hmmmmm. worked for a power company? Perhaps not an electrical "power "
company?
A weight lifter?
Meter Reader?

Sounds like a complete misnomer. Correctly that should be "energy" company.


All teasing aside, m II is quite correct in asking about percent impedance.
Have a look at any distribution or large power transformer and you will see
a rating called "%Imp."

I have seen pole transformers down to 1.2%Imp and up to 13.8%Imp.

This is where the electrical energy distribution companies get concerned
about losses. (see I even remembered my own comment. LOL)

Worked on a 2MVA Grounding Bank with a 89 %Imp. rating. (maybe it was 93???
Can't remember now)

As an aside... (utility guys will appreciate this one)
In the old days, before equipment was invented, we used to prove polarity of
CTs with a 6v lantern battery and an old Model T voltmeter coupled with a
variable resistor in series to avoid bashing the needle too hard. We would
generate positive and negative going pulse on the primary of the CT and see
the needle deflection on the secondary of the CT winding.

Trouble was this high impedance bitch would not pass any current from the 6V
lantern battery through the primary winding and through the CT primary
(bushing type). SO we get two 6V lantern batteries in series and try again
to no avail. hmmmmm...

Well we get talking about it and while still holding the leads on the
primary (14kV) bushings my partner begins to yell that the needle was now
deflecting upwards, so I pull it off!...Well! I drew about a 10" long arc
(yeah bare hands..no grid connection) and friggin' nearly fell off the
transformer, some 12-15' high, to the ground. WHEW!!!

Back we went to the 6V lantern battery, waited a little longer for this
impedance haystack to react and wore the 30kV gloves. Sitting on top was a
little more uncomfortable too...LOL



Here is your link with an oversimplified explanation.
http://www.transformerworld.co.uk/impedance.htm


---------------
"harry" wrote in message
...
Link?
I used to work for a power company. Never once heard of Impedance
being expressed as a percentage.
Transformers are rated in Kva.
There may be a continuous KVA and a higher one for a specified period.
Regulation is sometimes expressed as a %. ie how the output voltage
varies between no load and full load conditions.
Here's my link:-
http://en.wikipedia.org/wiki/Impedance_(electrical)
Now, where's yours?