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
7VAY150V
8VBY150V
9VCY150V
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.
Before working on a CT circuit, first
apply a short to the secondary wind-
ing of the CT.
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