Driving down energy costs

A full installation and commissioning contract has been awarded to Rockwell Automation Australia for 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.

The upgrade is designed to enable lower motor idle speeds for increased energy savings, while advancing system reliability and maintainability. Prior to the upgrade, speed control for the basic oxygen steelmaking (BOS) ID fans was provided via a slip energy recovery (SER) drive system. 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 shut-downs.

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 advantage of the PowerFlex7000 is that the transformer can be located remotely. This has allowed Rockwell Automation Australia 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.