Sonderborg Heat Company had prior experience with Danfoss VLT drives on smaller loads and was pleased with Danfoss' products and services; however Danfoss did not have frequency converters large enough for these applications when the plant was build in 1993. As a result the frequency converters were supplied by another manufacturer.
Over the years, the customer had poor experience with the reliability of these drives and the service from the other supplier. Therefor it was decided to replace these drives by Danfoss VLT High Power Drives as soon as these were available.