OpenEnergyMonitor Community

Obtaining negative power measures

I am using an emonPi to measure power consumption at two levels:

  1. Aggregated power consumption of the whole house
  2. Power consumption at the circuit level, in concrete the kitchen

The aggregated measures are consistent and make sense with the total billing at home. But I am having some issues with the kitchen level, as I have negative readings in the kitchen. I don’t understand this behaviour. Each day I measure around 80.000 measures, and I have around 90 negative measures. It is a small number in proportion, but it should be non-negative values at all. The aggregated measure is consistent, and I do not have even one negative reading.

I guess it could be issues of the calibration of the sensor, but again, why negative? I don’t know how the sensor works, but maybe someone could give me more insight into this.

Can anyone help me to sort out this problem?

It is possible that you have a very reactive load, like appliances on standby, that appear to be generating power. It is also possible that it is electrical interference.

In emonCMS, on the Inputs page, for that input if you put “Allow positive” somewhere in the input processing for the kitchen, but above “Log to feed” in the list, the negative readings should disappear.