Improvements in and relating to Electric Meters.
Year: 1891

page_text: Date of Application, 31st Dec., 1891
Complete Specification Left, 30th Sept., 1892-Accepted, 5th Nov., 1892
PROVISIONAL SPECIFICATION.
Improvements in and 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:-
In certain forms of electric meters it is desirable to establish a uniform, or
nearly uniform, temperature in the meter, to avoid irregularities that might other-
wise occur.
For example, in meters where mercury contacts, or oils or other
liquids, are employed, any considerable change in the temperature would affect
the mobility or viscosity of the above named substances, and therefore bring about
changes in the mechanical resistance; thus leading to incorrect records of electrical
energy passing through the meter.
By my invention I combine an electric thermostat with any suitable electric
meter, and arrange it in such a manner that it tends to preserve an equal temperature
of the apparatus, and a correct or regular record of the current energy passing
through the meter.
The principle adopted is the known one of the unequal expansion of two metals,
such as steel and copper, by heat. The two metals are riveted to each other in the
shape of a small thin bar, and this bar is rigidly held at one end, and adapted to
make an electrical contact on one face at the other end. The metals are so disposed
that when an increase of temperature takes place above the normal temperature
for which the meter is adapted, the copper, expanding most, tends to curl the bar,
with the copper on the outside or longest line of the curve. As it is held rigidly
at one end, the curl of the bar removes the copper face from the contact point, and
the electrical communication is broken. Conversely, the lowering of the temperature
makes a close contact, and thus closes the circuit.
The electric circuit controlled by the thermostat consists of a double or reverse
resistance winding, which is preferably placed next to the core of the electro
magnet used in the meter apparatus. The wire employed may be of German silver,
or other suitable metal, and assuming six layers of the winding to be sufficient for
the purpose in view, the current arranged to circulate in opposite directions in
each three of the layers. Consequently, opposite polarities are produced by the
reverse winding or direction of the current, and these being equal, neutralize each
other without disturbing the polar effect of the main winding or windings of the
electro magnet. Moreover, the reverse winding is non-inductive, so that on the
making and breaking contact by the thermostat, no sparking or secondary effect is
produced that is liable to affect the record of the meter.
The heat produced by the current in the resistance circuit, thus tends to keep
the meter at a proper and even temperature to ensure correct indication; and
the contact point is made adjustable with relation to the normal position of the
thermostat bar to adapt it for any required temperature. When the device is in
action a small amount of current passes through the heating coil, which is arranged
as a shunt to the mains supplying current.
Dated this 31st day of December 1891.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in and 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:-
In certain forms of electric meters it is desirable to establish a uniform-or nearly
uniform temperature in the meter, to avoid irregularities that might otherwise
occur. For example, in meters where mercury contacts or oils or other liquids are
employed, any considerable change in the temperature would affect the mobility or
viscosity of the above-named substances. Such a change would vary the mechanical
resistance to a body moving therein, and thus lead to incorrect records of electrical
energy passing through the meter.
By my invention I combine an electrical thermostat with any suitable electric
meter and arrange it in such a manner that it tends to preserve an equal temperature
of the apparatus, and therefor a correct and regular record of the current energy
passing through the meter. The thermostat controls an electric circuit which
consists of a double or reverse resistance winding, preferably placed next to the
core of the electro magnet used in the meter apparatus. The wire employed may
be of German silver, platinoid, or other suitable material, and assuming six layers
of the winding to be sufficient for the purpose in view, they are so arranged or
connected that the current circulates in opposite direction in each three of the
layers. Consequently, opposite polarities are produced by the reverse winding or
direction of the current, and being equal in effect, they neutralize each other
without disturbing the polarity produced by the main winding or windings of the
electro magnet. Moreover, the reverse winding is non-inductive so that on the
making and breaking contact of the thermostat which controls this resistance
circuit, no sparking or secondary effect is produced that is liable to affect the record
of the meter.
In the further description of the invention, reference is made to the accompanying
drawings, in which
Fig. 1 is an outer elevation, Fig. 2 is a vertical section, and Fig. 3 is a plan of
my improved meter as adapted for use with the present invention.
In Fig. 2, a represents a shunt winding wound upon an annular pole piece i
which depends by a flange forming a cover from the top of a circular electro
magnet case f. It will be seen that the annular pole piece forms the core of the
shunt winding a, and next to the said core the before named resistance winding is
placed, as is indicated by the darker lines a¹ in the section. This resistance circuit
is controlled by the thermostat shown on the upper part of the figures, in which
the compound bar u is composed of two thin strips of copper and steel riveted
together, and firmly held at one end by a terminal v. At the other end of the
bar u is placed another terminal, carrying an adjustable screw w, which bears on
the copper face of the bar by a platinum point. When the temperature becomes
too high in the resistance circuit, the greater expansion of the copper than the steel
causes the compound bar u to curl away from the contact screw w, and so breaks
the resistance circuit; but when the temperature falls sufficiently, the bar u returns
to its original position against the screw w and re-established the circuit.
It will be seen from the above description that the heat produced by the current
in the resistance. circuit-thus regulated by the controlling thermostat-tends to
keep the meter at a proper and even temperature, and the contact screw w being
adjustable with relation to the normal position of the compound bar u, adapts it
for any required temperature. This equitable temperature is a matter of great
importance in electric supply meters, in which liquids are employed, as it preserves

page_text: uniform viscosity and therefore uniform mechanical resistance to the motion
of the actuating armature; as has already been pointed out. In several
forms of meters, mercury contacts are employed, and also oil or other liquids
to prevent oxydation of the mercury, to reduce the friction on the armature bearings
by immersion in the said liquids, and to act as a liquid break in retarding the
speed of the armature. To these, the invention specially applies; and the drawings
show my improved slow speed meter (in which a liquid is used as a brake) as
described in the Specification to my application for Letters Patent No. 19,134
dated 5th November 1891. In these a and b represent the shunt and series winding
of an electro magnet, c is a cylindrical or shell armature immersed in glycerine-or
other suitable liquid-supported on a pivot d within a tubular pole piece e at the
centre of a magnet case f The armature makes electrical contact with mercury in
two cups-g and h-which are suitably connected to the circuit. An annular pole
piece depends from the top of the case by its flange, and a sheet metal or other
guard prevents liquid contact with the shunt winding a. A cement filling k is
run in funnel shape around the mercury cup to drain back any mercury displaced
therefrom. An adjustable pivot in a bracket m receives the upper part of the
armature shaft o, and a worm n thereon, drives by a horizontal shaft p a train of
wheels 9, to record on the dial r, the current passing through the meter.
meter is supported on a bases and enclosed by a cover t, which has glass dials
inserted therein, and through the front one, the condition of the safety fuse u¹ can
be inspected. The heating resistance coils may be arranged as a shunt to the
mains supplying current.
The
I am aware that electrical resistances and thermostats have been used in electric
meters for producing and regulating heat; and that magnetically neutralized
windings are known; and also that a moving part of electric meters has been
retarded by liquid resistance, therefore I make no claim to either of these things by
itself. Furthermore, I desire to state that the drawings appended to the Complete
Specification No. 19,134, dated 5. November 1891, being similar to those appended
to this Specification, I hereby declare that I make no claim to any of the features
claimed in the said Specification No. 19,134 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 with a rotatable armature, having
mercury contacts, and immersed in a liquid bath acting as a brake to the said
armature, of an electrical resistance heating circuit, and a thermostat operating
automatically to control the said heating circuit, substantially as and for the
purpose herein described.
2. In an electric meter, the combination with a rotatable armature of an electrical
resistance circuit wound upon an electro magnet in such a manner that current
circulating in the said circuit flows in reverse directions, and a thermostat operating
automatically to make and break the said resistance circuit by sufficient changes
in the temperature of the meter, substantially as and for the purpose herein
described.
3. In an electric meter, the combination with a rotatable armature of a
magnetically neutralized heating circuit, wound upon an electro magnet which acts
upon the said armature, and a liquid bath covering the armature, substantially as
and for the purpose herein described.
4. In an electric meter, the combination of an electrical heating resistance with a
current controlling device operating automatically by sufficient changes in the
temperature of the meter, and an armature rotatable in mercury, substantially as
and for the purpose herein described.
5. In an electric meter, the combination of a liquid bath acting as a brake to retard
the speed of a rotatable armature immersed therein, mercury contacts with the said

page_text: armature, an electrical resistance heating circuit, and a thermostat operating auto-
matically to control the said heating circuit, substantially as and for the purpose
herein described.
6. In an electric meter, the combination of a rotatable armature, mercury contacts
therefor, a liquid bath or brake in which the armature is immersed, an electro
magnet having an electric resistance heating circuit wound thereon in a mag-
netically neutralized manner, and a thermostat controlling the said resistance circuit,
substantially in the manner and for the purpose herein described.
7. In an electric meter, the combination of a rotatable armature, mercury contacts
therefor, a bath of viscous liquid in which the armature is immersed, a non-inductive
electrical resistance winding for heating purposes, a compound metallic bar in
circuit with the resistance winding and having an adjustable contact screw,
substantially as and for the purpose herein described.
Dated this 30th day of September 1892.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.