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