Using a VFD to Troubleshoot Pumping Problems

This technical report presents troubleshooting techniques for Variable Frequency Drives (VFDs) in pumping systems, emphasizing the necessity of understanding the entire system to effectively identify issues. It includes four case studies that illustrate common problems encountered in the field and how they can be misattributed to VFD malfunctions. The first case study discusses a user experiencing inconsistent flow rates, which was traced back to a drop in the water table rather than a fault in the VFD. The second case study highlights a delayed feedback issue due to the distance between the pressure transducer and the pump. The third case study examines a farmer's declining pump performance, revealing the need for well rehabilitation rather than a VFD issue. The final case study addresses overvoltage faults, identifying inadequate power supply as the underlying cause. Each case reinforces the importance of a comprehensive understanding of the system variables when troubleshooting VFD-related problems.