Powerlines

From: Don Maslin <donm_at_cts.com>
Date: Mon Apr 26 22:44:33 1999

On Mon, 26 Apr 1999, Daniel T. Burrows wrote:

>
>
> >"Daniel T. Burrows" <danburrows_at_mindspring.com> wrote:
> >> Close but not quite right. For single phase installations the power
> company
> >> supplies 2 hots and neutral. This is a center tapped secondary and the
> >> neutral is earthed at the service entrance.
> >
> >No, for split-phase, the power company does not "supply" a neutral from the
> >distribution system. The neutral is *only* tied to the center tap of the
> >secondary and to ground. It is not tied to anything on the primary side of
> >the transformer; that would be bad.
>
>
> That is what I was trying to decsribe above.
>
> >> The primary of this transformer
> >> is fed from only 1 high voltage phase.
> >
> >I don't believe this; it doesn't match the descriptions I've read
> elsewhere.
> >I've always seen it shown in diagrams with the primary connected across two
> >phases of the three-phase. Otherwise you need a high-current return path
> >somewhere else.
>
> Take a close look at rural areas and there is only 1 High voltage line
> present.
> It is fed to the HT input of all the pole transformers.
>
>
> >To even the loading of the phases, the transformers for split-phase service
> >have their primaries distributed between the three possible combinations of
> >the three phases.
>
> When there are 3 phases available that sometimes is the case. Look closely
> at the pole transformers and in most cases when there are 2 or more
> transformers mounted on 1 pole there is only 1 HT input to each transformer.
> If it were between phases there would be 2 HT inputs.
>
> Dan

Which, of course, is not to suggest that other pole routings may well
carry a different HT phase to achieve that balance.

                                                 - don
 
Received on Mon Apr 26 1999 - 22:44:33 BST