Process Alarm; X-Ray Alarm - Vega FiberFlex LFXG-H Operating Instructions Manual

Diagnostics and repair

Process alarm

This alarm alerts users when the process level is above (high limit) or below
a setpoint (low limit). Enter the choice of low or high limit and the setpoint on
the Alarm | Relay Setup tab.
This alarm works only with the output relay. HART messages, gauge status
diagnostics, and history information are not saved for this alarm.
The gauge acknowledges or resets the process alarm when the process
value returns to the setpoint value. Depending on your usage of the process
alarm relay, you may install a process alarm override switch to manually
turn off an annunciator when the gauge relay energizes.

X-ray alarm

This alarm compensates for falsely indicated process values that occur
when the gauge detects external radiographic sources (example: vessel
weld inspections often use portable radiographic (x-ray) sources). X-rays
that the gauge detects can cause a false low reading and adversely affect
any control based on the gauge output.
This alarm can:
• Alter the current loop output to indicate the alarm condition
• Trip the output relay, if it is configured to do so
The level gauge enters the x-ray alarm condition when it detects a radiation
field above a set threshold. The gauge sets the current loop output at its
value 10 seconds before the condition. It periodically dithers the output
about the average, cycling until the radiation field is back to the normal level
or until a time-out period of 60 minutes.
The standard x-ray alarm only triggers when the counts are greater than the
Cal Low count value. These counts are found on the process variable
menu. If the x-ray source is configured so the counts increase but do not
exceed the Cal Low counts, the x-ray alarm does not trigger and the gauge
reads the x-ray interference as a true process shift.
80 LFXG-H Installation and Operation Guide