Toshiba GR-200-5 Instruction Manual page 215

6F2T0207 (0.01)
Negative sequence overvoltage protection (OVN)
Negative sequence voltage, in the supply or source circuits, is used to detect phase unbalance
and phase reversal. The function of overvoltage protection of negative sequence (OVN) has four
stages (OVN1 to OVN4) and the time characteristic of each stage can be obtained from definite
time or inverse definite minimum time either.
To simplify the description, only OVN1 is discussed but is applicable to the other OVNs;
hence, read the expression for OVN1 as OVN2, OVN3 and OVN4 at each OVN stage unless a
special explanation or instruction has been provided.
GRE200 (5,6)
- 195 -