Performance Improvements with Advanced AC Drives in Plate Shearing Line at Steel Plant

This paper represents the comprehensive study, analysis and results achieved by various data evaluation of AC drive system over DC drive system in Essar steel limited in India. With innovations in advanced direct torque control and vector control technologies, performance of AC drives is similar to DC drives in entire speed range. Usage of these advance speed control techniques in AC drives gives excellent results to achieve desired torquespeed characteristics, dynamic response and over load capabilities similar to DC drives. In February 2010, replacement of DC drive system by AC drive system was carried out in hot rolled plate shearing line (PSL), which is cut to length application line in steel plant. Before replacement, design calculation of AC system was carried out for matching the plant requirements. By various technical and fi nancial comparisons, it is found that use of AC drives is more economical in comparison with DC drives.AC drives ensure improvements on energy effi ciency, reliability and enhancement of production with reduction in cost, maintenance and equipment down time. After replacement of DC drives to AC drives, following performancs ase observed in PSL:

Energy saving of 1.88 kWh/t.

Production rate increased from 55 t/h to 95 t/h.

Line speed increased from 19.5 meters per minute (m/min) to 23 m/min.

Line stoppage time reduced from 2000 minutes to 300 minutes per annum.