ABB RELION REX640 Technical Manual page 98

Basic functions
preventing the relay from making false decisions, such as issuing false control
commands.
There are two types of fault indications.
• Internal faults
• Warnings
Warnings are indications of less severe situations which can also be caused by
external reasons, for example, in case the RTD sensor measurement circuit is not
complete.
On the LHMI, the self-supervision status is available as an advanced page under
Relay Status page. The self-supervision status is indicated with Internal Fault,
Warning and All OK LEDs. In normal operation, All OK LED is lit. The selfsupervision
also controls the status of IRF output relay. The IRF output relay is energized under
normal conditions and de-energized under internal fault conditions.
Figure 23: Relay self-supervision status on local HMI
On the WHMI, the self-supervision status is available under Device menu. The top
right LED indicates the relay status.
Figure 24: Relay self-supervision status on Web HMI
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1MRS759142 F
REX640
Technical Manual