Calculating Settings For Sensitive Directional Residual Overcurrent Protection Sdepsde 67N - ABB REL650 Applications Manual

1MRK 506 334-UUS A
3.2.2
Application manual
Y
ANSI11000119 V1 EN
Figure 34: Single phase-to-ground fault
6. Set tVN to 0.001 s
Setting tVN gives the pick-up delay for residual voltage. The default value 0.001 s is
proposed.
7. Set tOffVN to 0.1 s
Setting tOffVN gives the drop-off delay for residual voltage. The default value 0.1 s
is proposed.
Set tOffVN to 0.1 s
8. Set tIN to 0.15 s
Setting tIN gives the pick-up delay for residual current. The default value 0.15 s is
proposed.
Calculating settings for sensitive directional residual
overcurrent protection SDEPSDE 67N
In high impedance grounded system the ground fault current, at single phase-to-ground
fault, is small compared to the fault current at phase-to-phase short circuit. Therefore it is
difficult and normally not possible to use distance protection as ground fault protection.
In many networks it is also required to detect and clear phase-to-ground faults with a high
resistance to ground in the fault point. The ground fault current is limited by the
REL650 setting examples
3I
0line
REL 650
REL 650
Section 3
Phase-ground fault
ANSI11000119_1_en.vsd
85