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5.89
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Functions
Quadrilateral Phase-Distance Elements
When you set the number of zones you want to enable (E21XP), this setting
applies to both the high-speed and conventional elements. For example, E21XP =
2 makes two zones (Zone 1 and Zone 2) available for both the high-speed and
conventional elements and hides the remaining zones.
shows the Relay Word bits for quadrilateral phase-distance elements.
shows the logic of the Zone 1 conventional quadrilateral phase-
distance element for the AB loop. Fault calculations for BC and CA faults have
similar logics.
Table 5.54
Quadrilateral Phase-Distance Elements Relay Word Bits
Relay Word Bit
Description
XAB1
Zone 1 quad A-B phase element
XBC1
Zone 1 quad B-C phase element
XCA1
Zone 1 quad C-A phase element
XAB2
Zone 2 quad A-B phase element
XBC2
Zone 2 quad B-C phase element
XCA2
Zone 2 quad C-A phase element
XAB3
Zone 3 quad A-B phase element
XBC3
Zone 3 quad B-C phase element
XCA3
Zone 3 quad C-A phase element
XAB4
Zone 4 quad A-B phase element
XBC4
Zone 4 quad B-C phase element
XCA4
Zone 4 quad C-A phase element
XAB5
Zone 5 quad A-B phase element
XBC5
Zone 5 quad B-C phase element
XCA5
Zone 5 quad C-A phase element
Summary of Contents for SEL-421-4
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