UMSITRPDS3-1 Calibration And Maintenance
November 2005
7-7
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.
To Next Page
Loading...
