ABB RELION REX640 Technical Manual page 1210

Protection related functions
r
en
r
a
xy
Ph leakage Ris and Ph capacitive React settings
The
distance estimation accuracy for earth faults. They are critical for an accurate fault
location in unearthed networks. In other types of networks they are less critical.
The
in terms of resistance per phase. The
total phase-to-earth capacitive reactance of the protected feeder per phase. Based
on experience, a proper estimate for
capacitive React .
Figure 690: Equivalent diagram of the protected feeder. R L0F = Ph leakage Ris.
The determination of the
network data or measurement.
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
In case of unearthed network, if the earth-fault current produced by the protected
feeder I
1210
2 2
3
3
r a a a
⋅ ⋅ ⋅
12 23 31
the equivalent radius [m] for conductor bundle
radius [m] for single conductor
distance [m] between phases x and y
Ph leakage Ris and Ph capacitive React settings are used for improving fault
Ph leakage Ris setting represents the leakage losses of the protected feeder
Ph capacitive React setting can be based either on
1
=
(
C
⋅
ω
n 0
is known, the setting value can be calculated.
ef
2
Ph capacitive React setting represents the
Ph leakage Ris should be about 20...40 × Ph
)
F
1MRS759142 F
of the
0F
(Equation 310)
REX640
Technical Manual