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

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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