Hi One minor point:
If you *do* decide to digitize the line, think about how much headroom you want on the digitizer. That applies both in the amplitude and time domains. On a 120V 60 Hz line, is an 800V 300 us pulse of interest? How about a half cycle at 2X or (1/4) line voltage? If you have a two phase circuit, are both phases of interest? We had a very similar hit here Saturday. Based on how things behaved. My guess is that the two phases didn’t quite do things the same way. It would be nice to have a record ….. Bob > On Mar 31, 2020, at 8:40 AM, Azelio Boriani <[email protected]> wrote: > > 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. _______________________________________________ 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.
