Hi,
I switched my ESS system from EM24 ethernet to VM-3P75CT (in ethernet too) and have some issue with power readings and real values, especially with small power (around grid-point set at the default 50W)
At first, I had completely bad readings due to the clamp not properly closed, I fixed that and secured it with a zip tie.
From my grid power meter, I see around 1250VA (wich looks ok for 5A) but VRM is displaying between -20W and +60W always at 5A !
I do understand the difference between apparent power and RMS power, but not in this order of magnitude.
I noticed that the VM-3P75CT is jumping from -5A to +5A, and I never saw a value in between.
I put a digital clamp amp meter, and it displays a constant 5A (same as the amps reported by VM-3P75CT) while power in Watts was jumping from -50W to 120W, but electric company grid meter was always around 1250VA.
My configuration is:
- single phase, only CT-1 used
- “L1 only” setup
- “Vector” type (tried arithmetic too, does not change anything)
- ethernet connection for VM-3P75CT
- 1.08 firmware on VM-3P75CT
- ESS system with Multi II 5000/48 and Cerbo GX
My “real” grid company consumption for one day was 26.1Kwh whereas VRM is only reporting 16.1Kwh from grid (huge difference !!).
The whole ESS seems now based on wrong grid values, I mitigate it a bit by setting negative grid setpoint (-30W) so the electric company grid meter is reporting 0VA (can’t see negative values)
Why there is no value between -5A and +5A on the meter, and why RMS power value is so different than EM24 was ?
Did I missed something on the setup ? Is there a calibration to do ?