ABB REJ 521 - REJ 521 Protection Relay Indications

1MRS 752179-MUM
Earth-Fault Relay
Operator’s Manual
REJ 521
21
3.3. Protection relay indications
The operation of the relay can be monitored by means of two different kinds of
indications on the HMI:
• LED indications: Start, Trip and Ready
• A text message on the LCD
The basic protection functions are not affected by fault indications.
3.3.1. Indicator LEDs
When a protection stage starts, the yellow indicator LED will be lit. When a
protection stage trips, the yellow indicator LED will remain lit and the red indicator
LED will be lit. When a starting protection stage is blocked, the yellow indicator
LED will start to blink.
3.3.1.1. Green indicator LED
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Two different functions are embedded in the READY indicator LED: power on and
IRF (internal relay fault).
• Indicator off:
The auxiliary voltage is not connected.
• Lit indicator:
The relay is in normal operation, i.e. the CPU operates. No internal faults have
occurred.
• Blinking indicator:
An internal relay fault has occurred. Refer to section Internal fault.
3.3.1.2. Yellow indicator LED
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START indicator
• Indicator off:
No protection stage has started.
Green
STARTREADY TRIP
Yellow
STARTREADY TRIP