Distance Relay Setting Examples
GARD 8000 Distance Relay
RFL Electronics Inc.
Short lines are defined by the IEEE Line Protection Guide (PC37.113) as lines with SIR > 4.
SIR for the line in the example is:
SIR =
5
Z
1
SL
0.8
.
Z
1
L
=
0.8 4.13
.
=
1.5 < 4
As this is not a short line, extended margins are not required and the zone settings 80%, 120%, 50%
are consequently used in this example.
Zone 1 reach
80% of ZL1 = 0.8 · 4.13 = 3.30
Time delay = 0
Zone 2 reach (forward pilot zone)
120% of ZL1 = 1.2 · 4.13 = 4.96
Zone 4 reach (reverse pilot zone)
50% of ZL1 = 0.5 · 4.13 = 2.07
August 1, 2009
8-20
973.334.3100
