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Ok, now i used this sketch https://github.com/openenergymonitor/emonTxFirmware/blob/master/emonTxV3/RFM/emonTxV3.4/emonTxV3_4_3Phase_Voltage/emonTxV3_4_3Phase_Voltage.ino

It is better but still i have strange voltage (126V) it should be around 240V. Also the phase 1 wattage is in negative value.

Any idea?

That means you are returning power to the supply on that phase. Have you read and carried out the setting up and calibration instructions?

I don't return power, it is impossible. 

Didn't do calibration but i think it wont solve this problem. Can someone post the sketch that is running ok with emontx shield for 3 phase system.

Had to change the value of double Vcal = 428.0; Now i have 228V which is correct. Is this normal?

Now i only have a problem with negative real power. More in the picture below.

Try reading the FAQ, then carry out a full calibration. A 3-phase supply is very, very rare in domestic premises in the UK, and I do not have access to one. The sketch gave me the expected answers on a single phase supply, and many users appear to have calibrated it successfully and have it in use. So I think any problem is with how you have installed it and because you have not followed the instructions to calibrate it.

The value of the voltage calibration is dependent upon your ac adapter, if you do not have the "shop" standard one, then the default value will be wrong. Even if you do have the standard adapter, accuracy will probably be improved with careful calibration because all the components are affected by manufacturing tolerances.

I would guess it's not possible to measure 3-phase power with the current hardware, because they only have one voltage measurement and 3-phase power has an angle difference of 120 degrees on different phases? Also the phases might have slightly different voltages if they don't have equal loads.

Khyron:

That is partially true and the limitations are spelled out in the comments at the top of the sketch. The fact remains that many users are successfully using the sketch to get a good approximation - within those known limitations - of their electricity usage on a 3-phase, 4-wire system. I also did a version for a user with a 3-wire system, where one phase is treated as the reference and the angle between phases becomes 60° - and there were no complaints so I presume that worked in a satisfactory manner too.

Yes it works ok. For the top problem i had clamps turned upside down so that is why the readings were off.