Self-Supervision - ABB REX 521 Operator's Manual

1MRS 751107-MUM
3.3.2.
Protection Relay
Operator's Manual
Fig. 3.3.1.-2 Indication of blocking
If a protection function trips, the name of the function and the text TRIP appear on
the display. The red LED indicator is lit. The faulted phases are displayed in this
case.
Should the protection function deliver a delayed trip for circuit-breaker failure
protection (CBFP), the red indicator starts blinking.
Fig. 3.3.1.-3 Indication of trip

Self-supervision

The protection relay is provided with an extensive self-supervision system. The self-
supervision system handles run-time fault situations and informs the user about
existing faults over the display and the serial communication.
When a fault has been detected, the green READY indicator starts blinking. At the
same time, the self-supervision (IRF) output relay is activated.
Additionally, a fault indication text INTERNAL FAULT appears on the display and
an event is generated.
Fig. 3.3.2.-1 Indication of fault
The fault indication has the highest priority and no other indication can overrun it.
The fault indication text is displayed until it is cleared by pressing the [C] button.
The green READY indicator continues blinking as long as the fault is present.
Should the fault disappear after a reset, the indicator stops blinking and an event is
generated over the serial communication. The self-supervision (IRF) output relay is
returned to its normal state.
3I>: BLOCK
3I> : TRIP
L1 , L2 , L3
INTERNAL FAULT
Relay Control
REX 521
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