6.137
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Applications Examples
Autoreclose Example
Autoreclose Example
This application example is for a double-ended 230 kV overhead transmission
line with SEL-421 protection at each end. The one-line drawing for this circuit is
shown in Figure 6.34. This example shows settings for the SEL-421 at Station S
(Harvard) in Figure 6.35.
Application
Autoreclose Mode of Operation
Apply the SEL-421 for one shot of three-pole autoreclose.
R1L6 Zone 6 Resistance—Left (–0.05 to –140 secondary) –5.87
50ABCP Positive-Sequence Current Supervision
(1.00–100 A secondary)
1.00
50QUBP Negative-Sequence Current Supervision
(OFF, 0.50–100 A secondary)
OFF
UBD Negative-Sequence Current Unblock Delay
(0.500–120 cycles)
0.500
UBOSBF Out-of-Step Angle Unblock Rate (1–10) 4
50Q1P Level Pickup (OFF, 0.25–100 Amps sec.) OFF
67Q1D Level 1 Time Delay (0.000–16000 cycles) 0.000
67Q1TC Level 1 Torque Control (SEL
OGIC Equation) 1
TR Trip (SEL
OGIC Equation) Z1P OR Z1G OR
M2PT OR Z2GT
OR OST
OUT205 Output OUT205 (SEL
OGIC Equation) OST
Table 6.38 Out-of-Step Tripping/Blocking (Sheet 2 of 2)
Setting Prompt Entry
Figure 6.34 230 kV Example Power System
SEL-421 SEL-421
Z
1L
, Z
0L
Z
1S
, Z
0S
BK1
S (Harvard) R (Princeton)
BK2
Z
1R
, Z
0R
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