Rockwell Automation executes AC Drive migration at Mozal Aluminium

For over 20 years, Rockwell Automation 1336 Drives have delivered the drive control required across Mozal, an aluminium smelter near Maputo, Mozambique. Now the industrial automation leader is in the final phase of upgrading this plant-wide drive layer with its Allen-Bradley PowerFlex 755 AC Drives, bringing the feature-rich functionality of its flagship drive technology into Mozal’s production architecture.

In addition to lowering risk of system downtime in the future and improving the plant’s long-term reliability, far greater process intelligence leading to massive gains in diagnostic capabilities; greater energy efficiency; and enhanced hardware and software support are among the benefits gained with this technology upgrade.

 With the PowerFlex 755’s intuitive HMI providing on-demand error reporting and diagnostic information, plant maintenance teams will have greater intelligence allowing them to fault-find faster and more efficiently and therefore reduce maintenance downtime.

“The PowerFlex 755 delivers a high level of actionable intelligence at the fingertips of maintenance teams, allowing them to diagnose and correct process issues without having to search and consult technical literature to understand the meaning of errors, where they occur, and how they should be addressed,” explains Teboho Matlolane, Project Engineer, Rockwell Automation Sub-Saharan Africa.

Other integrated functions, such as the drive’s TorqProve feature, enhances site safety on the many different crane and hoist applications across the smelter. Used to optimise control of load handling and lifting, this feature includes a continuous brake slip monitor that detects load slippages and will automatically hold and/or safely lower the load. The communications protocol needed to be able to keep the current systems running while ensuring that the drives are Connected Enterprise-ready on the EtherNet/IP standard.

“With many previously separate control functions such as brake choppers now integrated into the PowerFlex 755 drives, the amount of hardware required by the overall drive system has been reduced,” Phineas Ratshosa, Project Engineer, Rockwell Automation Sub-Saharan Africa, explains. “A streamlined, more direct and integrated drive architecture doesn’t just lower the physical and energy footprint required by the hardware, it further optimises maintenance and diagnostic efficiency for the plant.”

Production-sensitive migration

Beginning in 2014, with the scope of the migration numbering over 350 new drives, combined with the requirement of minimising any impact on operations, the migration has been done in four phases, each targeting one or more of the following plant areas: the Castline Tending Assemblies (CTAs); Trailer Loaders; Casthouse; Furnace Tending Assemblies (FTAs); Pot Line Tending Assemblies; Stacking and Transfer Cranes; and the Rodding Shop. There are many diverse positioning and hoisting machines in these plant areas, each requiring a unique solution. The migration continues to date and is scheduled to be completed in November 2020.

Rockwell Automation implemented a planned migration within the plant’s maintenance schedule to keep plant shutdown to a minimum. This required precise communication, planning, preparation and execution between Mozal Aluminium, South32, Rockwell Automation and other third party service suppliers.

In a streamlined and efficient installation and commissioning routine, Rockwell Automation, together with its local panel manufacturer Temoc Lda, assembled the new MCC buckets of the drives and ancillary hardware, testing each component individually, prior to integrating the new buckets into the existing panels.

For Rockwell Automation, it is another demonstration of the company’s intelligent, Industry-4.0 hardware optimising production and operations efficiency in Africa’s mining and metals industries.