3-12
Distance and Overcurrent Elements
Date Code 20011205
SEL-311A Instruction Manual
M311A049
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Fault Location in Percent of Set Reach
O
pera
tin
g
Time
in
Cycles
SEL-311A Mho Ground Operating Times
Single-Line-to-Ground Faults
SIR = 0.1
SIR = 1.0
SIR = 10.0
SIR = 30.0
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Fault Location in Percent of Set Reach
Tri
p
Time
in
Cycles
SEL-311A Phase Mho Operating Times
Phase-to-Phase Faults
SIR = 0.1
SIR = 1.0
SIR = 10.0
SIR = 30.0
Figure 3.8: Ground and Phase Distance Speed Curves
Additional Distance Element Supervision
The SEL-311A uses Relay Word bit VPOLV for positive-sequence memory supervision of mho
characteristics. VPOLV asserts when the memorized positive-sequence polarizing voltage is
greater than 1 Volt.
Summary of Contents for SEL-311A
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