Diagnose and repair a drum level transmitter fault

You are an Instrument Technician on the electrical, control and instrumentation crew.

Simulated workplaceIntermediate missionCAQA Powergen Station

What is going on

HRSG2 raised a drum level deviation alarm on 9 September with transmitter LT-2-201 reading 80 millimetres above LT-2-202. The unit controller transferred level control to LT-2-202 and HRSG2 continues at full load on a single transmitter, which the Electrical and Instrumentation Manager considers a risk. Work order WO-26-5140 and permit request PTW-26-1192 are open. The transmitter's impulse lines run from the drum at high pressure and temperature, and the loop must be taken out of scan so the control system does not act on your test signals. The market operator has directed the station to 380 megawatts from 2:00 pm tomorrow.

Rosa Kalinowski, Electrical and Instrumentation Manager
Subject: HRSG2 drum level transmitter LT-2-201

The drum level deviation alarm on HRSG2 has the control room running on one transmitter, which I do not like on a unit at full load. Please take WO-26-5140, request the permit, work through the fault finding from the impulse lines to the transmitter, calibrate or replace it, and return the loop to scan with a test record. The permit request is in the register. I need the loop back in control before the market direction at 380 megawatts tomorrow afternoon if at all possible.

Your brief

Take the permit, isolate the transmitter safely, fault find from the impulse lines to the transmitter and the loop, calibrate or replace the transmitter, return the loop to scan with a test record and close the work order with the results.

Work through it

You do not need to do it all. Doing a few of these will show you what the work is like. Your ticks and notes stay on this device.

Read the Procedure: Multiple Energy Source Isolation for Permit to Work and the Permit to Work and Isolation Policy, and list the energy sources and the isolation and proving steps for a drum level transmitter.
Update permit PTW-26-1192 in the Permit and Isolation Register with the isolation points, the loop out of scan instruction and the proving results, and set the status to Issued.
Describe your fault finding sequence from the impulse lines and root valves to the transmitter, the wiring and the control system input, and the test at each step.
Record the as found and as left calibration results at five test points on WO-26-5140 in Maintenance Work Orders and Defects.
Describe how you return the loop to scan, confirm agreement between LT-2-201 and LT-2-202 with the controller and hand level control back to the pair.
Enter the return to service in the Operations Log as the controller would expect to see it, including the time and the agreement between the two transmitters.
Close the permit in the register and set the work order to Complete with a note on the root cause.

My notes: what did I enjoy, and what surprised me?

What someone in this role would produce

Isolation and proving record on the permit
Fault finding sequence
Calibration record on the work order
Operations Log entry for return to service

Printing this is a record of what you explored. It is not a certificate or a qualification.