90 degree phase rotation commercial power (was: Re: A tale of woe, including carelessness, stupidity and laziness....)

Wed Aug 26 15:48:39 CDT 2015

On 8/26/15 12:33, Paul Koning wrote:

> 90?  Three phase power is 120 degrees apart, center-tapped "two
> phase" home power is 180 degrees, but I don't know of any power
> company service that produces 90 degree shifts.

There's a bunch of 90-degree two-phase stuff in Philadelphia; in
particular the city center has a lot of buildings that are fed 90-degree
two-phase from PECO.  I suspect (but do not actually know) that PECO
derives two-phase from three-phase using Scott-T transformers.

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