or relating to Electric Meters.
Year: 1891

page_text: Date of Application, 5th Nov., 1891
Complete Specification Left, 4th Aug., 1892-Accepted, 5th Nov., 189?
PROVISIONAL SPECIFICATION.
Improvements in or relating to Electric Meters.
I, FRANCIS TEAGUE, of the Acme Electric Works, Ferdinand Street, Chalk
Farm, in the County of London, Electrical Engineer, do hereby declare the
nature of this invention to be as follows :-
This invention relates to improvements in electric meters of the kind described
in the Specification to Letters Patent granted to me, No. 15489, bearing date
2nd October 1889, and to an application for Letters Patent No. 389, bearing
date 8th January 1891. A part or parts of my present invention may, however,
be applied to other kinds of meters employed for measuring electric energy.
My present invention comprises certain improvements in the construction and
arrangement of the parts of meters, (more particularly of the kind described in
No. 389 of 1891 above named), for the purposes of making them simpler, reducing
the cost, increasing the efficiency, and rendering them less liable to get out of
order. By one important part of my invention I greatly reduce the speed of
the armature and its spindle, thus reducing also the number and speed of the
wheels in the integrating gear, and the attendant friction.
In my before named Specifications, I describe the winding of the electro
magnet as being compound wound that is, with a shunt winding and a series winding
each being arranged to produce the same magnetic polarity in the usual and
well known manner. In my present invention 1 also use a compound winding,
composed of many turns of fine wire for the shunt winding, and a series winding
of but a few turns of thick wire-say from three to six turns-but so arranged
that the latter (when conducting current) tends to produce poles of unlike name
to those produced by the shunt winding, thus somewhat neutralizing the latter.
I find that this differential polar arrangement, when proportioned to suit the
maximum amount of current to be passed through a meter, compensates for
the proportional difference in friction between high and low speeds, and so
makes the speed proportionate to the current passing through the meter.
In
applying the series winding for the above purpose, I do not confine myself
to winding it upon the bobbin which carries the shunt winding, but may wind
it on any suitable part of the electro magnet-either inside or out-if the form
permits of this, and as there are but few turns this is easily and conveniently
done with reference to the circuit connections.
In my aforesaid Specification No. 15,489 of 1889, I stated that it was "desirable
to place a little paraffin on the mercury to prevent or retard oxidation," and I find
that Borel and Paccaud in their Specification No. 11,051 of 1885 say "it is
important to avoid absolutely the oxidation of the surface of the mercury in
which the moveable part of the circuit moves. This oxidation alters necessarily
the resistance opposed by the mercury to the moveable armature;" and they
proposed as one method of avoiding this inconvenience to "cover the surface
of the mercury with an inoxidable liquid, as for instance, purified oils." Further-
more, I find that Ferranti-in his Specification No. 13,621 of 1888-proposes
to "partially float the armature in a liquid" or employ a float on the armature
spindle which " may be entirely immersed to avoid the effect of surface tension,"
in order to lessen the friction on the pivot of the armature. Likewise, Professor
Perry in his Specification No. 873 of 1890-proposed to "surround a portion of
the outer part of the armature with paraffin oil or water or some other liquid
which will partially lift it from its bearings or diminish its weight on its bearings."
Now, by my present invention I not only employ a liquid in combination with
the mercury and the armature,. for the double purpose of avoiding oxidation of

page_text: the mercury, and reducing the friction on bearings by specific gravity, but also
for reducing the speed of the armature and its spindle; and thus obtaining the
advantages before mentioned.
In applying this part of my invention to practice, I find that oils are objection-
able from their liability to gum, and I employ glycerine instead. Sufficient is
used to completely cover the armature, so that the spindle only may be subjected
to surface tension in turning. By the depth of the liquid, and extent of armature
surface in contact therewith, I may regulate the number of revolutions per
minute it is desirable to give to the armature for a given amount of current.
For
example, a meter adapted for 30 amperes (and passing that amount) at an electro
motive force of 100 volts, has an armature speed of about 15 revolutions per
minute. The same meter passing 5 amperes has an armature speed of about
2 revolutions per minute, and if the latter amount of current is interrupted in an
intermittent manner, the armature responds-without apparent inertia to every
make and break of the circuit. By this reduction of speed the train of wheels
of the integrating gear is reduced in number, with a corresponding reduction of
friction at the spindle, bearings, and teeth of the wheels. I find that the meter
of the capacity given will start-showing perceptable motion-with a current as
low as one tenth of an ampere. It is to be observed that the liquids hitherto
applied to meters having mercury in two distinct vessels-either for the purpose
of avoiding oxidation, or reducing the friction of the armature spindle, have had
such liquids applied separately to each mercury trough. In my invention―on
the contrary--although I use two mercury troughs, I fill up the space between,
so that a liquid bath actually connects the two mercury conductors, and (preferably)
extends above the top of the armature, thus forming a liquid brake to the latter
to reduce its speed.
The
The armature is of copper or silver; nickel plated, and is supported by a jewelled
step within a tubular pole piece which is mounted vertically in the centre and at
the bottom of a circular magnet case. At the bottom of the magnet case is an
annular mercury trough, surrounding the tubular pole piece, and held in position
by it. The pole piece-being tubular-forms the inner mercury cup, in a similar
manner to that shown in my Specification No. 389 of 1891 aforesaid.
circular magnet case extends upwards some distance above the top of the central
pole piece, in a cylindrical manner, and at the top receives an annular pole piece,
(extending downward), which forms the core of the shunt winding. The armature
shell is adapted to rotate between the central pole piece and the annular pole
piece. A guard is secured at the bottom of the annular pole piece which extends
upward close to the inside of the magnet case to prevent the liquid coming in
contact with the conducting coil; and some cement is run in at the bottom between
the annular mercury trough and the side of the magnet case to direct mercury
back to the trough, should any become displaced therefrom.
The top of the armature has a jewelled pivotal bearing, made adjustable, and
supported by a suitable bracket secured to the top of the magnet case. A worm
or thread is formed on the upper portion of the armature spindle, which engages
with a suitable worm wheel connected to the train of integrating wheels, and
which are provided with suitable index fingers and dials in the known manner for
indicating the amount of energy expended in the circuit. The circular magnet
case is mounted upon a suitable base, and is provided with a suitable cover, and I
insert a safety fuse in the shunt circuit, arranged beneath glass, so that its
condition can be easily inspected. All the parts of the armature or spindle,
in contact with the mercury, are nickel plated; and I make holes in the
armature to allow the glycerine to have free access within its shell between the
mercury cups.
Dated this 5th day of November 1891.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Electric Meters.
I, FRANCIS TEAGUE, of the Acme Electric Works, Ferdinand Street, Chalk
Farm, in the County of London, Electrical Engineer, 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 improvements in electric meters of the kind described
in the Specification to Letters Patent granted to me No. 15489 bearing date
2nd October 1889, and to an application for Letters Patent No. 389 bearing date
8th January 1891. A part or parts of my present invention may, however, be
applied to other kinds of meters employed for measuring electric energy.
My present invention comprises certain improvements in the construction and
arrangement of the parts of meters (more particularly of the kind described in the
Specification to No. 389 of 1891, above named), for the purposes of making them
simpler, reducing the cost of manufacture, increasing their efficiency, and rendering
them less liable to get out of order. By one important part of my invention, I
greatly reduce the speed of the armature, and its spindle, thus reducing also the
number and speed of the wheels in the integrating gear, and eliminating the
attendant friction of the said superfluous wheels and their axles. This ensures,
therefore, greater accuracy in indicating varying amounts of electrical energy
passing through the meter.
In my before named Specification I described the electro magnet as being com-
pound wound, that is, with a shunt winding and a series winding-each arranged to
In my
produce the like magnetic polarity-in the usual and well known manner.
present invention. I also use a compound winding composed of many turns of fine
wire for the shunt winding and a series winding of a few turns of thick wire, (say
from three to six turns in a 30.ampere meter), but so arranged that when con-
ducting current the series winding tends to produce poles of unlike or opposite
name to those produced by the shunt winding; thus neutralizing the latter to a
slight extent. This I call a differential compound winding, and find that, when
proportioned to suit the maximum amount of current to be passed through a meter,
it compensates for the proportional difference in friction of the moving parts
between high and low speeds and so makes the speed proportionate to the current
passing through the meter. I do not confine myself to winding the series winding
upon the bobbin which carries the shunt winding, but may wind it upon any other
electro
suitable part of the electro magnet either inside or out-if the form of the
magnet permits of this-and, as there are but few turns of the series winding, this
is easily and conveniently done with reference to the circuit connections.
In my aforesaid Specification No. 15,489 of 1889, I stated that it was "desirable
to place a little paraffin on the mercury to prevent or retard oxidation ;" and I
find that Borel and Paccaud, in their Specification No. 11,051 of 1885 also say
"it is important to avoid absolutely the oxidation of the surface of the mercury in
which the moveable part of the circuit moves. This oxidation alters necessarily
" and the
the resistance opposed by the mercury to the moveable armature;
inventors proposed, as one method of avoiding this inconvenience, to "cover the
surface of the mercury with an inoxidable liquid, as for instance, purified oils."
Furthermore, I find that Ferranti, in his Specification No. 13,621 of 1888, proposes
to "partially float the armature in a liquid" or to employ a float on the lower
part of the armature spindle beneath the armature, which float "may be entirely
immersed to avoid the effect of surface tension," in order to lessen the friction on
the pivot of the armature. Likewise, Professor Perry, in his Specification No. 873
of 1890, proposed to "surround a portion of the outer part of the armature with
paraffin oil or water or some other liquid which will partially lift it from its bearings

page_text: or diminish its weight on its bearings." Now, by my present invention, I not only
employ a liquid in combination with the mercury and the armature for the double
purpose of avoiding oxidation of the mercury and reducing the friction on bearings
by specific gravity, but also for reducing the speed of the armature and its spindle,
thereby reducing the number and speed of the wheels in the integrating gear, and
the attendant friction, as before mentioned. This is indicated in Fig. 2 of the
drawings.
In applying liquids for the purpose of reducing the speed of the armature and its
spindle, I find that oils are objectionable, owing to their liability to gum, and
therefore I prefer to use glycerine instead. This acts upon the armature like a
liquid break, so that in a meter adapted for 30 amperes (and passing that amount
of current) at an electro motive force of 100 volts, the armature has a speed of
about 15 revolutions per minute only. The same meter, passing 5 amperes, has
an armature speed of about 2 revolutions per minute. The armature will start or
show movement with a current as low as one tenth of an ampere; and if the
current is interrupted in an intermittent manner, the armature responds-without
apparent inertia to every make and break of the circuit. It remains to be stated
that the liquids hitherto applied to meters having mercury in two distinct vessels -
either for the purpose of avoiding oxidation, or reducing the friction of the
armature spindle-have had such liquids applied separately to each mercury trough.
In my invention on the contrary, and although two mercury troughs are used-I
make one or two small holes in the armature so that the liquid bath connects the
mercury contacts and fills up the space between both inside and outside the armature
and above its top to the small diameter of its spindle; thus forming an efficient
liquid brake to the armature to reduce its speed. This also is indicated in Fig. 2
of the drawings.
-
In the further description of this invention, reference is made to the accompanying
drawings, in which,
Fig. 1 is a side elevation of my improved meter-its enclosing case being
removed.
and
Fig. 2 is a vertical section through the same, but with the said case in position,
Fig. 3 is a plan thereof, without the case.
In the drawings, a represents the shunt winding composed of many turns of fine
wire wound upou a tubular core and placed within a cylindrical magnet case, as
shown in Fig. 2; and 6 is the series winding composed of a few turns of copper
tape, wound or connected in a differential manner to the shunt. The armature c is
of copper or silver, plated with nickel, and is supported on a jewelled step pivot d
within a central and tubular pole piece e which is mounted in the centre of the
bottom of a cylindrical magnet case f. At the bottom of the inside of the magnet
case and surrounding the tubular pole piece e-is an annular mercury trough g,
in which the bottom edge of the armature c is adapted to rotate and make an outer
contact with the mercury contained therein. The inner mercury cup his formed
by an axially bored hole in the central pole piece e, and which is made deep enough
to enclose nearly the whole of the stem of the armature c. The outer part of the
cylindrical magnet case f is higher than the top of the central pole piece e, and at
some distance therefrom, and it is fitted at the top with a flange or cover which
forms part of an annular pole piece i that hangs downward into the interior of the
case. The annular pole piece i surrounds the central pole piece e (as is shown
in Fig. 2), and their diameters are such that a narrow annular space, truly concentric
or continuous at all parts of its circumference, is left, within which the armature cis
adapted to rotate. The annular pole piece i forms the core of the shunt winding 2,
and a sheet metal guard; surrounds the shunt winding almost or quite to the top
to guard it from liquid contact, and is securely upheld by a screwed washer and
elastic ring on the bottom end of the annular pole piece i. At the bottom of the
cylindrical magnet case f, some cement k is run between the case and the annular
mercury trough g, in a funnel shaped form, to drain any mercury back to the trough

page_text: if it becomes displaced therefrom. The serial coil b, in the form of an insulated
copper tape, is wound or connected in a differential manner to produce an opposite
magnetic effect to that of the shunt (as already described), and electrically connected
with the annular mercury trough g, and embedded within the cement k. The outer
end of the coil b is shown in Fig. 1 as rising from the case ƒ through an external
channel, to connect with the main circuit terminal.
The armature spindle o, passes through an orifice in a brass cap fitted over the
central space of the annular pole piece i, and is there pivotally supported in a
jewelled bearing in the adjustable screw 1; the latter being carried by the brass
bracket m screwed to the flange i, on the top of the magnet case as is shown in
Fig. 3. A worm or thread n is formed on the upper portion of the spindle o which
engages with a worm wheel having the required number of teeth to drive, by its
axle p, the integrating train of wheels at the proper rate of speed, so as to
indicate correctly the amount of energy expended in the circuit, by the index finger
and dial r. The cylindrical magnet case f is mounted upon a suitable base s and
enclosed by a covert shown in Fig. 3 with glass dials therein; and I insert a safety
fuse u in the shunt circuit, so arranged beneath glass that its condition can be
easily inspected.
I am aware that glycerine, oil and other liquids have been used in electric meters
for the purpose of opposing fluid friction to a moving part of such meters and
therefore I do not claim this; and I am also aware of Robert Snowdon's Patent
No. 7023 of 188, and I declare that I do not claim anything described or claimed
therein. Furthermore, I desire to state that, the drawings appended to the
Complete Specification of my application No. 22,852, dated 31 December 1891,
being similar to those appended to this Specification, I hereby disclaim any of the
features claimed in the said Specification No. 22,852 of 1891.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is
1. In an electric meter, the combination of a cylindrical electro magnet case
having internal poles, one being annular in form, dependent from the top of the
case and acting as a cover therefor, the other centrally placed at the bottom and
projecting vertically therefrom into the space enclosed by the said annular pole
and axially bored to form a mercury cup, a cylindrical armature pivoted within
the said mercury cup to rotate within the annular space between the poles and
having two mercury contacts, circuit connections therewith, a compound winding
placed within the magnet case, and an integrating gear driven directly from the
armature spindle, substantially as and for the purpose herein described.
2. In an electric meter, the combination of a cylindrical electro magnet case
having internal poles one being annular in form, dependent from the top of the
case and acting as a cover and core, the other centrally placed at the bottom and
projecting vertically therefrom into the space enclosed by the said annular. pole
and axially bored to form a mercury cup, a cylindrical armature pivoted within the
said mercury cup to rotate within the annular space between the poles and having
two mercury contacts, circuit connections therewith, a liquid bath submerging the
said armature and mercury contacts, and a differential compensating compound
winding, substantially as and for the purpose herein described.
3. In an electric meter, the combination of a cylindrical electro magnet case
having internal poles and a closed bottom, an annular mercury cup resting on the
bottom, a funnel shaped filling surrounding the said annular mercury cup and
draining into the same, and a central mercury cup, substantially as and for the
purpose herein described.
4. In an electric meter, the combination of an electro magnet excited by a
differential compensating compound winding, a perforated armature rotatable
between the poles of the said magnet, mercury contacts for the said armature and
circuit connections thereto, a fluid tight vessel surrounding the said poles, and a

page_text: bath of glycerine within the said vessel submerging the said armature, substantially
as and for the purpose herein described.
5. In an electric meter, the combination of an electro magnet excited by a
differential compensating compound winding and having a truly annular space
between its poles, an armature rotatable within the said annular space, two
mercury contacts for the said armature and circuit connections thereto, substantially
as and for the purpose herein described.
6. In an electric meter, the combination of a cylindrical electro magnet case
having a closed bottom, a central pole piece axially bored to form a mercury cup,
an annular mercury cup surrounding the said pole piece, a series winding wound
around the annular cup, a channel in the case from the interior to the upper portion
thereof for the passage of the series conductor, and a liquid bath submerging the
said mercury cups, substantially as and for the purpose herein shown and described.
7. In an electric meter, a cylindrical electro magnet case having internal poles
and a closed bottom, one of the said poles being annular in form and dependent
from the top of the said case and forming a core for a shunt winding, substantially
as herein shown and described..
8. In an electric meter, the combination of a cylindrical electro magnet case
having a closed bottom and a dependent pole piece forming a cover, arranged and
operating as a fluid receptacle, a pivoted armature rotatable within the said magnet
case, an annular mercury cup resting on the bottom and circuit connections there-
with, an internal winding, and a liquid bath submerging the said armature and
mercury cup, substantially as and for the purpose herein described.
Dated this 4th day of August 1892.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.