VFD debate: two experts debate the validity of variable-frequency drives (VFD)

摘要

In the movie Speed Keanu Reeves must keep a bus moving faster than 55 mph or suffer disastrous consequences. If the bus slips below 55 mph, it explodes. Most of the movie is spent following the bus through a predictable series of near misses -- the bus narrowly escapes a car-packed highway, jumps over a construction area, screeches over sidewalks and through narrow alleys. Like the bus in Speed, traditional irrigation pumping systems operate at a constant speed-- designed for the maximum water flowto efficiently use the equipment. For example, one might use a 15-hp pump to maintain the pressure and rate of flow that could be easily handled by a 1-hp pump. The problem is that you're paying for equipment you don't use. This excess pressure always represents wasted energy. Where flow rates are highly variable and pressures need to be closely controlled, growers may find value in using a variable-speed setup.