A turbine is a lockout with a twist most procedures get wrong: some things have to stay energised. The pitch system's UPS keeps the blades feathered; kill it and the rotor can load up in wind. The hub is a confined space eighty metres up, reached through a nacelle with medium-voltage switchgear at one end.
Technicians work in pairs, often contractors, often on turbines from two or three manufacturers across one site, each with a different isolation sequence.
The rotor lock is the point that matters most and is easiest to record wrongly: a lock on the disconnect is not a lock on the rotor.
A thorough technician isolates everything, including the one system that keeps the blades feathered. The procedure said "isolate all"; it should have said which not to.
Rotor lock engaged, pin not confirmed seated. Entry proceeds.
The isolation sequence for one manufacturer's turbine is applied to the other manufacturer's machine standing next to it.
Real isolation-point structure, illustrative tags, equipment that does not exist. Free to read and download. An example to learn from — not a document to adopt.
Nacelle gearbox inspection with hub entry for pitch bearing check. Rotor lock mandatory before hub entry.
- 12 isolation points
- 2 must stay energised
- 1 cannot be isolated — managed by other means
Also applies: NFPA 70E · 29 CFR 1910.146
Read the exampleA point can be marked KEEP ENERGISED with its reason. It appears on the procedure, on the live board as deliberately live, and it cannot be locked by mistake.
One procedure per turbine type, with the rotor lock as its own apply-and-verify point.
The nacelle has no signal. Attestations are captured with their field time and synced when there is.
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