Hi Bob,
On 02/27/2015 08:24 PM, Bob Camp wrote:
HI
On Feb 27, 2015, at 10:46 AM, Philip Gladstone
<[email protected]> 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.
Yes. They implemented the first Phasor-Measurement Unit (PMU), it went
into the IEEE 1344 standard, but had many issues with it and created a
new standard in IEEE C37.118, which has since been split into IEEE
C37.118.1 and C37.118.2 with the advent of the IEC 61850 context, where
the data-transport is being replaced, but the measurement methods is
maintained in C37.118.1.
For an intro, you can read this paper:
http://rubidium.dyndns.org/~magnus/papers/KTH_paper1.pdf
Cheers,
Magnus
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