Siemens 7MF4333 User Manual page 139

UMSITRPDS3-1
Check Impulse Piping
•
Check that high and low pressure pipe connections are not reversed.
•
Check for leaks or blockage.
•
Check for entrapped gas in liquid lines or for liquid in dry lines.
•
Check for sediment in transmitter's process connection blocks.
•
Check that blocking valves are fully open and that bypass valves are tightly closed.
•
Check that the density of the fluid in piping is unchanged.
Check Loop Power Supply/Wiring
•
Check loop power supply for blown fuse or tripped circuit breaker.
•
Check for 10.5 Vdc minimum across loop +/- terminals in transmitter terminal compartment.
•
Check power supply output voltage: 15 Vdc minimum; 45 Vdc maximum (30 Vdc in an intrinsically
safe circuit).
•
Check polarity of loop wiring at both power supply and transmitter.
•
Check for loose or broken loop wiring at power supply terminals, supply barriers (if used), junction
boxes, and transmitter terminal compartment.
•
Check for disconnected or broken current sense resistor and for short between shield and loop + wire.
•
Check for accumulation of moisture in transmitter terminal compartment.
•
Check loop cable for proper type and length.
•
Check for electrical interference between the loop cable and any adjacent cables in a cable tray or
conduit.
Check Transmitter Configuration
•
Check for proper operating mode: analog, address 0; digital, address 1-15.
•
Check for appropriate transfer function (linear or square root).
•
Check the switch point if the square root output current characteristic (i.e. transfer function) is
configured.
Check for a Transmitter Stuck in Fixed Current (Loop Override) Mode
•
Re-enter Fixed Current mode from HART Communicator Online menu and properly exit the mode.
Check for Variable Process Fluid Flow
•
Install mechanical dampers in process pressure piping.
•
Select a higher damping value (software filter time constant).
Check Primary Element
•
Check that primary element is correctly installed.
•
Check element for damage and leaks.
•
Note any changes in process fluid properties that can affect output.
November 2010
Calibration And Maintenance
7-7