Transformer wierd voltages

Dan, thanks for the update. Sounds like a typical no-joy experience, but glad you finally found the source of the issue.

Just for the record, though not related to your issue, and I know people will not like my saying it, but in facilities that I have had the power to do so, I've ripped out all Federal Pacific garbage I found, and replaced it with other equipment. FP has probably the worst record in my book for shoddy ****

Interesting! Just working on a power station where the generators have the star points connected together but not to ground. Nothing is allowed to be connected to the star point connection due to possible faults that may occur in the high voltage high resistance earth system. The job is for NASA at the end of the day and apparently they run this system all over the world. Get some funny readings with digital generator controllers and digital protection relays. Had to do a lot of funny things to get the protection and load sharing right.

The system is 480 volts and we have to synchronise and load share with a 2800 volt system through transformers. That is going to be interesting! NASDA are a pain in the 'A' sometimes. Will be interesting to see how we go in a weeks time. Consultant engineers are of no help by the way - left to a silly old electrical fitter and an electrician.

...due to possible faults that may occur in the high voltage high resistance earth system.

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Bob, the high-resistance grounding sytem is another item on my XHIT list (Xformer HIT list, also known as the $HIT list). No doubt, some "body" in NASA made the argument that "hey, without a hard ground, if one phase faults, we can keep running. Being a NASA project, it must be kept running, even if a few lives are endangered..."

That is the standard hype, and it will work okay IF there is a procedure in place to chase down those phase faults BEFORE the second or third phase also faults. Otherwise, it is a bad way to go. I know that NASA (having worked for them) is no different than most other places -- maintenance is only done when it has to be done. That means finding a phase fault falls to the bottom of the To Do list--just like that O-ring on the shuttle that blew up.