Improvements in Electric Meters.
Year: 1889

page_text: Date of Application, 16th July, 1889
Complete Specification Left, 16th Apr., 1890-Accepted, 28th June, 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by the firm of SIEMENS & HALSKE, of 94, Markgrafen
Strasse, Berlin, Electrical Engineers.]
Improvements in Electric Meters.
We, SIEMENS BROTHERS & Co., Limited, of 12 Queen Anne's Gate, Westminster,
in the County of Middlesex, Electrical Engineers, do hereby declare the nature of this
invention to be as follows:-
This invention relates to an improved construction of electric meters, more
particularly intended for measuring electrical energy, based on the method set forth
in the Specification to Patent No. 4947 of 1883, which consisted in the continuous
measurement at successive regular intervals of time, of the product of the strength
and potential of a current passing through a conductor and to totalise the same by
means of a counter or registering mechanism, under the assumption that the indications
obtained from the counter will correspond without material error to the actual con-
sumption of electrical energy.
The present improved construction of such apparatus differs from that above alluded
to essentially in that the current to be measured has to perfortn no other work than
the movement of a light pointer, so that the consumption of energy by the apparatus
itself is exceedingly small and consequently that the currents to be ineasured by the
apparatus can differ to a very great extent."
Whether the apparatus measures the consumed energy, or the sum of the consumed
strengths of current, that is to say, the consumed quantity of electricity, only depends
upon whether the position of the pointer is made to depend upon the product of
potential and strength of current or upon the strength of current alone. As, with
central stations, the potential is always maintained constant and it is only for these
that such registering apparatus are required, the following description of the apparatus
will only deal with the measurement of the quantity of current.
The apparatus consists essentially of a light arm or lever having a suitably curved
face which is caused by clockwork to be turned on its axis at regular intervals of
time from a stated rest until it meets the end of a pointer the position of which is
determined by the strength of the current, such angular motion of the arm being
transmitted to the wheel work of a counter or registering mechanism.
Thus the position of the pointer being dependent upon the strength of the current,
and the curved face of the rocking arm which is brought in contact therewith being
so formed that the extent of the are which it passes through until it meets the pointer
is proportionate to the strength of current which determines the position of the pointer,
then the counter will totalize all the several strengths of current which existed at the
times of measurement and will thus measure the quantity of electricity that has passed
through the circuit under the assumption that the separate measurements may each be
taken as indicating the mean strength of current passing during the interval between
two measurements, which, with continuous working, will be the case with sufficient
accuracy if the intervals between measurement are sufficiently small.
According to one mode of constructing the apparatus the movement of the measuring
arm is effected by means of an eccentric or cam shaped disc which receives continuous
regular rotary mnction by clockwork mechanism wound up by hand, the arm being
acted upon by a spring or weight so as to bear with a roller upon the eccentric or
cam so that as this rotates it allows the arm to advance towards the pointer until its
notion is arrested by the latter, the arm being held in that position until the eccentric
by its further rotation moves the arm back to its original position.
The pointer is connected to a magnetic core situated inside a solenoid through which
the current to be measured passes, which core is suspended from an adjustable spring

page_text: so that according as the strength of current increases or decreases, the core, in being
drawn more or less into the solenoid against the action of the spring will bring the
pointer into correspondingly varying positions. When, by the weakening of the
current the magnetic core is drawn upwards by the spring so as to bring the pointer
into such close proximity to a point of the arm near its axis that this is thereby
prevented from advancing at all, this position corresponds to the zero position of the
parts in which the current passing is so weak as not to be measured.
When on the other hand the strength of the current increases to such an extent that
the core in descending brings the pointer into the opposite extreme position in which
it will come in contact with a point near the extreme end of the arm when this moves
forward the apparatus will then measure the maximum strength of current capable of
being indicated thereby.
The intermediate points of the curved face of the arm are determined empirically so
as to cause the corresponding movements of the arin when it comes in contact with
the pointer at one or other of these points, to be always in proportion to the strength
of the current; this being so it will not signify whether the movements of the pointer
are always proportional to the strength of current or not, as, should from any cause,
such as variation in the magnetisın of the core, the positions of the pointer vary in
respect to a certain strength of current, it will only be necessary to adjust the position
of the core and pointer by means of the before mentioned regulating spring so that
the pointer allows of the correct amount of movement of the arm for a certain strength
of current in a certain position for it to operate correctly in every other position.
The motion of the arin may be transmitted to the counter by a pawl and ratchet
mechanism or by other suitable means. For reducing the friction of the pointer axis
as much as possible it is mounted with pointed ends in hard steel curved grooves of
greater angle than the angle of the pointed ends, so that the contact only takes place
at the points.
In order to ensure the correct position of the axis ends in these grooves, bevilled
filling pieces are inserted in the latter over the points, after these have been introduced
and are secured therein.
For obviating the necessity of frequently winding up the clockwork mechanism and
of employing powerful clockwork the following modified construction of the apparatus
is employed.
Instead of connecting the pointer to the magnetic core in such manner that the
former is in its position nearest the axis of the rocking arin when the core is with-
drawn from the solenoid by the spring that is to say when the current is weakest, the
reverse arrangement is adopted, this arrangement having the advantage that very
weak currents can be more accurately registered, in this case the arm is drawn back
by a spring against a fixed stop, which is so regulated that when no current is passing
the pointer being in its highest position is opposite and in close proximity to the
extreme division on the outer end of the arm, the curvature of which is in this case
convex relatively to the pointer. The forward motion of the arm towards the pointer
is in this case effected by means of a small fixed electro-magnet or solenoid with fine
wire coils which when excited attracts an armature or core pivotted loose on the axis
of the arm but connected to the arm by a spiral spring which is slightly stronger than
the first named spring that draws the arm back against the stop so that when the
armature is attracted by the electro-magnet the arm is drawn by the spiral spring
gently towards the pointer and is held there as long as the electro-magnet is excited,
after which the arm is drawn back by the other spring. The coils of the electro
magnet are in a shunt circuit of high resistance to the main circuit so that, when the
shunt circuit is closed the electro-magnet is always excited in a very uniform manner.
The closing of the shunt circuit may be effected in any known manner, by which a
current of short duration is established at regular intervals of time.
Thus for example it may be effected by means of a clockwork mechanism consisting
of an anchor escapement driven by a light spring and toothed gear, the spring being
wound up at each forward motion of the rocking arm by means of a toothed sector
carried by the same acting on a ratchet and pawl arrangement connected to the spring.

page_text: The clockwork effects the continuous rotation of a cam having one or drops, which
acts upon two contact springs so as to cause these to make and break a contact in the
shunt circuit one or more times in every revolution, the two springs being in con-
ducting connection and so arranged that when the one spring passes the nose of the
drop it suddenly establishes the contact and when immediately afterwards the other
spring passes the drop, the circuit is as suddenly interrupted again.
The electro magnet or solenoid can be enclosed in an iron casing to prevent it from
being influenced by the approach of other inagnets.
If the above described apparatus are to be employed for measuring the electrical
energy of circuits in which the potential is subject to considerable variations, there
may be used in place of the magnetic or soft iron core connected to the pointer, a
solenoid of fine wire which may enter the fixed solenoid in the same way as the core,
but which is preferably arranged as follows:-
The moveable solenoid is fixed on the spindle of the pointer which is arrangeri in
the middle thereof, and projects at right angles to its plane.
This solenoid is made of oblong form and is situated within the loops of two fixed
solenoids placed with their planes at right angles thereto, the spindle carrying the
noveable solenoid and pointer being made to conduct the current to the solenoid.
This may be effected in various ways; thus the one end of the spindle may be carried
in a mercury cup in which the one lead from the circnit dips, while the other end of
the spindle passes through a cup of glass pebble, or other non-amalgamatable material
which is also filled with mercury and into which dips the other lead. The hole of the
cup through which the spindle passes fits the spindle so nearly that the mercury
cannot leak through on account of the capillary repulsion.
The pointer and solenoid are adjusted in their zero position by means of a spiral
spring, one end of which is attached to the spindle while the other end is attached to
an adjusting screw the torsional force of the spring being such as to allow the pointer
to pass to the other extreme position when measuring a current of maximum force.
The curved face of the rocking arm is so formed that the angular movements which
the arin performs in advancing towards the pointer are proportional to the product
of potential and strength of current.
Duted this 16th day of July 1980
ABEL & IMRAY
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Electric Meters.
We, SIEMENS BROTHERS & Co. Limited of 12 Queen Ann's Gate, Westminster
in the County of Middlesex, Electrical Engineers, 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 :-
This Invention relates to an improved construction of electric meters, more
particularly intended for measuring electrical energy based on the method set forth
in the Specification to Patent No. 4947 of 1883 which consisted in the continuous
measurement at successive regular intervals of time, of the product of the strength
and potential of a current passing through a conductor and to totalise the same by
means of a counter or registering mechanisin under the assumption that the
indications obtained from the counter will correspond without material error to the
netual consumption of electrical energy. The present improved construction of such
apparatus differs from that above alluded to essentially in that the current to he
measured has to perform no other work than the movement of a light pointer so
that the consumption of energy by the apparatus itself is exceedingly small and
consequently that the currents to be measured by the apparatus can differ to a very
great extent.
Whether the apparatus measures the consumed energy, or the sum of the
consumed strengths of carrent, that is to say; the consumed quantity of electricity,

page_text: only depends upon whether the position of the pointer is made to depend upon the
product of potential and strength of current or upon the strength of current alone.
As with central stations the potential is always maintained constant and it is only
for these that such registering apparatus are required, the following description of
the apparatus will only deal with the measurement of the quantity of current.
The apparatus consists essentially of a light arm or lever having a suitably curved
face, which is caused by clockwork to be turned on its axis at regular intervals of
time from a stated rest until it meets the end of a pointer, the position of which is
determined by the strength of the current, such angular motion of the arm being
transmitted to the wheelwork of a counter or registering mechanism.
Thus the position of the pointer being dependent upon the strength of the current.
and the curved face of the rocking arm which is brought in contact therewith being
so formed that the extent of the arc which it passes through until it meets the pointer
is proportionate to the strength of current which determines the position of the
pointer, then the counter will totalize all the several strengths of current which
existed at the times of measurement and will thus measure the quantity of electricity
that has passed through the circuit under the assumption that the separate measure-
ments may each be taken as indicating the mean strength of current passing during
the interval between two measurements which with continuous working will be the
case with sufficient accuracy if the intervals between measurement are sufficiently
small.
The accompanying drawings shew two constructions of apparatus for carrying out
the above described invention; they only differ materially in that with the arrange-
ment shewn at Figs. 1 to 4 the movement of the lever g by means of which the
measurement is carried out is effected by a cam which is rotated continuously by
clockwork, wound up from time to time by hand, while in the arrangement at
Figs. 5, 5 and 6 the lever is moved by means of an electro magnet the coils of which
have a current of short duration passed through them at fixed intervals of time by
means of an automatic contact device.
In the apparatus shewn respectively in sectional elevation and plan at Figures 1
and 2, d is a pointer lever having its pivot at f and carrying at its short arm a magnet
or iron core a suspended in a solenoid 6 and supported by an adjustable helical
spring R.
This spring is so adjusted that the point of the long arm of the pointer is situated
at the lowest division of the lever g without touching this, when no current is passing,
while with the strongest current to be measured the point is situated opposite the
highest division on the lever, so that such division touches the point when the lever is
turned forward until its motion is arrested by the pointer. This angle of motion
forms the measure of the highest admissable strength of current for which the
The curvature of the surface of the
counter of the apparatus is constructed.
lever which is presented to the pointer & is so arranged that at all intemediate
values of the strength of current and the consequent positions of the pointer edge,
which is dependent thereon, the angular motion of the lever g shall be proportionate
to the strength of current. This affords the great advantage that it is unnecessary to
arrange the magnet system in such a manner that the movement of the pointer shall
be proportional to the strength of current, or has a definite relation thereto generally.
It is sufficient to determine the curvature of the lever in such a manner that the
angular motion of this lever shall always be proportional to the strength of current
existing at the time. Should, through changes in the magnetism or other causes an
alteration in the positions of the pointer ensue, it will be sufficient to adjust the pointer
by means of the spring R for a single strength of current, whereupon it will act
correctly again for all variations of strength.
For the purpose of transmitting the angular inotion of the lever g to the counter
mechanism, the axis of the lever carries a loose ratchet wheel in which is connected by
The lever g carries a spring pawl k taking
pinion and spur wheel to the counter.
into the ratchet wheel, so that this is always turned forward to an extent equal to that
of the lever, and it is prevented from turning backward by a fixed spring pawl

page_text: The lever is itself moved by a spring r in the direction towards the pointer, while
the eccentric e rotated by the clockwork in bearing against a roller on the lever g,
presses this backward once in every revolution against the action of the spring r.
In order that the pointer may turn with the least possible friction, and shall yet
have a secure bearing, the hardened steel points of the pointers axis are supported in
are shaped angular grooves forined in very hard steel blocks as shewn at Fig. 2ª.
The axial points being made with a somewhat sharper angle than that of the grooves,
only the extreme points of the foriner will be in contact with the latter. In order to
insure the horizontal position of the axis, steel blocks accurately filling the grooves are
cut off at an angle, are pushed in from the top until they touch the points of the axis,
and are then fixed. The axis is then securely supported without touching elsewhere
than at the extreme points.
In order to avoid the inconvenience of having to wind up the clockwork frequently
or of having to use large and powerful clockwork, which inconvenience would be more
particularly felt where there is only a small consumption of electricity-the arrange-
ment shewn at Figs. 5, 5 and 6 may be used. The pointer d is in this case formed as
a one armed lever, so that when not acted upon, its point is situated opposite the
outer end of the lever g. This arrangement has the advantage that very weak
currents can be more accurately registered, in which considerable angular displace-
ments of the pointer & correspond to small angular movements of the lever g.
The measuring lever g is in this case drawn against a fixed stop i by the spring r
such stop being so regulated that when no current is passing, the edge of the pointer d
is situated opposite and close to the outermost division of lever 9, without touching it.
The turning of the lever g towards the pointer d is in this case effected by means of
a small magnet a¹ with fine wire coil 1 through the armature a². This armature is
loose on the axis of the lever g with which it is however connected by the spring.
As this spring is only slightly stronger than the spring the lever g will, on the
attraction of the armature be drawn gently towards the pointer by the spring 72 and
will be held there until the magnet ceases to be excited, when the spring will draw g
back against the stop i.
The windings of the electro magnet bare included in a shunt circuit of very high
resistance, so that the magnet will be uniformly excited when the circuit is closed.
This can be effected in any manner whereby a current of short duration is produced
at regular intervals. In the arrangement shewn it is effected by a clockwork with
anchor escapement which has only a driving barrel with spring, an escapement wheel »
and a balance wheel p, the spring being wound up at each attraction of the armature a
by means of the toothed sector e fixed thereto, to a sufficient extent to enable the
clockwork to be kept in notion until it is again wound up. For producing the short
current through the magnet windings the contact arrangement shewn detached at
Fig. 5 may be employed. On the spindle of the spring barrel is fixed a cam disc,
with two perpendicular drops 7 n², on the curved surfaces of which cam slide the
ends of two springs to and was it rotates until they pass the nose of one of the drops,
when they spring inwards. The two springs are in metallic contact, the conducting
connection between the two contact screws vl and v² is therefore established when
both springs are respectively in contact with their contact screws.
This is however only the case when the one spring w¹ has passed the nose of a drop
while the other one has not yet passed it and is consequently pressed by the cam
against its stop. This arrangement has the advantage that the contact, and con-
sequently the current is suddenly closed and as suddenly broken again, so that neither
on closing nor on breaking the circuit can an undecided action be produced which
might result in incorrect indications.
In order to prevent the apparatus from being affected by the approach of strong
Inagnets, the solenoid b can be enclosed by an iron casing o.
If the apparatus above described is to be used not only for measuring expenditure
of current, but also for measuring the electrical energy in circuits in which the
potential is subject to considerable variations, there may be used, in place of a core of
steel or iron, a solenoid formed of fine wire suspended in the fixed solenoid, the

page_text: pointer being connected to the former. It is preferred however in this case to
employ the arrangement of a rotatable solenoid within a fixed one, such as is used for
electro dynamometers.
Figs. 3 and 4 shew respectively a sectional plan and vertical section of an
arrangement of this kind with the pointer attached to the rotatable solenoid; the
other parts of the apparatus which are the saine as above described, being omitted.
The rotatable solenoid S2 made of fine wire is situated between the fixed solenoid in
two parts SS' the windings of the one being at right angles to those of the other. The
moveable solenoid is mounted upon an axis f to which is fixed the pointer d. The
axis falso serves to convey the current to the solenoid S2 this being capable of being
effected in a variety of ways. In the arrangement shewn by way of example in the
drawing, the lower point of the axis f runs in a mercury cup into which the one lead
of the circuit dips, while the upper part of the axis, the pointed end of which runs in
a suitable bearing, passes through a cup of glass stone or other material that will
not amalgamate, which is filled with mercury into which dips the other lead of the
circuit.
The hole of the vessel through which the axis f passes is made of such a size
as only to leave a very small space between it and the axis, so that the mercury
is prevented by the capillary attraction from escaping through such space.
The mercury contacts both at the upper and the lower ends of the axis may be
dispensed with and the circuit leads be connected directly thereto, the leads being
made sufficiently free to allow of the slight angular movements of the axis without
opposing any appreciabie resistance: A helical spring R turned by a button Z, serves
to adjust the movable solenoid and pointer to the position of rest, the torsional
strain of the spring being so adjusted as to allow the pointer to move to the
extreme division of the lever g when subject to the action of the maximum energy
to be measured.
The oscillating lever g, not shewn, has, as in the previous arrangements a curved
edge facing the pointer, so formed that the angular motion performed thereby until
it comes in contact with the pointer is proportional to the product of potential and
strength of current which is to be measured, so that the consumption of energy is
directly indicated on the counter.
In order to prevent the solenoids S and S" from being affected by external
magnetism, it is preferred to make them astatic.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. The herein described construction of electric meter wherein a pivotted lever
is caused at regular intervals of time to move forwards and against the end of a
pointer or rod the position of which is governed by the current to be measured,
the varying angular movements of the lever produced thereby being transinitted to
n counter by which they are totalised, substantially as herein described.
2. Constructing the contact surface of the lever referred to in the preceding
claim with a curvature such that the extent of angular motion permitted thereby
at the varying positions of the pointer will be proportionate to the product of the
strength of the current to be measured with the potential thereof or to the strength
of current only, substantially as described.
3. In apparatus such as is referred to in the first claim effecting the forward motion
of the lever by means of a spring while the backward motion is effected by an
eccentric disc or cam receiving continuous rotary motion, which disc allows the lever
to be brought gradually forward by the spring without shock against the end of the
pointer which then arrests such motion substantially as herein described with reference
to Figs. 1 and 2 of the drawings.
4. In apparatus such as is referred to in the first claim, effecting the forward
motion of the lever by means of the armature of an electro magnet which is excited
by a shunt circuit, the closing and breaking of such circuit at regular intervals

page_text: being effected by a contact apparatus actuated by a clockwork mechanism which is
wound up by the motion of the said armature, substantially as described with
reference to Figs. 5 and 6 of the drawings.
5. For effecting the momentary closing and breaking of the shunt circuit referred
to in the fourth claim, the use of two contact springs in conducting connection
with each other which are acted upon by a revolving cam with one or more drops
in such a manner that on the one contact spring passing a drop, it effects the
closing of the circuit while on the second spring passing the drop, it effects the
breaking of the circuit again, substantially as described with reference to Fig. 5^
of the drawings.
6. Supporting the pointed ends of the axis of the pointer referred to in the first
claim, in are shaped angular grooves formed in hard steel blocks, the said points
being confined in the said grooves by filling pieces fitted therein bearing against
the points with bevilled end surfaces substantially as described with reference to
Fig. 2 of the drawings,
Dated
11
4
1000
ABEL & IMRAY,
Agents for the Applicants.