Turbine was down for cleaning and tested with Megger @250V resistance was 80 Megaohms just prior to this event,rotor(field)was refurbished by GE 2 yrs ago. As I'm writing this new springs were installed and there was slight sparking on one of the brushes but after a day of running it stopped...
thread237-287242
There was a thread back in 2010 posted by electrageek under same title and ended abruptly without conclusion.
I'm watch electrician in power generating facility and have a similar problem. One of the collector rings developed rough surface ab 1x2.5" and is arcing now.
Does...