[time-nuts] Recording mains frequency/phase [WAS: No GPS satellites]

Bob Camp kb8tq at n1k.org
Fri Feb 27 14:24:48 EST 2015


HI
> On Feb 27, 2015, at 10:46 AM, Philip Gladstone <pjsg-timenuts at nospam.gladstonefamily.net> wrote:
> 
> On 2/26/15 20:39, Charles Steinmetz wrote:
>> ben wrote:
>> 
>>> I'm going to have to build one of these. Assume you have some sort of
>>> circuit that converts low-voltage AC from a transformer secondary to
>>> a pulse train, start a timer, and count x amount of pulses?
>> 
>> Here is a zero-cross detector designed for this purpose:
>> 
>> <http://www.ko4bb.com/manuals/download.php?file=02_GPS_Timing/Simple_AC_Mains_Zero_Crossing_Detector.pdf>
>> 
>> 
>> Most mains-nuts feed the ZCD pulse to the DCD line of a PC's RS232
>> port and use the computer to time-stamp the crossings and append them
>> to a file of such time stamps.
> If we all did this, then I realize that we could identify the different power grids. However, I wonder if there is any interesting variation *within* a grid. As the electricity flows vary throughout the day, it seems possible that the phase difference between two people on the same grid would actually change (a bit).
> 
> Has anybody done this experiment?

It’s done by utilities to monitor power flow and balance electric grids. The first data on this (grid vs GPS) date to the 1980’s. I think the
paper I recall was done by Quebec Hydro. Since then it’s become a pretty standard monitoring tool. 

Bob

> 
> Philip
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