Sel 411L - Figure 3.117 OST Scheme Logic Resistive and Reactive Blinders

P.3.175
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Out-of-Step Logic (Zero Settings)
Figure 3.117 OST Scheme Logic Resistive and Reactive Blinders
Figure 3.118 shows the logic that determines whether the positive-sequence
impedance (Z1) falls within the Zone 6 and/or Zone 7 polygons, provided
there is no three-pole open (3PO) or loss-of-potential (ILOP) conditions.
R
jX
XT 7
XT 6
XB 6
XB 7
RR 7
RR 6
RL 6
RL 7
R1R6
X1 T7
X1 T6
X1 B6
X1 B7
Line
Operate
Restrain
R1R7
R1L7
R1L6