Technical Guide P92x/EN FT/E11
User Guide
MiCOM P921-P922-P923 Page 89/110
13. DISPLAY OF ALARMS
The presence of one or more alarm messages will be indicated by the default display
and by the yellow alarm LED flashing.
Alarms
The alarm messages can either be self-resetting or latched, in which case they must
be cleared manually. To view the alarm messages press the 1 key . When all alarms
have been viewed, but not cleared, the alarm LED will change from flashing to
constant illumination. To scroll through these pages, press the 1 key. The oldest
alarm will be displayed on the last page, the most recent one on the first page : each
message will be identified by a number. When all pages of the fault record have
been viewed, the following prompt will appear:
Clear All Alarms
To clear all alarm messages press 0 ; to return to the display of the first alarm
message and leave the alarms uncleared, press 1. There is no need to enter a
password before the alarm messages can be cleared. When the alarms have been
cleared the yellow alarm LED will extinguish, as will the red trip LED if it was
illuminated following a trip.
The alarm messages are classified as indicated below :
· electrical system alarms,
· relay hardware or software alarms.
13.1.1 Electrical system alarms
Any crossing of a threshold (instantaneous or time-delayed) generates an “electrical
system alarm”. For each alarm, the involved thresholds and phases are indicated.
For example :
V< 2/3
PHASE AB BC CA
NOTE : instantaneous information leads to a self-resetting alarm
message. The alarm LED will then be switched off as soon as the
instantaneous information has disappeared.
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