[BC] Transformers - thanks/more

[Clive Warner]

A thank you to all of you who found the tech note useful.

Oh BTW I meant 2KV on the insulation tester, not 20KV, I am not a complete
and utter maniac.

To some extent it depends where you are operating. I installed transmitters
everywhere from the middle of tropical rainforest to the sands of deserts.
If it's hot and arid where you are - maybe Arizona for instance - probably
you'd be able to install 90 out of 100 transformers 'out of the crate'. But
in more humid places, you're running too high a risk; the very last thing
anyone wants is to have to import a huge great heavy spare and tie up the
whole team in-territory for weeks on end.

A note on oil-filled transformers might also be helpful:

In some locations with very high humidity you'll need to recondition or
exchange the transformer oil. On my 'training' high power install, the 750KW
in Abu Dhabi, I had to connect a reconditioning machine to the big
transformers and run them for about 24 hours to dehydrate the oil to an
acceptable flashover voltage. The climate was very hot - around 40C - and
terribly humid (on an island in the ocean!). Even though the transformers
had only been stored in crates on site for about 8 months, the oil had
already absorbed so much moisture that when I flash-tested it, the reading
was below minimum spec.

If this happens you can either use a reconditioning machine or buy all-new
oil (very expensive) or exchange the oil with a local outfit that
reconditions it (if such exists)

In our case I was baffled when I opened the crate that contained the
conditioning machine. Several hours later I discovered the plumbing was all
back to front so we first had to redesign the machine before we could use
it. Then I discovered the machine trolley was 2" too wide to fit through the
door of the transformer room! Fortunately a cutting torch was at hand, I cut
a slot in the door frame (temporarily). The door frame had been installed
under pressure I think because when I cut through it, the loose vertical
part went at me like a clock spring. (These are the hard lessons of
installation engineering . . .)
It took about 24 hours per transformer. The machine is a combination
oil-boiler, vacuum pump, and Lord-knows-what gubbins whizzing and clanking
and smelling.

Anyway I guess engineers at the higher power stations like our friend from
VOA on this list somewhere, have all done routine oil tests. Quite fun
really. You have to remember one thing: you must never, ever, drop anything
into the transformer. (If you do, you may as well hand in your notice right
then.)
 Remove rings and watches. Attach spanner to neck via string. Remove cover.
Dip. Replace cover. Place sample in glass test chamber. Increase voltage
until flashover. Note reading.
Do not do this the morning after a night drinking absinthe and eating dodgy
kebabs in the nightclub of the Sheik Klifty Hotel.

Clive Warner