Improvements in Apparatus for Measuring and Recording Electric Currents.
Year: 1897

page_text: Date of Application, 6th Aug., 1897
Complete Specification Left, 4th May, 1898-Accepted, 4th June, 1898
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Measuring and Recording Electric
Currents.
I, HERMANN ARON, of No. 6, Lützowstrasse, Berlin, in the Kingdom of Prussia, in
the Empire of Germany, Dr. Philos. and Professor, do hereby declare the nature of
this invention to be as follows:-
:—
My invention relates to improvements in apparatus for measuring and recording
electric currents, and particularly to apparatus of that class in which oscillations
varying under the influence of electrical powers are utilised for measuring the
powers. The oscillations employed are of the kind of pendulum or balance oscilla-
tions, that is of such oscillations moving about a centre of equilibrium under the
influence of directing forces, that is without the aid of any outside means as for
instance the oscillations of a reversing motion or switch. The great simplicity of
a device of this principle affords a particular inducement for adopting a construction
based thereon. In practice, however, there are considerable difficulties opposed in
the way to realisation, and the single trials, of which I am aware, those of Boys
(patented in England No. 4472, 1881, and No. 3434, 1882), failed to lead to useful
results.
The principle, nevertheless, may be successfully employed for constructing
Ampère hour, as well as Watt hour meters. The realisation of either of them is
subject to difficulties of its own.
The Ampère hour meter, for the first, is that of greater simplicity; apparatus of
this kind, exclusively, have been the object of the endeavours of Boys, above.
referred to. In this case the apparatus consists of an iron needle arranged within
the magnetic field of the current to be measured, the oscillations of which needle
are directly transferred to a counting gear. Such transmission is performed in the
same manner as the number of oscillations of a pendulum of clockwork is trans-
ferred to a dial, that is, by means of a driving power and escapement.
The difficulty in constructing an apparatus of this kind exists, first, in providing
means for entertaining oscillations of the kind described. This question is so much
more difficult than with a clockwork, as the regulating forces for the pendulum or
the balance of clockwork are constant, while in the present case they vary within
wide limits. If, in apparatus as those invented by Boys, Ampère hours are to be
measured and recorded within the limits from 1 to 100, oscillations within the same
limits and regulating forces within the squares of such limits, that is from 1 to
10,000 must be taken into consideration. It will be understood, then, that the
difficulties are increasing out of proportion. From this point of view an apparatus
measuring C.E. that is the square root of Watt hours, offers but little
difficulties. For, owing to the fact of the tension E being nearly constant, the
counting operation of the apparatus, in fact, need only be performed approximately
within the limits of the square root of C, and, accordingly, in the given example,
where the current varies within the limits from 1 to 100, the oscillations in said
apparatus will only vary within the limits from 1 to 10, and the regulating forces
7

page_text: within the limits from 1 to 100, whereby the realisation of the practical performance
is materially facilitated.
The means for obtaining the oscillations of the kind described consist of a device
similar to that employed in a Watt-meter, comprising a stationary coil connected
to the main circuit, and an oscillating coil connected in a shunt-circuit. A
difference exists, however, between the arrangement in a Watt-meter and that of
the present device relative to two essential features, namely, firstly, that the magnetic
fields of the main coil and of the shunt coil are parallel to each other in the state of
equilibrium, instead of crossing each other, as in a Watt-meter, and, secondly, that
no spring power or other forces are employed, as in a Watt-meter, to control the
position of the needle and to perform the measuring action.
The improved
apparatus of my invention contains, indeed, two spiral springs, but they are destined
to serve quite another purpose, namely, to conduct the current to the swinging
coil, and these springs must be so soft, that in any case, they are unable to control
the needle, so that the needle will not be able to oscillate under the sole influence
of the said springs, as otherwise the instrument would be started while no current
is flowing through the circuit. But it is not alone for this that the said springs
must be very soft, their influence must be nought compared with that derived from
the current, as otherwise the desired true correctness of the oscillations would be
impaired.
Now, even if we succeed in establishing and maintaining oscillations of that kind,
which are proportional to the square root of C.E. we are still far from having
attained the object in view, to provide an electricity counter, the task of which
being not to measure the square root of C.E. but the square of that amount, that
is of C.E. itself.
I will now describe how I tried to realise this scheme :-
In combination with the main-work (which may be a clockwork) to produce
oscillations proportional to ✓C.E., I employ a clockwork of any common
construction, the accuracy of which in measuring time is of no importance, and,
accordingly, this clockwork might as well be replaced by any train of wheels or a
motor of in some degree regular motion, but after all a plain clockwork may
preferably be employed. This clock or wheelwork, which in opposition to the
main-work, I will call the auxiliary work, is not going continually, but is only
periodically set free by the action of the maiu-work, and, by being set free, it will,
during part of its motion, couple the main-work with a third train of wheels,
the counting work, from which the records of the Watt hours may be read
directly.
The theory of thus mechanically squaring the amounts obtained, is as
follows:-
1
1
Supposing the number n of oscillations performed by the main-work to be a /C.E.
in a given unity of time Z, then the duration of one oscillation will be
After a certain number m of oscillations of the main-work, the said auxiliary work is
--
ጎኒ a/C.E.
set free, the periods occurring being T=-
m
m
or T=
n
aČ.E.
the number N of such
1
a C.E.
=
יני
m
periods T in the unity of time Z, accordingly, will be N
During
each of said periods T the main-work will be coupled to the counting work through
the agency of the auxiliary work, during a given time t, which latter may be chosen
at convenience, but must be inferior to T. Within the said time t, the main-work
will perform t.n oscillations and this amount will be transferred to the counting
work. Now, as in the given unity of time Z, the number of periods T is N, the
said counting work will advance in the said unity of time Z by t.n.N.
oscillations. If we put the corresponding values instead of n, and N, we
t.a

page_text: As t, c, m, are constants, it will be seen that the indications of the counting
work are proportional to C.E., and, accordingly, the instrument records the Watt
hours.
The method herobefore described of transferring a motion, which is proportional
to C.E. to a counting work in such a manner that the motion of the latter will be
proportional to C.E. is one of general application and independent of the method
and means employed to create the motion of the main-work, the said method of
transferring notion, accordingly, would also be applicable in connection with a
nain-work, which moves in any other manner, but always proportional to
Dated this 5th day of August 1897.
C.E.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Measuring and Recording Electric
Currents.
I, HERMANN ARON, of No. 6, Lützowstrasse, Berlin, in the Kingdom of Prussia,
in the Empire of Germany, Dr. Philos. and Professor, 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 improvements in apparatus for measuring and recording.
electric currents and particularly to apparatus of that class, in which oscillations
varying under the influence of electrical powers, are utilised for measuring said
powers. The oscillations employed are of the kind of pendulum or balance
oscillations, i.e. of such oscillations moving about a centre of equilibrium undor
the influence of directing forces, i.e. without the aid of outside means, as for
instance the oscillations of a reversing motion or of a switch.
The great simplicity of a device of this principle affords a particular inducement for
adopting a construction based thereon." In practice, however, there are consider-
able difficulties standing in the way of realisation, and the sole trials, of which I
am aware, those of Boys (patented in England No. 4472 of 1881 and No. 3434 of
1882) failed to lead to useful results.
The same principle, nevertheless, may be successfully employed for constructing
Ampère-hour-meters as well as Watt-hour-meters. The realisation of either of
them, however, is subjected to difficulties of its own.
The Ampère-hour meter, for the first, is that of greater simplicity. Apparatus
exclusively of this kind has been the object of the endeavours of Boys, above
referred to. In this case, the apparatus consists of an iron needle arranged
within the magnetic field of the current to be measured, the oscillations of which
needle are directly transferred to a counting gear. Such transmission is performed
in the same manner, as the number of oscillations of a pendulum-clock is
transferred to a dial, i.c., by means of a driving power and escapement.
The difficulty experienced in constructing apparatus of this kind consists, first,
in providing means for entertaining oscillations of the kind described. This
difficulty is the more conspicuous, as the regulating forces for the pendulum or the
balance of clock-work are constant, while, in the present case, they vary within
wide limits. If, in apparatus of the kind invented by Boys, Ampère-hours are to
be measured and recorded within the limits from 1 to 100, oscillations within the
same limits and regulating forces within the squares of such limits, i.e. from 1 to
10,000, must be taken into consideration. It will be understood, then, that the
difficulties are increasing out of proportion. From this point of view, an apparatus

page_text: measuring C.E. i.e., the square root of Watt-hours, offers but little difficulties.
For, owing to the fact of the tension E, being nearly constant, the counting
operation of the apparatus, in reality, requires only to be performed within the
limits of the square-root of C and, accordingly, in the given example, where the
current is supposed to vary within the limits from 1 to 100, the oscillations in said
apparatus will only vary within the limits from 1 to 10, and the regulating forces
within the limits from 1 to 100, whereby the realisation of the practical performance
is materially facilitated.
The means for obtaining oscillations of the kind described consist of a device
similar to that employed in a Watt-meter, comprising a stationary coil connected
to the main circuit, and an oscillating coil in a shunt circuit. A difference
however, exists between the said arrangement of coils in a Watt-meter and that of
the present invention, such difference presenting two essential features, namely,
firstly, that the magnetic fields of the main coil and of the shant coil are parallel
to each other in the state of equilibrium instead of crossing each other, as in a
Watt meter, and, secondly, that no spring-power or other forces are employed, as
in a Watt-meter, to control the position of the needle and to perform the measuring
action. The improved apparatus of my invention, indeed, also contains two spiral
springs, but they are destined to serve quite another purpose, namely, of conducting
the current to the swinging coil, and these springs must be so yielding, that, in
any case, they are unable to control the needle, so that the said needle will not
be able to oscillate under the sole influence of said springs, as, otherwise, the
instrument would be started while no current is flowing through the circuit.
But
it is not alone for this reason that the said springs must be very soft; their
influence must be nought compared with that derived from the current, as,
otherwise the desired true correctness of the oscillations would be impaired.
Now, even if we succeed in establishing and maintaining oscillations of that kind,
which are proportional to the square root of C.E., we are, still, far from having
attained the object in view, to provide an electricity counter, the aim of which
is not to measure the square root of C.E., but the square of that amount, i.e. of
C.E. itself.
I will now describe how I tried to realize this scheme.
In combination with the main work (which may be a clock-work) to produce
oscillations proportional to C.E. I employ a clock-work of any common
construction, the accuracy of which in measuring time is of no importance, and,
accordingly, this clock-work might as well be replaced by any train of wheels, or
a motor of in some degree regular motion; but, after all, a plain clock-work inay
be preferred. This clock- or wheel-work, which, in opposition to the main work,
I will call the auxiliary work, is not going continuously, but it is only periodically
set free by the action of the main work, and, in being set free, it will, during part
of its motion, couple the main work with a third train of wheels, the counting
work, from which the records of the Watt-hours may directly be read.
The theory of thus mechanically squaring the amounts obtained, is as
follows-
Supposing the number n, of oscillations performed by the main work to be
a C.E. within a given unity of time Z then the duration of one oscillation
1
1
After a certain number m, of oscillations of the main
22 a C.E.
will be
work the said auxiliary work is set free, the periods occurring being T =
T =
m
วาง
or
'
N
1 a/C.E.
==
; the number N of such periods in the unity of time Z ac-
a/C.E.
cordingly, will be N
T
M
During each of said periods T, the
main work will be coupled to the counting-work, through the agency of the

page_text: but it must be inferior to T. Within the said time t, the main work will
perform t.n. oscillations, and this amount will be transferred to the counting-
work. Now, as in the given unity of time Z, the number of periods T,
is N, the said counting work will advance, in the said unity of time Z, by t.n.N.
oscillations. If we put the corresponding values instead of n, and N, we
t.a²
receive Z =
C.E.
m
As t, c, m, are constants, it will be seen that the indications of the counting
work are proportional to C.E., and, accordingly, the instrument records
Watt-hours.
In the accompanying drawings I have illustrated mechanical means for carrying
into practice the theory before described.
Figure 1 represents a front elevation of the instrument;
Figure 2 is the same elevation with the front dial plate removed and part of the
second plate broken away;
Figure 3 is a side-elevation, and
Figure 4 a plan of the same.
Both the main work and the auxiliary work are wound up by a common device A,
which, in this case, is supposed to be an electrical winding up mechanism.
Driving power is transmitted to both works or wheel-trains by means of a spring v,
and by means of a crown-wheel m, in each of the two works, motion is transmitted
to them in such a manner, that they move independently of each other. The
balance wheel a, the anchor b, and the small centre-wheel n constitute the main
work. To increase the regulating force of the needle, and, especially to secure its
working action on the anchor b, the said anchor b is not directly attached to the
needle, but through the medium of a sector c, provided with conical teeth
engaging a small bevel gear d on the axis e of the needle, Figure 1, whereby
motion is transmitted from the anchor b, to the said axis e, in such a manner, that
the angular throw of the said axis e, exceeds that of the anchor b. The axis e, of
the needle rests with a fixed gudgeon in a step-bearing, to reduce friction in turn-
ing. The current is fed to the needle by means of the spiral springs h and h¹³,
which being extremely soft and yielding, do not the least impair the duration of
the oscillations.
The anxiliary work consists of the small centre-wheel w, the balance wheel k, and
anchor l, to which latter a small pendulum u, is attached for regulating the motion.
Fixed to the axis of this wheel w, is a disc i having as many recesses or indentations,
as determined by the proportion between the number of teeth of the small centre-
wheel w, and that of the pinion on the axis of the balance-wheel k, in the present
case the number of recesses of the disc i, is 8. The gudgeon of the balance-wheel a,
of the main work carries, in front, two small gear-wheels r and r¹. In front of the
plate which separates the main-work from the auxiliary work, a lever p, is pivotally
mounted the upper end of which lever p, carries a pin t, which extending through a
slot of said plate, bears against the circumference of disc i. The lower end or arm
of said lever p carries a stud upon which are mounted the gear-wheels q and q¹.
While the pin t, of lever p rests upon a projecting tooth of disc i, the gear wheels g
and q' are engaged by the wheels r and r¹. The former wheel r, being concentric-
ally mounted with relation to wheel r¹, but independent in motion and connected to
the counting-work, couples the main work to the counting-work.
While the said pin t, of lever P, rests in an indentation or recess of disc i, the
said gear
wheels q and q' are thrown out of engagement with the said wheels and
1, and the main work is out of connection with the counting work.
The balance-wheel k of the auxiliary work carries two projecting studs, which
serve to prevent the said balance-wheel from making more than one revolution
during every release. The lower one of said studs, normally, bears against a
lever o.
As soon as the said lever o has been lifted by a stud projecting from the
small centre-wheel n of the main work, the said lower stud of wheel k will freely pass

page_text: while the upper one of said studs will come to bear against the said lever o. As the
said lever descends, the upper stud will become free to pass and the balanco-wheel
k, will make a full turn, after which it will be stopped by the lower stud bearing
against the said lever o, in its lower position. The small centre-wheel n, of the
main work carries four projecting studs to successively lift the lever o; accordingly,
the numbers of periods N for coupling and releasing between the main work and
the auxiliary work, will be quadruple the number of revolutions of the small centre-
wheel n, while the duration of every coupling or connecting period will be equal to
that of one revolution of the balance-wheel k. The duration of every period of
coupling of the counting work through the medium of wheels r r is determined by
the time, during which the pin t of lever p rests within a recess of the disc i.
The method hereinbefore described, of transferring a motion, which is propor-
tional to C.E. to a counting work in such a manner, that the motion of the latter
will be proportional to C.E., is one of general application and independent of the
method and means employed to create the motion of the main work. The said
method of transferring inotion, accordingly, would equally be applicable in connec-
tion with a main-work which moves in any other manner but always proportional
to ✓C.E.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. Apparatus for measuring and recording electric currents, so constructed as to,
first, create by the magnetic influence of the forces to be measured, a motion pro-
portional to C.E. and to then change said motion by an auxiliary work into one
proportional to C.E. substantially as and for the purpose set forth.
2. Apparatus for measuring and recording electric currents, so constructed as to,
first, create by means of a clock-work having a coil in shunt swinging within the
magnetic field of the main circuit (or vice versa) motion proportional to C.E. and,
to then change said motion by an auxiliary work into one proportional to C.E.,
substantially as and for the purpose set forth.
3. Apparatus for measuring and recording electric currents, so constructed as to,
first, create by means of a clock-work or wheel-train a motion proportional to
C.E. and, to then, change said motion into one proportional to C.E. by means of
a counting work periodically coupled to the main work through the medium of an
auxiliary work, substantially as described and for the purpose set forth.
Dated this 3rd day of May 1898
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.