13.10
SEL-351A Relay Instruction Manual Date Code 20080213
Testing and Troubleshooting
Relay Self-Tests
±15 V PS Warning ±14.40 V
±15.60 V
No Pulsed Measures the 15 V power supply every
10 seconds.
Failure ±14.00 V
±16.00 V
Yes Latched
TEMP Warning –40°C
+85°C
No Measures the temperature at the
A/D voltage reference every 10 seconds.
Failure –50°C
+100°C
Yes Latched
RAM Failure Yes Latched Performs a read/write test on system RAM
every 60 seconds.
ROM Failure checksum Yes Latched Performs a checksum test on the relay
program memory every 10 seconds.
A/D Failure Yes Latched Validates proper number of conversions
each 1/4 cycle.
CR_RAM Failure checksum Yes Latched Performs a checksum test on the
active copy of the relay settings every
10 seconds.
EEPROM Failure checksum Yes Latched Performs a checksum test on the
nonvolatile copy of the relay settings every
10 seconds.
The following self-tests are performed by dedicated circuitry in the microprocessor and the SEL-351A main board.
Failures in these tests shut down the microprocessor and are not shown in the STATUS report.
Microprocessor
Crystal
Failure Yes Latched The relay monitors the microprocessor
crystal. If the crystal fails, the relay dis-
plays
CLOCK STOPPED on the LCD dis-
play. The test runs continuously.
Microprocessor Failure Yes Latched The microprocessor examines each pro-
gram 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.
Table 13.3 Relay Self-Tests (Sheet 2 of 2)
Self-Test Condition Limits
Protection
Disabled
ALARM
Output
Description
Courtesy of NationalSwitchgear.com
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