Noise and oscillation on circuits with low power consumption

[djwakelee]

I recently setup the Vue2 and hooked up several of the CTs – 8 channels.  Everything worked great and displayed wonderful, and I could see clean graphs and power measurements for even lightly loaded circuits.  The furnace circuit properly showed the few idle watts for the electronics (even when off), and then bumped up to bigger numbers when running.  Other circuits in the < 10W realm also displayed correctly – such as those with only a power brick or Alexa – displaying accurate low power when idle, and accurate higher power when something on the circuit was turned on and used.

Happy with how things were working,  I then loaded up the system to all 16 channels and moved a couple of the CT’s.  I am now unable to accurately see the proper power consumption on any of the circuits when they are lightly loaded (< 10W or so).  The power measurements look like just noise on the graphs, and the power reading alternates from 0 and 5-10W or so.  These lightly loaded circuits also constantly jump around on the home screen, as the power readings flip from zero to something else.  If I turn on something else on the circuit that brings up the power draw to over 20W or so, the noise and oscillation goes away.

I am unclear why the system behavior has changed when I better finalized my setup with more CTs/channels.  Is this noise and oscillation at light load a known issue?  Is my Vue2 defective in some way?  How would I troubleshoot this problem further and correct the problem?

[scrambler]

If you moved CTs around, did you do a complete reset and re initialization of the APP.

Because it does all its calibration during the initial setup, and may be moving CTs around messed things up

[djwakelee]

Yes, I did reinstall/reinitialize the Vue 2 from scratch in the App after making the minor changes (a couple CT moves, and adding the 8 channels).  Though as I understand things, there isn’t any ‘calibration’ that occurs during setup – it just tries to auto detect the current flow of solar.  I’m not sure what could be calibrated on the CTs as the amount of current flow through each circuit will vary based on conditions at the time, and they don’t tell your to turn any breakers off to calculate a zero point – or anything like that (except solar).  But in any case, I did the initial setup after making the changes and it didn’t effect anything.

After further testing and observation, in addition to the jumpy/noisy circuits with light loads, I also see other completely bogus things going on.  I have a subpanel for a pool, and two CTs around the 240V breaker phases leaving the main panel to feed that.  During the day when solar is producing (say 6kW), one of the CTs for the pool subpanel starts to show small amounts of power being drawn.  Only a few watts, but power nonetheless, and only one phase.  Yet I haven’t opened my pool yet for the year, and the pool subpanel has all its breakers off.  There is no actual power going there, just false information.

Additionally, my solar CT’s and pool CT’s (and wiring) are significantly away from each other in the panel.  So external crosstalk / coupling of the CTs or wiring seems unlikely.  But, they are on adjacent channels feeding the Vue 2.  So this behaves like internal crosstalk inside the Vue2, where the adjacent channel is messing up its neighbor(s).

[scrambler]

It does detect the L1 L2 phase to find out what CT is on which one.

When you did your new setup, did you make sure the Solar breakers were OFF, AND that you had some significant house load on both phases?

[djwakelee]

Yes.  I don’t believe this is a reset / setup issue – seems to be dynamic based on what is going on with the other loads.

[Author]

Posts