Electronics > Beginners
Safest way to measure AC mains 220-250 voltage?
paulca:
I found this:
https://meters.co.uk/products/single-phase/
Would need the electrician to install it, but it has an RS485 MODBUS output and it would mean I don't need to feck about with the mains or blow myself up.
Thoughts?
soldar:
--- Quote from: paulca on July 20, 2019, 04:48:25 pm --- I found this:
https://meters.co.uk/products/single-phase/
Would need the electrician to install it, but it has an RS485 MODBUS output and it would mean I don't need to feck about with the mains or blow myself up.
Thoughts?
--- End quote ---
Looks nice. I think you can install it yourself but if you feel more comfortable having a pro do it then go for it. If you do it yourself you can get the split core which is easier to install. If you get a pro to do it then you can get the solid core which gives a bit better precision.
Basically it is the same that I have except mine has no communications capability. Mine is just the cheap Chinese eBay version. Just connect two wires to voltage and the current transformer around the main wire. You can do it with the general breaker cut off so there is no risk involved. Easy peasy.
This one costs the same and looks a bit better if you have the space for it.
ledtester:
Here's a design which utilizes HCPL-7520 linear optoisolators to provide isolation:
https://atmega32-avr.com/powerbox-the-safe-ac-power-meter-using-atmega32/
Perhaps others can comment on whether or not this part is appropriate for this kind of use.
Also, a couple of power meter projects that I've found useful to study:
- http://elm-chan.org/works/heco/report_e.html
- http://ww1.microchip.com/downloads/en/AppNotes/Atmel-2566-Single-Phase-Power-Energy-Meter-with-Tamper-Detection_Ap-Notes_AVR465.pdf
In particular, the way you measure the current has to be carefully considered since that has quite a large dynamic range -- from a few milliamps to several amps. The Elm Chan project solves that by using a 16-bit ADC. The Atmel/Microchip design uses op amps whose gains are dynamically controlled by the microcontroller.
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