It helps to have a digitizer on the line, a 'scope to sample the line, say, 20 seconds before and 20 second after a glitch. This way you can surely tell what happened without any speculation. There are a number of ready made digitizers (red-pitaya, digilent analog discovery, ...) if you don't want to use a real time sampling 'scope. Every modern microcontroller can also do the job considering the low sampling rate needed. Of course a safe analong front-end to interface to the mains is needed.
On Tue, Mar 31, 2020 at 7:24 AM Hal Murray <[email protected]> wrote: > > > A while ago, I clean things up so that my system that monitors the line > frequency was running off a UPS while watching the non-UPS line. I looked at > some graphs. It seemed to be working. I moved on to other things. > > Last Sat morning, it got tested. Here is the graph of that area: > > http://users.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-2020-Mar-28.png > > It's pretty obvious that power was off for 10 seconds, but what are the 2 > points in the middle? > > Below is the raw data from around that time. The second column is > seconds-this-day. The samples are 10 seconds apart, grabbing time and count > from the previous cycle. The 3rd column is the time and the 4th column is the > count of cycles since started. The last column is the number of cycles since > the previous sample. The next to the last column is the time since the last > sample. > > 58936 60238.841 1585413838.824846 184208171 9.998426 600 > 58936 60248.843 1585413848.839454 184208772 10.014609 601 > 58936 60258.845 1585413858.837680 184209372 9.998226 600 > 58936 60268.846 1585413868.835009 184209968 9.997329 596 > 58936 60278.857 1585413878.849946 184210296 10.014937 328 > 58936 60288.867 1585413888.865095 184210897 10.015149 601 <== > 58936 60298.876 1585413898.862521 184211146 9.997425 249 > 58936 60308.877 1585413908.876564 184211747 10.014044 601 > 58936 60318.888 1585413918.873961 184212347 9.997397 600 > 58936 60328.893 1585413928.888983 184212948 10.015021 601 > > The marked line is a typical sample. The one after is is only 249 cycles in > 10 seconds. The 2 lines above are both short. > > I'm pretty sure what happened is that there were two 5 second dropouts 10-15 > seconds apart. The first one just barely overlapped the end of a sample > period: 596 cycles rather than 599, 600, or 601. Note that the last dot on > the top line is slightly below the rest of the line. > > The second dot of the middle pair is the marked line. > > > -- > These are my opinions. I hate spam. > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
