Low wattage reading on L1. L2 reads properly

[kdrummer]

I'm bewildered here and need a sanity check. My split phase readings on L2 are correct, but my L1 wattage reading is 85% lower than what I would expect!

• Both CTs on L2 read properly
• Both CTs on L1 read low wattage, yet agree with each other
• Verified current and voltage calibration on both CTs with multimeter (clamp + probe)
• Reversing the L1 CT yields a negative wattage, so it should be on the correct way

Can I get a fresh pair of eyes or a new perspective on this? I'm not sure how I can correctly measure Volts & Amps, but get the wattage wrong only on L1. Any insights as to what I'm missing would be greatly appreciated!

Side issue: My readings for my AFCI breakers are all over the place. Do those possibly phase shift the voltage enough to throw off the reading?

Including the truncated code below in case it's relevant.

substitutions:
  disp_name: Energy_Monitor
  short_name: EM
  update_time: 10s
  current_cal: '11143'
  current_cal_sct006: '11143'
  current_cal_sct010: '41660'
  current_cal_sct024: '27518'
  voltage_cal: '7305'

sensor:
#IC1 Main-A
  - platform: atm90e32
    cs_pin: 5
    #CT 1
    phase_a:
      voltage:
        name: ${short_name} L1 Volts
        id: L1Volts
        accuracy_decimals: 1
      current:
        name: ${short_name} L1 Amps
        id: L1Amps
      power:
        name: ${short_name} L1 Watts 
        id: L1Watts
      gain_voltage: ${voltage_cal}
      gain_ct: ${current_cal_sct024}

    ...<truncated>...

#IC2 Main-B
  - platform: atm90e32
    cs_pin: 4

    ...<truncated>...

    #CT 6
    phase_c:
      voltage:
        name: ${short_name} L2 Volts
        id: L2Volts
        accuracy_decimals: 1
      current:
        name: ${short_name} L2 Amps 
        id: L2Amps
      power:
        name: ${short_name} L2 Watts 
        id: L2Watts
      gain_voltage: ${voltage_cal}
      gain_ct: ${current_cal_sct024}
    line_frequency: 60Hz
    gain_pga: 1X
    update_interval: ${update_time}

#Total Watts Main.  Actual measurement from L1/L2.  Other values are measured/accumulated.
  - platform: template
    name: ${short_name} Total Watts Main
    id: totalWattsMain
    lambda: return id(L1Watts).state + id(L2Watts).state ;
    accuracy_decimals: 1
    unit_of_measurement: W
    device_class: power
    update_interval: ${update_time}

#Total Amps Main
  - platform: template
    name: ${short_name} Total Amps Main
    id: totalAmpsMain
    lambda: return id(L1Amps).state + id(L2Amps).state ;
    accuracy_decimals: 1
    unit_of_measurement: A
    device_class: current
    update_interval: ${update_time}

[CircuitSetup]

It looks like the power factor for L1 is low, which is causing the power output to be low. Is it possible that whatever is using power is a motor or something non-inductive?

2 things to try:

• Switch L1 to CT5, phase_b and compare results
• Add in power_factor for both phases (see here for an example)

[CircuitSetup]

So, despite switching the current channel and the CT on L1, it is still reading low power? This would rule out the meter or the CT being defective. Either you have something using power on L1 that is extremely inefficient, or there is something else that we are overlooking. The latter is more likley.

Ideally, L1 and L2 should be 180 degrees out of phase from each other (which is why the CTs on a split single phase system are opposite each other on the mains wires). It sounds like something is distorting the waveform of L1, which degrades the power factor.

Are the CTs on the mains wires loose? If so, does anything change when moving them around?

Do you have a way to plug the AC transformer into L1? Maybe a nearby plug that is wired to that side of your panel? If the low output is switched to L2, that would be a pretty big clue.

[kdrummer]

First of all, I want to say that I greatly appreciate you following up on this and helping out <3. I chose this product based on glowing praise for its accuracy and ability to calibrate everything!

So, despite switching the current channel and the CT on L1, it is still reading low power?

Correct.

Are the CTs on the mains wires loose? If so, does anything change when moving them around?

CTs are a bit oversized compared to the wires, but nothing actually changes when moving them around.

Do you have a way to plug the AC transformer into L1? Maybe a nearby plug that is wired to that side of your panel? If the low output is switched to L2, that would be a pretty big clue.

Powering the EM from L1 sort of balances the issue out. Now the L1 PF looks about right and the L2 PF is a bit lower, but not as bad as it was before. Previously the PF was ≈0.16, so 0.63 feels great compared with what I was seeing before. Does anything look out of the ordinary here? I'm fine just moving the EM to L1 if this would appear to solve the issue, though I'm left without knowing the underlying cause.

Investigating this has given me more practical insight into Active Power (W) vs. Apparent Power (VA). As long as I can feel good that the measurements are correct, that can free me up to hunt down what's being so inefficient.

[CircuitSetup]

It looks like those last results are more accurate. If you were to measure both phases voltage/current I'm guessing the results would be similar.

If something large is turned on (HVAC, electric heater/oven, high wattage hair dryer) does the power factor change?

[kdrummer]

Not as far as I can tell. Here's the plot of PF/time for L1 & L2. There are regular fluctuations with things turning off/on all the time, and I noticed PF improved when the heat pump compressor turned on. When I first looked, I thought the PF had decreased when I turned the fan on, but that dip looks like a regularly repeating pattern. My biggest thing is trying to get a sense for if this all looks "normal." Would adding a second transformer providing VA2 provide a more accurate result, or would that be complete overkill?

[CircuitSetup]

Usually when you see a regular interval like that, it's a fridge compressor/evap fan turning on/off.

You may want to look at the power and PF on the same graph to see how that correlates.

If you add a second transformer (make sure to cut the jumpers on the back of the board if you do), it will be more accurate, but it's hard to say how much more accurate.

Either way, it does seem like your readings are accurate, although you may want to have an electrician come out and take a look at your panel. There may be something that isn't quite right, like an open or shared neutral. Do you ever see any light flickering when something large is turned on?