Measuring Apparatus for Rotary Phase Currents."
Year: 1897

page_text: Date of Application, 30th Jan., 1897
Complete Specification Left, 29th Oct., 1897-Accepted, 4th Dec.,
1897
[Communicated from abroad by SIEMENS AND HALSKE, 94 Markgrafenstrasse, Berlin,
in the German Empire Electrical Engineers.]
"Measuring Apparatus for Rotary Phase Currents."
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Annes Gate, Westminster, in
the County of London, Electrical Engineers, do hereby declare the nature of this
invention to be as follows :-
This invention is based upon the following method given by Behn-Eschenburg and
Aron for measuring rotary phase currents.
Referring to Fig. 1 of the accompanying drawing let the points A. B. C. represent
the terminals (arranged at the corners of an equilateral triangle) which on the one
hand are connected to the leads of the rotary phase current and on the other hand
to the leads of current consuming devices, such as lamps and motors.
The currents passing to A. B and C are indicated by Ia Ib Ic, the potential
difference between A and B being designated by Ec that between B and C, Ea, and
that between C and A, Eb. The energy of the rotary phase current given off from the
terminals A. B. C is determined by the difference of two dynamometer readings, of
which the one is produced by the combination of the current Ia with the potential
difference Eb, the other by the combination of the current Ib with the potential
difference Ea, these combinations being indicated by by the symbols (Ia Eb) and
(Ib Ea).
The work is consequently A=(Ia Eb)-(Ib Ea). According to the present
invention there is used for measuring the above work, an instrument based on the
principle of the rotary field. Such an instrument is shown in one construction at
Fig. 2 an outer iron ring R R formed of sheet iron with insulation between the
sheets, has four inwardly directed polar extensions of which two opposite each other
have windings S S of thick wire, while the other two have windings D D of thin wire.
Within this ring R R is a iron cylinder E E, which is constructed in the same
manner as the ring. Between the two is a small free space, in which is arranged a
rotatable drum F of copper or other suitable metal. The expenditure of energy is, in
this case, again determined by the difference of two readings of which the one is
produced by the combination of Ia with Eb and the other by the combination of Ib
with Ea. This combination must however be of a different kind from the preceding.
While the one pair of windings S S Fig. 2 has one of the working currents passing
through it, the other pair D D must be traversed by a current whose amplitude is
proportional to the amplitude of the potential difference Eb, but whose phase is
shifted accurately 90° relatively to the potential difference Ea. The same rule
holds good for the second reading. In other words, the phase of the currents
dependent on the potential difference Eb and Ea must be shifted 90° relatively to the
071

page_text: phases of the potential difference Eb and Ea. Let the symbol of a potential
difference which is equal to a potential difference E but whose phase is shifted 90°
relatively thereto be 1E; in this case the work will be measured with the last
described instrument by the difference of the combinations (Ia 1 Eb) and (Ib 1 Ea),
therefore A (Ia 1 Eb)-(Ib 1 Ea).
The shifting of the phases by exactly 90° can be effected by means of a Wheatstone
Bridge.
i
With a rotary phase current however this problem can be solved in a simpler
manner by employing in place of the potential difference E, and E, two other
potential differences which are equal to these or proportional thereto, but whose
phases are shifted 90° from them.
Referring to Fig. 3, if there be introduced a resistance between the terminals A
and C, and this be divided by the terminal O into two equal parts W₁ and W 3'
then the potential difference between B and O will have its phase shifted 90°
relatively to the potential difference E. For the first measurement therefore the
windings D D can be introduced between B and O, while the windings
S are
included in the lead to A. For the second measurement, the resistance W3 is
introduced between C and O, and the equal resistance W₂ between B and O, the
windings. D D being introduced between A and O, and the windings S S in the lead
to B, as at Fig. 4.
In this it it is necessary to insure, by means of non-inductive resistance, that the
current in the windings D D has the same phase as the generating potential difference.
By employing two instruments for simultaneous readings, it is possible to
permanently introduce the windings D₁ D₁ of the one instrument into the
connection B O, and the windings D₂ D₁ of the other instrument ikto the
connection A O, as shewn diagrammatically at Fig. 5.
It is then only necessary to insure that the resistance of the windings D₂ D₂
increased by the non-inductive resistance introduced in the branch A Ŏ shall be
equal to the corresponding sum of resistances in the branch B O and also equal to
the resistance in the branch CO.
Fig. 6 shews the same diagram somewhat Inore elaborated. Between the
terminals A B and C are introduced lamps, of any desired number, as the method
also holds good for unequal loads. Motors can also be connected to the terminals
A, B, C.
The working current passes from the feeder A, through the windings S₁ S₁ of
the instrument M₁ to A, also from the feeder B. through the windings S, S₂ of the
instrument M. to B, lastly from C. direct to C.
2
Furthermore there are introduced between A and O the resistance W, and the
windings D, D, of the instrument M,, between B and O the resistance W, and
the windings D, D₁ of instrument M₁, lastly between C and O the resistance W₁.
The three branches AO BO and CO have equal total resistances.
The revolving drums which are under the influence of the windings S S and DD
can also be mounted on a common axis and be combined with a spiral spring which
when subject to a certain tension will hold in equilibrium the difference of the
turning moments. exercised on the druins, so that by this means a pointer may be
made to indicate the total amount of work. Also, the drums may be made to rotate
under the action of a braking device and the work be measured by a counter.
The above described invention is not limited to the construction of apparatus
shewn at Fig. 2; it can be applied in all cases where a rotary field is employed for
measuring which is produced by means of two currents of shifted phases and
dependent upon quantity and pressure.
The apparatus can for instance be constructed with a circular plane disc in place
of the drum, such as is used in Blathy's meter.
Dated thin 20th day of 1907

page_text: We, SIEMENS BROTHERS & CO. LIMITED, of 12 Queen Anne's Gate, Westminster,
in the County of London, 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 is based upon the following method given by Behn-Eschenburg
and Aron for measuring rotary phase currents.
Referring to Figure 1 of the drawings accompanying our provisional specification
let the points A, B, C, represent the terminals (arranged at the corners of an
equilateral triangle) which on the one hand are connected to the leads of the rotary
phase current and on the other hand to the leads of current consuming devices,
such as lamps and motors.
The currents passing to A B and C are indicated by Ia Ib Ic, the potential
difference between A and B being designated by Ec that between B and C, Ea,
and that between C and A, Eb. The energy of the rotary phase current given off
from the terminals A B C is determined by the difference of two dynamometer
readings, of which the one is produced by the combination of the current Ia with
the potential difference Eb, the other by the combination of the current. 16 with
the potential difference Ea, these combinations being indicated by the symbols
(Ia Eb) and (Ib Ea).
The work is consequently A
=
(Ia Eb) (Ib Ea).
According to the present invention there is used for measuring the above work,
an instrument based on the principle of the rotary field. Such an instrument is
shewn in one construction at Figure 2; an outer iron ring R R formed of sheet iron
with insulation between the sheets, has four inwardly directed polar extensions of
which two opposite each other have windings S S of thick wire, while the other two
have windings D D of thin wire.
Within this ring R R is an iron cylinder E E, which is constructed in the sane
manner as the ring. Between the two is a small free space, in which is arranged a
rotatable drum F of copper or other suitable metal. The expenditure of energy is,
in this case, again determined by the difference of two readings of which the one is
produced by the combination of Ia with Eb and the other by the combination
of Ib with Ea. This combination must however b of a different kind from the
preceding.
While the one pair of windings SS Figure 2 has one of the working currents
passing through it, the other pair D D must be traversed by a current whose
amplitude is proportional to the amplitude of the potential difference Eb, but whose
phase is shifted accurately 90° relatively to the potential difference Ea.
The same rule holds good for the second reading. In other words, the phase of the
currents dependent on the potential difference Eb and Ea must be shifted 90°
Let the symbol of a
relatively to the phases of the potential difference Eb and Ea.
potential difference which is equal to a potential difference E but whose phase is
shifted 90° relatively thereto be 1E; in this case the work will be measured. with
the last described instrument by the difference of the combinations (Ia 1 Eb) and
(Ib 1 Ea), therefore: A = (Ia 1 Eb) — (Ib 1 Ea).
-
The shifting of the phases by exactly 90° can be effected by means of a Wheatstone
bridge.
With a rotary phase current however this problem can be solved in a simpler
manner by employing in place of the potential difference Eb and Ea two other

page_text: potential differences which are equal to these or proportional thereto, but whose
phases are shifted 90° from them.
Referring to Figure 3, if there be introduced a resistance between the terminals A
and C, and this be divided by the terminal O into two equal parts W₁ and W, then
the potential difference between Band O will have its phase shifted 90° relatively to
the potential difference Eb. For the first measurement therefore the windings D D
can be introduced between B and O, while the windings S S are included in the lead
to A or in a shunt thereof. For the second measurement, the resistance W is
introduced between C and O, and the equal resistance W₁₂ between B and O, the
windings DD being introduced between A and O, and the windings S S in the lead
to B, as at Figure 4.
2
In this it is necessary to insure, by means of onn inductive resistances, that the
current in the windings D D has the same phase as the generating potential
difference.
By employing two instruments for simultaneous readings, it is possible to
permanently introduce the windings D₁ D₁ of the one instrument into the
connection B O, and the windings D₂ D₂ of the other instrument into the connection
A O, as shewn diagrammatically at Figure 5.
It is then only necessary to insure that the resistance of the windings D₂ D₂
increased by the non-inductive resistance introduced in the branch A O shall be equal
to the corresponding sum of resistances in the branch BO and also equal to the
resistance in the branch CO.
Figure 6 shews the same diagram somewhat more elaborated. Between the
terminals A B and C are introduced lamps, of any desired number, as the method
also holds good for unequal loads. Motors can also be connected to the
terminals A. B. C.
The working current passes from the feeder A, through the windings S₁ S₁
of the instrument M, to A or to a shunt thereof also from the feeder B, through the
windings S, S₂ of the instrument M₂ to B, or to a shunt thereof lastly from C. direct
to C.
2
Furthermore there are introduced between A and O the resistance W₁, and the
windings D₂ D₂ of the instrument M, between B and 0 the resistance W, and the
windings D₁ D₁ of instrument M₁ lastly between C and O the resistance W3.
The three branches A O BO and CO have equal total resistances.
The revolving drums which are under the influence of the windings SS and DD can
also be mounted on a common axis and be combined with a spiral spring which when
subject to a certain tension will hold in equilibrium the difference of the turning
moments exercised on the drums, so that by this means a pointer may be made
to indicate the total amount of work.
Also, the drums may be made to rotate under the action of a braking device and
the work be measured by a counter.
The above described invention is not limited to the construction of apparatus
shewn at Figure 2; it can be applied in all cases where a rotary field is employed
for measuring which is produced by means of two currents of shifted phases and
dependent upon quantity and pressure.
The apparatus can for instance be constructed with a circular plane disc in
place of the drum, such as is used in Blathy's meter.
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. Measuring apparatus for rotary phase currents consisting of the combination of
two coils or groups of coils shifted in space relatively to each other, which coils
influence a suspended cylinder capable of rotation, or an equivalent device of any
suitable metal, the one coil or group of coils being introduced into the working
circuit of the one conductor or in a shunt thereof, while the other coil or group
of coils is introduced between one of the other two conductors and a terminal

page_text: which is connected through equal resistances to the first and the third conductors,
substantially as described.
2. The combination of two measuring apparatus for rotary phase currents such
as referred to in the first claim in such manner that the thick wire coils or
groups of coils of the first one are included in the circuit A of a rotary phase
current system A B C, Figure 6, or in a shunt of such circuit, while the
corresponding coils or groups of coils of the second apparatus are included in the
circuit B, or in a shunt thereof, the thin wire coils or groups of coils of the first
apparatus being included between B and terminal O while those of the second
apparatus are included between A and O, which latter is connected with C through a
resistance, so that equal resistances are included between A and O. B and O, and C
and O, substantially as described.