Prefabet Kozienice S.A., owned by CRH Ireland, have recently specified 30kW Optidrive units for their gypsum mixing plant in Poland. The company manufacture gypsum from the waste products of coal burnt in a local power station and then mix this with water to produce a raw material used in the manufacture of building blocks.
The mixing arms used to mix the gypsum and water are driven by 22kW motors. Each motor is controlled by an independent Optidrive, which in turn is linked to a PLC. The PLC is used to vary mixing speeds - choosing from one of four pre-programmed speeds - switch off the drives and change between automatic or manual control according to mixture levels and product temperatures.
With a current of 55Amps and an extremely heavy load at start up, Prefabet Kozienice S.A. required a drive that offered excellent reliability and even chose a drive with a higher power rating than the motor to further ensure trouble free operation.
Optidrive has certainly lived up to its reputation. The units operate continuously for periods of at least four weeks at a time with no interruptions to the production process.