![Schweitzer Engineering Laboratories SEL-421-4 Instruction Manual Download Page 38](http://html.mh-extra.com/html/schweitzer-engineering-laboratories/sel-421-4/sel-421-4_instruction-manual_1216726038.webp)
1.8
SEL-421 Relay
Instruction Manual
Date Code 20171021
Introduction and Specifications
Applications
Applications
Use the SEL-421 in a variety of transmission line protection applications. For
information on connecting the relay, see
Protection Applications Examples
for a description of various protection applica-
tions using the SEL-421.
The figures in this subsection illustrate common relay application configurations.
,
, and
demon-
strate relay versatility with Global setting ESS (Current and Voltage Source
Selection). These figures show the power and simplicity of the four prepro-
grammed ESS options. For more information on setting ESS, see
Voltage Source Selection on page 5.2
.
The SEL-421 has two sets of three-phase analog current inputs, IW and IX, and
two sets of three-phase analog voltage inputs, VY and VZ. The drawings that fol-
low use a two-letter acronym to represent all three phases of a relay analog input.
For example, IW represents IAW, IBW, and ICW for A-, B-, and C-Phase current
inputs on terminal W, respectively. The drawings list a separate phase designator
if you need only one or two phases of the analog input set (VAZ for the A-Phase
voltage of the VZ input set, for example).
The SEL-421 supports remote data acquisition through use of the SEL-2240
Axion. The SEL Axion provides remote analog and digital data over an
IEC 61158 EtherCAT TiDL network. This technology provides low and deter-
ministic latency over a point-to-point architecture. The SEL-421 can receive as
many as eight fiber-optic links from as many as eight Axion remote data acquisi-
tion nodes. See
for more details about TiDL applications.
Figure 1.2
Protecting a Line Segment With M
IRRORED
B
ITS
Communications on a
Fiber Channel
Figure 1.3
Single Circuit Breaker Configuration (ESS := 1)
SEL-421
Relay
CB
TX/RX
SEL-421
Relay
TX/RX
M
IRRORED
B
ITS
Communications
SEL-28XX
SEL-28XX
BUS 1
BUS 2
CB
SEL-421 Relay
BUS
CB1
3
3
IW
VAZ
VY
1
Analog Input
IW
VY
VAZ
Function
CB1 protection, line protection
Line protection
Synchronism check
Summary of Contents for SEL-421-4
Page 6: ...This page intentionally left blank ...
Page 14: ...This page intentionally left blank ...
Page 30: ...This page intentionally left blank ...
Page 104: ...This page intentionally left blank ...
Page 128: ...This page intentionally left blank ...
Page 536: ...This page intentionally left blank ...
Page 584: ...This page intentionally left blank ...
Page 616: ...This page intentionally left blank ...
Page 696: ...This page intentionally left blank ...
Page 750: ...This page intentionally left blank ...
Page 755: ...Instruction Manual PM400 01 NB SEL 400 Series Relays Instruction Manual 20171006 ...
Page 776: ...This page intentionally left blank ...
Page 932: ...This page intentionally left blank ...
Page 976: ...This page intentionally left blank ...
Page 1024: ...This page intentionally left blank ...
Page 1038: ...This page intentionally left blank ...
Page 1064: ...This page intentionally left blank ...
Page 1128: ...This page intentionally left blank ...
Page 1206: ...This page intentionally left blank ...
Page 1316: ...This page intentionally left blank ...
Page 1350: ...This page intentionally left blank ...
Page 1464: ...This page intentionally left blank ...
Page 1468: ...This page intentionally left blank ...
Page 1492: ...This page intentionally left blank ...
Page 1518: ...This page intentionally left blank ...