SMAR ld301 - Page 65

Maintenance
5.3
Symptom: NO COMMUNICATION
Probable Source of Trouble:
 Terminal Connections
 Check the terminal interface connection of the configurator.
 Check if the interface is connected to the wires leading to the transmitter or to the terminals
[ + ] and [ - ].
 Check if the interface is HPI311 – M5P models (for Hart protocol).
 Transmitter Connections
 Check if connections are according to wiring diagram.
 Check if there is resistance in the 250 Ω line. See load limitation in Section 1.
 Power Supply
 Check output of power supply. The voltage at the LD301 terminals must be between 12 and 45
Vdc, and ripple less than 500 mV.
 Electronic Circuit Failure
 Locate the failure by alternately testing the transmitter circuit and the interface with spare parts.
 Transmitter Address
 Check if the transmitter address is compatible with the one expected by the configurator.
Symptom: CURRENT in 21.0 mA or 3.6 mA
Probable Source of Trouble:
 Pressure Tap (Piping)
 Verify if blocking valves are fully open.
 Check for gas in liquid lines or for liquid in dry lines.
 Check the specific gravity of process fluid.
 Check process flanges for sediments.
 Check the pressure connection.
 Check if bypass valves are closed.
 Check if pressure applied is not above upper limit of the transmitter range.
 Sensor to Main Circuit Connection
 Sensor connection to the Main Board.
 Check connection (male and female connectors).
 Electronic Circuit Failure
 Check the sensor circuit for damage by replacing it with a spare one.
 Replace sensor.
Symptom: INCORRECT OUTPUT
Probable Source of Trouble:
 Transmitter Connections
 Check power supply voltage.
 Check for intermittent short circuits, open circuits and grounding problems.
 Noise Measurement Fluid
 Adjust damping
 Pressure Tap
 Check for gas in liquid lines and for liquid in steam or gases lines.
 Check the integrity of the circuit by replacing it with a spare one.
 Calibration
 Check calibration of the transmitter.