Consumption CTs

[Solar_ice_caps]

Standard Split-phase residential home. We have 2 CTs measuring consumption: One on L1 and one on L2 coming off a 125A breaker in a meter-main panel feeding an interior panel which feeds the whole home. The only other breaker in the meter-main is a PV backfeed.

The problem I'm having is that one of the CTs (L2) is measuring negative current "some" of the time. If it were all of the time, I would assume it is a polarity issue either at the CT itself or at the terminals of the monitor. When large 240V appliances are turned on though, the readings jump up into the positive.


Any thoughts on what might be going on here? It's a pretty old house so I wouldn't rule out a wiring issue in the slightest.

 

[ATSman]

I question how the PV source is connected to the house.
Can you draw us a sketch on how the PV panels are connected to the grid?
120V ?
240V ?

 

[Solar_ice_caps]

I question how the PV source is connected to the house.
Can you draw us a sketch on how the PV panels are connected to the grid?
120V ?
240V ?

The PV is connected via a 2-pole, 240V backfeed breaker in the same panel as the 125A breaker that is feeding the lines these CTs are on. The PV should not be affecting the CT measurements. I’ll see if I can get a picture.



This was before the wires were landed and CTs installed but shows the locations

 

[David Castor]

If I was in this situation, my first guess would be a problem with the CTs, the test equipment, configuration settings, or the connections. Make sure the CTs are both oriented to give the same polarity.