Figure 88: Relay self-supervision status on Web HMI
In addition, the last boot reason and time are shown on both LHMI and WHMI.
6.2.1 Internal faults
When an internal relay fault is detected, the relay protection operation is disabled,
the self-supervision output relay is de-energized, and the change-over contact is
released. In the main unit, the main indication of an internal fault is a flashing green
Ready LED behind the power module, and on the HMI, a rapidly flashing red Home
button.
Different actions are taken depending on the severity of the internal fault. In case
of a temporary fault, the protection relay tries to recover from the situation by
restarting. The restart procedure includes two stages; when the relay detects a
fault, it restarts itself in a few seconds after the fault occurrence. If the relay did
not recover after the first restart, or the fault reoccurs during the next 60 minutes,
the second restart is delayed for 10 minutes. In case of a permanent fault, the
protection relay stays in the internal fault mode. All output relays are de-energized
and contacts are released for the internal fault. The protection relay continues to
perform internal tests during the fault situation. If the internal fault disappears, the
fault indication LEDs stop flashing and the protection relay returns to the normal
service state.
One possible cause for an internal fault situation is a so-called soft error. The soft
error is a probabilistic phenomenon which is rare in a single device, statistically
not happening more often than once in a relay’s lifetime. No hardware failures are
expected and a full recovery from the soft error is possible by a self-supervision
controlled restart of the relay.
The self-supervision signal output operates on the closed-circuit principle. Under
normal conditions, the IRF output relay is energized and the contact gap 3-5 is
closed. If the auxiliary power supply fails or an internal fault is detected, the IRF
output relay is de-energized and the contact gap 3-5 opens.
Troubleshooting
1MRS759118 D
90 REX640
Operation Manual
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General
