KROHNE OPTISENS AAC 050 EN - Manual (Page 24)

Manual OPTISENS AAC 050
OPTISENS AAC 050 24
6.
Alarm
Additional to the limit function the device provides various check functions that raise alarm.
In case of an alarm, relay 3 switches, undelayed, and the cause of the alarm is indicated in the display.
If the cause of alarm is such that control is no longer possible or might even be dangerous, the controller is
automatically deactivated until the alarm is switched off.
Switching off the alarm is done automatically by the device as soon as the cause of alarm is eliminated.
Sensor check during calibration
If a sensor gives unsatisfying results during calibration, an alarm is issued. The alarm is held until a new
calibration shows satisfying sensor data. In case of calibration failure the controller is not deactivated, to
enable you to continue the dosing or treatment process until a replacement sensor is at hand.
Sensor check during measurement
During measurement all connected sensors are checked. If an analog input does not receive a correct signal,
for e. g. if a cable is broken or a sensor damaged, an alarm is issued, and the controller deactivated. Alarm
and controller stop remain until the analog input receives correct signals again.
Dosage control
If a controller output is 100% longer than the defined dosage time, an alarm is issued, and the corresponding
controller is deactivated. The alarm remains until the controller output drops below 100% - it can also be
extinguished by setting the controller to manual mode.
Cause of alarm only active in AUTO mode deactivates controller
Slope error no no
Error input 1 no yes
Error input 2 no yes
Limit yes no
Dosage yes yes