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I once went to investigate an overspeed incident with a newly upgraded Siemens 360MW unit.
When I asked,"What happened?" I was shown a video!!
At the time of the overspeed, there was a bloke brushing by the non-drive end of the generator. When an overspeed occurs, there is contact between rotating and static components causing the turbine and generator to "corkscrew" and displace axially.
Anyway, the security video showed A. Cleaner brushing away, he then stopped, lifted his head and turned to look at the unit, just as the corkscrewing generator destroyed the shaft seals. As there was metal to metal contact and the release of hydrogen, there was an instantaneous explosion. Luckily, A. Cleaner was shielded by the stator and was not injured, although I would not allow charging for the cost of new underwear in the final adjustment!
Subsequent review of the Data Log revealed that the entire unit went from 100% to 0% in around three seconds!
Needless to say, I did dind this claim quite theatrical!
Then there was the lout, trying to steal a copper earth cable from a Power transformer, also caught on video........but that can wait for another day...........!
Rgds.
Dave
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