A9MEM3255 energy meter giving inconsistent data in 3Ph4w with 3 CT connection

[Sabyasachi]

Hi All, 

I have been trying to read the registers of Active power(p1,p2,p3) and energy(p1,p2,p3), of the Float32 format, using RS485 communication.

I have configured the setting on SE meter to run as 3ph4Wire system, with 3 CTs, No VT connection, with all the CTs having the turns ratio of 100/5, I am aware that, we are supposed to configure the CT ratios in the  meter itself, and I have done so, keeping Secondary turns 5 and Primary turns 100.

Even the wiring is done according to what is mentioned in the Datasheets, 

I tried reading all individual phase voltage, individual phase currents, and I'm getting the data correctly.

All the 3 CTs are connected to the same 200 W bulb.

When I'm trying to read the individual float32 active power registers, for phase 1 , i'm getting a value of 0.19879496097564697 Kw , phase 2 : 0.10172723978757858 Kw, phase 3 : 0.10699596256017685 Kw.

Where I should be getting values of all 3 phases as around 0.200 Kw, so, the phase 1 seems to be somewhat accurate, however phase 2 and phase 3 are not. Even though all the CTs are connected in same direction.

The total active power that was showing on the screen itself was around 400 Watts.

Could somebody help me out with this problem.

Thanks and regards.

[Jesus_Diaz]

Hi @Sabyasachi,

Can you increase the load and re-check? Usually, it is recommended to try with at least 10% of the rated current of the CT.

Also, I would suggest connecting to the meter using ION Setup and getting all the measurements (currents, voltages, power, per phase) from the meter to have a better understanding.

Best regards.

[Sabyasachi]

Hi @Jesus_Diaz ,

How come for the CT1 , we are getting proper, nearly accurate values?

And why for only CT2 and CT3 are we facing this problem?

[Ramasamy_N · Accepted solution]

Hi @Sabyasachi 

Please connect with country technical support team with all 3 CTs secondary current values, if this query is not addressed yet, the CT secondary current value will be around 5mA for 200W load current. Please check CT1, CT2 and CT3 secondary values and connect with the country technical team.