[time-nuts] Blackout in Europe and power line frequency jump

[Hal Murray]

> http://www.leapsecond.com/pages/mains/

Fun read.  Thanks.

> Is a wall clock accurate to 5 seconds a day? a week? a month? The
> power industry has standards for all this, I'm sure ...

An old tale.  Palo Alto runs its own local electrical distribution system.  A 
friend of a friend called them up to find out how good it was as a time 
source.  When he finally got through to somebody who knew what he was talking 
about, the answer was simple. "We're not tariffed for that."

---------

I occasionally day-dream of setting up something so I can monitor the line 
voltage, frequency, current, whatever... but I've never gotten off the ground.

Of course, then I'd have to get a UPS so I could save the data for the 
interesting events.

Plan 0 is to use the audio input hardware that comes with a PC, say off a 
wall wart with a few resistors to adjust the full scale.

Plan 1 is to get a multichannel A/D board.  Anybody know of one that has a 
Linux driver?  (Or just a good one with clean specs so I could write the 
driver.)


As long as I'm dreaming...  I need to replace my main electrical service 
entrance.  Is there some affordable setup to measure current?  I'm thinking 
of a UL approved current transformer, but my alarms go off when I think of 
low level signals getting near power wiring, especially big wires.

One thing I haven't figured out is how much data to save.  16 bits at 8K HZ 
(telephone number) is 1.4 GB per day, so it's not a big deal to save a day or 
week of raw data.  Probably the right thing to do is to buffer the raw data 
for a week and post process the raw data to automatically save something like 
the phase difference relative to a good local PPS source with the expectation 
that I'll grab the raw data by hand before it gets overwritten if something 
interesting happens.

While I'm at it, I might just as well watch a geophone.  :)

And temperature...




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