U.6.8
SEL-421/SEL-421-1 Relay User’s Guide Date Code 20020501
Testing and Troubleshooting
Testing Features and Tools
Main Board Processing Module Tests
Use signals from the SEL-4000 Low-Level Relay Test System to test the relay
processing module. Apply appropriate signals to the low-level test interface
J20 from the SEL-4000 Relay Test System (see Figure 6.1 on page 6.7).
These signals simulate power system conditions, taking into account PT ratio
and CT ratio scaling. Use relay metering to determine whether the applied test
voltages and currents produce correct relay operating quantities.
The UUT Database entries for the SEL-421 Relay in the SEL-5401 Relay Test
System Software are shown in Tab le 6.4 and Table 6.5.
Table 6.4 UUT Database Entries for
SEL-5401 Relay Test System Software—5 A Relay
Label Scale Factor Unit
1IAW75 A
2IBW75 A
3ICW75 A
4IAX75 A
5IBX75 A
6ICX75 A
7VAY150 V
8VBY150 V
9VCY150 V
10 VAZ 150 V
11 VBZ 150 V
12 VCZ 150 V
Table 6.5 UUT Database Entries for
SEL-5401 Relay Test System Software—1 A Relay
Label Scale Factor Unit
1IAW15 A
2IBW15 A
3ICW15 A
4IAX15 A
5IBX15 A
6ICX15 A
7VAY150 V
8VBY150 V
9VCY150 V
10 VAZ 150 V
11 VBZ 150 V
12 VCZ 150 V
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