Application - ABB RELION REX640 Technical Manual

1MRS759142 C
4.2.4.7
REX640
Technical Manual
GUID-40A550B7-1DFE-4009-9272-E9187FAB5E74 V1 EN
Figure 258: Combined non-directional overconductance and non-directional
oversusceptance characteristic
The non-directional overconductance and non-directional
oversusceptance characteristic provides a good sensitivity and
selectivity when the characteristic is set to cover the total admittance
of the protected feeder with a proper margin.
The sign of the admittance characteristic settings should be
considered based on the location of characteristic boundary in the
admittance plane. All forward-settings are given with positive sign
and reverse-settings with negative sign.

Application

Admittance-based earth-fault protection provides a selective earth-fault protection for
high-resistance earthed, unearthed and compensated networks. It can be applied for
the protection of overhead lines as well as with underground cables. It can be used as
an alternative solution to traditional residual current-based earth-fault protection
functions, for example the IoCos mode in DEFxPDEF. Main advantages of EFPADM
include versatile applicability, good sensitivity and easy setting principles.
Section 4
Protection functions
473