10.4 Acknowledgement / reset (AKN)
The frost protection relay does not release the fan again until frost alarm is no
longer pending and the signal has been reset.
Release conditions
You can choose between the following alarm reset alternatives:
•
3x automatic acknowledgement (YES3): Only the third frost alarm occurring
within half an hour needs to be acknowledged and reset
•
Manual acknowledgement (YES): All frost alarms have to be acknowledged and
reset
If the frost protection unit has an alarm latch of its own, you have to reset the frost
alarm at the frost protection unit. The plant will not restart until you have reset the
frost alarm at the frost protection unit and acknowledged and reset it at the
controller.
Note
Apply the following procedure in case of a pending frost alarm:
Procedure for a
pending frost alarm
1. Press
the
ESC
button once
=> acknowledges the fault
2. Press
the
ESC
button again
=> resets the fault
See also subsection 11.2.2 “Fault acknowledgement”.
10.5 Display
The controller displays a pending frost alarm as follows:
Pending frost alarm
°C
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Siemens
Universal Controllers RLU2…
CE1P3101en
Building Technologies
Frost protection (FROST)
29.08.2008