Improvements in Apparatus for Measuring Electric Currents.
Year: 1891

page_text: Date of Application, 7th Dec., 1891
⚫ Complete Specification Left, 30th Aug., 1892-Accepted, 7th Dec., 1892
:
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Measuring Electric Currents.
I, Professor HERMANN ARON Ph.D. of 6, Lützowstrasse, Berlin W. in the
Kingdom of Prussia, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improvements in apparatus for measuring electric
currents, and ny invention has for its object to provide means for overcoming
the difficulties which have been experienced in measuring the energy consumed in
a system of interlaced alternating currents with different phases (multiphase
currents). These difficulties are to be attributed to the circumstance that, in a
system of this kind, the actual working currents are only released from their
interlaced state when they are passing the motor. or the lamps, or the other
translating devices, and therefore in each of the feed conductors (supply wires)
the sum or the difference of two adjacent working currents had to be dealt with.
To obtain satisfactory results in recording the energy consumed, I imagined a
device by which the difference between two adjacent feed conductors was made to.
act upon the tension existing between the same, or in which the difference
between the two tensions was made to act upon the common supply (namely, its
current), and the respective three values were summed up by the apparatus.
Apparatus constructed on this principle were found to give very good practical
results, but they were of a too complicated mechanism for being introduced into
general use, and I therefore endeavoured to find means of considerably simplifying
them, in which I succeeded in the following manner :-
In a system of alternating currents with different phases, represented by the
diagram shown in Figure 1, the work performed may be expressed by either of
the following equations, in which A, B, C, signify the feed lines (namely, their
currents), a, b, c, the working currents, and a ẞy their respective tensions.
The action of a multiphase current system is—
P
-
a (ac)ẞ (c – b).
II. Ka B - ẞ A.
The combination represented in this equation may very easily be realized.
Figure 2 represents in diagram the connection serving for the purpose. An
essential feature in the same is this, that, for measuring the energy of the three
working circuits, only two feed-lines and two shunt circuits for the tension are
required, whereby great simplicity of arrangement is obtained.
Instead of measuring the energy in the main current in the manner described,

page_text: proportional currents derived by induction or branching off from the main current
may be measured with the same result.
Figures 3, 4 and 5 serve to illustrate several modifications of performing my
said invention.
Figure 3 represents an apparatus for measuring electric currents of the
kind for which I obtained Letters Patent in the United Kingdom No. 8856,
June 20, 1887, and the working order of which in general is as follows-
To the pendulum P of a clockwork I, I secure instead of the usual bob, a
magnet swinging with the pendulum in proximity to a coil, through which the
current to be measured is passing. The attraction of the coil on the magnet is
proportional to the strength of current. The said attraction, added to the
attraction of the earth changes the speed of the clockwork and the deviation from
the normal speed caused by the magnetic influence affords a true measure for the
amount of current consumed.
In the apparatus shown in Figure 3, another clockwork II is arranged at the
side of the one, the pendulum of which is influenced by the magnetic attraction
of the coil. The pendulum of this second clockwork II is not influenced, the speed
of the clock therefore is normal. The deviation between the two clockworks is
automatically registered and indicated by a differential wheel-work 111 arranged
between the two clockworks I and II.
With the apparatus for measuring multi-phase currents, the magnet usually
secured to the pendulum of the clockwork I is replaced by two coils of very thin
wire through each of which passes a current proportional to one tension. The
said two coils a and B are swinging within a pair of fixed coils A B, through which
passes the current to be measured.
Another device for measuring the consumption of electrical energy is represented
in Figure 4.
The current to be measured flows through two coils A B, each forming a field
within which a small cylindrical or annular armature is arranged to swing; the
said armatures are each provided with a commutator and through the armature
flows a current proportional to the tension to be measured. The speed of the
motor supplies the measurement of the energy consumed, and in order that this
speed be proportional to the strength of current to be measured, the motor must
perform some work in a determined manner.
In a measuring apparatus for multi-phase currents, two such motors are
required, which being coupled to each other, are connected according to the
arrangement shown by the diagram in Figure 2.
Another device is illustrated in Figure 5, consisting in a suitable arrangement
for producing a rotary magnetic field by which a cylinder d or disk is driven.
The working order of this device is as follows-
Through each of the coils a and ẞ flows a current a and ẞ proportional to the
tension, and through the coils B and A flow the feed currents B and A. Each
coil produces a magnetic field, the strength and direction of which periodically
vary; the two magnetic fields, however, are not coincident, according to the
nature of the current with different phases. Now, by arranging the two magnetic
fields in such a manner that (with direct or indirect relation to a third movable
conductor) they form an angle opposed to each other, I obtain a rotary field of
Ferrari's system. This rotary field will impart motion to a cylinder d, Figure 5,
or to a disc, and the speed of motion of such cylinder or disc will, in a given
space of time and with a constant average tension be proportional to the
temporarily existing strength of the current.
The same system of measuring the energy may be employed with measuring
apparatus, which register, at distinct regular intervals, the indications of an electro-
dynamometer. The dynamometer in such case, must consist of two sets of coils,
in which two coils for the main current, connected to the feed conductors, work
their influence on two coils in a shunt circuit, according to the afore-stated
equation II.

page_text: The following modification further might be employed-
The two measuring groups of a main and of a shunt circuit work indepen-
dently of each other but in a sense opposite to each other. Now, by combining
the two registering wheel-works with a differential counter, their records are
algebraically subtracted from each other, while, during the time in which no
current is passing, the said differential counter remains at the state of rest.
Figure 6 illustrates a device of this kind employed to indicate the difference of
speed between the two groups ẞ A and a B of a motor counting apparatus for
measuring electric currents.
Figure 7 represents a device of the same kind employed to indicate the
difference of speed between the two clock-works I and 11; to the pendulum of
each of said clock-works a coil a and ẞ in a shunt circuit is connected, swinging
within coils B and A respectively of a main circuit. The two clock-works
and I are connected by a differential counter III.
By similar devices the mechanical registrations of two dynamometers may be
subtracted from each other.
Dated this 5th day of December 1891.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Measuring Electric Currents.
I, Professor HERMANN ARON, Ph.D., of 6, Lützowstrasse, Berlin W. in
the Kingdom of Prussia, 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 electric
currents, and my invention has for its object to provide means for overcoming the
difficulties which have been experienced in measuring the energy consumed in a
system of interlaced alternating currents with different phases (multiphase currents).
These difficulties are to be attributed to the circumstance that, in a system of this
kind, the actual working currents are only released from their interlaced state
when they are passing the motor, or the lamps, or the other translating devices and
therefore in each of the feed conductors (supply wires) the sum or the difference of
two adjacent working currents had to be dealt with.
To obtain satisfactory results in recording the energy consumed, I imagined a
device by which the difference between two adjacent feed conductors was made to
act upon the tension existing between the same, or in which the difference between
the two tensions was made to act upon the common supply (namely, its current),
and the respective three values were summed up by the apparatus.
Apparatus constructed on this principle were found to give very good practical
results, but they were of a too complicated mechanism for being introduced into
general use, and I therefore endeavoured to find means of considerably simplifying
them, in which I succeeded in the following manner.
In a system of alternating currents with different phases represented by the
diagram shown in Figure 1, (referring to the drawings filed with the Provisional
Specification) the work performed may be expressed by either of the following
equations, in which A, B, C, signify the feed lines (namely, their currents),
a, b, c the working currents, and a, ẞ, y their respective tensions.
The action of a multiphase current system is-

page_text: distribution of currents, if the self-induction in the shunt-circuits may be neglected
in view of their very high resistance.
This equation 1, remains the same if I subtract the term c (a + B+ x)
=σ
ра.
The combination represented in this equation may very easily be realised.
Figure 2 represents in diagram the connection serving for the purpose. An
essential feature in the same is, that, for measuring the energy of the three
working circuits, only two feed lines are required and two shunt circuits for the
tension, whereby the arrangement is considerably simplified.
Instead of measuring the energy in the main current in the manner described,
proportional currents derived by induction or branching off may be employed.
Figures 3, 4 and 5 serve to illustrate several modifications of performing my
said invention.
Figure 3 represents an apparatus for measuring electric currents of the kind for
which I obtained Letters Patent in the United Kingdom No. 8856, June 20, 1887,
and the working order of which in general is as follows-
To the pendulum P of a clockwork I, I secure, instead of the usual bob, a
magnet swinging with the pendulum in proximity to a coil, through which the
current to be measured is passing. The attraction of the coil on the magnet is
proportional to the strength of current. The said attraction added to the attraction
of the earth changes the speed of the clockwork and the deviation from the
normal speed caused by the magnetic influence, affords a true measure for the
amount of current consumed.
In the apparatus shown in Figure 3, another clockwork II is arranged at the
side of the one, the pendulum of which is influenced by the magnetic attraction of
the coil. The pendulum of this second clockwork II is not influenced, the speed
of the clock therefore is normal. The deviation between the two clockworks is
automatically registered and indicated by a differential clockwork III arranged
between the two clockworks I and II.
With the apparatus for measuring multiphase currents, the magnet usually
secured to the pendulum of the clockwork I is replaced by two coils of very thin
wire through each of which passes a current proportional to one tension. The
said two coils a and ẞ are swinging within a pair of fixed coils A B, through
which passes the current to be measured.
To make the working of this device more fully understood, reference must be
had to the diagrammatical views in Figures 1 and 2. According to the equation II,
as above stated, the algebraical sum is desired to be formed of the products a B
and A 6. The tension a is lying between the conductors B and C, while the
current B is flowing through the conductor B. Now, in order to form the products
of a and B, I make a current B flow through a coil B (Figures 2 and 3) while
through another coil a placed between B and C, I send a current a proportionate
to the tension between B and C. On approaching the two coils a and B to each
other, either an attractive or repulsive force will be established between the two
coils, said force being proportionate to the product of the two currents and also
proportionate to the product a B, because the current in the shunt circuit is
proportionate to the tension.
While in the diagram of Figure 2, the coils a and B are arranged one over
another, to show the same more clearly, the Figure 3 shows the two coils a and B
swinging one inside the other, which arrangement is preferable for practical use.
In the same manner as the product a B is formed, I obtain the other product - A ẞ.
The two binding screws belonging to coil B, Figure 3, are connected to

page_text: conductor B (Figure 1), while the two binding screws belonging to coil A (Figure 3)
are connected to conductor A (Figure 1) and the two binding screws connected by
a short bridge (Figure 3) are connected to conductor C (Figure 1). The circuits
of the two oscillating coils a and ẞ are so arranged that coil ẞ (Figure 3) is
connected to one binding screw of conductor A and another binding screw of
conductor C, whereby the tension B (Figure 2) is measured. The other coil a
(Figure 3) is connected to one binding screw belonging to conductor B and
another binding screw belonging to conductor C whereby the tension a (Figure 2)
is measured.
The same circuit connections described with reference to the device shown in
Figure 3 are to be adopted for the other devices represented in Figures 4, 56
and 7.
Another modification of the device for measuring the electric energy consumed
is represented in Figure 4.
The current to be measured flows through two coils A B each forming a field
within which a small drum or ring armature with commutators e is turning, brushes d
having a sliding contact against said commutators. Through the said armature
flows a current. proportional to the tension to be measured. The speed of the motor
affords the measure of the energy consumed and in order that the said speed be
proportional to the strength of current to be measured, the motor must drive an
apparatus which gives an output in a certain manner.
In a measuring apparatus for multiphase currents two such motors are required,
which are coupled to each other. The circuits of said motors are connected
according to the general arrangement shown in Figure 2.
Another modification of the device is illustrated in Figure 5, consisting in a
suitable arrangement for producing a rotary magnetic field by which a cylinder d
or disc is driven. The working order of this device is as follows-
Through each of the coils a and ẞ flows a current a and ẞ proportional to the
tension, and through the coils B and A flow the feed currents B and A. Each coil
produced a magnetic field, the strength and direction of which periodically varies;
the two magnetic fields, however, are not coincident, according to the nature of
the current with different phases. Now, by arranging the two magnetic fields in
such a manner that (with direct or indirect relation to a third, movable conductor)
they form an angle opposed to each other, I obtain a rotary field of Ferrari's
system. This rotary field will impart motion to a cylinder d, Figure 5, or to a disc
and the speed of motion of such cylinder or disc will in a given space of time and
with a constant average tension be proportional to the temporarily existing strength
of the current.
The same system of measuring the energy may be employed with measuring
apparatus, which register, at distinct regular intervals, the indications of an electro
dynamometer. The dynamometer, in such case, must consist of two sets of coils,
in which two coils for the main current, connected to the feed conductors, work
their influence on two coils in a shunt circuit according to the afore stated
equation I 1.
The following modification further might be employed→
The two measuring groups of a main and of a shunt circuit work independently
of each other but in a sense opposite to each other. Now, by combining the two
registering wheel-works with a differential counter, their records are algebraically
subtracted from each other, while, during the time in which no current is passing,
the said differential counter remains at the state of rest.
Figure 6 illustrates a device of this kind employed to indicate the difference of
speed between the two groups ẞ A and a B of a motor counting apparatus for
measuring electric currents.
Figure 7 represents a device of the same kind employed to indicate the difference
of speed between the two clockworks I and II to the pendulum of each of said clock-
works a coil and ẞ in a shunt circuit is connected swinging within coils B and A

page_text: respectively of a main circuit. The two clockworks I and II are connected, by a
differential counter III.
By similar devices the mechanical registrations of two dynamometers may be
subtracted from each other.
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. An apparatus for measuring alternating electric currents of different phases
(multiphase currents) which consists in the combination with two systems of coils,
each of which systems, either directly or indirectly, measures the product of the
current of one feed conductor and that tension which exists between that conductor
and a third conductor, of mechanical means, by which the difference of the two
products is algebraically integrated or registered.
2. The combination with two measuring apparati each of which integrates
or registers the product of the current of one feed conductor and the tension
existing between that and a third conductor, of a differential counter serving
to mechanically subtract the inductions of the two measuring apparati.
Dated this 25th day of August 1892.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Agents.