VAF instruments OILCON MARK 6M, Technical Manual

Page: 106 / 175

105
15.12 DIFFERENTIAL PRESSURE TRANSMITTER PROBLEMS
NOTE:
For disassemble and re-assemble instructions consult section 8.2.7.
15.12.1 No line current
Probable causes Action
1
Transmitter connections. - Check the wiring polarity and continuity.
- Check for shorts or ground loops.
- Check if the power supply connector is connected to the
main board.
2
Power supply. - Check the power supply output.
The voltage must be between 12 and 45 VDC at the
transmitter terminals.
3
Electronic circuit failure. - Check the main board for defects by replacing it with a
spare one.
15.12.2 Current of 21.0mA or 3.9mA
Probable causes Action
1
Pressure tap (piping).

Verify if the blocking valves are fully open.

Check for gas in the liquid lines.

Check the specific density of the process fluid.

Check the process flanges for sediments.

Check the pressure connection.

Check if the bypass valve is closed.

Check if the pressure applied is not over the upper limit
of the DPT range.
2
Sensor to the main circuit
connection.

Check all connections (male and female connectors).
3
Electronic circuit failure. 
Check the sensor circuit for defects by replacing it with
a spare one.
Replace if necessary.