R.A.25
Date Code 20111215 Reference Manual SEL-421 Relay
Relay Word Bits
Row List
14 XCG3 Zone 3 quad C-phase-to-ground element
14 * Reserved
14 XAG4 Zone 4 quad A-phase-to-ground element
14 XBG4 Zone 4 quad B-phase-to-ground element
14 XCG4 Zone 4 quad C-phase-to-ground element
14 * Reserved
15 XAG5 Zone 5 quad A-phase-to-ground element
15 XBG5 Zone 5 quad B-phase-to-ground element
15 XCG5 Zone 5 quad C-phase-to-ground element
15 CVTBLH CCVT transient blocking logic active—high-speed ele-
ments
15 CVTBL CCVT transient blocking logic active
15 VPOLV Polarizing voltage valid
15 * Reserved
15 * Reserved
Table A.4 Relay Word Bits: Series Compensated Line Logic
a
a
Not in the SEL-421-1 nor the SEL-421-2.
Row Name Description
16 SERCAB Series-compensated line AB-phase output
16 SERCBC Series-compensated line BC-phase output
16 SERCCA Series-compensated line CA-phase output
16 SERCA Series-compensated line A-phase output
16 SERCB Series-compensated line B-phase output
16 SERCC Series-compensated line C-phase output
16 * Reserved
16 * Reserved
Table A.5 Relay Word Bits: Out-of-Step Elements (Sheet 1 of 2)
Row Name Description
17 X6ABC Impedance inside Zone 6 out-of-step
17 X7ABC Impedance inside Zone 7 out-of-step
17 50ABC Positive-sequence current above 50ABCP threshold
17 UBOSB Unblock out-of-step blocking
17 OSBA A-phase out-of-step block
17 OSBB B-phase out-of-step block
17 OSBC C-phase out-of-step block
17 OSB1 Block Zone 1 during an out-of-step condition
18 OSB2 Block Zone 2 during an out-of-step condition
18 OSB3 Block Zone 3 during an out-of-step condition
18 OSB4 Block Zone 4 during an out-of-step condition
18 OSB5 Block Zone 5 during an out-of-step condition
Table A.3 Relay Word Bits: Distance Elements (Sheet 4 of 4)
Row Name Description
NOTE: The SEL-421-1 and the
SEL-421-2 do not provide high-speed
distance elements, so the CVTBLH
Relay Word bit is unavailable.
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