Rockwell drives down energy costs

Rockwell Automation Australia has been commissioned to install an induced draft (ID) fan upgrade at the BlueScope Steel, Port Kembla steelworks plant. Installed in December 2004, the first of three 3000 kW, 6600 V PowerFlex 7000 variable speed drives (VSD) is already operational. The entire upgrade is scheduled to be completed by June 2005.

According to Scott Southby, Rockwell product manager, the upgrade is designed to enable lower motor idle speeds for increased energy savings, while advancing system reliability and maintainability. "Before the upgrade, speed control for the basic oxygen steelmaking (BOS) ID fans was provided via a slip energy recovery (SER) drive system," said Southby. "In terms of energy usage and maintainability, the PowerFlex 7000 is a much better option." As the steelworks process is dependent on each fan providing induced draft for one of the three separate BOS vessels, the SER drives are being replaced progressively - one at a time over a period of six months - during scheduled plant shutdowns.

Flexibility in the design of the PowerFlex7000 medium voltage VSD was a key factor. While every drive of this type requires an isolation transformer, the benefit of the PowerFlex7000 is that the transformer can be located remotely. This has allowed Rockwell to position the new drives in the existing footprints that the SER drives occupied. "Having the transformers away from the drives also means that they're not contributing to heating the switch room - there's another saving, right there, in cooling costs," Southby added.

Rockwell Automation was chosen for its ability to provide a full turnkey solution: hardware, installation and commissioning. The PowerFlex7000's high efficiency and small footprint were other key factors.