Strange voltage and power factor values and installation issues

[kasemu]

Hi,
We have installed 2 meters (each meter is a 3 phase meter) for sub-metering in a residential house (1 phase installation per apartment). One of the meters, after correcting installation, works fine now. The other one, in my opinion measures strange voltage values. We had since the begining connectivity problems with this meter (it uses NB-IoT technology). Please see the graphs of the various parameters the meter is measuring.

The electrician insists that there is nothing wrong with the installation of the second meter. However, I found discrepance between what the Ferraris meter measures (utility) and the smart meter measures. This discrepance together with some strange dashboard values makes me suspect there is something wrong. With the Ferraris meter we get 17 kWh for a few days time period and with the smart meter we get 21 kWh for exactly the same period of time.

The company that sold us the meter told me the electrician should check installation again and this is quite problematic as he was already several times there. They say "the problem with the installation is not on the part of the connection on the meter, the connections on the meter are correct. The problem is if the phase that is connected on PIN 1 is the same as CT 1 is measuring.
That is why we need to know if the CT 1 that measures Load 1 has the same reference voltage connected in Pin 1- (Phase 1)".

Since I am not in the electricity field, I am not sure what he means with "reference voltage". Does he mean the electrician needs to check that the voltage of Load 1 that measures CT1 is the same as the voltage connected in Pin1?

Thanks in advance

 

[Lucien Nunes]

I think it is simply referring to the same problem as you had with the other meter, i.e. that the voltage input was measuring one phase while the current transformer was measuring another. I don't think that applies here as the readings are not so outlandish.

 

[kasemu]

I think it is simply referring to the same problem as you had with the other meter, i.e. that the voltage input was measuring one phase while the current transformer was measuring another. I don't think that applies here as the readings are not so outlandish.

I agree. The point is that the electrician insisted saying that his installation is correct. I will have to contact him again and say that it does not really look correct and he should double check.

Could you kindly explain what do you mean by "I don't think that applies here as the readings are not so outlandish." Thank you - I am not english native speaker.

 

[Lucien Nunes]

I do not think that the current and voltage measurements are out of phase in this particular installation, because that usually causes the readings to be complete nonsense as they were on the other meter, not just of poor accuracy. I don't have time now to look more closely at the plots.

 

[marconi]

Please would you send photos so I can see what is in the blue circles?

Are the two apartments connected to the same phase L1; or to L1 and L2.

The meter outputs look fine to me apart from the voltage plot. It seems odd that the three voltage plots (red, blue and green) are identical - superimposed on each other. One would expect some variation between them at the scale of this plot. This would indicate that the L1, L2 and L3 voltage references for the meter are provided from one of the three phases.

One can see a periodic load turning on and off - is there a fridge or freezer? The low power factor is when most of the apartment loads are off or in standby so not consuming real power - the background reactive power is 'consumed' by any transformers inside electrical items eg: door bell or small motors in say time clocks which remain constantly energised. When real power is consumes it so much greater than the background reactive power that the power factor improves. ( Power Factor = Real Power/Apparent Power)

 

[kasemu]

Please would you send photos so I can see what is in the blue circles?

Are the two apartments connected to the same phase L1; or to L1 and L2.

The meter outputs look fine to me apart from the voltage plot. It seems odd that the three voltage plots (red, blue and green) are identical - superimposed on each other. One would expect some variation between them at the scale of this plot. This would indicate that the L1, L2 and L3 voltage references for the meter are provided from one of the three phases.

One can see a periodic load turning on and off - is there a fridge or freezer? The low power factor is when most of the apartment loads are off or in standby so not consuming real power - the background reactive power is 'consumed' by any transformers inside electrical items eg: door bell or small motors in say time clocks which remain constantly energised. When real power is consumes it so much greater than the background reactive power that the power factor improves. ( Power Factor = Real Power/Apparent Power)

Thanks a lot for the detailed feedback!
I will not be able to send other photos soon, but I am asking directly the electrician about the connections in the blue circles as well as the phases connected to the apartments. I shoud also be able to provide more feedback on the voltages - you are right that is odd!

 

[kasemu]

I do not think that the current and voltage measurements are out of phase in this particular installation, because that usually causes the readings to be complete nonsense as they were on the other meter, not just of poor accuracy. I don't have time now to look more closely at the plots.

Allright - thanks.