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3-10
Distance, Overcurrent, Voltage,
Date Code 20011205
and Synchronism Check Elements
SEL-311B Instruction Manual
Ground Distance Elements
The SEL-311B Relay has three independent zones of mho ground distance protection. All zones
are independently set. Zones 1 and 2 are forward direction only, and Zone 3 can be set either
forward or reverse. The mho ground distance elements use positive-sequence voltage
polarization for security and to create an expanded mho characteristic.
Impedance Reach (Zones 1–3)
Enable Setting:
E21MG
Mho Ground
Settings range for Mho elements
(Z1MG through Z3MG):
OFF, 0.05 to 64
W
sec, 0.01
W
steps (5 A nominal)
OFF, 0.25 to 320
W
sec, 0.01
W
steps
(1 A nominal)
Minimum sensitivity is controlled by the pickup of
the supervising phase and residual overcurrent
elements for each zone.
Accuracy:
±
5% of setting at line angle for 30
≤
SIR
≤
60
±
3% of setting at line angle for SIR < 30
Transient Overreach:
< 5% of setting plus steady-state accuracy
Phase and Residual Current Fault Detectors (Zones 1–3)
Setting Range for Phase and Residual
Current Fault Detectors (50L1 through
50L3 and 50GZ1 through 50GZ3):
Note:
If EADVS = N, levels 2 and 3 fault
detectors are set at their minimum
values and are hidden.
0.50–100.00 A secondary, 0.01 A steps
(5 A nominal)
0.10–20.00 A secondary, 0.01 A steps
(1 A nominal)
Accuracy:
±
0.05 A and ±3% of setting (5 A nominal)
±
0.01 A and ±3% of setting (1 A nominal)
Transient Overreach:
< 5% of pickup
Max. Operating Time:
See pickup and reset time curves in Figure 3.14
and Figure 3.15.
Other Settings
Settings range for zero sequence
compensation (ZSC) factor magnitude:
k0M1 = 0.000–6.000 unitless (Zone 1)
k0M = 0.000–6.000 unitless (Zone 2 and 3
advanced setting hidden and set to
k0M1 when EADVS = N)
Settings range for zero sequence
compensation (ZSC) factor angle:
k0A1 = -180.0 to +180.0 degrees (Zone 1)
k0A = -180.0 to +180.0 degrees (Zone 2 and 3
advanced setting hidden and set to
k0A1 when EADVS = N)
where
(
) (
)
(
)
ANG
1
Z
MAG
1
Z
3
ANG
1
Z
MAG
1
Z
ANG
0
Z
MAG
0
Z
1
A
0
k
1
M
0
k
Ð
·
Ð
-
Ð
=
Ð
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