I visited the local power company in western Pennsylvania one afternoon
(fellow engineers that I know showed me around).  While at the control room, I
asked them why the frequency reading on a display was not exactly 60 Hz.
They said that it rarely is, and that they run above or below 60 for some
period of time to 'catch' back up to where they ought to be.  It sounded like
a portion of the explanation was hooey, but then, if a zero crossing circuit
wants to track total time, and it fell behind, it would have to catch up.
(yea, far fetched).  That was the best explanation I could get.  The moral of
the story is that one should not count on the power company for any accuracy
at all.

Chris Eddy

Sean Breheny wrote:

> Actually, though, I have seen graphical representations of the phase over
> large power grids and it DOES vary, quite a bit. In fact, you can tell
> which way power is traveling down a power transmission line by looking at
> which end of it leads in phase. Power distribution people use this info to
> determine power flow around a large grid AND to see when the grid might
> break down (TOO large a phase gradient, in many cases).
>
> Sean
>
> At 09:55 PM 6/8/99 -0400, you wrote:
> >>The power companies may complain too because the power meters would give
> >>incorrect readings.
> >>
> >  But mostly, I think, it needs to be exactly SOMETHING so that the
> >  power companies can trade energy back and forth across the power
> >  grid. Imagine connecting two lines when one is at positive peak
> >  and the other is at negative peak. KABLOOEY!
> >
> >  Reg Neale
> >
> |
> | Sean Breheny
> | Amateur Radio Callsign: KA3YXM
> | Electrical Engineering Student
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