Landis+Gyr E650 Series User Manual page 18

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Apparent energy
Calculation method 1
(vectorial addition)

Calculation method 2
(from rms values)
© Landis+Gyr AG
The apparent energy is calculated in the combimeters in two ways:

by vectorial addition of the active and reactive energy of the individual
phases

by multiplying the rms values of voltage and current of the individual
phases
The method of calculation can be parameterised (only one possible in each
case).
From the mean values A1, A2 and A3 and R1, R2 and R3 the microproc-
essor calculates the apparent energy of the individual phases ±S1, ±S2
and ±S3 as well as the total apparent energy ±S.
Mean values
per second
1
±A
å
å
2
±A
3
±A
R1
±
å
2
±R
3
±R
Fig. 1.12 Total apparent energy according to calculation method 1
Only fundamental wave considered for reactive energy
Only the fundamental wave is considered for the calculation of the reactive
energy share; possible harmonics are not taken into account.
From the mean values U1
processor calculates by multiplication the apparent power of the individual
phases ±VA1, ±VA2 and ±VA3 and summates these for the total apparent
power ±VA.
Mean values
per second
I 1
rms
I 1 U1
å
rms rms
U 1
rms
I 2
rms
I 2 U2
å
rms rms
U 2
rms
I 3
rms
I 3 U3
å
rms rms
U 3
rms
Fig. 1.13 Total apparent power according to calculation method 2 (ZxD400Cx
combimeters only)
D000030110 d – E650 Series 3 (ZMD400AT/CT, ZFD400AT/CT) – User Manual
(A1 + A2 + A3) + (R1 + R2 + R3) 2
, U2 , U3 and I1
rms rms rms
ò
Measured quantities
+S (Import)
ò
å
-S (Export)
ò
Description of Unit
Measured quantities
+S (Import)
2
-S (Export)
, I2 , I3 the micro-
rms rms rms