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5.53
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Out-of-Step Logic (Conventional)
Table 5.47
OOS Logic Relay Word Bits
Name
Description
50ABC
Positive-sequence current level detector
X6ABC
Zone 6
X7ABC
Zone 7
UBOSB
Unblock out-of-step blocking
OSB
Out-of-step blocking
OSTI
Incoming out-of-step tripping
OSTO
Outgoing out-of-step tripping
OST
Out-of-step tripping
67QUBF
Negative-sequence forward directional element
67QUBR
Negative-sequence reverse directional element
OOSDET
OOS condition detected
OSB1
Block Zone 1 during out-of-step condition
OSB2
Block Zone 2 during out-of-step condition
OSB3
Block Zone 3 during out-of-step condition
OSB4
Block Zone 4 during out-of-step condition
OSB5
Block Zone 5 during out-of-step condition
OSBA
A-Phase out-of-step blocking
OSBB
B-Phase out-of-step blocking
OSBC
C-Phase out-of-step blocking
Summary of Contents for SEL-421-4
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