Poul-Henning Kamp wrote, quoting me, ">Power companies bill on time-integrated power - watt-hour >meters in the US. Watt-hour meters are still mostly driven >by electric clocks, in a way. The frequency does matter.
Uhm, sorry, that is just plain wrong. The Ferrantis (sp?) power meter which is the most widely used meter in the world is not frequency sensitive within a band of +/- 10% or more." You are correct, and I sit corrected. I was looking for a simple example of why frequency mattered. I did not feel good abut it as I wrote, but I didn't look it up. I knew that crossed-coil wattmeters were not sensitive to frequency as long as the coil inductance didn't matter. ">1. It is unlikely that any power network just lets itself go, >with no standard time/frequency to hold. The under-frequency >relays would make that hazardous. Does not follow." Well, it doesn't follow from the watt-hour meter, but look at the larger network picture. The most certain way to tell that the network supplies and loads are not balanced is to measure the frequency. The frequency reflects the speed of the generators. Generator speed is determined by the balance between steam power to the turbine and load on the generator. Steam power determines fuel cost. If the frequency is used to determine power balance then it follows that all users of the network must agree on a nominal frequency. Given a nominal frequency and the ability to detect overload by dropping frequency then it is possible to protect the network before the generators come to a stop. This is not linear because the load goes up as frequency drops and transformer iron saturates. As an example of the relationship between steam power and frequency, there was a paper mill with three generators driven by co-generation turbines. That is, the local boilerhouse steam pressure had to be let down anyway, so turbines were used to drop 400 PSI steam to 30 PSI steam for low pressure equipment. It happened that an oil leak froze the governor for one of the turbines. The operator wanted to shut the turbine down, but forgot his training. Instead of closing the manual steam valve, he tripped the generator's circuit breaker. This left the generator and turbine with no load and full steam. The turbine and generator rapidly accelerated beyond their rated speeds. The generator disintegrated and threw cubic foot chunks of metal through the roof. No one was killed, somehow, but the operator was badly burned by escaping steam. Bottom line, it is within reason that some networks do not synchronize clocks with something standard. It is not reasonable that the network dispatchers do not care about frequency and do not work to regulate it. It's not regulated with any accuracy that we'd spend much time discussing on this list but it is regulated. When I toured the Pennsylvania, New Jersey and Delaware dispatch center some years ago, I thought they had talked about keeping a daily cycle count. The count had economic importance, in that a high count meant that sources gave power away and a low count meant that users paid too much. I can't justify that in terms of the fact that power is VxI on the real axis. It has no frequency component. (Plain old VxI measured with separate meters is volt-amps and VxI on the imaginary axis is volt-amps reactive or VARS.) Too bad that there's no one that understands power dispatching that also has an interest in precision time. How many of you have collected a radio clock that was meant to compare time on a local power network with WWV or something more recent? Are they still being made? Regards, Bill Hawkins _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts