Improvements in Electricity Meters.
Year: 1889

page_text: VALLZEID OL LUITIATION.
Improvements in Electricity Meters.
I. FRANCIS TEAGUE, of Crown Yard, Stanhope Street, in the County of London,
N.W., Electrical Engineer, do hereby declare the nature of this invention and in
what manner the same is to be perforined, to be particularly described and ascertained
in and by the following statement :—
This invention relates to the measurement of electricity consumed in, or passing
through, a working circuit, by means of a small motor; which is actuated either by
the main current that is desired to measure, or by a shunt current of a known, pro-
portion to, and derived from, the said main current. The current measured is
indicated in desired units, by one or more 'index fingers, travelling over suitably
marked dials.
The working principle of the motor is the known one, (experimentally shown by
Faraday), of the rotation of currents by magnets. The magnets used are electro
magnets, and the rotation of the copper armature of the motor (through which
currents are passing from the working circuit) is communicated to the above named
index fingers by a train of wheels driven by the spindle of the armature.
The armature is suspended vertically, and it consists of a truly formed copper
cylinder, closed at the upper end by a plate or dise of larger diameter than the cylinder.
The outer edge of the disc is flanged in a downward direction, and adapted to dip
into, and revolve in, a circular mercury trough. The lower cylindrical portion of the
armature is open, and is likewise adapted to dip into another similar mercury trough,
and both these troughs are connected to the working circuit. The armature is
suspended upon a vertical spindle which, at its upper end, passes through a hole in the
disc and terminates in a jewelled centre bearing. The spindle is secured to the disc
portion of the armature, but is insulated therefrom, and it is supported at the lower
end upon a jewelled centre bearing; so that when currents are passing through the
meter, the spindle and the armature revolve together. Upon the upper end of the
spindle a small thread or worth is cut, which engages with a correspondingly formed
worin wheel, and this is the first of the train of wheels that serves to drive the index
fingers before named.
The electro magnet cores are vertically mounted upon a base of soft iron, which
forms the yoke of two outside cores. A pole piece is bolted to the top of these
cores, which wholly surrounds the armature for a large portion of its depth. A
circular core of soft iron is also mounted upon the centre of the yoke and extends
upward to the level of the top of the outer pole piece, to form an inner pole piece, and
is concentric therewith. The outer pole piece is bored out slightly larger than the
external diameter of the armature, while the central core is turned slightly smaller
than its internal diameter, so that a narrow annular space is provided just sufficient
to allow the arinature to revolve therein with the necessary clearance. The upper
portion of the central core is bored and fitted to receive the lower step bearing of the
armature spindle; and on the exterior, a shoulder is provided, adapted to carry the
lower mercury cup in which the bottom of the armature dips.
The central core thus forms an inner pole piece to the cylindrical armature, and
may be wound with a suitable conductor, to excite a desired polarity, or not, as
required. But the two exterior cores are each wound so that the outer pole piece will
be the opposite pole, for example, a North pole. In this case, the central core must
be made a South pole either by its winding, or by magnetic induction, if not wound.
The armature is thus placed in a very strong magnetic field, and being delicately
poised upon its axis, with its weight partially or wholly supported by the mercury

page_text: in the cups, is free to revolve when the slightest current is passing through the
circuit.
In
The cores may be wound with a series winding only, or with a compound winding.
In the former case, the apparatus becomes a current meter, and may be called a
coulomb or ampere hour meter, for measuring the quantity of current flowing under
a known and normal electro motive force. With a compound winding, the apparatus
becomes an energy meter to record watt hours of energy consumed or exerted.
the compound winding, the magnetic cores are usually wound with a series winding
first, and afterwards the shunt winding is superposed upon the series coil.
The series coil may he regarded as a compensating coil, to increase or reduce
the strength of the magnetic field when the current or electro motive force varies
in the circuit. Should any variation take place in the circuit from any cause.
to increase the speed of the armature, then this speed would increase the friction of
the apparatus, In this case, the current passing through the series coil would tend to
compensate for this by increasing the strength of the magnetic field. Conversely, if
less current passed, the speed and friction would be reduced, as also, the strength of
the magnetic field. The object therefore, is to keep the strength of the magnetic
field at the same ratio to the resistance of the apparatus, at all speeds of the
armature.
•
In order to keep the strength of the magnetic field at a constant ratio to the
resistance of the apparatus, itself, it is not only necessary that the current passing
through the series coil should also pass through the armature,-thus increasing and
decreasing together-but it is also required that the variation in the strength of the
field should be at a uniform rate, between the maximum and minimum speeds of the
arinature. Therefore, it is necessary to so proportion the iron cores to the magnetising
effect of the coils, that they shall never become magnetically saturated; otherwise the
indicating gear will register incorrectly. A good relative proportion of iron is found
to be that which would require twenty five per cent. more than the maximum current
used to magnetically saturate the iron.
For commercial purposes, it is necessary to provide against the fraudulent tampering
with the poles by magnetically short circuiting them. In this case, the outer field.
answering to the two cores and pole piece described as North, in the example given
above, is made of a complete cylindrical. form, with a concentric central core, as also
named above as a South pole. In this case the winding is done on a former and
placed within the cylindrical field magnet. The indicating gear is also covered over with
à case, secured to an annular pole piece of the said field magnet, to which access can
only be gained by cutting a sealed cord passing through holes in the ends of the
fastening screws.
These meters may be used with direct or alternating currents, but to fit them for
the latter use, the iron is laminated to prevent the formation of Foucault currents
therein, and the layers are insulated from each other. The indicating gear is placed
at the top of each meter and is enclosed in a suitable case, to preserve it from dust
or tampering, with a glass face to allow the indications to be read.
In the accompanying drawings, Fig. 1 is an elevation, partly in section, and Fig. 2
a plan of a compound wound meter, with solid cores adapted for use with direct.or
continuous currents of electricity. Fig. 3 is an elevation, one half in section, and
Fig. 4 is a plan, partly in section, of a compound wound circular magnet meter.
Figs. 5, 6, 7 and 8, are diagrams indicating the methods of winding and the circuit
connections.
Referring to Fig. 1, represents a copper armature, insulated from, but secured
to, a vertical spindle b which is pivoted at its upper end upon a jewelled centre
bearing b and at the lower end upon a jewelled step centre bearing within the
bored upper end of the central iron core c. The outer cores are indicated by d. d.
connected at the lower ends to the yoke, and at the upper ends secured to a pole
pieced, and by the nuts (3,d³. The magnet coils are indicated by ee of which e¹ denotes
the series winding, and e" the shunt winding. The lower part of the central core c is
screwed into or otherwise connected to the yoke d, and is arranged with a shoulder c¹
2

page_text: to carry the lower mercury cup. Resting upon the pole piece is an upper
mercury cup, into which dips the flanged disc a', of the armature a.
When currents are passed through the magnet coils, and the armature, the motion
of the latter is communicated through the worm b³ formed on the armature spindle b, to
a worm wheel behind 3 (not shown), on the small horizontal shaft ; which shaft.
also carries a worm that engages with a corresponding worm wheel on the vertical
shaft. The shaft carries the first index finger at its upper end, and the remainder
of this indicating and integrating gear is worked from the shaft 2 as shown, or in any
other suitable known manner. The whole of the integrating gear is enclosed by a
metallic case g³, secured to the pole piece by small bolts and nuts and covered by
a glass top g, through which the record can be seen. The ineter is suitably mounted
on a base of insulating material, and this base also carries the terminals.
Fig. 2 is a plan of Fig. 1, showing the terminals, hd, to which the serial winding
is electrically connected, and h² ², to which the shunt winding e² is also electrically
connected.
Fig. 3 represents a circular magnet meter, one half of which is in sectional elevation,
and the other half in outer elevation; and Fig. 4 is a plan, partly in section, of the
same with the case 3, and upper mercury trough f¹ removed. This meter is intended
to measure either alternating or direct currents of electricity, and is also compound
wound. The armature and its spindle, top and bottom bearings for same, and
integrating gear are omitted from these figures, but exactly correspond to those parts
in form, arrangement and function, as shown and described for Figs. 1 and 2, and
need not therefore, be specifically described..
In this case, the central iron core c, the circular magnet d, yoke and pole
piece are all laminated, as shown, to prevent the formation of Foucault currents:
the laminations being insulated from each other. The series coil e', and shunt coil
are wound upon a suitable former and placed within the circular magnet d, as shown.
The terminals and are placed within the magnet and coils, and suitably insulated
therefrom, and the circuit connections pass through holes made in the bottom, and
are attached to the several terminals. The case enclosing the integrating gear is
secured by small screwed rods and nuts g' to the pole piece d as already described
for Figs. 1 and 2; and the pole piece is secured to the circular magnet and yoke.</
by bolts and nuts . The ends of the bolts have a small hole drilled in them,
through which is threaded a small silken cord, and fastened and sealed; in order to
prevent tampering with the interior of the meter without detection.
It is desirable to place a little paraffin on the mercury to prevent or retard oxidation;
and to electro plate the armature with iron where contact is made with the mercury.
It is to be understood also, that brush contacts may be made with the armature instead
of the mercury contacts described, through the latter are preferable.
Figs. 5, 6, 7 and 8 are diagrams indicating the manner of winding the électro"
magnets, and of making the circuit connections. In Fig. 5 the cores d, d, are each
wound with a series winding e¹ and connected with the working circuit e through the
mercury cups f and f1, and the armature . The central core c is not wound in this
case, and the arrangement may be considered as that of a current meter.
Fig. 6 represents a compound winding, the coil e' being a series winding, and e² the
shunt winding. These windings are further distinguished by a thick and thin line
respectively. The connection with the working circuit e, of the series winding e' is
made through the mercury cups and fl and armature, as before; and of the
shunt winding e with the circuit e as shown. In this case also the central core is
unwound, and the arrangement is that of an energy or watt meter.
Fig. 7 represents the central core c as wound with a series winding el, and the
outer cores d, d, with the shunt winding ; and Fig. 8 represents a compound
wound circular magnet meter. The circuit connections of the series coil c¹ (denoted
by a thick line), and of the shunt winding (denoted by a thin line) are as shown,
and similar to the other examples described. The compound winding of Fig.
done upon a reel or former and placed within and close to the aunular core d. Both
of these arrangements are suitable for watt meters.
is

page_text: 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. An electricity meter, operated by the rotation of currents by one or more
electro magnets, in which a vertical armature, directly working an integrating gear,
is electrically connected in series with the main circuit in which the current is
required to be measured, and the winding of one or more of the said electro magnets,
substantially as described.
2. In an electricity meter operated by the rotation of currents by one or more
electro magnets, the combination of a cylindrical armature having an upper and a lower
mercury contact, series circuit connection therewith, a vertical spindle having pivoted
bearings supporting the said armature, and a worm or screw at the upper end
of the spindle adapted to drive an integrating gear, substantially as and for the
purpose described.
3. In an electricity meter operated by the rotation of currents by electro magnets,
the combination of an inner circular magnetic core and pole piece, with an outer
concentric pole piece and a core or cores therefor, a lower and an upper mercury trough
having circuit connections in series with a rotatable armature, and
or compound winding for exciting polarity, substantially as and for the purpose
described.
a series
4. A meter for alternating or direct currents of electricity operated by the
rotation of currents by electro magnets, comprising a laminated outer magnet and
pole piece, a laminated inner magnet and pole piece, a pivoted armature rotatable
between the said pole pieces engaging with integrating gear, and a compound
winding and circuit connections, substantially as and for the purpose descibed.
5. In an electricity meter operated by the rotation of currents by one or more
electro magnets, the combination of a shunt winding, circuit connections, and
rotatable armature, arranged and operating to maintain a uniform ratio of strength
in the magnetic field, substantially as and for the purpose described.
6. In an electricity meter operated by the rotation of currents by magnets, a
circular magnet forming a case for enclosing or carrying an exciting coil or coils,
rotatable armature, indicating gear and circuit connections, with means for securing
the same from tampering substantially as and for the purpose described.
Dated this 2nd day of October 1889.
FAIRFAX & WETTER,
433. Strand, London, Agents for the Applicant.