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Re: Self-built power transformer
At 23:46 1/10/98 -0600, you wrote:
>Original Poster: ESchulz531-at-aol-dot-com
>
>OK,
> I still think you have too few primary turns for your core and what voltage
>you want to use. I suggest that you wind the primary first and do some test
>to see at what voltage your transformer saturates. Use a variac,
voltammeter,
>and an ammeter. Slowly increase the voltage to the primary and watch the
>primary current. When the current all of a sudden start to go up like a x^3
>function you have reached saturation. Record this voltage and never run your
>transformer at or above this voltage.
Have been following this thread with some interest. Appreciate there is
more to the TF game than simple turns-ratios etc. Accept that rewinding a
secondary on existing TF may be simplest way out, in that core calcs etc
already done.
OK. The local 'ye-olde-junk-shop' has several *large* TFs which are rated:
3.5 kVA
P: Common / 120 / 240 / 415 V
S: 3.5 kV
Physically they are on a rectangular/square core (this is approx from memory):
X-section 2" x 2"
Outside 9" x 12"
As stated previously I simply cut-off the end, take-off the secondary and
count the turns, then rewind for say 14 kV (assume 0.25A rms). Lots of
LDPE left over and wire easy enough to find.
NOW ...... with reference to the above post, I get the impression that
fewer primary turns leads to earlier core saturation (remember I'm a simple
medico). Would there be *any* advantage to using the 415V primary tap with
240V, and winding for 14kV against this ?
Obviously this will use more turns .... doesn't bother me. Interested in
making the TF as *robust* as possible.
Was thinking 0.56mm wire (= 24SWG/23AWG) which according to my chart is
rated RMS at 0.63A.
Thoughts welcomed ;-)
Mark
http://www.cobweb-dot-com.au/~dkfinnis