GUID-4FEEEF83-D0D7-49A8-90F6-453E28AE27B2 V2 EN
Figure 417: Equivalent diagram of the protected feeder. R
L0F
= Ph leakage Ris.
The determination of the Ph capacitive React setting can be based either on network data
or measurement.
If the total phase-to-ground capacitance (including all branches) per phase C
0F
of the
protected feeder is known, the setting value can be calculated.
Ph capacitive React
C
n F
=
⋅
( )
1
0
ω
GUID-3D723613-A007-47ED-B8D7-F9D55C5FBF38 V2 EN (Equation 155)
In case of ungrounded network, if the ground-fault current produced by the protected
feeder I
ef
is known, the setting value can be calculated.
Ph capacitive React =
⋅3 V
I
xy
ef
GUID-B5941588-6DFC-4BF9-8EEB-DB7139F7B996 V1 EN (Equation 156)
V
xy
Phase-to-ground voltage
21FL 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 a ground-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.
Section 5 1MAC059074-MB A
Protection related functions
818 615 series ANSI
Technical Manual
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