How to solve 3-ph voltage measurement?

I have emoncms running on my home server now... but no emonTX (or other device) to feed it data - yet.

I live in Sweden, where practically all consumer units (distribution boards) are fed with three-phase power. Ideally I'd like to measure real and apparent power on all three phases. However I have no power sockets close to the distribution board, so voltage measurements are a problem. Also, I cannot get at the energy meter (I live in a flat, and the energy meter is behind a locked door for which I don't have the key, in the basement, several floors down). Besides, I'd like to keep the same equipment when moving to be able to do long time comparisons and plots.

Since the phase current and voltage must be measured simultaneously I cannot see any way to do what I want without some work inside the consumer unit.

Adding sockets would be expensive and complicated: 3 MCBs, 3 sockets, 3 AC/AC wall-warts... Perhaps there is a DIN-rail-mountable energy meter with some sort of wireless transmitter that I could use instead? If so, I haven't been able to find one.

Budget is €250 (including the €70 or so to get an electrician to install the meter, if I go that way).

Any ideas?

MartinR's picture

Re: How to solve 3-ph voltage measurement?

You could use DIN rail mountable door bell transformers instead of the wall warts. I planned to do this originally but the transformers I tried produced distorted waveforms at the 250V that my supply is at most of the time. You may have more success if your voltage is lower. There are some around that only occupy 1 DIN unit. Three of these plus 3 emonTxs (2 with no RF) should come within budget.

arvidb's picture

Re: How to solve 3-ph voltage measurement?

That sounds like a great idea! Thanks!

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