ABB RELION Series, Техническое руководство

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In case of unearthed network, if the earth-fault current produced by the protected
feeder I
ef
is known, the setting value can be calculated.
Ph capacitive React
U
I
xy
ef
=
⋅
3
GUID-60CC60C2-2547-404D-ABEB-74D112142F48 V3 EN
(Equation 64)
U
xy
Phase-to-earth voltage
SCEFRFLO can also determine the value for the Ph capacitive React setting by
measurements. The calculation of Ph capacitive React is triggered by the binary signal
connected to the
TRIGG_XC0F
input when an earth-fault test is conducted outside the
protected feeder during commissioning, for example, at the substation busbar. The
Calculation Trg mode has to be “External”. After the activation of the
TRIGG_XC0F
triggering input, the calculated value for setting Ph capacitive React is obtained from
recorded data as parameter XC0F Calc . This value has to be manually entered for the
Ph capacitive React setting. The calculated value matches the current switching state
of the feeder and thus, if the switching state of the protected feeder changes, the value
should be updated.
Figure 257 shows an example configuration, which enables the measurement of
setting Ph capacitive React .
GUID-DB04812D-DFF9-4E3F-9CC3-486322E70420 V1 EN
Figure 257: An example configuration, which enables the measurement of
setting Ph capacitive React
If the earth fault is detected by the residual overvoltage function (
START
of
ROVPTOV), but not seen by the forward-looking earth-fault protection function
(
START
of DEFLPDEF), the fault is located outside the protected feeder. This is
mandatory for valid measurement of setting Ph capacitive React . After a set delay
(TONGAPC), the input
TRIGG_XC0F
is activated and the parameter XC0F Calc in
the recorded data is updated. The delay (TONGAPC) must be set longer than the start
delay of the directional earth-fault function DEFLPDEF, but shorter than the
minimum operating time of the directional earth-fault functions in any of the feeders.
For example, if the start delay is 100 ms and the shortest operating time 300 ms, a value
of 300 ms can be used. Circuit breaker and disconnector status is used to verify that the
entire feeder is measured.
Modeling a non-homogeneous line
A typical distribution feeder is built with several different types of overhead lines and
cables. This means that the feeder is electrically non-homogeneous. SCEFRFLO
Section 5
1MRS758755 A
Protection related functions
496 REC615 and RER615
Technical Manual