>        YEP
>        Telecom Australia use this method off three phase, with the high
>supply voltage so that it does not have long term low power cycles on the
>battery bank.
>
>
>        Dennis

I don't follow you here. Can you please elaborate a little ?  Are you
suggesting telecom .au is running low voltage backup battery banks which
are not separated galvanically from the mains ? Note that by using coils
in series with the thyristors the max. current requirements are reduced,
but that is cheating from the point of view of a 'no coils, no
transformers' design. Also the coils get to be pretty huge beyond a point,
and they are loaded with DC so anti-saturation measures are required on
single phase. None of this makes them cheap.

Peter

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