Coming into this late so I have a very basic question. What level if resolution is required? Are variations in the line frequency expected to be at the 1% level or is this parts per million? Can we measure the frequency by averaging many cycles or are we looking for transients where the frequency jumps?
Chris, The NERC is not really talking about changing frequency. I mean, it will still be 60 +/- 0.05, or whatever. The proposal is about eliminating the time error correction (TEC). This is a more gradual process, a steering of sorts. Ok, I know time and frequency are related, but the point is what you really want to monitor is the time error, that is the accumulated phase drift. Especially over days and weeks. In a case like this recording time error and then calculating frequency, or average frequency, is likely better than trying to make a bunch of periodic frequency measurements and then stitching them all together to guess the accumulated time. Around here the mains time drifts by a couple of seconds over the coarse of a day. Because of TEC it tends to head back to zero, on average. Note that a couple of seconds is a couple hundred cycles. So it's trivial to monitor this if you just count cycles and compare then to a reference. The reference should be accurate to better than 1ppm. /tvb _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.