Power calculation formulas — phasor form
Error ΔP

Service conditions
Load presets
Revenue impact
True monthly usage
Error kWh / month
Billing error / month

kWh = (true power in kW) × hours/day × days/month
Billing error = error kWh × rate

Power reading comparison
Form 12S (2 elements)
Measures directly
Form 2S (1.5 elements)
Assumes V L2 = V L1
Blondel (true)
Non-Blondel
Calculation breakdown
Blondel
Non-Blondel