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Service Manual
Third edition, June 1997
9.14 Finding Cause of Ground Failure Warning
When the warning message “Level Unit Ground Failure” is
displayed on the Work Station or when the ground failure
LED on a Transmitter Interface in the Level Unit lights up,
there is a need to find the cause of the ground failure.
The ground failure could be located in the cables between the
Transmitter and Level Unit or between Transmitter and
temperature sensors, IG pressure sensors, extra temperature
sensors or Local Display (if these options are included). It
could also be located within the units themselves or in their
wire terminals.
You need a multimeter when searching for a ground failure.
Follow the steps below to find the cause of the ground fail-
ure:
1. Open the LI Status-window in the Service part of the
Work Station Software. In this window the status of the
LI’s ComFail, GroundFail, +15 V and -15V are shown.
Find the LI that is causing the ground failure. Or check
ground failure LED on LI to find out which LI is caus-
ing the ground failure.
9.14.1 Ground Failure – Transmitter Interface
Note: Before pulling the connectors out, check that they are marked
so that they can be replaced correctly.
2. On the LI that is causing the ground failure, pull out the
connectors to the Transmitters one by one. Check when
ground failure LED goes off, to find which transmitter
that is causing the ground failure.
9.14.2 Ground Failure – Transmitter Cable
3. Check the cable between Transmitter and Transmitter
Interface in the Level Unit following the steps in chap-
ter 9.14.8 below.
9.14.3 Ground Failure – Temperature Sensors
4. Check both temperature sensors and cable to tempera-
ture sensor by removing the wires to the temperature
sensors from the terminal in the transmitter housing.
5. Hold the wires together so that they are in contact with
each other and measure the resistance to ground. If the
resistance is larger than 10 MΩ go to step 10 below.
6. Check the cable between the Transmitter and the wire
terminal of the temperature sensors following the steps
in chapter 9.14.8 below.