Fine tuning / accuracy of CT clamps in home assistance with esphome

ESPHome
1

Hi everyone,

I have 3 ct clamps connected to the mains and am wondering about accuracy.

For this experiment, I connected all 3 CT clamps to the very same circuit, where only the fridge is connected to. I also have an energy measuring plug for the fridge.

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In the image you see the power consumption as calculated by the 3 CT clamps and the power as calculated by the plug. As you can see, I’m facing with 2 problems:

  1. I have a constant noice from the CT.
  2. the CT measurements don’t go to zero, they go to unavailable (same for the amperage)

Please note that the voltage measure I’m using for the power calculation is coming from the smart plug.

here is my ESPhome code:

sensor:
  - platform: ct_clamp
    sensor: adc_sensor_i1
    name: "I_ph1"
    id: I_ph1
    update_interval: 2s
    sample_duration: 2s
    filters:
      - calibrate_linear:
          # Measured value of 0 maps to 0A
          - 0 -> 0
          # 1 V --> 30 Amp from CT sensor
          - 1.0 -> 15.0
  - platform: ct_clamp
    sensor: adc_sensor_i2
    name: "I_ph2"
    id: I_ph2
    update_interval: 2s
    sample_duration: 2s
    filters:
      - calibrate_linear:
          # Measured value of 0 maps to 0A
          - 0 -> 0
          # 1 V --> 30 Amp from CT sensor
          - 1.0 -> 15.0
  - platform: ct_clamp
    sensor: adc_sensor_i3
    name: "I_ph3"
    id: I_ph3
    update_interval: 2s
    sample_duration: 2s
    filters:
      - calibrate_linear:
          # Measured value of 0 maps to 0A
          - 0 -> 0
          # 1 V --> 30 Amp from CT sensor
          - 1.0 -> 15.0

  - platform: adc
    pin: GPIO32
    id: adc_sensor_i1
    # raw: true
    attenuation: auto
    # update_interval: 1s
  - platform: adc
    pin: GPIO33
    id: adc_sensor_i2
    # raw: true
    attenuation: auto
    # update_interval: 1s
  - platform: adc
    pin: GPIO34
    id: adc_sensor_i3
    # raw: true
    attenuation: auto
    # update_interval: 1s

  - platform: wifi_signal
    name: "WiFi RSSI"
    update_interval: 60s

these are the ct clamps I’m using (15A → 1V)

and this is the circuit I’m using for wiring them.

Any suggestions on how to solve the problems?

Thanks!

2

Hey,

did you get your system working?
I would be interested in the same setup.

3

Hi, no I haven’t. It seems that my system is about 2 to 5% higher than what the meter records. I’ve kept it like this for now. Also, I would love to see the CT clamps count backwards when feeding into the grid. The values I’m getting seem to be absolute values.