The ventilation motors and the frequency converters in the area of the induced draft of the dedusting system had been in operation for four years and needed to be replaced to minimize the risk of an unscheduled breakdown. That's why Stahl Gerlafingen wanted Siemens to provide a fast and reliable retrofit solution with the following requirements:

• Replacement of obsolete components step by step while maintaining the high availability of Stahl Geralfingen's plants.
• Minimum risk with maximum energy efficiency.
• Service window of just two weeks.
• Solution for spare parts (components have been totally discontinued and spare parts were no longer available).

In a service window of just two weeks, Siemens installed two Loher low voltage fan motors - each with a power rating of 1800 kW and a Loher DYNAVERT-I frequency converter. At the same time, Siemens ensured high availability with a smart spare part concept and supported the customer in its application for per-kilowatt charges.

Stahl Gerlafingen AG is one of the last steel foundries in Switzerland and has a long tradition. Its buildings may be over 200 years old, but the furnaces have been continually modernized. They process 60 percent of Swiss scrap metal, which amounts to 732,000 metric tons per annum. The melt furnaces run round the clock in four-shift operation for 48 weeks of the year.