Case Study: OneSteel Mini Mill Upgrade

Scope: Design, manufacture, install and commission a replacement drive system for a 16-stand steel rolling mill with a capacity of 260,000ton/yr, product range of 260 different section grades and finish speeds up to 15m/sec.

The original mill drive system consisted of 6 x 800kw finish stands, 6 x 500kw intermediates, 4 x 300kw rougher’s and 4 flying shears. The drive system was based on AEG DC drive regulators controlling a customised 4-quadrant thyristor power stage. Age and lack of support meant the AEG regulators presented a significant risk to the operation.

Ten Siemens Simoreg CM Digital DC drive regulators were used to replace old AEG units. The existing power circuit and power electronics were retained. Siemens Simoreg units are specifically designed as a replacement for older DC drive regulators and are an economical option to the full replacement of complete DC drives. The Simoregs are supplied with a 40 amp DC field controller and can be configured to control multiple power stages.

The new speed, current and field regulators for No.1 and No.2 flying shears were configured and tested in the factory prior to shipment. Production constraints necessitated that the design be a flexible, fast change-over system that allowed the new drives to be partially commissioned during short production outages and then the old AEG drive to be returned to service. Only when the new system was fully tested, could the old AEG system be removed and the Simoreg drives installed.

Client: OneSteel