## Re: C-2C with Y windings?

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• ... It looks like my fingers got ahead of my brain with that. ... I ve seen in some transformer catalogs that the rating of a transformer for rectified output
Message 1 of 5 , Dec 1, 2000
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--- In microhydro@egroups.com, hugh piggott <hugh.piggott@e...> wrote:
> >Thanks Hugh,
> > The 240V Y vs. 415V delta explanation makes sense to me.
>
>
> not to me though - I would say the other way around :-)

It looks like my fingers got ahead of my brain with that.

>
> >Since
> >my motor can be configured 240V or 460V, and since the transformer
> >in my battery charger can be configured for 120V, 208V, or 240V
> >input it should work out ok.
>
> Battery chargers are not an ideal load for induction motor
> generators. they do work but the output is sometimes less than you
> would expect. I think this is due to the weird current waveform.
>

I've seen in some transformer catalogs that the rating of a
transformer for rectified output depends on the type of output filter
used. If a capacitor is used, current only flows during the portion
of the sine wave where the voltage is higher than the capacitor
voltage. If a DC inductor is used as the filter, current can flow
over more of the AC cycle and the transformer rating may be 1.8-2 x
that with a capacitor filter. I have a bunch of soda can sized motor
start capacitors, and a nice 500uH 30A DC inductor from which to make
an ouput filter for the rectified 24V AC from the transformer. I
would imagine that the ideal case would be for the current to also
vary in a nice sine wave, in sync with the voltage. I think if I dug
into my old physics and intro to EE books I could figure out the
proper LC arrangement for a target current, or conversely, given the
available inductor calculate what the critical current for 60 Hz
operation would be. I guess that is something I should try to
calculate. Has anyone in the group ever worked through the
calculations for the effect of the ouput filter on the transformer PF?

Joe
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