Calculating sensor for power (V x A)

Configuration Frontend
1

Hi,
I am trying to have a sensor which shows Power/Watt by calculating my current power for the Tesla Wallbox out of Voltage and Ampere. Unfortunately my config doesn’t work (shows value not available) . Where’s my error?

- sensor:
    - name: "Wallbox_Watt"
      unique_id: Wallbox_Watt
      state: >-
        {{ (states(('sensor.tesla_wall_connector_phase_a_voltage')|float(0) * ('sensor.tesla_wall_connector_phase_a_current')|float(0)) + 
            states(('sensor.tesla_wall_connector_phase_b_voltage')|float(0) * ('sensor.tesla_wall_connector_phase_b_current')|float(0)) + 
            states(('sensor.tesla_wall_connector_phase_c_voltage')|float(0)) * ('sensor.tesla_wall_connector_phase_c_current')|float(0)) }}
      unit_of_measurement: W
      device_class: power
      state_class: measurement

Thx for your help!

2 
{{ (states('sensor.tesla_wall_connector_phase_a_voltage')|float(0) * states('sensor.tesla_wall_connector_phase_a_current')|float(0)) + 
   (states('sensor.tesla_wall_connector_phase_b_voltage')|float(0) * states('sensor.tesla_wall_connector_phase_b_current')|float(0)) + 
   (states('sensor.tesla_wall_connector_phase_c_voltage')|float(0) * states('sensor.tesla_wall_connector_phase_c_current')|float(0)) }}
3

this works, thank you! :slight_smile:
that was a dumb error :crazy_face:

1 Like
4

Thank you for posting this!

I ended up using this to calculate the current consumption from this device, but I believe it’s incorrect as reported for my device. When my vehicle was charging, it was showing 14.x kW, but this device on a 60 amp circuit is only supposed to have an output of 11.5 kW. I ended up removing phase C from the calculation and it looks correct on my end.

Does this seem right? Or is it regional specific? I’m located in the US.

5

When calculating in a 3-phase system you should use the phase voltage, and not the line voltage.
V(p) = V(L) / sqrt(3).

Without excluding any phase, try to divide your total power by 1.73205080757 and you should have the right value, otherwise I will have to go back to the old books (or look for an electricity expert).

6

No, it’s the same regardless the line frequency or voltage, as soon you are in an AC circuit.