i have just installed a three phase monering system and apart from no instructions supplied with the unit i found these and wired it up correctly. I have looged the unit onto my wifi and everything seems to be fine apart from ? one of my phases is showing a negative value as though I am send electric back to the grid. I am not I donlt have any agreement of mechanism to do this if I wanted to. I have checked all of the sensors on the different phases and they are all connected the same with the load in the correct direction. Any ideas what cause be causing this and how to correct it?

Hi：

If the power value is always negative,please check the CT direction of the corresponding phase.
If the negative value only appear some times ,please check the problem of "phase mismatch" like this link
https://www.iammeter.com/newsshow/blog-meter-accuracy#phase-mismatch-in-installation

If you want to check the consistency of the 3pahse ,please use this method.

https://www.iammeter.com/newsshow/blog-meter-accuracy#how-to-confirm-whether-the-energy-meter-is-damaged-during-shipment

I have revered the sensor which goes over one of the live from the meter and now it doesn't show a negative reading. I presume you are going to tell me that it's incorrect. But when I move the clamp sensor to a different phase the negative value changed to that phase so I figure that the clamp is faulty. Is it Ok to continue this way? I need an accurate reading of my consumption and a constant large negative value screws up the totals. Also once it's working correctly is the only way to clear the data and start a fresh is to delete the profile and start with a fresh install?

Hi:

Please go through this chapter in my first reply carefully, it has already answered your question.
https://www.iammeter.com/newsshow/blog-meter-accuracy#phase-mismatch-in-installation

Ex: If you power the Ua with the voltage of phase A but clamped CTa on the wire of phase B, it would appear a negative value sometimes definitely.
This is the so-called "phase mismatch" described in the above link.

Please note, the power value is the active power value,
Active Power value = voltage * current * power factor.

If both voltage and current are not from the same phase ,the power value would also calculated wrong.
If there is "phase mismatch" in installation,it would introduce a 120 degrees phase difference in the calculation of power factor, which would bring a negative value in the power factor, and result in a negative power value finally.