Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Appendix A
UUser’s Guide
Firmware Versions
Firmware Versions
This manual covers SEL-421/SEL-421-1 Relays containing firmware bearing
the following firmware version numbers (most recent firmware listed at top):
Instructions for determining the firmware version of your SEL-421/
SEL-421-1 Relay are in
Firmware Version Number on page U.6.37 in the
Table A.1
Firmware Versions
Firmware Identification (FID) Number
Description of Changes
This firmware differs from the previous version as follows:
SEL-421-R103-V0-Z002002-D20020417
SEL-421-1-R103-V0-Z002002-D20020417
Spurious Quart interrupts caused by vary-
ing character spacing will cause the relay to
disable. This condition occurs when a com-
munications processor is automatically
retrieving data from the relay simulta-
neously with a serial port terminal session.
This firmware differs from the previous version as follows:
SEL-421-R102-V0-Z002001-D20020403
SEL-421-1-R102-V0-Z002001-D20020403
Initial Release with Synchrophasor Mea-
surement capability to the SEL-421 (not in
the SEL-421-1)
Added VAZ, VBZ, VCZ settings options to
SYNCP
Added VAY, VBY, VCY settings options to
SYNCS1, SYNCS2 and ASYNCS2
Added ACOS, ASIN, CEIL, FLOOR and
LOG math functions to SEL
OGIC
control
equations
Added new analog quantities for use in
SEL
OGIC
control equations:
Terminal W and X current magnitudes
Terminal Y and Z voltage magnitudes
Instantaneous sequence quantities
Contact inputs
Modified CHI output for SEL-2030 com-
patibility
This firmware differs from the previous version as follows:
SEL-421-R101-V0-Z001001-D20010104
Added 8-cycle lockout for subsequent
ALTI or ALTV switches
SEL-421-1-R101-V0-Z001001-D20010104 Initial SEL-421-1 Relay Release
SEL-421-R100-V0-Z001001-D20010703
Initial SEL-421 Relay Release.
Summary of Contents for SEL-421
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