Processes with high automatization often contain VFDs which causes harmonics in the power supply. This can affect machineries and could cause downtime in production lines like at REWE in Dortmund.
REWE Dortmund Großhandel eG is a federation of over 300 independent retail dealer and supplies approx. 540 grocery stores. The center is the 100.000 m² warehouse and distribution center in Dortmund-Asseln with affiliated butcher. After a fire destroyed the butcher in 2009, it had been rebuild and expended in 2011 into an 18.000 m² large butcher shop. Since end of 2011 REWE produces 250 tons of meat for the grocery stores and up to 25 tons of sausages every day. The new butcher shop contains state of the art logistics and meat processing systems.
The new meat cutter and the included VFDs creating the typically current harmonics of a six-pulse-converter (5th, 7th, 11th, 13th, etc). These harmonics result in commutation notches in the voltage which influences the whole process. It causes disturbances in the light and blackouts. Furthermore it influenced the sausage stuffing and caused long production stops which disturbs the process flow. Occasionally up to 50 % of the employees had to go home for the day caused by disturbances in the process.
Solution – ADF Active Dynamic Filter with harmonics compensation
REWE decided to use a Comsys ADF Active Dynamic Filter to eliminate the problems in the power supply. The installed system consists of one ADP P300-300/480 with a capacity of 300 A harmonics compensation to provide the needed harmonic power for the meat cutter.
After the installation and short commissioning, all disturbing harmonics have been canceled and the commutation notches disappeared. For the first time it was possible to start all meat cutter at the same time, without any effect on the light or the sausage stuffing process.
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