Improvements in Electric Meters.
Year: 1896

page_text: Improvements in Electric Meters.
I, EMILE BATAULT of 6, Rue de l'Université, Geneva, Switzerland, Doctor of
Medicine do hereby declare the nature of this invention to be as follows:-
My invention relates to apparatus for measuring the quantity or energy of electric
alternating or intermittent currents passing through a circuit.
This meter is nothing more than a very simple alternating current motor. Motor
devices as electric meters have already been proposed many times but have not been
found accurate at different loads, except perhaps when using a great consumption of
energy, what of course cannot be admitted in practice.
To inake such small motors accurate, as meters, with an unimportant supply of
energy, different auxiliary means have been employed as brakes, such as air fans,
fluid paddles and the like, combined with permanent magnets.
My combination overcomes these difficulties without any special brake, the whole
scale of registration being accurate and the starting possible with a very small
current. It consists of following parts: A shunt electro-magnet with its armature
held at a certain distance from its poles; a metallic disc, or other revolution's surface,
rotating freely in the magnetic field produced between the poles and the armature
and series coils disposed close to the rotating surface near one branch of the magnet
and carrying the current to be measured.
I sometimes carry out my invention in the following manner: A U-shaped shunt-
wound electro-magnet A A¹ A2 is placed with its branches A A2 upwards so that
their extremities come in the same horizontal level; above the U, at a small distance,
is provided a fixed horizontal armature B-armature and magnet are made of iron
wire or thin iron plates. A horizontal metallic disc D, preferably of aluminium, on
a vertical shaft C is arranged to rotate horizontally between the electro-magnet and
its armature, that is to say in the magnetic field so produced. The diameter of the
disc is about the same as the external width of the pole pieces. The inagnetism of
the shunt magnet induces eddy currents in the disc at both extremities of a same
diameter at the same time, and if the disc is caused to rotate by any given impulsion,
these eddy currents oppose themselves to its motion, the checking action varying
directly as the speed. Series coils E E¹ carrying the main current are suitably
disposed above and below the disc to one side of one of the branches of the shunt
magnet. The spiral series coils or solenoids are placed so that their axis is
perpendicular to the plane of the disc, the flat surface of the coil being parallel to the
disc, so that the current passing through them will induce also Foucault currents in
the disc.
The consequence of the two fields produced by the shunt and series coils, differing
in phase, is a torque which drives the disc; this torque being quite proportional to
the current flowing in the main coils, when the E. M. F. is constant. The speed of
the disc is proportional to the current to be measured because, as said before, the disc
revolving in a magnetic field which opposes itself to its motion, requires for said
motion a supply of energy proportional to the speed.

page_text: If the shunt magnet is not vitalized and if we pass a current in the main coils,
disposed as described, the disc shows no tendency to move even at heavy loads.
If, the series coils being taken away, the armature is perfectly symmetrical to the
magnet, that is, exactly in the plane of the U iron core (position shown as B in
Fig. 2) so that we can say that the magnetic field produced is perfectly perpendicular
to the plane of the disc, we can vitalize the.shunt magnet and the disc remains
without movement.
If we pivote the armature in its center F, so that it can be moved round F in a
horizontal plane, we see that the slightest change in its position sets the disc in
motion. In the position shewn as B B, Fig. 2, the direction of movement is that
of the arrow. A change in the position of the arinature in the other sense B³ B' runs
the disc in the opposite direction. In other words, if, after having removed the
coils E E, the armature is placed in such a position that it does not exactly cover the
poles of the shunt magnet, a motion is imparted to the disc. This motion is very
likely due to the distortion of the magnetic lines inducing eddy currents in the dise
and the direction of the rotation will be that of the distortion.
Now, the shunt being excited and the armature in the indifferent symmetrical
position, over the poles, if we bring back the main coils in their position E E¹ near
one branch of the magnet we see that, without any current passing through them, the
disc begins to move, the effect is greater still if the coils are short-circuited on
themselves.
An analogous effect is produced if instead of the main coils we approach near the
branch of the magnet any non magnetic metallic piece and is stronger still with a
magnetic one. By slightly displacing the armature round its center as said before,
we can stop this motion of the dise and find exactly a place where there is no
tendency to movement. If, in this position, we pass a current through the series
coils a driving effect is produced in the dise which, revolves at a certain speed
corresponding to the intensity of the current.
If, nothing being changed in the shunt magnet, the game current is reversed in the
main coils, the dise is driven in the opposite direction, with exactly the same speed,
even if it was full load flowing through the meter. However, in using the meter
exactly in such conditions it would not be practically quite accurate and would run
too slowly for small currents, because when the driving force is very small the friction
of the disc spindle, even when reduced to a minimum, introduces an error; this error
can, from what we have seen, be easily corrected by putting the armature in such a
position that it gives to the disc a tendency to move in the direction which has been
chosen as the normal one to run the meter. This tendency to motion may be such
as to counterbalance the retarding effects of friction, without giving any actual
motion to the disc. I have noticed that with an aluminium dise, which metal is
never quite free from impurities, this tendency to movement may even be
exaggerated and impart a very slow motion to the disc in certain positions, the disc
stopping always again nearly in the saine positions. It is altogether advisable not
to have too high speeds at full loads, what is easy to realize, as it is possible to begin.
to meter very accurately with low speeds, two revolutions in one minute or even less.
If higher speeds than 2 or 3 revolutions in one second were wanted, it might be that
the influence of the friction of the air on the disc would cause a slight defect of
registration, which could be counterbalanced by introducing in the center of one
or both of the series coils a small iron core, of which the volume and the distance to
the dise could be determined to exactly produce the wanted effect. A mange of speed
from 1 to 70 or 80 may easily be obtained without any iron core in the series coils
and with great accuracy.
An advantage of the U disposition of the shunt magnet with a horizontal dise is
that, the Foucault currents induced in the disc have a tendency to lift it up,
diminishing partly in that way, its weight, and producing a slight trepidation which
is a good condition for its free motion. This condition may be still exaggerated by
putting in the lower part of the disc spindle a small round iron core G and 'by
bending inwards some of the iron plates of the shunt magnet, as in H H', so that

page_text: they come a little over the iron core G. Under such circumstances a part of the
magnetic lines of the shunt magnet passes through this accessory core and lift it up,
so that the weight of the disc and spindle is only the difference between the force of
gravitation and the magnetic force tending to lift up the core.
I do not confine myself to an armature being placed above the shunt magnet. This
armature might be a second magnet placed above the first one and so excited that
the magnetic field would be in the same conditions as with the armature, that is,
both magnets being in the same phase and adding their magnetic actions.
To avoid the variations that might be introduced by applying near the meter
metallic masses, especially iron pieces, it is good to put on both external sides of the
branches of the shunt magnet and near them, iron screens K K1, going nearly as
high as the upper part of the armature. These screens make the meter run quicker
but proportionaly so on the whole scale, so that no error of registration results from
them.
Our iron case round the instrument has the same effect but changes the conditions
of speed when the meter is covered by its box or not, what is inconvenient.
For the three wire distribution another pair of coils may be placed near the second
branch of the U shunt magnet as shown in L, or. the two coils near one branch may
be independent and used separately, as it is not necessary to have two main coils to.
drive the disc, one only can be employed if wanted.
For biphased meters I employ two shunt magnets M, N, placed at two opposite
extremities of a same diameter of the disc, as shown in Fig. 3. The pole pieces of
each shunt magnet in this case are so disposed above and below the disc, at its
periphery, that Foucault currents are induced in it. The series coils P P and R R¹
are placed near the pole pieces, as before, and separate for each shunt which is
excited by a different phase.
Here again is an observation to be inade. If a shunt magnet is vertically placed,
as just described, with its pole pieces above and below the horizontal disc, so that it
is perfectly symetrical to the disc, the axis of its cores being normal to the tangent
at the periphery, that is to say in the prolongation of a radius, no motion is imparted
to the disc when the series coils have been removed. But, if the magnet remaining
vertical we move it so that the cores are no more in the line of a diameter (as in.
position M¹) the disc is driven in one direction; and it is driven in the opposite
direction if the displacement of the shunt magnet is made in the other way. Owing
again to these simple means, we can regulate the starting speed of the meter to
obtain an accurate registration which could also be employed for a single phase,
both electro-magnets being preferably in one shunt, for the two or three wires
distribution.
Dated this 10th day of November 1900
I, EMILE BATAULT of 6, Rue de l'Université, Geneva, Switzerland Doctor of
Medicine, 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 :--
My invention relates to apparatus for measuring the quantity or energy of electric
alternating or intermittent currents passing through a circuit.
This meter is nothing more than a very simple alternating current motor. Motor.

page_text: devices as electric meters have already been proposed many times, but have not been
found accurate at different loads, except perhaps when using a great consumption of
energy, what of course cannot be admitted in practice.
To make such small motors accurate as meters with an unimportant supply of
energy, different auxiliary means have been employed as brakes, such as air fans,
fluid paddles and the like, combined with permanent magnets.
My combination overcoines these difficulties without any special brake, the whole
scale of registration being accurate and the starting possible with a very small current.
It consists of following parts: A shunt electro-magnet with its armature held at a
certain distance from its poles; a metallic disc, or other solid of revolution, rotating
freely in the magnetic field produced between the poles and the armature and series
coils disposed close to the rotating surface near one branch of the magnet and carrying
the current to be measured.
I, sometimes carry out my invention in the following manner: A U-shaped shunt-
wound electro-magnet A A³ A2 (Fig. 1 of the drawings filed with my Provisional
Specification) is placed with its branches A¹ A2 upwards so that their extremities come
in the same horizontal level; above the U, at a small distance, is provided a fixed
horizontal armature B-armature and magnet are made of iron wire or thin iron
plates.
A horizontal metallic disc D, preferably of aluminium, on a vertical shaft C'is
arranged to rotate horizontally between the electro-magnet- and its armature, that is
to say in the magnetic field so produced.
The diameter of the dise is about the same as the external width of the pole pieces.
The magnetism of the shunt magnet induces eddy currents in the disc at-both
extremities of a same diameter at the same time, and if the disc is caused to rotate
by any given impulsion, these eddy currents oppose themselves to its motion, the
checking action varying directly as the speed. Series coils E E¹ carrying the main
current are suitably disposed above and below the disc to one side of one of the
branches of the shunt magnet. These spiral series coils or solenoids are placed so
that their axis is perpendicular to the plane of the disc, the flat surface of the coil
being parallel to the disc, so that the current passing through them will induce also
Foucault currents in the disc.
The consequence of the two fields produced by the shunt and series coils, differing
in pluse, is a torque which drives the dise; this torque being quite proportional to
the current flowing in the main coils, when the E.M.F. is constant. The speed of the
dise is proportional to the current to be measured because, as said before, the disc
revolving in a magnetic field which opposes itself to its motion, requires for said
motion a supply of energy proportional to the speed.
If the shunt magnet is not vitalized and if we pass a current in the main coils,
disposed as described, the dise shows no tendency to move even at heavy
loads.
If, the series coils being taken away, the armature is perfectly symmetrical to the
magnet, that is, exactly in the plane of the U iron core (position shown as Bin Fig. 2)
so that we can say that the magnetic field produced is perfectly perpendicular to the
plane of the disc, we can vitalize the shunt inagnet and the disc remains without
movement.
If we pivote the armature in its centre F, so that it can be moved round F in a
horizontal plane, we see that the slightest change in its position sets the dise in
motion. In the position shewn as B' B, Fig. 2, the direction of movement is that of
the arrow. A change in the position of the armature in the other sense B3 B4 runs
the disc in the opposite direction. In other words, if, after having removed the
coils E E, the armature is placed in such a position that it does not exactly cover the
poles of the shunt magnet, a motion is imparted to the disc. This motion is very
likely due to the distorsion of the magnetic lines inducing eddy currents in the disc,
and the direction of the rotation will be that of the distortion.
Now, the shunt being excited and the armature in the indifferent syminetrical
position, over the poles, if we bring back the main coils in their position E E' near

page_text: one branch of the magnet, we see that without any current passing through them,
the disc begins to move. The effect is greater still if the coils are short-circuited on
themselves.
An analogous effect is produced if instead of the main coils we approach near the
branch of the magnet any non-magnetic metallic piece and is stronger still with a
magnetic one. By slightly displacing the armature round its center, as said before,
we can stop this motion of the disc and find exactly a place where there is no tendency
to movement. This motion may be stopped also by providing near the branch of the
magnet, but on the side opposite to the main coils, any metallic piece of suitable
size. If, in these conditions, we pass a current through the series coils a driving
effect is produced in the dise which revolves at a certain speed corresponding to the
intensity of the current.
If, nothing being changed in the shunt magnet, the same current is reversed in
the main coils, the dise is driven in the opposite direction, with exactly the same
speed, even if it was full load flowing through the meter. However, in using the
meter exactly in sneh conditions it would not be practically quite accurate and would
run too slowly for small currents, because when the driving force is very small, the
friction of the disc spindle, even when reduced to a minimum, introduces an error;
this error can, from what we have seen, be easily corrected by putting the armature
in such a position that it gives to the dise a tendency to move in the direction
which has been chosen as the normal one to rim the meter, or also by means of any
metallic piece of suitable size fixed as said before, opposite to the main coils.
This tendency to motion may be such as to counter-balance the retarding effects
of friction, without giving any actual motion to the disc. I have noticed that with
an aluminium dise, which metal is never quite free from impurities, this tendency to
movement may even be exaggerated and impart a very slow motion to the disc in
certain positions, the dise stopping always again nearly in the same positions.
It is altogether advisable not to have too high speeds at full loads, what is easy to
realize, as it is possible to begin to meter very accurately with low speeds, two
revolutions in one minute or even less.
The main coils may be provided with an iron core of suitable volume and the cores
of the upper and lower coil connected together externally by an iron armature. In
this case the action on the disc is greater than without iron, but remains
proportional.
An advantage of the U disposition of the shunt magnet with a horizontal dise is
that the Foucault currents induced in the disce have a tendency to lift it up,
diminishing partly in that way its weight, and producing a slight trepidation which
is a good condition for its free motion.
This condition may be still exaggerated by putting in the lower part of the dise
spindle a small round iron core G and by bending inwards some of the iron plates of
the shunt magnet, as in H H', so that they come a little over the iron core G.
Under such circumstances a part of the magnetic lines of the shunt magnet passes
through this accessory core and lift it up, so that the weight of the disc and spindle
is only the difference between the force of gravitation and the magnetic force tending
to lift up the core.
I do not confine myself to an armature being placed above the shunt magnet.
This armature might be a second magnet placed above the first one and so excited.
that the magnetic field would be in the same conditions as with the armature, that
is, both magnets being in the same phase and adding their magnetic actions.
To avoid the variations that might be introduced by applying near the meter
metallic masses, especially iron pieces, it is good to put on both external sides of the
branches of the shunt magnet, and near them, iron screens K K', going nearly as
high as the upper part of the armature, or even a complete iron casing all round,
These screens make the meter run quicker but proportionaly so on the whole scale,
so that no error of registration results from them.
For the three wires distribution another pair of coils may be placed near the second
branch of the Ụ shunt magnet as shown in I, or the two coils near one branch may

page_text: be independent and used separately, as it is not necessary to have two main coils to
drive the disc, one only can be employed if wanted.
For biphased meters I employ two shunt magnets M, N, placed at two opposite
extremities of a same diameter of the disc, as shown in Fig. 3. The pole pieces of
each shunt magnet in this case are so disposed above and below the disc, at its
periphery, that Foucault currents are induced in it. The series coils P P and R R¹
are placed near the pole pieces, as before, and separate for each shunt which is excited
by a different phase. Three magnets may be used for triphased currents, with three
pairs of series coils.
Here again is an important observation to be made. If a shunt magnet is vertically
placed, as just described, with its pole pieces above and below the horizontal disc, so
that it is perfectly symmetrical to the disc, the axes of its cores being normal to
the tangent at the periphery, that is to say in the prolongation of a radius, no motion
is imparted to the disc when the series coils have been removed. But, if the magnet
remaining vertical we move it so that the cores are no more in the line of a diameter
(as in position M¹) the disc is driven in one direction; and it is driven in the opposite
direction if the displacement of the shunt magnet is made in the other way. Owing
again to these simple means, we can regulate the starting speed of the meter to
obtain an accurate registration, which could also be employed for a single phase,
both electro magnets being preferably in one shunt, for the two or three wires
distribution.
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. In an electricity meter, the combination of a shunt electro-magnet provided at
distance with a movable armature or of several displaceable shunt electro-magnets,
with a disc or other solid of revolution rotating in the magnetic field produced by
said electro-magnet or magnets; and with one or several solenoids carrying the
current to be measured and disposed on the side and close to a pole of the magnet,
their axis being parallel to that of the rotating solid; (said solenoids being eventually
provided with magnetic cores and having externally a magnetic iron connection
between them) in order to produce, under the influence of the eddy currents induced
in the movable body, in one way by the magnets and in the other by the solenoids
an adjustable torque, this torque being proportionnate to the current to be
measured.
2. In an electricity meter of the kind claimed above the combination of a shunt
excited electro-magnet with a movable armature situated in front of the pole pieces
in order to produce by the lateral displacement of the armature a change in the speed
of rotation of the body moving in the magnetic field, rotation produced as said by the
influence of the presence of the main coils.
3. In an electricity meter of the kind claimed above, the combination of two
shunt inagnets either excited separately or together in tension, the lateral displace-
ment of which produces a change in the speed of rotation of the moving body.
4. An electric meter as herein before described consisting of a shunt electro-
magnet A A¹ A with its armature B movable round its center F, of a rotating dise
and of series coils E E¹, respectively L L' placed near the poles.
5. In an electricity meter as above described, with symmetrical magnetic field, the
regulation of the movement imparted to the disc by the influence of the presence of
the main coils, by providing on the opposite side of these coils any metallic piece of
suitable size..
C