Improvements in Electric Meters.
Year: 1898

page_text: Date of Application, 15th Oct., 1898-Accepted, 21st Jan., 1899
COMPLETE SPECIFICATION.
Improvements in Electric Meters.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23, Southampton Buildings, in the
County of London, Patent Agent, do hereby declare the nature of this invention
(a communication to me from Roger Sherman White, of 193, Schermerhorn
Street, Borough of Brooklyn, in the City and State of New York, United States
of America, Inventor), 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 various new and useful improvements in electric
meters of the type employing an electric motor influenced by the current to be
measured and operating a register-train, the motor armature being provided with
a retarding device influenced preferably by the motor field-magnets, and by
means of which the proper load upon the motor will be secured. The objects
of the invention are to provide a meter of this type capable of very accurate
registration and of a simple construction. In order to provide a motor-meter
which shall quickly respond to changes in load, and which shall accurately
register the current, it is desirable that the armature should be very light, and
that the magnetic field should be as intense as possible. At the present time
motor-meters are made employing a retarding device which comprises a disc of
non-magnetic metal carried by the armature shaft, and in some instances forming
a base or support for the armature coils. This disc is influenced either by the
field magnets of the motor, or by a separate magnet or magnets. The employ
ment of a dise of non-magnetic metal on the armature shaft makes the armature
unduly heavy, so that it does not quickly and accurately respond to changes in
the current. In order to overcome this difficulty and to make an armature as
light as possible, a flat annular ring is, according to this invention, employed
as a retarding device, the extent of surface of such ring being substantially equal
to the magnetic field in which it rotates. By employing a non-magnetic annular
ring instead of a disc as heretofore used, a considerable portion of unnecessary
metal is saved, and whereby the armature can be made of a minimum weight.
The armature coils of this improved motor-meter are preferably carried on a flat
non-metallic support, such as a sheet or disc of mica, and the flat annular ring
which constitutes the retarding device is preferably secured to such non-metallic
disc either on top of the armature coils or on the opposite side of the disc from
the armature coils, whereby a very light armature will be secured, which can be
made of a relatively large diameter and will be subject to all changes in the
current to be measured.
In motor-meters as now constructed it is the custom to employ permanent field-
magnets for effecting the rotation of the armature. When such permanent field-
magnets are employed, it has been found that abnormal conditions such as short
circuiting or reversal of the current, affects the magnetism and thereby influences;
the operation of the meter. With permanent field-magnets, it has been found
impossible to secure intense magnetic fields, since an intensely magnetised, per..
manent magnet quickly loses its magnetism, and consequently the rotative effect.
[Di 077

page_text: of the armature under the influence of a definite amount of current would be
gradually decreased, so that the motor would be inaccurate. It is therefore the
custom in motor-meters as now constructed, to first intensely magnetize the per-
manent field-magnets and to then weaken such magnetism in order to obtain a
relatively constant magnetic field. As stated therefore, at the present time it is
neither possible to employ armatures of a minimum lightness, nor is it possible.
to obtain field-magnets of a maximum strength, so that the present meters do
not respond accurately and instantly to changes in the current which influences
them.
In order to overcome the objections before noted to the employment of per-
manent field-magnets, the field magnet or magnets of this improved meter is or
are provided with a coil thereon by which the permanent magnetism will be
retained, and by which an intensely magnetic field may be secured. In order to
effectively regulate the speed of rotation of this improved motor-meter, it is
preferred to employ in conjunction with the permanent field-magnets, one or
more retarding magnets having windings thereon and arranged at the neutral
point or points on the armature between the field-magnets, whereby such retard-
ing magnet or magnets will additionally serve to retard the speed of rotation of
the armature by their action upon the retarding device. By varying the number
of turns of the coil or coils on the retarding magnet or magnets, it is possible
to very accurately regulate the retarding effect and to thereby secure a motor-
meter wherein the armature will instantly and accurately respond to and indicate
changing currents which may influence it, making it unnecessary to change the
more expensive windings on the permanent field-magnets.
If an armature is used such as that herein referred to, having a relatively
great diameter, and if said armature is mounted on a vertical shaft, the enclosing
casing will necessarily have a considerable width with respect to its height, and
hence may not be so convenient and attractive in form as one of reversed propor-
tions. It is therefore preferred to rotate the armature in a vertical plane, the
shaft being horizontal and carried at its ends in jewel bearings. The employment
of a horizontal shaft and two end bearings would ordinarily result in much greater
friction than would be the case with a vertical shaft and a single jewel bearing,
but means have been invented by the communicator by which this friction may
be reduced or entirely eliminated. Broadly stated, these improved means for
relieving a rotating shaft of friction in its bearing or bearings consist of a magnet
with respect to which the shaft rotates, whereby the magnetic attraction will
relieve the bearing of the weight of the shaft in whole or part.
In order that the invention may be better understood, attention is directed to
the accompanying drawings forming a part of this specification, and in which
Fig. 1 is a sectional view showing one field-magnet and illustrating the prefer-
able construction of armature and commutator, Fig. 2, a diagrammatic view
illustrating the electric connections, and Fig. 3, an elevation illustrating the
armature and armature shaft, the latter being horizontal and combined with
a, horse-shoe magnet for relieving the friction in the end bearings.
In all of the above views corresponding parts are represented by the same
numerals of reference.
I represents a shaft mounted in a suitable framework and preferably on cone
or jewel bearings, so as to rotate with a minimum friction. This shaft is pro-
vided with a worm 2 at its upper end, which operates the register-train, not
shown, or it may operate the register-train. in any suitable way. Carried upon
the shaft 1 is a sleeve 3 secured thereto by a set-screw 4 or in any suitable way.
5 is a thin disc of non-metallic material, preferably mica, which constitutes the
body or support of the armature. This disc is made as thin as possible, so that
an
armature of great lightness will be secured, The disc 5 is secured to the
sleeve 3 in any suitable way, as, for example, by a washer 6. The disc 5 carries
the armature coils 7 which are arranged flat upon the disc and secured in place
by an adhesive substance, such as shellac. The coils connect to a commutator 8

page_text: made of as small diameter a possible, and bearing upon said commutator are
the two brushes 9, 9, mounted in any suitable way. Both the bars of the com-
mutator 8 and the brushes 9, 9, are heavily gold-plated, whereby any tendency
of oxidation is avoided and bright contact surfaces secured at all times. 10 repre-
sents the retarding device, which preferably comprises a flat annular ring, as
shown, which ring is made of a non-magnetic metal, such as aluminum. It is
preferred to make the retarding device 10 of aluminum in order that the rota-
ting parts of the armature may be made of a minimum lightness. Preferably
the flat annular ring 10 is mounted on the coils 7 of the armature, and is secured
in place thereto in any suitable way, such, for example, as by the small spring
clips 11, which clamp the ring in place. Instead of using clips for this purpose
it will, of course, be seen that the retarding ring 10 may be secured in place by
means of an adhesive substance, by rivets, or in any other suitable way. It
is not necessary that the retarding ring 10 should be placed on top of the coils 7,
as explained, since said retarding ring may be secured on the under side of the
disc 5, as will be understood. It will of course be further understood that the
retarding ring may be mounted elsewhere on the shaft than in conjunction with
the motor armature, and be affected by separate and independent retarding
magnets. It is preferable, however, that the retarding ring should be carried
on the armature, as such a construction enables the armature to be made of a
minimum lightness and the field magnets of the motor to be utilized for the pur-
pose of opposing the retardation of the armature...
12, 12 represent the field-magnets of the motor, which are preferably arranged
tangentially to the armature, as shown in Figure 2, and which may be of any
suitable construction.
These field-magnets are permanently magnetized, and their fields are as intensely
magnetic as can be secured. In order to prevent the field-magnets from losing
their magnetism in use, each magnet is provided with a separate coil 13 thereon,
by means of which the permanent magnetism will be always maintained of a
constant intensity.
This improved meter will be adjusted to the proper standard by varying to
the correct extent the retarding effect upon the retarding device. This regulation
may be thus effected by varying the length of turns of the coil or coils 13. It
is preferred however, to make the permanent magnets 12 and their coils always
of a constant standard, and to utilize one or more separate retarding magnets 14
co-operating with the armature on the neutral line between the two field-magnets.
In Figure 2 is illustrated one of these retarding magnets, but it will be obvious
that two of them may be used at diametric points on the armature.
The retarding magnets 14 are somewhat smaller than the field-magnets 12.
They are permanently magnetized and they are provided each with a coil 15
thereon, the lengths or number of turns of which may be varied to adjust the
speed of rotation of the armature to the correct point.
In connecting this improved motor-meter in circuit, it is preferred to adopt
the arrangement illustrated in Figure 2. 16, 16 represent the supply mains,
17, and 18 the branches leading therefrom, and 19, 20, the consumption circuit,
having the translation devices 21 therein. The branch 18 leads to a binding
post 22, and the two coils 13 of the field-magnets will be connected in series with
each other and with the coil or coils of the retarding magnet or magnets
between said binding post 22 and a second binding post 23, as shown. The
Brushes 9 of the motor armature are connected in a separate shunt 24 across
said binding posts, as shown. A wire 25 connects the binding post 23 with the
consumption main 19.
In operation, the circuit including the permanent field-magnet coils takes
the place of a separate shunt necessary in meters of type employing simple
permanent field magnets.
By making use of permanent field magnets each with a separate coil thereon
by which its magnetic field may be always maintained of a relatively high inten-

page_text: sity, and by employing an armature of the type described, having a retarding
device carried thereby comprising a flat, annular ring, a motor -meter is obtained
which will respond with great accuracy to variations in the current, since the
armature is of a minimum lightness and the fields of a maximum strength..
When a meter employing a relatively large armature, such as herein described,
is used, and the armature shaft is arranged vertically, the enclosing casing will
necessarily be of a considerable width with respect to its height. Such a form
may not be so convenient or attractive, or so well suited for attachment. to a
wall, as a casing of reversed proportions. It is therefore preferred to mount
the armature to rotate in a vertical plane, using a horizontal shaft, as shown in
Fig. 3. With this construction the armature shaft 1. is provided at its ends
with reduced portions 26 working in jewel bearings 27 formed in the ends of
adjusting screws 28. These adjusting screws are carried in brackets 29, which
are adjustably secured by means of screws 30 to the two pole-pieces of a per-
manent horseshoe magnet 31, the extremities of such poles being arranged in
proximity to the ends of the armature shaft 1, so that the latter will be attracted,
it being, of course, understood that the said armature shaft is made of some
magnetic metal," such as iron or steel. 'In this way, the attraction between the
magnetic poles and the armature shaft will greatly, if not entirely, relieve the
bearings 27 of the weight of such shaft, whereby, the friction will not only be
reduced but there will be little or no wear. By adjusting the brackets 29 verti-
cally on the two pole pieces, the degree of magnetic attraction may be properly
regulated, and by adjusting the armature shaft 1 laterally with respect to such
pole pieces by means of the adjusting screws 28, the armature shaft and armature
may be very accurately balanced with respect to the two seats of magnetic attrac-
tion.
It will be understood, of course, that the improved means which have been
described for relieving a rotating shaft of friction at its bearing or bearings is
not limited to use with meters of this type.
Having now particularly described and ascertained the nature of my said in-
vention. and in what manner the same is to be performed. I declare that what I
claim is:
1. In an electricity meter operated by the effect of the current on a rotating
armature, the provision of an armature having a relatively large diameter and of
great lightness whereby the armature will be strictly accurate in its registration
and will be instantly susceptible to changes in the current measured, as and for
the purposes described.
2. In an electricity meter wherein the current to be measured rotates an
armature connected with the registering devices, the employment of a retarding
device in the form of a flat, annular ring, which is preferably carried directly
upon the rotating armature and which is affected by the field-magnets of the
armature, as and for the purposes set forth.
3. In an electricity meter wherein the current to be measured rotates an arma-
ture connected to the registering devices, said armature being in the form of a
flat disc of relatively great diameter but of extreme lightness, the employment
of permanent magnets arranged in connection with said disc to rotate the same,
and energizing coils on said magnets affected by the current to be measured, as
and for the purposes set forth.
4.. The employment, in an electricity meter, of one or more retarding magnets
for resisting the rotation of the armature and arranged substantially coincident
with the neutral line of the armature, as and for the purposes set forth.
5. As an improved mechanism for overcoming or reducing friction between a
rotating shaft of an electric meter and its bearing, the employment of a magnet
which attracts the shaft and relieves the bearing of a part of the weight of the
shaft, as and for the purposes set forth.

page_text: 6. The employment in an electricity meter of a horse shoe magnet the two
poles of which co-operate with the ends of a horizontally mounted shaft and
serve to attract the shaft so as to relieve its bearings of the weight thereof, the
said shaft being carried in adjustable brackets, whereby the magnetic attraction
may be regulated, and also preferably being carried in adjustable bearings in
said brackets, by which the shaft may be balanced with respect to the seats of
magnetic attraction, as and for the purposes set forth.
Dated this 15th day of October 1898.
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.