On 06/20/16 10:21, Lennart Sorensen wrote:
On Sat, Jun 18, 2016 at 07:58:10PM -0400, Michael Galea wrote:
You know of course that the grid frequency is only approximately 60.00 hz.
For example, it was 59.97 hz on Friday at around 5 PM. I have heard rumors
that the generators spin the grid up to above 60 hz in the early morning
hours to compensate for the drift, but I don't know if thats a fact. I
often see the grid at 60.01 hz, in the middle of the day though.
Hmm, my APC SmartUPS just reports 60.0 or 60.2Hz all the time, so I
don't think I believe it to be accurate. :)
What gismo are you using to measure that?
The device I'm using are twin SEL751A automation relays from Schweitzer
Engineering laboratories. Both give me pretty much the same readings,
and I have no reason to doubt them. They are microprocessor based
devices with good sampling rates and high accuracy. When I say 60.XX,
its me thats truncating the digits (not the SEL)..
Someone remarked that the accuracy of 60 hz is good, and that
over-frequencies would cancel under-frequencies. I would really doubt
that they could do that to any great degree of accuracy. The grid is the
largest machine on Earth, and there is more than just a single generator.
--
Michael Galea
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