Good to give mains respect. It can deliver kilowatts of power without breaking a sweat, and breakers are slow enough you could see multiple joules of energy into your device. It's an expert magic smoke emancipator.
Disagree on the surprise that the setup worked, though. Mains is only regulated to a few % in frequency from what I've read. But you can see 0.05 Hz deviations (or 1%aka 1000 ppm). Even a junky crystal at ~100ppm is an order of magnitude better. A 10 ppm oscillator isn't hard to find, so the computer is likely somewhere in the middle. The math all checks out.
> and breakers are slow enough you could see multiple joules of energy into your device.
The magnetic part of a miniature circuit breaker will trip in nanoseconds with enough fault current or over voltage, but the thermal elements can take longer to trip for a lower amount of fault current or voltage. Instantaneous trip ratings are generally max out at 16.67ms to clear the fault in one cycle.
Large frame circuit breakers have protection relays that detect fault current and over voltage and trip the breaker.
So... The setup was already running and they happened to catch the Feb 8 in incident? What a luck!
There is open distributed monitoring for all kinds of signals, like seismometer networks, weather, ads-b...
Is there anything like this for the power network? Like a reference design or an esp32-shield?
How would it look like if we were serious?
I would make it three phase, with direct coupling to also see the exact voltage changing over the day. Sometimes we have issues with local voltage rising too high and PV inverters shutting off. I'd like to see and log this.
An audio ADC should be good, but needs three channels.
For distributed sensing and logging, you would need a reasonable accurate time synchronization. Raw ntp over internet might not be good enough, at least not for localizing fault propagation issues over the whole continent. Better stick a 5€ GPS module on there.
Ting by Whisker Labs [1] in the US has this data aggregated by their home electrical safety monitoring devices, and there’s GridRadar [2] in Europe. As you mention, its GNSS based time sync with something a little less featured than PMUs [3] (phasor measurement units) traditionally used for grid health monitoring.
I remember reading an article about this being used in some forensic capacity to determine the date/time a video was taken by comparing the frequency noise.
8 comments
[ 3.8 ms ] story [ 29.4 ms ] threadDisagree on the surprise that the setup worked, though. Mains is only regulated to a few % in frequency from what I've read. But you can see 0.05 Hz deviations (or 1%aka 1000 ppm). Even a junky crystal at ~100ppm is an order of magnitude better. A 10 ppm oscillator isn't hard to find, so the computer is likely somewhere in the middle. The math all checks out.
The magnetic part of a miniature circuit breaker will trip in nanoseconds with enough fault current or over voltage, but the thermal elements can take longer to trip for a lower amount of fault current or voltage. Instantaneous trip ratings are generally max out at 16.67ms to clear the fault in one cycle.
Large frame circuit breakers have protection relays that detect fault current and over voltage and trip the breaker.
Breaker trip curves for Cutler Hammer BR breakers: https://www.eaton.com/content/dam/eaton/products/low-voltage...
I'll test if this antenna methods works as an alternative. I'd feel more comfortable sharing with others if mains voltages are eliminated entirely.
There is open distributed monitoring for all kinds of signals, like seismometer networks, weather, ads-b... Is there anything like this for the power network? Like a reference design or an esp32-shield?
How would it look like if we were serious?
I would make it three phase, with direct coupling to also see the exact voltage changing over the day. Sometimes we have issues with local voltage rising too high and PV inverters shutting off. I'd like to see and log this. An audio ADC should be good, but needs three channels.
For distributed sensing and logging, you would need a reasonable accurate time synchronization. Raw ntp over internet might not be good enough, at least not for localizing fault propagation issues over the whole continent. Better stick a 5€ GPS module on there.
Anybody seriously working on this..?
[1] https://power-quality.tingfire.com/
[2] https://gridradar.net/en/wide-area-monitoring-system
[3] https://en.wikipedia.org/wiki/Phasor_measurement_unit
I remember reading an article about this being used in some forensic capacity to determine the date/time a video was taken by comparing the frequency noise.