Strange measurement Energy Meter VM-3P75CT

Q&A and troubleshooting
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1

I Use the VM-3P75CT energy meter for the grid connection.

It seems when i disconnect the power from this energy meter, and switches this back on, the meter is using this as “zero offset” for the complete meter range.

I used 2 of them, one for grid connection, it seems i need to disconnect all the cables, switch the power to the meter on, and then connect all the current sensors. otherwise the offset is wrong.

The other meter is measuring the heat pump power ( ac loads ). this is doing the same, when the heatpumt is running stand by it is using 300W ( around 100W / phase ). on enabling the power of the meter is seems to use this stand by load as zero… is there a way to enable / disable this function or putting values by hand in it? it is all connected via Can to a Cerbo.

2

Hi @Ronald, the VM-3P75CT doesn’t have a no-load offset compensation function at startup. Sounds like something else must be the reason why you’re seeing unexpected values.

3

Hi Luc,

During the evening i will have a look again,
The only way i can repeat this issue is cut off the power to the energy meter, and during load enable back the power to the energy meter, then i directly have an offset of the measured current…

Workaround is remove the conectors from the current transformers, enable power to the meter and then reconnect the current transformers … then everything works as expected.