13-8 Testing and Troubleshooting Date Code 20001006
SEL-351 Instruction Manual
Self-Test Condition Limits
Protection
Disabled
ALARM
Output Description
The following self-tests are performed by dedicated circuitry in the microprocessor and the
SEL-351 Relay main board. Failures in these tests shut down the microprocessor and are not
shown in the STATUS report.
Micro-
processor
Crystal
Failure Yes Latched The relay monitors the
microprocessor crystal.
If the crystal fails, the
relay displays “CLOCK
STOPPED” on the LCD
display. The test runs
continuously.
Micro-
processor
Failure Yes Latched The microprocessor
examines each program
instruction, memory
access, and interrupt.
The relay displays
“VECTOR nn” on the
LCD upon detection of an
invalid instruction,
memory access, or
spurious interrupt. The
test runs continuously.
RELAY TROUBLESHOOTING
Inspection Procedure
Complete the following procedure before disturbing the relay. After you finish the inspection,
proceed to the Troubleshooting Procedure.
1. Measure and record the power supply voltage at the power input terminals.
2. Check to see that the power is on. Do not turn the relay off.
3. Measure and record the voltage at all control inputs.
4. Measure and record the state of all output relays.
Courtesy of NationalSwitchgear.com
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