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5.52
SEL-421 Relay
Instruction Manual
Date Code 20171021
Protection Functions
Out-of-Step Logic (Conventional)
➤
Setting R1L6 must be set greater than R1L7.
➤
Setting X1T6 must be set less than X1T7.
➤
Setting X1B6 must be set greater than X1B7.
➤
The minimum separation between settings R1R6 and R1R7 is 0.25/I
NOM
.
➤
The minimum separation between settings R1L6 and R1L7 is 0.25/I
NOM
.
➤
The minimum separation between settings X1T6 and X1T7 is 0.25/I
NOM
.
➤
The minimum separation between settings X1B6 and X1B7 is 0.25/I
NOM
.
➤
Setting OSBD must be greater than OSTD by a minimum of 0.5 cycle.
Table 5.46
OOS Logic Relay Settings
Setting
Prompt
Range
Default
(5 A)
EOOS
Out-of-Step
Y, Y1, N
N
OOSB1
Block Zone 1
Y, N
Y
OOSB2
Block Zone 2
Y, N
Y
OOSB3
Block Zone 3
Y, N
Y
OOSB4
Block Zone 4
Y, N
N
OOSB5
Block Zone 5
Y, N
N
OSBD
a
a
Hidden when EOOS = Y1.
Out-of-Step Block Time Delay (cycles)
0.500–8000
2.000
OSBLTCH
Latch Out-of-Step Blocking
b
b
The OSB (Out-of-Step Blocking) logic resets automatically after it asserts for more than 2
seconds. You can latch OSB if the power swing moves outside of Zone 6 before the two-second
timer expires.
Y, N
N
EOOST
Out-of-Step Trip Delay
c
c
Option I enables tripping on the way into Zone 6; option O enables tripping on the way out of
Zone 6; option N disabled OST (Out-of-Step Trip).
N, I, O, C
N
OSTD
Out-of-Step Trip Delay (cycles)
0.500–8000
0.500
X1T7
Zone 7 Reactance—Top (
) (0.25–700)/I
NOM
23.00
X1T6
Zone 6 Reactance—Top (
)
(0.25–700)/I
NOM
21.00
R1R7
Zone 7 Resistance—Right (
)
(0.25–700)/I
NOM
23.00
R1R6
Zone 6 Resistance—Right (
)
(0.25–700)/I
NOM
21.00
X1B7
d
Advanced Setting if EADVS := Y. If the Advanced Settings are not enabled (setting EADVS := N),
the relay hides the setting.
Zone 7 Reactance—Bottom (
)
(–0.25–700)/I
NOM
–23.00
X1B6
Zone 6 Reactance—Bottom (
)
(–0.25–700)/I
NOM
–21.00
R1L7
Zone 7 Resistance—Left (
)
(–0.25–700)/I
NOM
–23.00
R1L6
Zone 6 Resistance—Left (
)
(–0.25–700)/I
NOM
–21.00
50ABCP
Pos.-Seq. Current Supervision (A)
(0.20–20) • I
NOM
1.00
50QUBP
Neg.-Seq. Current Supervision (A)
(OFF, 0.10–20) • I
NOM
OFF
Neg.-Seq. Current Unblock Delay (cycles)
0.500–120
0.500
UBOSBF
Out-of-Step Angle Unblock Rate
1–10
4
OOSPSC
No. of Pole Slips Before Tripping
1–10
1
Summary of Contents for SEL-421-4
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