[time-nuts] 60hz west coast electric grid gone berserk

Chris Albertson albertson.chris at gmail.com
Fri Sep 9 18:51:40 UTC 2011

On Fri, Sep 9, 2011 at 10:17 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>> What software do you use for the monitoring?
> Things are pretty simple if you have a Linux box.  Here is the code I'm using:
>  http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz.py

You really don't even need software as the Linux PPS project ships a
test program that logs the time stamps.   The RS232 standard is fine
with connecting a 9VAC signal directly to the serial port but I'm
conservative and opto-isolators are dirt cheap.

That said, I found an even easier way to monitor AC.  I have an
battery backup box that keeps the PC running for about 10 minutes
after a power failure.  The box connects to the computer via USB and
some of the data passed over the USB cable are measurements of the AC
mains power, line frequency and voltage.  This gets logged.

If you have one of these UPS units you might even have a log of AC
line frequency and not even know it.

Even better, these UPSes come with software that can send this data to
a central monitoring location.   The intent is so one person can watch
thousands of UPSes that might be all over a large company, under
people's desks and know when batteries need to be replaced.  But it
also helps to monitor mains power quality over an entire campus

Chris Albertson
Redondo Beach, California

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