Setting Process Safety Parameters - ABB LWT300 series User Manual

Setting failure mode
You can specify whether high or low failures (saturations and alarms) raise an alarm. The default value is
Low.
To specify the failure mode:
1 Select Process Alarm > Failure Mode.
2 Press Edit.
3 Highlight High or Low and press OK.
Setting saturation limits
Although process alarm levels cannot be modified, you can modify saturation limits.
To do so:
1 Select Process Alarms > Saturation Limits > High Saturation or Low Saturation.
The low saturation default value is 3.80 mA. This value can be edited between 3.80 and 4.00 mA.
The high saturation default value is 20.50 mA. This value can be edited between 20.00 and 20.50 mA.
2 Press Edit.
3 Set the new saturation value and press OK.

Setting process safety parameters

Safety parameters can be configured to determine LWT behavior in cases where level measurements
become uncertain or impossible (e.g., levels getting exceedingly high or loss of signal (echoes).
Process safety parameters (as illustrated in Figure 35) are set from the Device Setup menu.
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Figure 34 The Device Setup menu
Setting a blocking distance
The blocking distance is the distance where you do not want the instrument to take measurements
because you know that these measurements will include erroneous or useless data (e.g., right at the
junction between a nozzle and the inside of the vessel, where a giant pulse usually forms.)
To set a blocking distance:
1 Select Device Setup > Safety Setting > Blocking distance.
2 Press Edit.
3 Set the necessary blocking distance and press OK.
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User Guide