phonetic alphabet stands for "Z", which stands for
longitude zero.
UV
Undervoltage
WEI
Weak end infeed logic
VT
Voltage transformer
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 511 418-UEN A
Section 8
Glossary
650 series 2.2 IEC
47
Communication protocol manual