Re: current transformer winding wire help please


Genome <ilike_spam@xxxxxxxxxxx> wrote in message
news:Ojhae.1420$p06.691@xxxxxxxxxxxxxxxxxxxxxxx
>
> "Gordon W" <welch@xxxxxxxxxxxxxxx> wrote in message
> news:1114209775.518036@xxxxxxxxxxxxxxxxxxxxx
> > I am thinking of using 0.125mm wire for the secondary of a current
> > transformer but don't know its current rating. DAGS and wire tables
give
> me
> > other specs but not current.
> > Any info or url would be appreciated.
> > Thanks
> > Gordon
> >
>
> A guess for iron transformers is 4A/mm^2 or 4E6A/m^2 and that's for a
guess
> of a 30C rise above ambient based on a guess based on another guess.
>
> Isn't it strange that if you use a word repeatedly it begins to lose its
> sense?
>

love it. :o)

> Barry will ask you some more questions.
>
> DNA
>
>
Thank you Genome and John Fields for your replies, I guess I should have
given more information. Hope this is not too long and I don't show my
ignorance too much.
I've got my computer turning on/off the booster to my solar hot water system
but I don't have any feedback (closed loop to monitor).
The thought was to put a current transformer in series with the heating
element, rectify etc and feed +5V to the computer when the heater was on.
I've done an experiment with a small iron cored transformer, the bobbin is
20x10x10mm, a layer of 10A wire (the heater is 240VAC at 7.5A) well
insulated from the secondary of lots of turns (my rev counter gave up part
way through) of the 0.125mm wire.
Rectified/filtered output came out at 71V and 11mA with a 6K resistive load
and 47V and 30mA with a 1.5K load.
I can easily reduce the turns to lower the voltage but what current should I
aim for so that this 'thing' will live happily ever after ? The transformer
will be in a ventilated plastic box under the house. Ambient sometimes gets
to 35 °C.

Thanks again

Gordon

.

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