LEGRAND Raritan PX3TS User Manual page 861

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 PX3TS 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
Upper Critical = 33
Upper Warning = 25
Lower Critical = 10
Lower Warning = 18
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 PX3TS 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
Appendix J: Additional PX3TS Information
Deassertion value
Deassertion level = 31
•
33 - 2 = 31
Deassertion level = 23
•
25 - 2 = 23
Deassertion level = 12
•
10 + 2 = 12
Deassertion level = 20
•
18 + 2 = 20
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