>From a Time-Nut perspective, isn't phase/frequency of the (nominal) 60 Hz all we'd be interested in? Phase is best measured at a zero crossing as this is the (only) phase measurement point which is independent of amplitude. Mike
-----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Charles Steinmetz Sent: Saturday, December 20, 2014 4:57 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Simple AC mains zero-cross detector Magnus wrote: >So, I do not completely agree that a through-zero measurement with a >TIC has all the information No, a series of time-stamped zero crossings doesn't have all of the information in the original signal, and a small glitch that occurs during the middle of a cycle (far away from a zero cross) could hide and show nothing more than a slight displacement of one or two zero crosses. Grid-nuts can ignore such short glitches. Utilities can't, particularly in today's cybersecurity environment. Horses for courses. From my observations of the AC mains while I was testing the simple ZCD, I would expect such hidden glitches [that are real grid-related phenomena, not just someone starting a motor downstairs] to be very rare. The grid phenomena I saw typically last more than one grid cycle and thus affect more than one zero cross, and/or are large in magnitude and cause serious displacement of at least one zero crossing, or several extra zero crossings. Best regards, Charles _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
