The finishing group of stands of the 1700 SRS-1 continuous mill of ArcelorMittal Temirtau JSC is characterized by high rolling speeds and high productivity. The use of DC motors as power sources for the main drives of the stands of high-power thyristor converter units significantly affects the nature of the operating modes of the power supply system and the quality of electricity on the buses of the SRS-1 substation. Experiments were performed to study the electricity grid supply substation in which the basic indexes of quality of electric energy and the built waveform voltage SAG during rolling. Voltage dips are observed throughout the rolling process and reach 10% of the rated network voltage. Due to the complexity of removing individual parameters of electric drives and conducting experiments on a real mill, an adequate model of the electric drive of the stand of the finishing group of the 1700 SRS-1 mill was developed and built.