Improvements in Electric Meters.
Year: 1890

page_text: Date of Application, 11th June, 1890
Complete Specification Left, 7th Mar., 1891—Accepted, 6th June, 1891
PROVISIONAL SPECIFICATION.
Improvements in Electric Meters.
We, SEBASTIAN ZIANI DE FERRANTI, of 120 Fellows Road, Hampstead, in
the County of Middlesex, Electrician, and ARTHUR WRIGHT, of 3 Clermont Road,
Preston Park, Brighton, Electrician, do hereby declare the nature of this invention
to be as follows:-
Our invention has for its object to provide means by which the accuracy and
working range of electric meters can be greatly improved and increased. By
accuracy we mean that their recording power shall be in proportion to the current
passing through the meter and by working range we mean the range between the
maximum current the meter is supposed to carry and the smallest current it will.
start or begin to record with.
Our invention is particularly applicable to those meters which consist of a
combination of some form of electric motor and a counting train, the number of
whose revolutions indicate more or less approximately the amount of current which
has passed through the motor in a given time. This form of meter we term motor
meters. As is well known owing to the friction of the counting mechanism and the
fact that the turning moment tends to make the speed of these motors increase at a
higher rate than the increase of current, great difficulty is experienced in making
the meter start with a small per centage of its full load and at the same time
preserve the constancy of its recording power, for instance in the meter patented
by A. Wright and others No. 1480 of 1889 by winding the magnet with a shunt
winding through which the current to be measured does not pass and by adjusting
the resistance of its shunt circuit the meter can be made to start with as small a
current as may be desired, but this means of obtaining a very early start has
sometimes the effect of increasing the meters recording power for the smaller
currents for instance in a 50 ampére meter it is quite possible by a shunt winding to
make the meter start with a of an ampére but if this were done it is very likely
that the number of revolutions per ampére per hour when 5 ampéres were passing
through the meter would be greater than the number of revolutions per ampére per
hour when 50 were passed through it. Our invention has for its object to provide
means by which the accuracy of the recording power shall be maintained without
diminishing its working range or diminishing its starting power.
To do this in meters of the above kind and in all shunt wound or compound
wound meters, or meters in which an additional circuit is placed round the main
magnet through which is passed a constant current independent of the current to be
measured we provide means for diminishing the amount of current passing through
the shunt so soon as sufficient of the main current is passing through the meter to
ensure its motion not being stopped by any friction of the mechanism.
We sometimes employ a moveable contact piece, (actuated by the magnetism of
the main magnet or by a subsidiary electro magnet) which on being lifted or moved,
breaks a short circuiting contact and inserts an extra resistance in the shunt circuit
when the meter has fairly started. The insertion of this extra resistance at this
early period can be made to correct any increased recording power for small values
of current over that for the higher current, which it would have, had this resistance
not being inserted, while the fact of this resistance being short circuited or cut out
before the meter has started or is going with sufficient force to get over friction
will insure a comparatively large current going through the shunt circuit to help
start the meter at low current values.
This insertion of an extra resistance in the shunt circuit by which the shunt
current is diminished after the meter has fairly started can also be effected by the

page_text: mechanical effects of the rotation of the motor such as a contact breaker actuated
by some form of centrifugal governor which is made to act on a sufficiently high
speed being reached or again by any mechanical action resulting from the rotation
of the motor's armature-for instance the movement of air set in motion by a fan
on the armature's axis can be made to actuate this shunt contact piece. Instead of
a definite resistance being inserted by the above contact mechanism the shunt
circuit can be altogether broken. More than a single resistance might be used and
the resistances be introduced one after the other as the speed of the meter increased.
Or the strength of current passing through the shunt circuit when the meter had
fairly started might be varied without the use of contact mechanism. For example
the additional coils of the meter might be supplied with current from the secondary
coils of a converter through the primary coils of which the shunt current is made
to pass and the converter be so formed that as more current passed through the
primary its action on the secondary should decrease either by the movement of an
iron core varying the position of its secondary coils or in other ways.
In motor meters not compound wound that is in which the working coils are all
traversed by the current to be measured we can effect the same object by various
means of increasing their action on the armature directly or indirectly through
electro magnets of which the following are examples.
In the well known Borel form of meter where the rotation of the metallic
armature is caused by an unsymmetrical placing of a magnetic material or pole in
an alternating magnetic field, the said magnetic pole can be shifted to or from the
armature by the main working coil or an outside electro magnet traversed by the
same current so as to gradually decrease or increase the turning effect on
the armature according as to whether this tends to increase or decrease more
rapidly than the main current. Or again in the well known Schallenberger
alternating meter where a rotation of the armature is caused by the action of a main
and induced current acting on it at two different angles. The angle of the
secondary coil in which the currents are induced can be shifted automatically by
the action of the main coil on it against a spring or by an outside electro magnet or
coil in order to diminish or increase the turning moment of the two coils on the
arinature as the current is increased so as to maintain the same ratio between the
speed of rotation and the current passing at high as at low current.
In the form of induction alternating meter patented by Arthur Wright and
others, one method of attaining the above object is to provide the electro magnet
with moveable pieces of iron which will more or less alter the action of the magnet
on the armature as the main current varies. The said moveable iron piece
being actuated by an external magnet, by the main magnet or by the armatures
rotation.
The fan blades used in meters for retarding the rotation of their spindles we form
in such manner that as the speed increases they move away from positions radial
to the spindle towards tangential positions so as to decrease their action against
the air.
The edges of the fan blades which are away from the spindle may for this
purpose be secured to projections from radial aims which extend from the spindle
so that when the spindle is rotated the blades may bend away from their radial
position and their inner ends allowed to move outwards. To assist this movement
the edges of the blades nearest to the spindle may be made to carry small weights
and the deflecting of the blades be so assisted by centrifugal action.
Or instead of the fan blades being secured at their outer edges to projections from
the arms the blades might be slit so as to form them with a central free tongue with
the free end of the tongue towards the spindle and this free end of the tongue be
secured to an arm extending from the spindle leaving the remainder of the inner
end of the blade free to turn outwards and this inner end of the blade may similarly
have weights attached to it which by centrifugal action assist in inclining the blades
as the speed of rotation of the spindle increases.
Similarly if the fan blades are secured at their upper ends to arms extending from

page_text: the spindle as described in the Patent to A. Wright and others herein before
mentioned weights may be attached to the bottom edge of the blades and the arms
which carry the blades may be cranked or bent so that the centrifugal action of the
weights may assist in the inclining of the blades as the speed of rotation of the
spindle increases.
Dahi 11th day of T... 1900
COMPLETE SPECIFICATION.
Improvements in Electric Meters.
We, SEBASTIAN ZIANI DE FERRANTI, of 120 Fellows Road, Hampstead,
in the County of Middlesex, Electrician, and ARTHUR WRIGHT, of 3 Clermont
Road, Preston Park, Brighton, Electrician, 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:
Our invention has for its object to provide means by which the accuracy and
working range of electric meters can be greatly improved and increased. By
accuracy we mean that their recording power shall be in proportion to the current
passing through the meter and by working range we mean the range between the
maximum current the meter is supposed to carry and the smallest current it will
start or begin to record with.
Our invention is particularly applicable to those meters which consist of a
combination of some form of electric motor and a counting train, the number of
whose revolutions indicate more or less approximately the amount of current
which has passed through the motor in a given time. This form of meter we
term motor meters. As is well known owing to the friction of the counting
mechanism and to the fact that the turning moment tends to make the speed of
these motors increase at a higher rate than the increase of current, great difficulty
is experienced in making the meter start with a small percentage of its full load
and at the same time preserve the constancy of its recording power. For instance
in the meter patented by A. Wright and others No. 1480 of 1889 by winding the
magnet with a shunt winding through which the current to be measured does not
pass and by adjusting the resistance of its shunt circuit the meter can be made to
start with as small a current as may be desired, but this means of obtaining a very
early start has sometimes the effect of increasing the meters recording power for
the smaller currents. Thus in a 50 ampère meter it is quite possible by a shunt
winding to make the meter start with a of an ampère but if this were done it
is very likely that the number of revolutions per ampère per hour when 5 ampères
were passing through the meter would be greater than the number of revolutions
per ampère per hour when 50 were passed through it. Our invention has for its
object to provide means by which the accuracy of the recording power shall
be maintained without diminishing its working range or diminishing its starting
power.
To do this in meters of the above kind and in all shunt wound or compound
wound meters, or meters in which an additional circuit is placed round the main
magnet through which is passed a constant current independent of the current to
be measured we provide automatic mechanism for diminishing the amount of
current passing through the shunt so soon as sufficient of the main current is passing
through the meter to ensure its motion not being stopped by any friction of the
mechanism.
Various ways of effecting this in various forms of meter are shown in the
drawings hereunto annexed.

page_text: Figures 1 and 2 are elevations partly in section of a meter such as that described
in the Patent above mentioned to Wright and others with means applied to it for
decreasing the amount of current passing through the additional circuit so soon as
the meter is fairly started.
Figure 3 is a horizontal section taken through the line ab Figure 1 and
Figure 4 a horizontal section taken through the line ed Figure 1. Figure 5 is a
diagram view shewing the electrical connection.
Figure 6 is a diagram view of an arrangement in which the insertion of an extra
resistance into the shunt circuit is effected by the action of a centrifugal governor
carried by the axis of the armature.
Figure 7 is a diagram view of an arrangement in which the same result is obtained
by the action of fan blades on the armature axis.
Figure 8 is a diagram view of an arrangement in which the shunt circuit is
altogether broken by the same means.
Figure 9 is a diagram view of an arrangement in which three resistances are
introduced one after the other as the speed of the meter increases.
Figure 10 is a diagram view of an arrangement in which the amount of
current passing through the shunt circuit is controlled without the use of contact
mechanism.
In the arrangement shewn at Figures 1 to 4 the decreasing of the amount
of current passed through the additional circuit after the meter has fairly
started is effected by the then putting in of a resistance into this additional
circuit.
A is the armature composed of a metallic wheel carried on a spindle B. C'C' are
curved pole pieces of electro magnets C C made to surround the circumference of
the armature wheel A.
The current to be measured is passed through the main windings of these
electro magnets. The shunt circuit is carried through additional windings of these
magnets indicated by the dotted lines D in the diagram Figure 5. E is an
armature of soft iron situated below the lower end of the core of one of the electro
magnets and carried by a spring blade E'. When no current is passing through
the coils of the electro magnet the armature E is held down by the spring
onto a metallic contact point F. When sufficient current passes through the coils
to enable the magnet to lift the armature the armature is raised away from this
contact point.
G Gare resistance coils. Hand are two terminals to which the conductors
by which current is to be supplied are connected.
HI are two terminals by which current is led off from the meter. The two
ends of the main winding of the electro magnets C are connected to the
terminals HH A conductor J passes directly from the terminal I to the
terminal I The two ends of the additional winding of the electro magnets
are connected one to the conductor J and the other to one end of the winding of
the resistance coils G G and through them to the terminal H³. K is a wire
connecting the metallic blade E' with the wire which passes from one resistance
coil to the other.
When there is no current or but little current passing through the coils of the
electro magnets the armature E rests on the contact point F any current passing
through the additional winding D of the electro magnets would then pass through
the resistance G blade E' armature E and contact F to the terminal H' and not
through the resistance G¹ but when sufficient current is passing through the coils
to cause the armature E to be lifted away from the contact point F then the
current has to pass through both resistance coils and consequently less current
passes.
This insertion of an extra resistance in the shunt circuit by which the shunt
current is diminished after the meter has fairly started can also be effected by the
mechanical effects of the rotation of the motor such as a contact breaker actuated

page_text: by some form of centrifugal governor which is made to act on a sufficiently high
speed being reached.
In this
If desired the shunt current might be entirely broken in the same way.
Figure 6 is a diagram view of mechanism suitable for effecting this.
diagram A is the ring armature of meter fixed on to axis which carries fans C
and actuates recording mechanism D.
G is a small centrifugal governor fixed to axis B at H, the spring arms K K
carry small weights L L which on the meter revolving sufficiently fast draw up
collar M and thereby cause lever N pivoted at P to lift contact out of mercury
and thus remove the short circuit on the extra resistance coil S thus throwing this
extra resistance in series with the other coil T which is in series with the shunt
winding on the main electro magnets.
Or the insertion of an extra resistance in the shunt circuit may be effected by
any mechanical action resulting from the rotation of the motor's armature-for
instance the movement of air set in motion by a fan on the armature's axis can be
made to actuate this shunt contact piecc.
Figure 7 is a diagram view of mechanism acting in this way.
CC are the fans fixed on axis B, which on revolving in the direction shown,
cause pivotted fan H to be blown away from contact screw K and thus break the
short circuit on the extra resistance coil S.
Instead of a definite resistance being inserted by the above contact mechanism
the shunt circuit can be altogether broken in the same way as illustrated at
Figure 8.
More than a single resistance might be used and the resistances be introduced one
after the other as the speed of the meter increased.
An arrangement for effecting this is shown in the diagram Figure 9 where the
rotating fans blow on to the vanes A B and C (which vary in stiffness) and cause
them to leave their contact screws and thus successively put in more and more
resistance bobbins A' B' and C₁ so as to maintain the accuracy of the meter through
its whole range.
Or the strength of current passing through the shunt circuit when the meter had
fairly started might be varied without the use of contact mechanism.
An arrangement for effecting this is shown in the diagram Figure 10.
C is a small converter whose fine wire primary is connected to the poles of the
circuit and whose secondary is in series with the additional winding on the main
meter magnet M, alongside the main magnet winding.
A is a moveable armature completing more or less the magnetic circuit of
the small converter C according as it is more or less attracted away by the
main magnet M and thus weaken or increase the induced current generated in
its secondary.
In motor meters not compound wound that is in which the working coils are all
traversed by the current to be measured we can effect the same object by various
means of increasing their action on the armature directly or indirectly through
electro magnets of which the following are examples.
In the well known Borel form of meter where the rotation of the metallic
armature is caused by an unsymmetrical placing of a magnetic material or pole
in an alternating magnetic field, the said magnetic pole can be shifted to or from the
armature by the main working coil or an outside electro magnet traversed by the
same current so as to gradually decrease or increase the turning effect on the arma-
ture according as to whether this tends to increase or decrease more rapidly than
the main current.
An arrangement for effecting this is shewn at Figure 11.
In this figure A. is a metallic disc mounted on an axis B. CC are iron cores.
D D are coils through which the current is passed. E E are electro magnets
through the coils of which current also passes. F F are springs which hold the
cores away from the magnet poles.

page_text: When the cores C C are attracted by the magnets E E their power is increased
which in turn increases the rotating speed of the disc A thus correcting the falling
off at full load.
Or again in the well known Schallenberger alternating meter where a rotation of
the armature is caused by the action of main and induced current acting on it at
two different angles. The angle of the secondary coil in which the currents are
induced can be shifted automatically by the action of the main coil on it against a
spring or by an outside electro magnet or coil in order to diminish or increase the
turning moment of the two coils on the armature as the current is increased so as
to maintain the same ratio between the speed of rotation and the current passing
at high as at low current.
An arrangement for effecting this is shown at Figure 12.
A is a disc mounted on a spindle B. C is the secondary coil surrounding the
disc and capable of being rocked around its spindle. DD are primary coils through
which the current is passed. E is an iron armature fixed to the secondary coil.
is an electro magnet through the coils of which the current is also passed.
When the armature is drawn towards the magnet additional power is induced in
the coil, thus increasing the speed of rotation of the disc A. and correcting the falling
off which would otherwise take place at full load.
In the form of induction alternating meter patented by Arthur Wright and
others, one method of attaining the above object is to provide the electro magnet
with moveable pieces of iron which will more or less alter the action of the magnet
on the armature as the main current varies. The said moveable iron piece
being actuated by an external magnet, by the main magnet or by the armature's
rotation.
An arrangement for effecting this is shewn at Figure 13.
A is the armature carried by a spindle B. CC are elongated pole pieces of
electro magnets D D. E is an iron bar drawn away from the tail ends of the pole
pieces C by springs F. When the iron bar E is drawn towards the magnet poles
the power of the magnets is increased and the tendency of the rotation of the
disc to be too little when full current is passing is corrected.
The fan blades used in meters for retarding the rotation of their spindles we
form in such manner that as the speed increases they move away from positions
radial to the spindle towards tangential positions so as to decrease their action
against the air.
The edges of the fan blades which are away from the spindle may for this purpose
be secured to projections from radial arms which extend from the spindle so that
when the spindle is rotated the blades may bend away from their radial position
and their inner ends allowed to move outwards. To assist this movement the edges
of the blades nearest to the spindle may be made to carry small weights and the
deflecting of the blades be so assisted by centrifugal action.
In Figure 14 we have shewn fan blades carried in this way by the armature
spindle of an electric meter.
A represents an armature. Bits spindle. CC radial arms standing out from
the spindle. The outer ends of these arms are bent so as to be parallel with the
spindle and have fan blades D of mica or like material secured to them.
EE are small weights secured to the edge of the blades which is nearest to the
spindle so as to assist in the deflecting of the blades by centrifugal action.
Instead of the fan blades being secured at their outer edges to projections from
the arms the blades might be slit so as to form them with a central free tongue
with the free end of the tongue towards the spindle and this free end of the
tongue be secured to an arm extending from the spindle leaving the remainder of
the inner end of the blade free to turn outwards and this inner end of the blade
may similarly have weights attached to it which by centrifugal action assist in
inclining the blades as the speed of rotation of the spindle increases. This
construction is shown at Figure 15.

page_text: Similarly if the fan blades are secured at their upper ends to arms extending
from the spindle weights may be attached to the bottom edge of the blades and the
arms which carry the blades may be cranked or bent so that the centrifugal action
of the weights may assist in the inclining of the blades as the speed of rotation of
the spindle increases. A side elevation and plan view of this construction are shewn
at Figures 16 and 17.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The combination in an electric motor meter of a main winding through which
the current to be measured passes, a spindle driven by the action of the current
passing through this winding, a second winding through which a shunt current passes
and assists in driving the spindle and mechanism whereby the amount of current
passing through the shunt circuit is decreased or the passage of current through it
entirely arrested when the meter is fairly started.
2. The combination in an electric motor meter of a main winding through which
the current to be measured passes, a spindle driven by the action of the current
passing through this winding, a second winding through which a shunt current
passes and assists in driving the spindle, and mechanism whereby increased
resistance is thrown into the shunt circuit when the meter is fairly started.
3. The combination in an electric motor meter of a main winding through which
the current to be measured passes, a spindle driven by the action of the current
passing through this winding, a second winding through which a shunt current
passes and assists in driving the spindle, and mechanism brought into action by
the passing of current in the main winding to decrease or arrest the passage
of current through the shunt or additional winding when the amount of current
passing in the main winding is sufficient to keep the spindle of the meter in
rotation.
4. The combination in an electric-motor meter of a main winding through which
the current to be measured passes, a spindle driven by the action of the current
passing through this winding, a second winding through which a shunt current
passes and assists in driving the spindle, and mechanism brought into action by
the passing of current in the main winding to decrease or arrest the passage
of current through the shunt or additional winding as the speed of rotation of
the spindle increases.
5. The combination in an electric motor meter of a main winding through which
the current to be measured passes, a spindle driven by the action of the current
passing through this winding, a second winding through which a shunt current
passes and assists in driving the spindle, and mechanism for decreasing or cutting
off the passage of current through the shunt circuit brought into action by the
rotation of the spindle of the meter.
6. The combination of the armature A, spindle B, electro magnets C with their
pole pieces passing around the circumference of the armature, the main winding
of the electro magnets C through which the current to be measured is led, the
additional winding through which a shunt current is led, resistances G G through
which the shunt current also passes, and the armature E and contact F for short
circuiting one of the resistances substantially as described.
as
7. In motor meters in which the working coils are traversed by the current
to be measured, increasing or decreasing their action on the armature
may be required by the action of electro magnets energized by the passing
current.
8. Securing fan blades to the spindles of electric meters in such a manner that
as the speed increases they are by centrifugal action made to move away from
positions more or less radial to the spindle towards tangential positions so as to
decrease their action against the air.

page_text: 9. Securing fan blades to the spindles of electric meters in such a manner that as
the speed increases they are by centrifugal action moved towards positions in which
their action against the air is decreased.
•
10. The employment of small weights carried by the blades to increase
this action.
Dated this 6th day of March 1891
S. Z. DE FERRANTI.
ARTHUR WRIGHT.