U.1.10
SEL-421/SEL-421-1 Relay
User’s Guide
Date Code 20020501
Introduction and Specifications
Applications
Directional Comparison
Blocking Trip (DCB)
schemes
Current reversal guard logic
Carrier coordinating timers
Carrier send and receive extend logic
Zone 3 latch eliminates the need for offset three-phase
distance elements
Time-step distance backup protection
Direct Transfer Trip-
ping (DTT) schemes
SEL
OGIC
control equations program the elements that key
direct tripping
SCADA applications
Analog and digital data acquisition for station wide functions
Communications
capability
SEL ASCII
M
IRRORED
B
ITS
communications
SEL Fast Meter, SEL Fast Operate, SEL Fast SER
SEL Compressed ASCII
Optional protocols: Ethernet, UCA2, FTP, Telnet
Optional DNP 3.0
Customized protection
and automation schemes
Separate protection and automation SEL
OGIC
control
equation programming areas
Use timers and counters in expanded SEL
OGIC
control
equations for complete flexibility
Synchronized phasor
measurement
Phase and positive-sequence voltage measurements synchro-
nized within 0.25 degrees, sampled at 20 times per second
Table 1.1
Application Highlights
(Sheet 2 of 2)
Application
Key Features
NOTE:
Synchrophasor capability is
not available in the SEL-421-1 Relay.
Summary of Contents for SEL-421
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