LEGRAND Raritan PX3-3000 Series, User Manual

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Appendix L: Additional PX3 Information
901
In the threshold settings, the Deassertion Hysteresis field determines a
new level to trigger the "deassertion" action.
This function is similar to a thermostat, which instructs the air
conditioner to turn on the cooling system when the temperature exceeds
a pre-determined level. "Deassertion Hysteresis" instructs the PX3 to
de-assert the worse state for a sensor only when that sensor's reading
reaches the pre-determined "deassertion" level.
For upper thresholds, this "deassertion" level is a decrease against each
threshold. For lower thresholds, this level is an increase to each
threshold. The absolute value of the decrease/increase is exactly the
hysteresis value.
For example, if Deassertion Hysteresis = 2, then the deassertion level of
each threshold is either "+2" or "-2" as illustrated below.
Threshold value Deassertion value
Upper Critical = 33 Deassertion level = 31

33 - 2 = 31
Upper Warning = 25 Deassertion level = 23

25 - 2 = 23
Lower Critical = 10 Deassertion level = 12

10 + 2 = 12
Lower Warning = 18 Deassertion level = 20

18 + 2 = 20
To use each threshold as the "deassertion" level instead of determining
a new level, set the Deassertion Hysteresis to 0 (zero).
Note: The difference between Upper Warning and Lower Warning must
be at least "two times" of the deassertion value.
How "Deassertion Hysteresis" is helpful:
If you have created an event rule that instructs the PX3 to send
notifications for deassertion events, setting the "Deassertion Hysteresis"
is helpful for eliminating a number of notifications that you may receive
in case a sensor's readings fluctuate around a certain threshold.
Deassertion Hysteresis Example for Temperature Sensors