Sonoff Pow

Calibration

Sonoff Pow might need calibration as correct measurements are influenced by hardware and timing differences.

I used the following procedure to calibrate.

1. Prerequisites
   • Calibrated multimeter ;-)
   • Optional calibrated power meter ;-)
   • 60W light bulb
2. Enable the calibration commands by updating define USE_POWERCALIBRATION in user_config.h
3. Recompile and upload to Sonoff Pow
4. Connect the Pow to the optional power meter.
5. Connect the 60W light bulb
6. Open a webbrowser to Pow showing the main page and another webbrowser showing the Console
7. Turn power on and wait a few seconds for the pow to settle on a stable power reading
8. Verify the power reading with the power meter or expected 60W and if needed change the power offset value with command HLWPcal
9. Verify the voltage reading with the multimeter and if needed change the voltage offset value with command HLWUcal
10. Verify the current reading with the calculated value of P (step 8) / U (step 9) and if needed change the current offset with command HLWIcal
11. Optionally disable the calibration commands by recompiling and uploading the firmware

Result explanation

The Sonoff Pow can provide Energy, Power, Voltage and Current information in different ways.

Push result using Telemetry

The preffered way is using the periodic telemetry data. Setting teleperiod 300 will send telemetry data every 5 minutes. Depending on messageformat and mqttunits the result would be:

• Result when messageformat 0 (Legacy) and mqttunits 0:

tele/pow1/YESTERDAY_ENERGY 0.234
tele/pow1/TODAY_ENERGY 0.016
tele/pow1/PERIOD_ENERGY 5
tele/pow1/CURRENT_POWER 53
tele/pow1/POWER_FACTOR 1.00
tele/pow1/VOLTAGE 214
tele/pow1/CURRENT 0.247
tele/pow1/TIME 2017-01-01T13:50:17

• Result when messageformat 0 (Legacy) and mqttunits 1:

tele/pow1/YESTERDAY_ENERGY 0.234 kWh
tele/pow1/TODAY_ENERGY 0.016 kWh
tele/pow1/PERIOD_ENERGY 5 Wh
tele/pow1/CURRENT_POWER 53 W
tele/pow1/POWER_FACTOR 1.00
tele/pow1/VOLTAGE 214 V
tele/pow1/CURRENT 0.247 A
tele/pow1/TIME 2017-01-01T13:50:17

• Result when messageformat 1 (JSON):

tele/pow1/TELEMETRY {"Time":"2017-01-01T13:50:17", "Energy":{"Yesterday":"0.234", "Today":"0.016", "Period":5, "Power":53, "Factor":"1.00", "Voltage":214, "Current":"0.247"}}

Pull result using status message 8

To request information you can use command status 8 which results in one of the following messages:

• Result when messageformat 0 (Legacy):

stat/pow1/RESULT PWR: Voltage 214 V, Current 0.247 A, Power 53 W, Today 0.016 kWh, Factor 1.00

• Result when messageformat 1 (JSON):

stat/pow1/RESULT {"StatusPWR":{"Voltage":214, "Current":"0.247", "Power":53, "Today":"0.016", "Factor":"1.00"}}

Meaning

The presented information has the following meaning:

Legacy	JSON	Unit	Description
YESTERDAY_ENERGY	Yesterday	kWh	Total Energy usage between 00:00 and 24:00 yesterday
TODAY_ENERGY	Today	kWh	Total Energy usage today from 00:00 until now
PERIOD_ENERGY	Period	Wh	Energy usage between previous message and now
CURRENT_POWER	Power	W	Current power load
VOLTAGE	Voltage	V	Current line voltage
CURRENT	Current	A	Current line current
POWER_FACTOR	Factor		The ratio of the real power flowing to the load to the apparent power in the circuit