ERARING Power Station has dismissed suggestions that an upgrade of its plant last year led to the explosion of a transformer.
Eraring completed an upgrade of its unit 2 generator a year ago, but did not replace the transformer that accompanied it, the utility confirmed.
Industry sources suggested the 28-year-old transformer, which feeds electricity into the grid, may not have coped with increased capacity.
Eraring operations executive Jeff Hogan said the transformer, which exploded last Friday, had the capacity to handle the generator upgrade from 660 megawatts to 750 megawatts of power.
‘‘I categorically do not believe that the upgrade had any bearing on this incident whatsoever,’’ Mr Hogan said, adding that internal and WorkCover investigations would determine the cause.
Asked if transformers had a lifespan or a point at which they were replaced, he said: ‘‘I’m not going to get into the technicalities of it too much.
‘‘We do thorough high-voltage tests on the transformers on a regular basis and check oil conditioning.’’
Industry sources suggested the transformer may not have been replaced because it was expensive.
They said the 28-year-old transformer should have been replaced, which would have allowed a modern non-toxic, biodegradable oil to be used.
Eraring confirmed it used a mineral oil called Nytro Libra, which was similar to diesel.
The utility said the transformer had contained 80,000litres of oil, correcting earlier statements from its senior staff that the amount was 8000 litres.
Mr Hogan said barriers designed to contain oil spills had collected a lot of oil, which was trucked to waste areas at Kooragang.
Eraring concedes some oil breached the barriers and spilled into stormwater drains and the lake, but could not say what quantity.
A large oil slick was seen in Myuna Bay, Whiteheads Lagoon and Silverwater at the weekend.
Mr Hogan said the oil had dissipated yesterday, but concerns remain about oil residue around rocks, habitat and shores harming biodiversity.
Native Animal Trust Fund chairwoman Audrey Koosmen said the rocks should be cleaned, but the NSW Office of Environment and Heritage said the oil would naturally disperse.