Well, this synchronization follows the laws of physics. If the energy generated doesn't equal the energy consumed, then the frequency may raise or lower. This is for steam turbines. If the energy come front an inverter from a DC tie line, as it does from the four regions in the US, the frequency is anything it wants to be. Well not quite. Raising the inverter frequency a hair causes the tie line to be the major source of energy. One could track the use of energy by frequency to make investment decisions in manufacturer's stocks.
The problem with zero crossing triggers is the amount of noise caused by solid state power supplies and by tap changing by the power companies to match loads to minimize transmission losses. I've considered using a mechanical synchronous motor and slotted wheel to eliminate noise near the zero crossing, but now that I am 80, I don't give a darn, you see. Bill Hawkins -----Original Message----- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Albert via time-nuts Sent: Saturday, March 10, 2018 5:58 PM There isn't a whole lot of justification for measuring power line frequency. We are all synchronized (in the first world at least) and while there are phase instabilities, it's seldom the frequency varies enough to overcome the noise. As for voltage, it's much more steady than several years ago. Most people have 122 Volts, give or take a couple. Again, not a whole lot of purpose in recording it. The distortion is another story. It's never quite sinusoidal but there is also some random noise picked up between the generators and the load. Looking at the 'scope it's seldom it looks like the textbook picture of a sine wave. Chances are most distortion is odd harmonic. Distortion probably mostly comes from loads which are not resistive, such as switching power supplies, rectifiers, fluorescent lamps, and such. These loads draw currents that are not sinusoids and so cause voltage drops that are also of that character. Bob _______________________________________________ time-nuts mailing list -- email@example.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.