| Electronics > Projects, Designs, and Technical Stuff |
| 3 phase 4 wire(480V) AC to 12VDC (100mA) power supply for energy metering applic |
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| Sultanpepper123:
I am currently working on a 3 phase energy meter project. I don't have a lot of experience in designing power supply circuits (AC/DC) let alone a 3 phase 4 wire one (L1,L2,L3 adn N) with a transformer to be galvanically isolated. Since energy measurement is being done for all three phases, the metrology (Microcontroller + metering IC) part must be able to measure energy even if two phases go out, so AC supply must come from all three phases. I've scoured the internet and found a few approaches, some used a transformer, some didn't. Can i use something like this ( IRM-20-12 ) for the time being or if there is a better model please let me know. If the answer is yes then i think the next question is how do i connect it to all 3 phases since the power module only take Line and Neutral ? If the answer for the previous question is no, what would be my options for a prototyping stage and another for a cost efficient and not so brutal to design ? |
| dmendesf:
China is your friend: https://m.pt.aliexpress.com/item/32824299597.html?trace=wwwdetail2mobilesitedetail&spm=a2g0s.9042311.0.0.2742b90aahVt7s If you want to do it yourself use a Viper style power supply (but chose a IC with a higher breakdown voltage... There are >1000V options) and do 3 single phase rectifiers at the input.. so if one phase goes down you only get a slightly lower voltage and higher ripple. Be cautious, at this voltage any mistake kills. |
| RIKRIK:
Not sure if this would be useful, but if you google arduino electricity meter, there's some interesting ideas https://www.instructables.com/id/Simple-3-Phase-Arduino-Energy-Meter/ P.s I know this won't power it like you want but, three different power supplies sounds like a challenge, would running it off of mains with a back up battery be easier .You could also get a sd card module to back up all the data on. Kind regard , rick |
| NiHaoMike:
Use 3 half wave rectifiers, each must be individually fused with proper HRC fuses, but it's OK to put the EMI filtering and inrush protection after the rectifiers. You can consider using microwave oven diodes for the rectifiers, since they're fairly cheap but quite robust. |
| capt bullshot:
Quite a time ago, I've seen a circuit like this in a three-phase meter (L1,L2,L3,N connected). It uses a simple SMPS to step down and isolate the 12V suppy from an intermediate (ballpark 150V) DC voltate, derived from the line voltages by capacitive droppers having rather high series resistors. For the rather low power requirement that you have, this should also work. Stress voltage across the diodes is reduced to said intermediate voltage, higher frequency components are dealt by the rather high impedance resistors in series with the capacitors. I don't remember the actual component values. Capacitors have to be rated for the line voltage, resistors are requires to be robust (pulse load, max. voltage rating) and silent failing to open circuit. No fuses required, the resistors are expected to cost way less than appropriate fuses. |
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