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1735 Users Manual The neutral conductor may be connected, however, it does not influence the measurement even in open state. If no neutral conductor is connected, a virtual "metering neutral" is established in the Logger via symmetrization resistors. In the Blondel (or Aron) circuit, phase L2 becomes the return line for L1 and L3 causing the current I L2 to be obtained as the sum of the two negative currents I L1 I L3. i2 (t) =-[i1(t)+ i3(t)] In general, the instantaneous total power is: • Ptot(t)=v1(t) i1(t)+ v2(t) i2(t)+ v3(t) i3(t) • Ptot(t)= v1(t) i1(t)- v2 [i1(t)+ i3(t)]+ v3(t)i3(t)= =[v1(t)- v2(t)] i1(t)+[ v3(t)-v2(t)]i3(t) However, since the voltages between the lines of a poly-phase are measured in the delta connection, the following formula results for the total power: Ptot(t)= v12(t) i1(t)+v32 i3(t) Integration via a period results in: Ptot= V12 I1 cos (V12, I1) +V32 I3 cos (V32, I3) Therefore, the total power corresponds to the total power of the Wye connection. For control purposes, it can be derived from the sum of the powers P12 and P31. Since I L2 is only calculated as an auxiliary value and is not measured, P23 must be set to zero (as per definition), because it does not exist in the Aron circuit. The power factor PF has no physical meaning in the Aron circuit, because one would compare the current to the voltage between the lines of a poly-phase system. Reactive and apparent power should be understood as pure computing values and have no physical meaning. Invalid measurements are suppressed from the display by the symbol '----'. The exact formulae for calculating the active power are given in the section Measurement Theory. Save With Save/Enter you will get a screenshot and thus store the actual display in the memory location shown subsequently. 38

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1735
Users Manual
38
The neutral conductor may be connected, however, it does not influence the
measurement even in open state. If no neutral conductor is connected, a
virtual ”metering neutral” is established in the Logger via symmetrization
resistors.
In the Blondel (or Aron) circuit, phase L2 becomes the return line for L1 and
L3 causing the current I
L2
to be obtained as the sum of the two negative
currents I
L1
I
L3
.
i2 (t) =-[i1(t)+ i3(t)]
In general, the instantaneous total power is:
•
Ptot(t)=v1(t) i1(t)+ v2(t) i2(t)+ v3(t) i3(t)
•
Ptot(t)= v1(t) i1(t)- v2 [i1(t)+ i3(t)]+ v3(t)i3(t)=
=[v1(t)- v2(t)] i1(t)+[ v3(t)-v2(t)]i3(t)
However, since the voltages between the lines of a poly-phase are measured in
the delta connection, the following formula results for the total power:
Ptot(t)= v12(t) i1(t)+v32 i3(t)
Integration via a period results in:
Ptot= V12 I1 cos (V12, I1) +V32 I3 cos (V32, I3)
Therefore, the total power corresponds to the total power of the Wye
connection. For control purposes, it can be derived from the sum of the powers
P
12
and P
31
.
Since I
L2
is only calculated as an auxiliary value and is not measured, P
23
must
be set to zero (as per definition), because it does not exist in the Aron circuit.
The power factor PF has no physical meaning in the Aron circuit, because one
would compare the current to the voltage between the lines of a poly-phase
system. Reactive and apparent power should be understood as pure computing
values and have no physical meaning.
Invalid measurements are suppressed from the display by the symbol ‘----‘.
The exact formulae for calculating the active power are given in the section
Measurement Theory.
Save
With
Save/Enter
you will get a screenshot and thus store the actual display in
the memory location shown subsequently.