Steel mill hooked on drives supplier

Electrical switching & drive systems & components

Fourth Quarter 2004 Electrical switching & drive systems & components

Trident Steel in Alrode, Gauteng, has long been a committed customer of Danfoss, and once again that company was able to come to the rescue at a moment's notice when one of its competitor's DC motors in Mill No. 1 literally blew up recently.

Five thousand tons of steel a month go through the three mills at Trident Steel, to be converted into steel tubing and pipe of varying thicknesses and length. The steel mill had already converted from DC to AC in several instances, with maintenance foreman Peter Dippenaar trying other well-known brand names before settling on the Danfoss range.

It had taken some convincing from Dippenaar before Trident Steel was willing to make the change, but once the advantages of running on AC motors and drives was made obvious the change over from DC has been relatively simple to implement with Danfoss' support.

"We were the first steel mill in South Africa to run with AC converters on a tubing mill," says Dippenaar. "We had steel mill operators from around the world come to visit our mill to see for themselves the advantages of using AC drives."

AC motors and drives are far easier to control and run in sync when constant speed and welding thickness are the criteria. Furthermore, a 75 kW AC motor will do the same job as a 90 kW DC motor in this type of application. Maintenance on AC is far lower than on DC, a matter of great importance to the maintenance foreman.

"When we lost the DC motor at Mill No. 1, I was told it would take six to eight weeks to get delivery of a new motor," says Peter Dippenaar. "But Dave Dyce, the sales engineer at Danfoss, was able to come in with his team, take out the old motor and replace it with the Danfoss system (two 75 kW motors and two VLT5102 AC drives) within a matter of 24 hours."

Danfoss has recently completed a project called 'Big little Big'. The project was implemented in order to reduce the physical size of the current VLT5000 series. Since completion of the project, in many cases the VLT5000 now boasts one of the smallest footprints on the market. Some units have been reduced by up to 80% in size. The two units delivered to Trident Steel were among the first of the new type to be delivered in South Africa. The retrofit from DC was no problem as far as space was concerned.

The Danfoss Service Department worked overtime to modify some of its workshop units to accommodate Trident Steel while the new units were on their way from Denmark, where the Danfoss head office and factory are situated. At their client's request, the loan units were delivered at 22:00 the same evening.

"I have always had very good general support from Danfoss," continues Dippenaar, "and I know I can rely on their 24 hour repair backup service. It is easy for me to programme the units myself and what is more, I know the Danfoss motors and drives will do the job I need."

For more information contact David Dyce, Danfoss, +27 (0) 11 803 8390, [email protected], www.danfoss.co.za

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Electrical switching & drive systems & components

Steel mill hooked on drives supplier

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