Columbus Stainless is the only fully integrated, technologically advanced, single-site stainless steel producer in Africa. Based in Middelburg, Mpumalanga, the plant produces a wide range of austenitic, ferritic, utility and duplex grades of stainless steel suitable for most applications and supplied to various final customers, distributors, engineering shops and mines in South Africa and globally. “We have been operating for more than 50 years,” explains Stef Du Toit, Columbus Stainless cranes engineer. “To remain successful in what we do, we have ensured that our facilities can keep up with demand and experience minimal downtime. This means working with the right technology partners.”
For more than 20 years, Columbus Stainless has worked with Nidec Control Techniques to ensure operations run smoothly. Most recently, the Nidec team used their expert engineering capabilities to upgrade the main hoist of the steel plant ladle cranes. “These gantry cranes are critical production cranes which carry between 110 and 115 tons of molten steel in ladles along the steel-making plant. The two main hoist motors are synchronously locked together,” explains Derek Coetzee, head of engineering at Nidec Control Techniques. The motors’ control technology needed replacement to ensure the facility would remain future-fit and to avoid breakdowns caused by obsolete technology. Nidec was awarded the turnkey contract to upgrade the variable frequency drives with redundancy features − a project usually awarded to a crane company. “Our strong track record and longstanding relationship meant that we were entrusted with this project. We had the suitable technology and we made sure that we got the right skills on board to ensure the crane load capacity met the customer requirements by the close of the project,” he says.
A custom-engineered solution
Coetzee explains: “An interesting aspect of this project was that our solution needed to be able to fit into the same space as the existing system. Our compact technology put us ahead of our competitors and we were able to engineer a system which could meet the demands of the facility while not disrupting existing structures.” The specific Nidec Control Techniques products used for this application included two Unidrive M700 units connected in parallel, with each driving a 250 kW eight-pole IMfinity premium efficiency induction motor. “The M700 AC drive is a high performance motor control system providing ultimate control flexibility in high specification industrial applications. Combined with motors which are designed for a demanding industry, we are confident that this solution will see Columbus remain industry leaders,” comments Bruce Grobler, regional manager of Nidec Control Techniques. A door-mounted HMI also provides full diagnostics for the system.
Nidec takes pride in their complete turnkey solution offering, which aims to provide standard and customised drives from small machine automation projects right up to complete automation and electrical solutions. “When it came to this project, we took into account the operational needs of the client and proposed a solution which would see the operation succeed now and into the future. Furthermore, commissioning went smoothly. Our accredited personnel always ensure the reliability and safety of equipment and complete installations in compliance with local technical regulations and safety standards,” adds Grobler.
Built for the long haul
The ladle cranes at Columbus Stainless have been operating for approximately 25 years and still have many years of service life ahead – if supported by the right technology. “As technology improves, it is natural that certain solutions become outdated or obsolete. Newer technology not only has the potential to improve uptime, it also offers added benefits from an intelligent and compact design and connectivity,” says Grobler.
The M700 is Nidec Control Techniques’ flagship drive and has been used in other areas of the Columbus plant. Du Toit comments that the local availability of the technology is an added bonus. “These drives are vital to our production efficiency and it is important we minimise downtime as far as possible. The availability of spares and support in-country is a huge benefit to us.”
Grobler concludes: “We are delighted to have completed another successful project for Columbus Stainless. A relationship that started out small over two decades ago has grown, thanks to our consistent and sustainable technology solutions. We look forward to the years ahead as we work in partnership with the Stainless team to keep the plant at the top of its game.”
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