5-16
Metering and Monitoring
Date Code 20020129
SEL-387E Instruction Manual
The relay then restarts (just like powering down and then powering up the relay), and all
diagnostics are rerun before the relay is enabled.
The quantities shown in the STATUS report are discussed below. The applicable limits for
warning or failure of each self-test are summarized in Table 5.2.
The STATUS button on the front-panel interface can also be used to access the information in
the report. See
Section 8: Front-Panel Interface
.
Channel Offset
The relay measures the internal dc offset (OS) voltage of each of the nine current and three
voltage input channels and compares each measured value against a fixed limit of 30 mV. If an
offset measurement is outside the fixed limit, the relay declares a warning.
Power Supply
The relay measures the internal power supply (PS) voltages and reg5 and –5 voltages,
and compares the values against fixed limits. If a voltage measurement is outside the limits, the
relay declares a warning or failure.
Temperature
The relay measures its internal temperatures (TEMP). If the relay measures a temperature less
than –40
C or greater than +85
C, a warning is declared. If the relay measures a temperature
less than –50
C or greater than +100
C, a failure is declared. The temperature warning does not
pulse the ALARM output contact.
RAM
The relay checks the random-access memory (RAM). If a byte cannot be written to or read
from, the relay declares a RAM failure. There is no warning state for this test.
Flash ROM
The relay checks the flash read-only memory (ROM) by computing a checksum. If the
computed value does not agree with the stored value, the relay declares a ROM failure. There is
no warning state for this test.
Analog-to-Digital Converter
The relay verifies the A/D converter function by checking the A/D conversion time. The test
fails if conversion time is excessive or a conversion starts but does not finish. There is no
warning state for this test.
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