To calculate the electrical energy requirement of arc furnaces, a statistical model has been developed which takes account of the main variables influencing the arc furnace process. The model has been verified with data from more than 50 arc furnaces of different design that operate with various charge materials. Standard deviations of the modelling error are, typically, 25 kWh/t for individual melts and 10 kWh/t for monthly average values. With the aid of the model it is possible to analyse the electrical energy consumption of a furnace and evaluate it in comparison with other furnaces, and thereby expose weaknesses in the method of furnace operation with regard to energy utilisation and assess the effectiveness of measures implemented to reduce the energy consumption, e.g. scrap preheating.

Regression equation for the specific electrical energy requirement W_R

Input data for the model
GA	Tapping weight
GE	Charge weight
GDRI	Weight of DRI
GHBI	Weight of HBI
GShr	Weight of shredder scrap
GHM	Weight of hot metal
GZ	Weight of flux materials
TA	Tapping temperature
ts	Power-on time
tN	Power-off time
MG	Burner natural gas
ML	Lance oxygen
MN	Post-combustion oxygen
WV	Energy losses (if measured)
WVm	Mean value of the energy losses
NV	Furnace-specific factor (0.2 ... 0.4)

Evaluation example: Development of monthly average values of the electrical energy consumption due to different measures for improvement of the operating practice of an AC furnace.