ABB RELION 620 Series Technical Manual page 857

1MRS757644 F
620 series
Technical Manual
If the total phase-to-earth capacitance (including all branches) per phase C
protected feeder is known, the setting value can be calculated.
Ph capacitive React
=
(
ω
n
GUID-3D723613-A007-47ED-B8D7-F9D55C5FBF38 V2 EN
In case of unearthed network, if the earth-fault current produced by the protected
feeder I is known, the setting value can be calculated.
ef
Ph capacitive React
GUID-60CC60C2-2547-404D-ABEB-74D112142F48 V3 EN
U Phase-to-earth voltage
xy
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 441 shows an example configuration, which enables the measurement of
setting Ph capacitive React.
GUID-DB04812D-DFF9-4E3F-9CC3-486322E70420 V1 EN
Figure 441: 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.
Protection related functions
1
)
C
⋅
0 F
U
⋅ 3
xy
=
I
ef
Section 5
of the
0F
(Equation 169)
(Equation 170)
851