Lamtec LT 2 Assembly And Commissioning Manual page 65

6 Commissioning / Shutdown
Possible warning / faults
Offset voltage outside the limits
Probe voltage U-O < -20mV
2
• Trigger of the warning:
- Probe voltage U-O
• Resolution:
- Probe is not in ambient air
- Reverse polarity swap probe connection terminals 33-34
- Change the probe / sensor
D-P offset calibration too low, not enough gas (compressed air)
• Trigger of the warning:
Rise in pressure in preliminary filter during offset calibration with insufficient
compressed air (<0.5mbar).
• Possible causes:
- There is no instrument air (compressed air) at the test gas connection of the
probe, or inadequate pre-pressure (0,3bar)
- The shut-off plug valve in the PCB is not open.
- The test gas throttle in the PCB is not open sufficiently.
- The signal from the differential pressure sensor has drifted (recalibrate to "0").
- Probe preliminary filter cracked or broken (replace)
D-P offset calibration too high, dirty preliminary filter
• Trigger of the warning:
Rise in pressure in preliminary filter during offset calibration with excessive
compressed air.
• Possible causes:
- Instrument air (compressed air) at the probe test gas connection has excessive
pre-pressure.
- The signal from the differential pressure sensor has drifted (recalibrate to "0").
- Probe preliminary filter is dirty (clean it)
in ambient air is outside the range of -20...+20mV
2
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