Hach ORBISPHERE K-M1100 User Manual page 55

Measurement Menu
Measurement alarms configuration
Set the thresholds for the low/high concentration levels, according to the application. Each alarm type
can be individually enabled or disabled without losing its settings.
These events can activate the relays and can be displayed.
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Low-low: 2nd stage for too low concentration
Low: 1st stage for too low concentration
High: 1st stage for too high concentration
High-high: 2nd stage for too high concentration
Hysteresis: A percentage of the above concentration values. The hysteresis is used to prevent relay
"flickering" when the measurement is just at the alarm levels. Set this to a minimum, but enough to
eliminate flickering.
As an example, if the High Alarm is set to 40 units and the Hysteresis is set to 10%, then the High
Alarm is activated once the measurement reaches 40 units, but only deactivated once the
measurement drops below 36 units. With the Low Alarm the opposite is true, in that if the Low Alarm
is set to 20 units and the Hysteresis set to 10%, then the Low Alarm is activated when the
measurement drops below 20 units, and deactivated when the measurement rises above 22 units.
Delay: The delay in seconds, before alarms go on whenever concentration values go above "High
alarms" or below "Low alarms". Set this to a minimum value, but enough to avoid alarms for
non-representative peaks beyond the set level.
Figure 37 Alarms system diagram