Improvements in Apparatus for Measuring Electric Currents.
Year: 1892

page_text: Date of Application, 24th June, 1892
Complete Specification Left, 20th Mar., 1893-Accepted, 20th May, 1893
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Measuring Electric Currents.
1, HERMANN ARON of 6 Lützowstrasse in the City of Berlin in the Kingdom
of Prussia and Empire of Germany, Dr. Philosophy & Professor, do hereby declare
the nature of this invention to be as follows:-
My invention relates to that class of apparatus for measuring electric currents
for which I have obtained Letters Patent in Great Britain No. 6770 dated
April 24th, 1884 and No. 8856 dated June 20th, 1887, and in which a clock-work
or clock-works are employed to indicate the deviations from the true time caused
by the influence of the current to be measured.
The object of my present invention is, first, to provide an improved construction
of the escapement of the clock or clocks, for the purpose of preventing undue
influences, such as the influence of terrestrial magnetism exercised on the escape-
ment wheels of the usual construction, and, secondly, to provide a common driving
mechanism for the two clock or wheel works of the incasuring apparatus.
With electricity-counters of the class before mentioned, the exactness of the
indications materially depends on two particulars, namely, the form or shape and
arrangement of the measuring parts and the suitable size of the angle of oscillation.
The latter circumstance is of particular consequence and offers considerable
difficulties in clock-work regulated by an escapement instead of by a pendulum.
If in a measuring apparatus of the kind before stated, we observe the effect
worked by the electrical circuits on the magnets and vice versa during the different.
phases of motion, we find that the influence is a periodical function of the angle of
Oscillation. This force is dependent on the distribution of the lines of force, and
besides, it is at any moment proportional to the sine of the said angle of oscillation,
the said sine, however, varies within wide limits during one revolution, changing
from 0 to 1 at 90 degrees and returning from 1 to 0 and from 0 to 1 at 180 and
270 degrees, respectively.
This is the reason why comparatively insignificant deviations in the regular
motion, nevertheless cause remarkable deviations in the result of measuring if the
throw or oscillation is large. Such deviations, however, are of no accountable
consequence if the throw is but small and does not exceed about 40°.
Such a small throw, however, is contrary to the true conditions of a precise
clock-work with an escapement of any usual construction and would render its
regulation extremely difficult, if not impossible. In a clock with anchor escape-
ment for instance, the plate and elliptical pin must, in their reciprocating motion
describe a large angle, in order to allow the fork and pin to engage at such an
angle compared with which the angle of oscillation of the escapement wheel is very
large, otherwise the wheel would not be free to swing independently of the
escapement and of the driving mechanism during the greater part of its throw.
Similar conditions exist with cylinder escapements and escapements of other kinds.
To overcome the difficulties mentioned and to realise the two desired conditions
which appear to exclude each other in a clock-work, I divide the escapement into
two separate parts, each of which is mounted on a shaft, the two shafts being
brought into gear with each other by suitable gear wheels, or levers, or other
suitable means.
One of the said parts 1 expose to the influence of the current to
be measured, and this part of the escapement, in its reciprocating oscillations,
receives comparatively a very small throw, while the other part (in an anchor-
escapement, for example, the plate and pin) receives an ample throw or large angle
of oscillation to either side.

page_text: In employing a magnet for exercising the influence of the current, it will be
preferable to use astatic systems for the purpose of preventing them from being
influenced by terrestrial" magnetism and other undue effects, except those of
the coil..
In employing coils, instead of a magnet, it will be equally advisable to use two of
them, which may preferably be mounted on a common axis and which are astatic,
or the astatic state of the coils may be obtained by combining two clock-works,
the difference of the speed of which is indicated. by a differential wheel-work. In
this case, each of the two clock-works is provided with an equal coil, having
the same number of tairns and receiving the same current; if there is any undue
influence, for instance, from terrestrial magnetism, it will equally work on both
clocks and make both of them equally deviate from the true time, no difference
will, accordingly, be indicated on the differential dial. The influence to be
measured, worked by currents or magnets in a system of the latter kind, must-be
made to work opposite effects in each of the two clock-works, in such a manner
as to make one clock go fast and the other go slow, the difference to be measured
of the two clock-works will thereby be indicated even in a more perfect manner.
In employing coils, it will further be preferable to arrange the same in such a
manner as to form a shunt circuit with high resistance, measuring the tension; the
main circuit or a proportional part of same, in such case, flows through the
stationary coil, or this may be reversed; in both cases, I obtain a Watt-hour
counting apparatus.
By sending the main current, or a proportional part of the same, through the
oscillating coil swinging under the influence of a stationary magnet, or magnets,
I obtain a Coulomb-counting apparatus.
The current may preferably be supplied to the swinging coil through a couple of
steel spiral springs, or better still through springs of non-magnetic material, which,
at the same time, serve to supply the current and also add to the regulating force;
with the said two springs, a third spring may be suitably combined, which serves
to control the normal speed of the clock in any known manner.
Another feature of my invention has reference to improved means for driving
the two clock-works of apparatus for measuring electric currents by meaus of a
common driving power. Winding up the clock-works of the kind described by
hand has been experienced to be connected with many inconveniences and in
constructing suitable means for electrically winding up the said clock-works,
I found that it was necessary to drive the same by a driving mechanism common
to both. After trying a variety of constructions, I found the best means for
imparting a common motion to both clock-works to be the reversal of the
differential wheel work, which latter, hitherto, has been only cinployed to combine
two movements or wheel works in such a manner as to obtain their difference in
speed. By reversing the effect of the differential wheel-work, I impart rotary
motion to a shaft common to two crown wheels loosely mounted thereon and having
between them a planet wheel, the shaft of which is fixed on and follows the rotation
of the cominon shaft. The said planet wheel serves as a clutch for the two crown
wheels, each of which transmits the driving power to a separate clock-work. If the
speed of the two clock-works varies, one of the two crown wheels in gear with the
mediate planet wheel will turn slower than the other and the planet wheel in
between will be caused to turn on its own shaft with a speed corresponding to
the difference of speed between the two crown wheels. But as long as the said two
crown wheels are turning with equal speed, the planet wheel will not turn on its
own shaft, but only turn with its shaft round the common driving shaft.
It will be obvious that this system of a driving mechanism common to both clock
works allows of the greatest variations of speed in the two separate clock works
driven through the two crown wheels, as both clock-works are entirely independent
of each other in speed in spite of receiving motion by a driving power common
to both.
The same arrangement might equally well be employed for actuating the striking

page_text: train of electrical clock-works, thereby avoiding the necessity of separate means for
winding up said striking train.
Dated this 23rd day of June 1892.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Measuring Electric Currents.
1, HERMANN ARON Philos. Dr. of 6 Lützowstrasse in the City of Berlin in the
Kingdom of Prussia and Empire of Germany, 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 that class of apparatus for measuring electric currents
for which I have obtained Letters Patent in Great Britain No. 6770 dated
24 April, 1884, and No. 8856 dated 20 June, 1887; apparatus in which a clock-
work or clock-works are employed for indicating the deviations from the true time
caused by the influence of the current to be measured on the pendulum or escape-
ment of the clock-work.
The object of my present invention is, first, to provide an improved construction
of the escapement of the clock-work to be influenced by the current, for the purpose
of preventing undue influences, such as of terrestrial inagnetism, exercised on the
escapement wheels of the usual construction, and, secondly, to provide a common
driving mechanism for the two clock- or wheel-works of the measuring apparatus.
With electric-meters of the class before mentioned, the exactness of the indi-
cations materially depends on two particulars: namely, on the form or shape and
arrangement of the measuring parts, and on the suitable size of the angle of
oscillation. The latter circumstance is of particular consequence and offers
considerable difficulties in clock-works regulated by an escapement instead of by a
pendulum.
If, in a measuring apparatus of the kind before stated, the effect worked by the
electrical circuits on the magnets is observed, and vice versa, during the different
phases of motion of the escapement, we find that such influence is a periodical
function of the angle of oscillation. This force is dependent on the distribution of
the lines of force, and, besides, it is at any moment proportional to the sine of the
said angle of oscillation; the said sine, however, varies within wide limits during
one revolution, changing from 0 to 1 at 90 degrees and returning from 1 to 0 and
from 0 to 1 at 180 to 270 degrees, respectively.
This is the reason why comparatively insignificant deviations in the regular
motion, nevertheless, cause remarkable deviations in the result of measuring, if the
throw, or oscillation, is large. Such deviations, however, are of no accountable
consequence, if the throw or oscillation is but small.
Such a small throw, however, is contrary to the true conditions of a precise clock-
work regulated by an escapement of any usual construction, and it would render
the regulation extremely difficult, if not impossible. In a clock-work with anchor
escapement, for instance, the plate and elliptical pin must, in their reciprocating
motion, describe a large angle, in order to allow the fork and pin to engage at such
an angle, compared with which the angle of oscillation of the escapement wheel is
very large, otherwise the wheel would not be free to swing independently of the
escapement and of the driving mechanism during the greater part of its throw
Similar conditions exist with cylinder escapements and escapements of other kinds.
To overcome the difficulties mentioned and to realise the two desired conditions;
which appear to exclude each other in a clock-work, divide the escapeinent into
two separate parts, each of which is mounted on a shaft of its own, the two shafts
being brought into gear with or connected to each other by suitable gear wheels,

page_text: levers, or other suitable means. One of the sand parts of the escapement I expose
to the influence of the current to be measured, and this part of the escapement, in
its reciprocating oscillations, receives comparatively but a very small throw, while
the other part (in an anchor escapement, for example, the plate and pin) receives
an ample throw or large angle of oscillation to either side..
In the accompanying drawings:-
Figures and 2 illustrate this part of my invention as applied to an anchor
escapement of a clock-work.
Figure 1 is a perspective view of the two parts of the escapement; and
Figure 2 is a front view of the same.
A, is the driving wheel engaged by an anchor B on a shaft C in the well known
manner. On the shaft C is mounted an arm D, the free, forked end of which is
engaged by a pin E carried by an arm on the shaft F and set parallel to said shaft
so as to turn around the same. These parts, as described, form the one part of the
escapement having an ample throw.
The shaft F carries a gear wheel G engaging with a wheel H of a larger
diameter on a shaft 1, said shaft I carries a magnet surrounded by a coil K,
or a coil may be mounted on the shaft to swing within another coil or in
proximity to a magnet. The shaft I forms the other part of the escapement
having a small throw or angle of oscillation. The shafts F and I may be connected
by levers or other suitable means for transmitting motion, instead of by the gear
wheels G and H, and the magnet J and coil K may be replaced by other means,
through which the influence of the electric current is made to act for changing the
normal motion. It will be easily seen, then, that the shaft I, which carries the
part influenced by the current, receives but a slight reciprocating motion, while
the shaft F has its normal ample throw,
If a magnet is employed for exercising on it the influence of the current, it will
be preferable to use, in the well known manner, astatic systems of the magnet, for
the purpose of preventing them from being influenced by terrestrial magnetism or
other undue effects, besides those of the coil through which the current to be
measured is flowing.
In employing coils, instead of a magnet, it will be equally preferable to use two
of them, which may preferably be mounted on a common shaft and which are
astatic. Or the astatic state in the coils may be obtained by combining two clock-
works, the difference in the speed of which is indicated by a differential wheel
work. In such case, each of the said two clock-works is provided with an equal
coil, having the same number of turns and receiving the same current.
If any
undue influence is being exercised, for instance, by terrestrial magnetism, it will
equally work on both clock-works and make both of them equally deviate from the
true time. No difference will, accordingly, be indicated on the differential dial.
In a system of the latter kind, the influence to be measured must be made to work
an opposite effect in either of the two clock-works, that is, the said influence must
make one clock go fast and the other go slow by this means, the difference, to
be measured of the two clock-works will be indicated even in a more perfect
manner.
In employing coils, it will, further, be preferable to arrange the same in a manner
to form a shunt circuit, with high resistance which measures the tension. In such
case, the main circuit, or part of the same, flows through the stationary coil, but it
might as well flow through the swinging coil; in both cases, I obtain a Watt hour
counting apparatus.
By sending the main current, or a proportional part of the same, through the
oscillating, coil swinging under the influence of a stationary magnet or magnets,
obtain a recording ammeter.
In my previous Patent, No. 6770 of 1884, I have shown and described a variety
of arrangements of the swinging coil relative to the stationary coil or coils; the
said arrangements have been found practicable with pendulum clocks, but, with

page_text: clock-work regulated by an escapement, the said arrangements are not successfully
applicable. By a number of trials, I have found that, in a clock-work with
escapement, the best arrangement of coils destined to swing within each other is
that which resembles a dynamometer, the swinging coil having its axis set parallel
to the plane of the turns of the wire. An arrangement of this kind is shown in
Figures 3 and 4, Figure 3 being a vertical section through the two coils, and
Figure 4 a side elevation of the same.
I is the shaft of the escapement, and J the coil swinging with said shaft; K' is
the stationary coil, having its wire turns wound parallel to those of the swinging
coil when the latter keeps its normal or central position. When the coil is
swinging, the turns of the two coils will form an angle towards each other, and
thereby exercise a regulating force upon each other. The current is supplied
to the swinging coil by means of two springs L, which also serve to return the-
swinging coil to its normal or central position, and, further, to regulate the period
of oscillation. The said regulation may be further obtained by a separate
spring L. I prefer to supply to the swinging coil a current, the tension of
which is proportional to the main current, and to send through the stationary
coil the main current or a current proportional to the same.
Another feature of my invention has reference to improved means for driving,
from a common driving power, the two clock-works of apparatus for registering
electric currents, such as shown in the Specification and drawings of my previous
Patent No. 8856 of 1887.
I have found by experience that the two clock-works, the deviations of which
are registered, should be wound up electrically, instead of by hand, and that the
winding up through the action of the electrical current requires the two clock--
works to be driven by a common shaft, in such a manner as to allow to each of the
two clock-works independent motion of each other. To realise this, I found that.
the best means for obtaining independent motion derived from a common driving
shaft consists in the reversal of the differential wheel work, which, hitherto, has
been only employed to combine two movements, or wheel works, in such a manner
as to obtain their difference of speed. By reversing the effect of the differential
wheel work, impart rotary motion to a shaft on which two crown wheels are
loosely mounted opposite each other, the said crown wheels being engaged by an
intermediate planet wheel, the shaft of which is fixed to and follows the rotation of
the common shaft. The said planet wheel serves as a clutch for the two crown.
wheels, each of which transmits motion to a separate clock-work.
A device of this kind is illustrated by Figures 5, 6 and 7 of the drawings;
Figure 5 being a vertical section through the set of wheels:
Figure 6, a side elevation of the same: and
Figure 7, a front elevation of one of the crown wheels and the planet wheel in
gear with the same.
M and M are the two crown wheels loosely mounted on a common shaft N
which receives motion by a weight O, or by any other driving mechanism, such as.
a spring, etcetera. The two wheels M and M' are both in gear with an intermediate-
planet wheel P, the shaft P¹ of which is mounted in a fixed manner on the shaft N..
Each of the two wheels M and M' is in gear with a train of wheels (not shown in
the drawings) to transmit motion to a clock-work. Now, if one of the two clock-
works, by the influence of the current to be measured, varies in speed relative to
the other clock-work driven by the other crown wheel, the planet wheel P will be
caused to turn on its shaft P' with a speed corresponding to the difference of speed
between the two crown wheels M and M. But as long as the said two crown
wheels continue running with equal speed, the planet wheel will not turn on its
own shaft P, but only rotate with its shaft round the common driving shaft N.
It will be obvious that this system of a driving mechanism common to both
clock-works allows of the greatest variations of speed between the two separate
crown wheels M and M', and, accordingly, between the two clock-works receiving

page_text: motion through the said crown wheels. The two clock-works, though driven by a
common shaft and a common driving power, are perfectly independent of each other
in speed.
The same mechanism might as well be employed for actuating the striking train
of electric clock-works, thereby obviating the necessity of employing separate
means for winding up the striking train.
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. In apparatus for measuring electric currents of the class in which clock-work
is made to deviate from the true time by the influence of the current to be
measured, the combination, with said clock-work, of an escapement composed of
two parts, which two parts are so connected to or in gear with each other that the
one part under influence of the current to be measured oscillates with a com-
paratively small angle of oscillation, while the other part, the escapement proper of
the clock, swings with a comparatively large angle of oscillation, substantially as
described.
2. In apparatus for measuring electric currents of the class in which clock-work
is made to deviate from the true time by the influence of the current to be
measured, the combination, with the escapement of said clock-work, of two or more
coils mounted on the shaft of said escapement, and one or more coils surrounding
the coil or coils on the shaft in such a manner that the turns of wire of the two sets
of coils, in the normal position, are in a plane parallel to each other and to the
shaft of the escapement, substantially as and for the purpose described.
3. In apparatus for measuring electric currents of the class in which the current
is measured by the deviations of two clock-works, one of which is made to deviate
from the true time by the current to be measured, the combination, with the two
clock-works, of a common shaft, two crown wheels loosely mounted on said shaft,
an intermediate planet wheel, loosely mounted on a shaft of its own but fixed to the
common shaft, and driving mechanism to rotate said common shaft, substantially as
and for the purpose described.
Dated this 18th day of March 1893.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.