Re(Yo)
Im(Yo)
Susceptance forward
OPERATEOPERATE
Conductance forward
OPERATE
Susceptance reverse
OPERATE
Conductance lt Ang >0
Susceptance lt Ang <0
Conductance reverse
GUID-0A34B498-4FDB-44B3-A539-BAE8F10ABDF0 V1 EN
Figure 168: 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.
4.2.4.6 Application
Neutral admittance protection provides a selective earth-fault protection function
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.
As a start condition for the neutral admittance protection, the residual overvoltage
condition is used. When the residual voltage exceeds the set threshold Voltage start
value, an earth fault is detected and the neutral admittance calculation is released.
In order to guarantee a high security of protection, that is, avoid false starts, the
Voltage start value setting must be set above the highest possible value of Uo
Section 4 1YHT530004D05 D
Protection functions
330 615 series
Technical Manual
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