Application Guide - NP900 Series
31 (504
)
Table 3.1.2.4-29 Harmonic voltage measurements in NP900.
Name
Range
Step
Description
U1 Harmonics
U1 fund…U1 31harm
0.00…100000.0V
0.01V
Selectable per unit, primary and
secondary harmonics per component for
voltage input U1
U2 Harmonics
U2 fund…U2 31harm
0.00…100000.0V
0.01V
Selectable per unit, primary and
secondary harmonics per component for
voltage input U2
U3 Harmonics
U3 fund…U3 31harm
0.00…100000.0V
0.01V
Selectable per unit, primary and
secondary harmonics per component for
voltage input U3
U4 Harmonics
U4 fund…U4 31harm
0.00…100000.0V
0.01V
Selectable per unit, primary and
secondary harmonics per component for
voltage input U4
3.1.3
F
REQUENCY TRACKING AND SAMPLING
In NP900 series the measurement sampling can be set to frequency tracking mode or
fixed user given frequency sampling mode. Benefit of the frequency tracking is that the
measurements are in given accuracy range even when the fundamental frequency of the
power system changes.
Measurement error with fixed 50Hz sampling
frequency when frequency changes. Constant current
of 5A, frequency sweep from 6 Hz to 75 Hz
Measurement error with frequency tracking when
frequency changes. Constant current of 5A, frequency
sweep from 6 Hz to 75 Hz
Figure 3.1.3-20 Frequency tracking effect when the fundamental frequency is changing
from 6 Hz to 75 Hz
As can be seen in the figure above the sampling frequency has major effect to the
measurement accuracy of the IED. If the sampling is not tracked to the system frequency
it can be seen that even a change from set 50Hz to measured system frequency 60Hz
Содержание NP900 Series
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Страница 49: ...Application Guide NP900 Series 49 504 A996A Figure 3 2 1 3 25 Definite time operating characteristics...
Страница 50: ...Application Guide NP900 Series 50 504 A996A Figure 3 2 1 3 26 IEC predefined characteristics NI VI LTI and EI...
Страница 52: ...Application Guide NP900 Series 52 504 A996A Figure 3 2 1 3 28 IEEE predefined characteristics EI MI and VI...
Страница 243: ...Application Guide NP900 Series 243 504 A996A Figure 3 3 2 1 122 NPS biased thermal trip curves with kNPS values 7 and 10...
Страница 491: ...Application Guide NP900 Series 491 504 A996A 3 7 5 6 SETTING EXAMPLE...
Страница 504: ...Application Guide NP900 Series 504 504 A996A A996A...