[time-nuts] Recommendations for Mains Power Monitor / Logger

[Bill Hawkins]

Well, this synchronization follows the laws of physics. If the energy
generated doesn't equal the energy consumed, then the frequency may
raise or lower. This is for steam turbines. If the energy come front an
inverter from a DC tie line, as it does from the four regions in the US,
the frequency is anything it wants to be. Well not quite. Raising the
inverter frequency a hair causes the tie line to be the major source of
energy. One could track the use of energy by frequency to make
investment decisions in manufacturer's stocks.

The problem with zero crossing triggers is the amount of noise caused by
solid state power supplies and by tap changing by the power companies to
match loads to minimize transmission losses. I've considered using a
mechanical synchronous motor and slotted wheel to eliminate noise near
the zero crossing, but now that I am 80, I don't give a darn, you see.

Bill Hawkins


 -----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob
Albert via time-nuts
Sent: Saturday, March 10, 2018 5:58 PM

 There isn't a whole lot of justification for measuring power line
frequency.  We are all synchronized (in the first world at least) and
while there are phase instabilities, it's seldom the frequency varies
enough to overcome the noise.
As for voltage, it's much more steady than several years ago.  Most
people have 122 Volts, give or take a couple.  Again, not a whole lot of
purpose in recording it.
The distortion is another story.  It's never quite sinusoidal but there
is also some random noise picked up between the generators and the
load.  Looking at the 'scope it's seldom it looks like the textbook
picture of a sine wave.  Chances are most distortion is odd harmonic.
Distortion probably mostly comes from loads which are not resistive,
such as switching power supplies, rectifiers, fluorescent lamps, and
such.  These loads draw currents that are not sinusoids and so cause
voltage drops that are also of that character.
Bob