TELECOM Digest OnLine - Sorted: Re: 208/240V, was: 25Hz Power

Re: 208/240V, was: 25Hz Power

Paul (
Thu, 16 Mar 2006 15:38:55 UTC

Paul Coxwell <> wrote in news:telecom25.105.9

> Several points have been raised in this discussion to
> which I would like to respond.
> [...]

Thank you for the great write-up. My father was a power EE, and I had
worked some as an electrician, so I have picked up some of this info
over the years. I especially remember my father describing the
high-leg delta connection when I was a kid, but I never ran into one
in practice.

> On the primary side of these transformers, everything here is
> connected between phases. In fact NONE of our HV lines have a neutral
> run with them, so three-phase primaries are always delta-connected,
> and the primary on a single-phase transformer is connected across two
> phases of the HV. That primary supply to the final transformers is
> almost always 11kV (measured phase to phase), although there are still
> a very few local distribution networks operating at 6.6kV in a couple
> of areas. Thus a single-phase HV spur line has to be run as two "hot"
> phases.

Is the generator end wye-connected for a ground (earth?) reference, or
is there ground fault detection circuitry on delta connected
generators? Or is ground reference / ground fault not as big a
concern there as here? Just curious.

> As noted before, in Continental Europe 3-phase supplies into homes are
> very common, however, and to British and American minds they seem to
> take 3-phase to extremes. In France, for example, it's not at all
> uncommon to find a small house which has a full 3-phase 4-wire
> 380Y/220V service, with the main breaker set to just 15 amps per
> phase! Arranging heating and cooking loads on a service like that can
> be quite a juggling act.

I can imagine. Is something like an electric range connected to 380?
Is it wired single phase or three phase?


Another Paul

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