Variable Speed Drives Save the Day at Danish Dairy

The Challenge

An elevator in the cheese drying system broke down, bringing the entire plant to a standstill. The suppliers estimated that it would take a fortnight to source the parts to rectify the situation with huge ramifications for the stocks of unfinished cheese that would need to be moved, meaning large storage and transport costs would be incurred.

The Solution

There were ongoing problems with the original programming and, as Per Hansen, Chief Electrical Engineer at the dairy explained, “In one day, Control Techniques achieved what the manufacturers could not. But it was a temporary fix and we asked Control Techniques to give us a better permanent solution. Control Techniques engineers replaced the existing software with their own elevator software and managed to get us up and running again later that same day.”

Control Techniques Denmark carried out a complete rebuild of the elevator control system using Unidrive AC drives and Unimotor servo motors under the overall control of the existing PLC controller. Each of the Unidrives, working in servo mode, is fitted with plug-in Application Modules. In cooperation with the supplier of the PLC controller, Control Techniques software engineers completely rewrote the positioning software. The positioning is carried out by the software within the Unidrives’ own Application Modules, eliminating the operational problems.

The Benefits

"“The system now responds faster and more accurately,” said Mr Hansen, “and, above all, reliably. Reliability is my number one requirement in this production facility. Each week I have to answer for every minute’s lost production – and what I am going to do to eliminate weak points. That’s why I have used Control Techniques drives – with back-up from their local Drive Centre – ever since this plant opened in 1989.”

“This is a very busy plant,” concluded Mr Hansen, “and any stoppage has major cost implications. That is why I have to have complete confidence in my drives and in the local support that is available. With Control Techniques, I have both!”