ABB RED650 - Page 923

3I
O
Three times zero-sequence current.Often referred to as the
residual or the earth-fault current
3U
O
Three times the zero sequence voltage. Often referred to
as the residual voltage or the neutral point voltage
1MRK 505 394-UEN A Section 26
Glossary
Line differential protection RED650 2.2 IEC 917
Technical manual