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OPERATE
Neutral
admittance
calculation
BLOCK
START
IRES
Io
Uo
RELEASE
t
Timer
URES
Blocking
logic
Operation
charasteristics
FAULT_DIR
Figure 279: Functional module diagram
Neutral admittance calculation
When the residual voltage exceeds the set threshold
Voltage start value, an earth
fault is detected and the neutral admittance calculation is released.
To ensure a sufficient accuracy for the Io and Uo measurements, it is required that
the residual voltage exceeds the value set by
Min operate voltage. If the admittance
calculation mode is "Delta", the minimum change in the residual voltage due to a
fault must be 0.01 × Un to enable the operation. Similarly, the residual current must
exceed the value set by
Min operate current.
The polarity of the polarizing quantity Uo can be changed, that is,
rotated by 180 degrees, by setting the
Pol reversal parameter to "True" or
by switching the polarity of the residual voltage measurement wires.
As an alternative for the internal residual overvoltage-based start condition, the
neutral admittance protection can also be externally released by utilizing the
RELEASE
input.
When
Admittance Clc mode is set to "Delta", the external logic used must be able
to give RELEASE in less than 0.1 s from fault initiation. Otherwise the collected
pre-fault values are overwritten with fault time values. If it is slower,
Admittance Clc
mode must be set to “Normal”.
Neutral admittance is calculated as the quotient between the residual current and
residual voltage (polarity reversed) fundamental frequency phasors. The
Admittance
Clc mode setting defines the calculation mode.
Admittance Clc mode = "Normal"
Yo
Io
Uo
fault
fault
=
−
(Equation 57)
Admittance Clc mode = "Delta"
Yo
Io
Io
Uo
Uo
Io
Uo
fault
prefault
fault
prefault
=
−
−
−
=
−
(
)
∆
∆
(Equation 58)
Protection functions
1MRS759142 F
492
REX640
Technical Manual
Содержание RELION REX640
Страница 1: ... RELION PROTECTION AND CONTROL REX640 Technical Manual ...
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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: ......