Application Guide - NP900 Series
338 (504
)
A996A
relay and for that the vector group selection of the transformer setup has either “N” or “n”
representing either HV side or LV side grounding.
What this selection actually does is that it deducts the calculated zero sequence current
from the per-unitized currents before differential calculation thus negating the outside
earth fault effect.
Figure 1.1.1.6-160 Correctly selected transformer setting prevents the differential function
operation in out of zone earth faults.
This selection basically does for the “N” or “n” selected side or both of them the zero
sequence elimination by applying the before mentioned correction.
IL1
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Corr
= IL1
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-
IL1
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+ IL2
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+ IL3
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3
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...