Here's one to ponder on.
A few years back we had a fault on a 33/11KV 20MVA transformer. Buchholz surge, it was due to low oil level. It was the middle of a freezing night so it was decided to leave it until daylight and just close the bus-section to get the plant up and running. Walking out of the switchyard I hit one of the liquid NER tanks with an 18" spanner out of shear frustration. That didn't sound right thinks I, we had a ladder with us so I climbed up and opened the cover. Oh S**T was my reaction. The tank was bone dry, the electrode was so corroded it had collapsed. Effectively we had no earth on that transformer. We had 3 more units but at 3AM I wasn't looking in to them.
The question is what would have happened if we had a phase-earth fault on the 11KV system?
I've had all sorts of lurid ideas, none of them very pretty!
Checking the other units didn't look very good, all had to be taken out of service in turn for major repairs. It wasn't poor maintenance, it was pure neglect!
What Would Have Happened?
Re: What Would Have Happened?
