When an elevator in a cheese drying system broke down at a Danish dairy, the entire plant was brought to a standstill with a loss of some five tonnes of cheese per hour an estimated cost of 40,000 per shift. The suppliers estimated that it would take a fortnight to get the parts to rectify the situation. Engineering staff were facing the possibility of having to remove stocks of unfinished cheese to warehouses elsewhere in Denmark, with storage and transport costs escalating as time went on.
We already used drives from Control Techniques elsewhere in the plant, so I contacted the Control Techniques Drive Centre in Greve. 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, says Per Hansen, Chief Electrical Engineer at MD Foods' R dk rsbro Dairy in Denmark.
We had been having constant problems with the original programming, explains Mr Hansen. It was written in such a way that we couldn't adjust the programming ourselves and we had already spent some 80,000 crowns ( 8,000) trying to get it right. 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.
Some months later, Control Techniques Denmark carried out a complete rebuild of the elevator control system utilising 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 the unique Control Techniques plug-in Application Modules. In co-operation with the supplier of the PLC controller, Control Techniques software engineers completely rewrote the positioning software.
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