Procedure For Preventive Maintenance of Temperature Transmitter

1. Firstly, identify the temperature transmitter that you are planning to perform the preventive maintenance. The purpose is to have clarity for obtaining the permit to work accordingly. If the transmitter is associated with DCS then it is highly likely that it would be hooked up with any control loop; take the board room operator to take the control loop on MANUAL mode. If it is integrated with SIS or ESD system, it should be BYPASSED to avoid any inadvertent triggering of logic during the preventive maintenance steps. Obtain safety defeat permission from the respective authority as per your company’s procedure.

2.    Inspect the cable gland and wiring connection of the transmitter for any damage.

3.    Make sure all electrical connections are tightened properly.

4.    Check the housing seal for any breakage.

5.    Disconnect the sensor wire from the transmitter.

6.    Connect the Temperature Calibrator with the transmitter.

7.    Connect HART communicator with the transmitter.

8.    Apply 100Ω resistance (For Pt-100) through the temperature calibrator and verify ZERO calibration of the transmitter. IF required, apply ZERO Trim command from HART communicator.

9.    Apply 25% resistance of the calibration range and verify 8mA output current along with 25% temperature value on the local display.

10. Apply 50% resistance of the calibration range and verify 12mA output current along with 50% temperature value on the local display.

11. Apply 75% resistance of the calibration range and verify 16mA output current along with 75% temperature value on the local display.

12. Apply 100% resistance of the calibration range and verify 20mA output current along with 100% temperature value on the local display.

13. Disconnect the calibration setup.

14. Connect the sensor wire with the transmitter.

15. Verify the local value on the transmitter.

16. Put the transmitter into services from the HMI.

Note: (status- in progress; procedure for sensor verification hasn't been added yet).