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3.3
Date Code 20171021
Instruction Manual
SEL-421 Relay
Testing
Relay Test Connections
Relay Test Connections
The SEL-421 is a flexible tool that you can use to implement many protection
and control schemes. Although you can connect the relay to the power system in
many ways, connecting basic bench test sources helps you model and understand
more complex relay field connection schemes.
For each relay element test, you must apply ac voltage and current signals to the
relay. The text and figures in this subsection describe the test source connections
you need for relay protection element checks. You can use these connections to
test protective elements and simulate all fault types.
5
IBX
15
A
6
ICX
15
A
7
VAY
150
V
8
VBY
150
V
9
VCY
150
V
10
VAZ
150
V
11
VBZ
150
V
12
BCZ
150
V
Table 3.2
UUT Database Entries for SEL-5401 Relay Test System Software—1 A
Relay (Sheet 2 of 2)
Label
Scale Factor
Unit
NOTE:
The procedures specified in
this subsection are for initial relay
testing only. Follow your company
policy for connecting the relay to the
power system.
WARNING
Before working on a CT circuit, first
apply a short to the secondary wind-
ing of the CT.
Summary of Contents for SEL-421-4
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