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a low threshold at 20 Pa and a hysteresis at 5 Pa: the alarm stay triggered until the value goes below 75 (or up to 25).
• Tap "Alarm parameters".
• Tap "Hysteresis".
• Enter the hysteresis.
The hysteresis must be between the low threshold and the high threshold (only if two thresholds are config-
ured).
Set the alarm acknowledgement
Alarm acknowledgement: when an alarm goes off, it is possible to acknowledge it by pressing the value in alarm
on the screen: the audible alarm, if activated, turns off and the displayed value blinks during the acknowledgement
duration. At the end of the acknowledgement duration, if the transmitter is still in alarm state, the audible alarm is
reactivated.
• Tap "Alarm parameters".
• Tap "Acknowledge".
• Enter the alarm acknowledgement in minute.
The acknowledgement duration must be between 0 and 60 min.
9.5 Set the autozero
Enter the interval between two autozeros: thanks to the temperature compensation of the gain (from 0 to 50 °C
/ 14 à 122 °F) and to the autozero system, Class 320 transmitters guarantee an excellent long-term stability, along
with a great measurement accuracy.
Autozero principle: the microprocessor drives a solenoid valve that compensates for any long-term drift of the sen-
sitive element.
Compensation is made by regular automatic adjustment of the zero. True differential pressure measurement is then
made regardless of the environmental conditions of the transmitter.
"I/O Configurations" menu is displayed.
• Tap "Autozero".
• Tap "Autozero interval".
• Enter the autozero interval in minute.
The autozero interval must be between 10 and 60 min.
The autozero is managed by a solenoid valve. The behaviour of this solenoid valve is linked to the ambient temper-
ature. An automatic monitoring of the internal of the temperature of the device ensures the correct operation of the
solenoid valve.
When starting the device or when the solenoid valve is activated for the first time, the solenoid valve is automatically
triggered for 30 seconds (160 seconds if the internal temperature if the device is lower than 0 °C/32 °F) if the internal
temperature of the device is higher than 0 °C/32 °F.
During the first 20 minutes, the solenoid valve is automatically triggered to perform an autozero every 3 minutes.
Between 20 minutes and 60 minutes, the solenoid valve is automatically triggered to perform an autozero every 10
minutes.
After the first hour of operation, the device will perform an autozero according to the user's configuration.
If the internal temperature of the device falls below 1 °C/34 °F, the solenoid valve is automatically activated every 30
minutes. The autozero is not take into account during this operation.
9.6 Set the relays (optional)
"I/O Configurations" menu is displayed.
• Tap "Relays configuration".
• Tap the required relay: "Relay 1", "Relay 2", "Relay 3" or "Relay 4".
Set inputs and outputs
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