Energy saving through VFDs for fan drives in tobacco threshing plants

This paper presents the experimental studies of VFD drives for conditioning of tobacco. In particular the classifier fan is operated with and without VFD. The speed of the fan is adjusted depending on the grade of tobacco. Three different classifier fans driven by different rating motors are chosen for experimental studies. The motors can be supplied either from grid supply or inverter. Measurements such as input current, power factor, running load are made on each drive at different speeds with and without damper control during the processing of tobacco for a given load cycle over the selected period. The reduction in the energy consumption of the VFD fan drives is obtained and cost benefit analysis is made. Further, the payback period is also computed. From the experimental studies it is found that the airflow varies according to the speed of the fan motor and use of damper circuit can be completely eliminated. Various performance characteristics are presented.