Gearboxes contribute to steel mill power boost

Edited by the Engineeringtalk editorial team Jun 18, 2004

A ground-breaking combined electrical and mechanical upgrade of the Tandem Cold Mill at Corus Steel in Port Talbot, South Wales will more than double the power handling capability in the mill.

A ground-breaking combined electrical and mechanical upgrade of the Tandem Cold Mill at Corus Steel in Port Talbot, South Wales by ABB in partnership with David Brown Engineering will more than double the power handling capability in the mill.

The five-stand tandem cold rolling mill currently produces up to 1Mt of strip steel a year, which is cold-rolled to improve its properties.

The product is used for the fabrication of a wide range of items, including for car bodies and casings of domestic appliances.

The first phase of the upgrade is now complete and involved replacement of three of the five DC motors.

The new units on stands 1, 2 and 3 are ABB DriveIT medium voltage drives ACS 6000 with integrated gate commutated thyristor (IGCT) convertors and David Brown single helical single reduction gearboxes handling up to 6.9MW.

The three gearboxes in the current phase of the project range in reduction from 3.5:1 down to 2.1:1.

The IGCT technology of the drives combines the high switching frequency of the integrated gate bipolar transistor (IGBT) semiconductors with the unsurpassed reliability of the power electronics.

Engineers from David Brown, a Textron Fluid and Power company, managed the on-site mechanical installation of the new equipment, and ensured the all-important precise alignment of the new drive configuration.

The new gearbox and AC motor configuration has been designed to occupy the same footprint as the original DC motor, thereby removing the main obstacle to upgrading because reorganising the layout of rolling mill equipment invariably involves monumental cost and long term disruption.

The three oldest DC motors, which date back to the original creation of the plant facility in the 1940s, required urgent replacement because of reliability issues and the high cost of maintenance.

The first phase of the upgrade was completed in July 2003; installation took 7 days and the commissioning of the new equipment a further 2 days.

During phase one of the project there is only a small increase in production capacity because the new motors are detuned to the power ratings of the original equipment.

However, once phase two is completed and the power availability is maximised production capacity will increase by approximately 50%.

The first phase of the project also included the development of a new control system by ABB and the creation of a test-bed on site to allow the motor/gearbox combination to run load-free so that the final speed and system checks could be carried out before the first installation.

ABB's SimulateIT drive train dynamic analysis (DDA) enabled the exchange of the drive systems with an extremely short downtime.

DDA also allowed precommissioning in a simulation model with fully automated self-adjustment of the control parameter at the computer, taking into consideration the full drive train including the new delivered gearboxes.

The new AC motor and gearbox combinations have been detuned to operate on the same 2.9MW basis as the original DC motors.

However, once the phased upgrade is complete the mill will deliver the substantial increase in production capacity.