Telic Engineering / Field notes

Field notes. From the job.

Short practical notes from gas turbine controls, instrumentation and commissioning work. The same notes Remco posts on LinkedIn, kept in one place.

· Week 42 · Latest

Commissioning handover dossier

A start-up is not finished when the unit runs.
A start-up ends at the handover. Open turbine control cabinet with laptop, transmitter and calibrator, trip pushbutton station, trend display and punch list, with six numbered handover items 01AS-LEFT SOFTWAREbacked up, version labelled 02LOOP CHECK SHEETSsigned per tag 03CALIBRATIONtransmitters and valves 04TRIP TEST RECORDSevery one witnessed 05BASELINE DATALOGnormal start, loaded run 06PUNCH LISTowner and date per item

A start-up is not finished when the unit runs. It is finished when the operator can run it without me.

What I leave behind at commissioning handover:

  1. 1.As-left software, backed up, version and date labelled
  2. 2.Loop check sheets, signed per tag
  3. 3.Calibration records for transmitters and valves
  4. 4.Trip test records, every one witnessed
  5. 5.Baseline datalog of a normal start and a loaded run
  6. 6.Punch list with owner and date per item, nothing open by word of mouth

And one walk-through at the control cabinet and field instrumentation with the people who stay on site.

What do you want on your desk at handover? What would you add, or ask for first?

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· Week 41

Redundant controls health

Redundancy hides failures.
Redundancy hides failures. Redundant turbine control cabinet with redundant power supplies, CPU A and B, I/O modules cabled to terminal boards, remote I/O nodes on a network, a detail of 2-out-of-3 input voting, and an engineering laptop, with six numbered health check points PS1 PS2 CPU A CPU B TERMINAL TERMINAL TERMINAL TERMINAL REMOTE I/O ETH F1 F2 FEED 1 · 2 DETAIL A SENSOR 1 · 2 · 3 2oo3 INPUTS 3 DRIFTING VOTED A B 01DIAGNOSTICSall modules, not only HMI 02CONTROLLERSonline, in sync, standby ready 03VOTINGinputs that disagree 04ELECTRICALground faults, fuses, wiring 05NETWORKevery path up 06SOFTWAREsame version, backup current

Redundancy hides failures. That is what it is designed to do.

A dual or TMR turbine control keeps running with one channel down. So a failed module, a dead power supply or a drifting input can sit there for months. The second fault is the one that can trip the unit.

What I look at in a controls health check:

  1. 1.Diagnostics on every controller and I/O module, not only the alarms on the HMI.
  2. 2.All controllers online and in sync, standby ready to take over.
  3. 3.Voting: redundant inputs that no longer agree.
  4. 4.Electrical health: feeds, supplies, ground faults, loose wiring, blown fuses.
  5. 5.Every network path up.
  6. 6.Same application and firmware everywhere, backup current.

How often do you check your redundant controls, and what is on your list?

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· Week 40

GG exchange checks

After a gas generator exchange the engine is new.
Six checks before the first start Cutaway drawing of an aeroderivative gas turbine with the six check points numbered as in the list: speed pickups, VSV stroke, fuel valve, thermocouples, engine data and overspeed trip. HPCCOMBHPTPTEXHAUST 01SPEED PICKUPSgap set, clean on crank 02VSV STROKEfull range, both sides 03FUEL VALVEstroke and feedback 04THERMOCOUPLESall reading at ambient 05ENGINE DATAnew unit, not the old one 06OVERSPEED TRIPtested, not assumed

After a gas generator exchange the engine is new. The control doesn't know that yet.

What I check on the controls side before the first start:

  1. 1.Speed pickups. Gap set, clean signal on crank.
  2. 2.VSV stroke. Feedback follows demand over the full range, both actuators.
  3. 3.Fuel valve stroke and position feedback.
  4. 4.All thermocouples reading, and agreeing with each other at ambient.
  5. 5.Engine-specific data in the control updated to the new unit, not left from the old one.
  6. 6.Overspeed trip tested, not assumed.

None of it is difficult. It's just easy to skip when everybody wants the unit back online.

So what's on your list? What would you add, or check first?

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Start-up or engine exchange coming up and you need a controls engineer who closes it out properly? Send me a message, happy to support.

Send the start date, estimated duration, scope, systems on site and location. You get availability and an estimate the same working day.

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Question from purchasing or compliance? Company details, insurance, HSE and quality policies and procedures are on the Working with Telic page.

Remco Petersen
Telic Engineering B.V.
Markenplein 24, 1011 MV Amsterdam
The Netherlands
remco.petersen@telic-engineering.nl
+31 6 51345316
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