Eliwell EWCM 4120, Manual, Page: 51 / 75

51
ALARMS
The alarms can be one of 3 types:
Automatic reset alarm : alarm active if the cause of the alarm is present, otherwise not.
Manual reset alarm: alarm active if the cause of the alarm is present, if the cause of the alarm has ceased the alarm
can only be reset manually (by simultaneously pressing the UP and DOWN keys).
Semi-automatic alarm: Behaves like an automatic alarm as long as the number of events in the unit of time is less
than a certain value, otherwise like a manual alarm. The unit of time can be programmed using parameter AL00 , the
number of responses can be individually programmed for each semi-automatic alarm.
Alarm events are stored with a time resolution of T=(
AL00 /32) minutes; multiple events occurring in period T are
counted as one single event.
Manual reset performed while an alarm cause is present does not enable the alarm to be reset.
It is possible to force the semi-automatic alarm to be considered only as an automatic alarm or a manual reset alarm,
by setting the appropriate number of alarm responses:
 If the number of responses=0, the alarm is managed as a manual reset alarm only. At the first response, the
alarm will become active and can be reset manually;
 If the number of responses=33 the alarm is managed as an automatic alarm only. At the first response, the
alarm becomes active but automatically resets when the cause has ceased;
A bypass time is defined for semi-automatic alarms and can be set by parameter. It allows the alarm signal to be
delayed, for example to enable the system to stabilise.
If the
bypass time = 0 , the alarm response is immediate (see the following diagram).
Alarm signal
See special display diagram