ABB RELION 670 Series Applications Manual page 623

1MRK 504 152-UEN B
The zero sequence voltage for a fault at the remote line end and appropriate fault resistance is
calculated.
To avoid unwanted trip from the weak-end infeed logic (if spurious signals should occur), set
the operate value of the broken delta voltage level detector (3U0) higher than the maximum
false network frequency residual voltage that can occur during normal service conditions. The
recommended minimum setting is two times the false zero-sequence voltage during normal
service conditions.
Application manual
Section 15
Scheme communication
617