Siemens SITRANS P Manual do Utilizador descarregar pdf (Página 139)

UMSITRPDS3-1 Calibration And Maintenance

November 2010

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.

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Siemens SITRANS P Manual do Utilizador Página 139