GE 745 - 6.6.2 Self-test Errors

CHAPTER 6: ACTUAL VALUES TARGET AND FLASH MESSAGES
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–25
6.6.2 Self-test Errors
The 745 performs self-diagnostics at initialization (after power-up), and continuously
thereafter (in a background task). The tests ensure that every testable unit of the hardware
is functioning correctly.
CAUTION
Any self-test error indicates a serious problem requiring service.
Major self-test errors:
Upon detection of a major self-test error, the 745:
• disables all protection functionality
• turns on the front panel Self-Test Error LED
• turns off the front panel In Service LED
• de-energizes all output relays, including the self-test relay
• indicates the failure by inserting an appropriate message in the target message
queue
• records the failure in the event recorder
Minor self-test errors:
Upon detection of a minor self-test error, the 745:
• turns on the front panel Self-Test Error LED
• de-energizes the Self-Test Relay
• indicates the failure by inserting an appropriate message in the target message
queue
• records the failure in the event recorder
All conditions listed in the following table cause a target message to be generated.
Table 6–4: Self-test error interpretation
Event message Target message Severity Cause
Logic Input Power Self-Test Warning 0
Replace Immediately
Minor This error is caused by failure of the
+32 V DC power supply used to
power dry contacts of logic inputs.
Logic inputs using internal power are
affected by this failure. This may be
caused by an external connection
which shorts this power supply to
ground.
Analog Output Power Self-Test Warning 1
Replace Immediately
Minor This error is caused by failure of the
+32 V DC power supply used to
power analog outputs. Analog
output currents are affected by this
failure.
Unit Not Calibrated Unit Not Calibrated
Replace Immediately
Minor This error message appears when
the 745 determines that it has not
been calibrated. Although the relay
is fully functional, the accuracy of
measured input values (e.g. currents
and line voltage) as well as
generated outputs (e.g. analog
outputs) is not likely to be within
those specified for the relay.