Improvements in or appertaining to Apparatus for Measuring Electric Currents.
Year: 1890

page_text: Date of Application, 21st Nov., 1890
Complete Specification Left, 21st Aug., 1891-Accepted, 21st Nov., 1891
PROVISIONAL SPECIF
ATION.
Improvements in or appertaining to Apparatus for Measuring
Electric Currents.
I, Professor HERMANN ARON, Ph. D., of 107, Bülowstrasse, Berlin, in the
Kingdom of Prussia, Empire of Germany, do hereby declare the nature of this
invention to be as follows:-
My invention relates to improvements in apparatus for measuring electric
currents, particularly of that kind for which I have obtained Letters Patent in
Great Britain No. 6770, dated April 24th 1884, No. 8856, dated June 20th 1887
and No. 6876 dated May 8th 1888. Several features of the improvements of my
present invention, may, however, with success, be applied to apparatus of kinds
other than described in the Specifications of the aforesaid Patents.
The object of my present invention, is, first, to provide improved means for
connecting and disconnecting an apparatus for measuring electric currents into the
main circuit and out of the same without any material loss of tension, the improved
means of iny invention being calculated to cut the apparatus in and out of circuit
independently of the intensity or volume of current flowing through the circuit at
the inoment when the apparatus is being connected or disconnected.
Supposing the apparatus to be employed, as usual, in a main circuit. for producing
electric light, the cutting in and out of circuit may be done as well when only a
single lamp is lighted, as when a number or all of them are lighted, and the loss of
tension thereby occasioned is reduced to the lowest possible amount.
In carrying my invention into effect I provide an electro-magnet wound with two
wire-coils, one coil having a comparatively large number of turns of thin wire and
the other coil a comparatively small number of turns of thicker wire, the two coils
being connected in series.
At the moment when one or several lamps are being lighted, the current will
flow, with a considerable loss of tension, through both coils and instantaneously
attract the armature of the electro-magnet, whereby the apparatus is cut in or
connected in circuit, from that moment, the iron armature being closely up to the
poles of the magnet, but a few ampère-turns will be sufficient to retain the armature
in its attracted position, especially as, from the same moment, what is called the
magnetic hysteresis" enters into action, whereby a few ampère-turns already will
call forth a stronger magnetic induction, than they would have been able to produce,
if the strong magnetic induction on the core had not been previously called forth
by the coil of thin wire.
k
Now, as the iron armature is being retained in its attracted position by only a
few ampère-turns, the thin wire coil may be cut out, and this cutting out is auto-
matically performed by the iron armature connecting the terminals of the wire and
short-circuiting the current. To produce this short-circuit, the terminals of the
thin wire-coil are arranged to form bearing surfaces for the iron armature, whereby,
as currents of great volume are passing through the apparatus, a correspondingly
strong pressure will be exercised by the armature on its supporting or bearing
surfaces and the resistance of the points of contact will, accordingly, be reduced to
its lowest amount.
The same method of cutting out the coil of thin wire may be employed, if,
instead of one single electro-magnet wound with two kinds of wire coils, as
described, two electro-magnets are used, one of which is wound with many turns of
thin wire, while the other is wound with few turns of thicker wire, and the armatures
of both magnets so connected as to form one mechanical system or to practically
act as a single magnet. But, by an arrangement of this kind, the considerable

page_text: advantage would be lost which is derived from the magnetic hysteresis. The
operation would be, that the armature would, first, be attracted by the action of
the electro-magnet wound with the thin wire, while the armature is retained
and the thin wire coil cut out by the magnet wound with thicker wire.
Dated this 20th day of November 1890.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in or appertaining to Apparatus for Measuring
Electric Currents.
I, Professor HERMANN ARON Ph. D., of 107 Bülowstrasse, Berlin, in the
Kingdom of Prussia, Empire of Germany, 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, reference being had to
the accompanying four sheets of drawings, and to the figures and letters of reference
marked thereon :—
Figures 1 and 2 show my improvements in their application for starting or
connecting electric-measuring-apparatus, Figure 1 showing the coils, as hercin-
after described, connected in series, whilst Figure 2 shows them connected
parallel.
Figures 3 and 4 show modifications of my invention.
My invention relates to improvements in apparatus for measuring electric
currents, particularly of that kind for which I have obtained Letters Patent in
Great Britain No. 6770 dated April 24th 1884, No. 8856 dated June 20th 1887,
and No. 6876 dated May 8th 1888; the several features of my present invention,
may, however, be applied with equal success to apparatus of other kind than
described in the Specifications of the aforesaid Patents.
The object of my present invention is to provide, in a circuit with parallel
connecting translating devices, such as lamps, etcetera, improved means for starting
or connecting into circuit electrical devices, such as suitable apparatus for measuring
electric currents, independently of the strength of current actually flowing through
the circuit at the time, the starting or cutting in of the apparatus or device being
obtained with equal security, while the minimum strength of current exists, as with
the maximum strength, and no material loss of tension is occasioned by the cutting
in or out of the apparatus. By the use of the improvements of my present inven-
tion, the apparatus for measuring the current will be as well cut in, if only one
single electric lamp is being lighted, as if a number of lamps be lighted at a
time, and the loss of tension is reduced to an almost imperceptible minimum.
The improved means which constitute my present invention consist of an electro
magnet, or electro magnets having a double coil, one of fine wire with a large
number of turns, the other of thick wire with few turns. The two coils may be
wound one over another around a common core, or they may be wound on separate
cores, as represented in the accompanying drawings, in which the two coils a and b
are shown to be connected in series in Figure 1, a being the coil of fine wire with a
large number of turns and the coil of thick wire with few turns.
The moment that but one lamp, or a few lamps in the circuit are being lit, the
electric current will, with great loss of tension, pass through both coils a and b of
the electro-magnet A, the armature C of which will be instantly attracted to the
core or cores. Through the motion of the said armature C, the pendulums of the
clockwork of the apparatus for measuring the current are set free to swing, as fully
described in the Specification of my previous Patent No. 8856 of 1887. Now, as
soon as the attracted armature C approaches the poles, but a few ampère turns
will be sufficient to maintain it so attracted, the more so, as from the same moment
what is called the "magnetical hysteresis "enters into action, whereby even a few

page_text: ampère turns call forth a stronger magnetical induction than they would have been
able to produce, if the strong magnetical induction on the core had not been
previously operated by the coil of fine wire a.
Now, as the iron armature is being retained in its attracted position by the
sole action of the few ampère turns b, the coil a of fine wire may again be cut out,
and this cutting out is automatically performed by the iron armature C connecting
the terminals of the wire a, thereby short circuiting the current and cutting the
coil a out. To produce this short circuiting, the terminals c c are arranged to form
bearing surfaces for the armature C. Consequently, when currents of great strength
are passing through the apparatus, I thereby further obtain a correspondingly strong
pressure which will be exercised by the armature C on its supporting or bearing
surfaces cc, whereby the resistance of said contacts will be reduced to its lowest
amount.
When the two coils a and b, instead of being connected in series, as shown in
Figure 1, are connected parallel as shown in Figure 2, the operation will in some
degree be altered, inasmuch, as, in the beginning, only the coil a of fine wire will
be cut in, energising the core of the magnet A if but the slightest amount of current
is flowing through, upon which, as the armature C becomes attracted and makes
contact with the bearing surfaces c c, the coil with the small resistance will be
connected parallel to the coil with strong resistance, whereby a system of a very
low combined resistance will be obtained.
The two arrangements shown in Figures 1 and 2, may be further modified by
replacing the single electro-magnet A with two different coils, by two separate
magnets, the one of which carries a great number of turns of fine wire, while on
the other are wound few turns of thick wire. In this modification, however, the
great advantage derived from the magnetical hysteresis would not be obtained.
The operation would be thus, that the attraction of the armature C is initially
obtained, by the magnet with inany turns of fine wire, whereupon the few turns of
thick wire of the other magnet retain the armature which cuts the fine wire coil out
by short circuiting.
In electrical apparatus and devices, where currents of very great strength are
used, but in which very weak currents are equally required to act, the arrangements
of my invention, as before described, in either of the modifications, may preferably
be employed as a translator, that is, for the purpose of producing a contact which
closes a circuit into which an electro-magnet is connected which operates to start
the measuring device.
Or the improved arrangements of my invention as before described, may be
employed to close a circuit in shunt of the main circuit, the said shunt circuit
containing suitable devices, as for instance, a clockwork or a rotating or oscillating
electrical motor, or the like, to which devices motion is imparted even by the
slightest amount of current, and so the said shunt circuit will facilitate the over-
coming of any frictional resistance and aid in imparting motion to the electrical
device.
In all cases, where currents of great strength are being used, it will not be
advisable to employ, for the fine wire coil, a size of wire sufficiently strong to
allow the full amount of current to pass; I prefer to use a wire of inferior size and
connect the coil in a shunt circuit of small resistance.
In the several modifications above described, the electro magnet or magnets A
might be replaced by a coil or coils of wire, consisting, each, of a double coil, one
of thin wire and a great number of turns, the other of strong wire and few turns.
The armature C, in such case, might be replaced by an iron core, which, being
drawn into the coil, performs the same operation as has been described above with
reference to the armature C.
In all those cases where the application of iron in the device is objectionable,
particularly in circuits with alternating currents, I not only replace the electro
magnet or magnets by a coil or coils, as described, but I also replace the aforesai.l

page_text: iron core to replace the armature by a coil with a great number of turns of thin
wire, which coil I connect into a shunt circuit. A device of this kind is shown in
Figure 3 of the drawings. The effect obtained is the same as with the magnet or
magnets and armature.
The coil C' of thin wire placed inside of the double coil A¹ will be attracted,
first, by the many turns of thin wire a of great resistance and afterwards retained
in its attracted or drawn-in position by the few turns of strong wire b of small
resistance. When the contact plate c has reached the bearing surfaces cc of the
wires, the coil of thin wire a is cut out by short circuiting.
In Figure 4 a similar arrangement has been illustrated, the difference consisting
only in that the inside coil CT, instead of being drawn into the outside coil A' in
the axial direction, is pivotally arranged to turn within the coil A'.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. Improved means for starting or connecting apparatus for measuring electric
currents, such means consisting in the combination, with the starting or connecting
part or parts, of a coil consisting of an electro magnet energised by two coils
connected in series, one of which coils is composed of wire of strong resistance, the
other coil containing wire of small resistance, the coil of strong resistance being
short circuited and cut out by the attraction of the armature or its equivalent, such
as an iron core, or a coil with thin wire placed in a shunt circuit, substantially as
and for the purpose described.
2. Improved means for starting or connecting apparatus for measuring electric
currents, such means consisting in the combination, with the starting or connecting
part or parts, of a coil consisting of an electro magnet energised by two coils
connected parallel, one of which coils is composed of wire of strong resistance,
the other coil containing wire of small resistance, said coils operating in a manner
to initially attract the armature by the sole action of the strong resistance coil,
whereby the coil of small resistance is cut in to retain the armature or its equivalent,
such as an iron core or a coil with thin wire placed in a shunt circuit, substantially
as and for the purpose set forth.
3. Improved means for starting or connecting apparatus for measuring electric
currents, such means consisting in the combination, with the starting or connecting
part or parts, of a coil consisting of two electro magnets, one of which is wound
with a coil of strong resistance, the other with a coil of small resistance, the
armature or its equivalent such as an iron core, or a coil with thin wire placed in a
shunt circuit being attracted, first, by the magnet and coil of strong resistance and
retained, then, by the magnet and coil of small resistance, the other coil being cut
out by short circuiting, substantially as and for the purpose set forth.
4. Improved means for starting or connecting apparatus for measuring electric
currents, such means consisting in the combination, with the starting or connecting
part or parts, of a coil consisting of an electro magnet or electro magnets energised
by two coils, one of which coils is composed of wire of strong resistance, the other
coil containing wires of small resistance, and of a shunt circuit arranged to be
closed by the attraction of the armature of said magnet or magnets or its equivalent
such as an iron core, or a coil with thin wire placed in a shunt circuit, said shunt
circuit serving to operate the device to be started or connected, substantially as and
for the purpose described.
5. Improved means for starting or connecting apparatus for measuring electric
currents, such means consisting in the combination, with the starting or connecting
part or parts, of a coil consisting of an electro magnet or electro magnets energised
by two coils, one coil containing wire of strong resistance, the other coil wire of
small resistance, of a shunt circuit arranged to be closed by the attraction of the
armature of the said magnet or maguets or its equivalent such as an iron core, or a

page_text: coil with thin wire placed in a shunt circuit, and of a suitable clock work, wheel
work, or motor contained in the said shunt circuit, serving to start or connect the
apparatus, substantially as and for the purpose described.
Dated this 20th day of August 189.1.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.