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I3P
Second
harmonic
blocking
BLOCK
OPERATE
START
BLK2H
I_A
Earth fault
detector
I_B
I_C
IRES
Timer
t
Io
Figure 422: Functional module diagram
Earth-fault detector
The operation is based on comparing the amplitude and the phase difference
between the sum of the fundamental frequency component of the phase currents
(ΣI, residual current) and the fundamental frequency component of the neutral
current (Io) flowing in the conductor between the transformer or generator's
neutral point and earth. The differential current is calculated as the absolute
value of the difference between the residual current, that is, the sum of the
fundamental frequency components of the phase currents I_A, I_B and I_C, and the
neutral current. The directional differential current ID_COSPHI is the product of the
differential current and cosφ. The value is available in the monitored data view.
ID
COSPHI
I
Io
_
(
) cos
=
−
×
Σ
ϕ
(Equation 177)
Σ
I
Residual current
ϕ
Phase difference between the residual and neutral currents
Io
Neutral current
An earth fault occurring in the protected area, that is, between the phase CTs and
the neutral connection CT, causes a differential current. The directions, that is, the
phase difference of the residual current and the neutral current, are considered in
the operation criteria to maintain selectivity. A correct value for
CT connection type
is determined by the connection polarities of the current transformer.
The current transformer ratio mismatch between the phase current
transformer and neutral current transformer (residual current in the
analog input settings) is taken into account by the function with the
properly set analog input setting values.
During an earth fault in the protected area, the currents ΣI and Io are directed
towards the protected area. The factor cosφ is 1 when the phase difference of the
residual current and the neutral current is 180 degrees, that is, when the currents
are in opposite direction at the earth faults within the protected area. Similarly,
ID_COSPHI is specified to be 0 when the phase difference between the residual
current and the neutral current is less than 90 degrees in situations where there is
Protection functions
1MRS759142 F
750
REX640
Technical Manual
Содержание RELION REX640
Страница 1: ... RELION PROTECTION AND CONTROL REX640 Technical Manual ...
Страница 2: ......
Страница 3: ...Document ID 1MRS759142 Issued 2023 02 07 Revision F Copyright 2023 ABB All rights reserved ...
Страница 167: ...Figure 62 Signal outputs in power supply module 1MRS759142 F Basic functions REX640 Technical Manual 167 ...
Страница 184: ...Figure 84 mA channels working as mA outputs Basic functions 1MRS759142 F 184 REX640 Technical Manual ...
Страница 1868: ...Figure 989 ANSI extremely inverse time characteristics General function block features 1MRS759142 F 1868 REX640 Technical Manual ...
Страница 1869: ...Figure 990 ANSI very inverse time characteristics 1MRS759142 F General function block features REX640 Technical Manual 1869 ...
Страница 1870: ...Figure 991 ANSI normal inverse time characteristics General function block features 1MRS759142 F 1870 REX640 Technical Manual ...
Страница 1874: ...Figure 995 ANSI long time inverse time characteristics General function block features 1MRS759142 F 1874 REX640 Technical Manual ...
Страница 1875: ...Figure 996 IEC normal inverse time characteristics 1MRS759142 F General function block features REX640 Technical Manual 1875 ...
Страница 1876: ...Figure 997 IEC very inverse time characteristics General function block features 1MRS759142 F 1876 REX640 Technical Manual ...
Страница 1877: ...Figure 998 IEC inverse time characteristics 1MRS759142 F General function block features REX640 Technical Manual 1877 ...
Страница 1878: ...Figure 999 IEC extremely inverse time characteristics General function block features 1MRS759142 F 1878 REX640 Technical Manual ...
Страница 1882: ...Figure 1002 RI type inverse time characteristics General function block features 1MRS759142 F 1882 REX640 Technical Manual ...
Страница 1885: ...Figure 1004 UK rectifier inverse time characteristic 1MRS759142 F General function block features REX640 Technical Manual 1885 ...
Страница 1959: ......