Evaluation of Variable Frequency Drives (VFD’s) for Agricultural Ventilation Fan Speed Control

Comparison tests between a Variable Frequency Drive (VFD) and a triac speed controller showed the VFD controlled fan to supply a more stable airflow as the pressure against the fan varied. This is important because agricultural ventilation fans are often exposed to windy conditions, which affect the static pressure they operate against.

The ventilating efficiency was also found to be higher with the VFD than the triac when the fan was operated at reduced speed.  In situations where a fan is operated at reduced speed for significant amounts of time, a VFD can compensate for its higher initial cost in only a few years.

Project funded by EPRI/ATA and Illinois Power.