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Measurement Accuracy
Measurement Functions
All the direct measurements are based on fundamental frequency
values. (The exceptions are frequency and instantaneous current
for arc protection.) The figure shows a current waveform and the
corresponding fundamental frequency component, second
harmonic and rms value in a special case, when the current
deviates significantly from a pure sine wave.
10
rms
5
f1
f2
0
-5
-10
0.00
0.05
Figure 5.1 – Example of Various Current Values of a Transformer Inrush Current
Table 5.1 – Phase Current Inputs I
Measuring range
I ≤ 7.5 A
Inaccuracy
I > 7.5 A
The specified frequency range is 45 Hz – 65 Hz.
Voltage Inputs U
, U
A
B
The usage of voltage inputs depends on the configuration parameter
"voltage measurement mode". For example, U
voltage input U
if the mode "1LL+U
0
Table 5.2 – Voltage Inputs U
Measuring range
Inaccuracy
The specified frequency range is 45 Hz – 65 Hz.
f2/f1 (%)
IL2
0.10
0.15
0.20
Time (s)
, I
, I
L1
L2
L3
0 – 250 A (5A)
0.5 % of value or 15 mA
3 % of value
, U
C
/LLy" is selected.
0
, U
, U
A
B
C
0 – 5 xI
n
0.5% or 0.3 V
5
Chapter
Load = 0%
100
50
0
0.25
0.30
InrushCurrentLoad0
is the zero sequence
c
857-UM001A-EN-P – July 2009
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