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Central, IA | I know you can run a 3 phase load with a single phase power supply using a VFD. The point I was making was that the load in the OP's message had to be a 3 phase load if a VFD was involved.
Energy savings is not my motivation on my ventilation. Over the last 5 years I have converted all of our turkey finisher buildings to tunnel ventilation. I have accumulated 150 52" fans (27,000 cfm) that have a 1.5hp single phase motor on them. I would like to be able slow the speed of 1 fan per building in the winter time to reduce the minimum ventilation rate. Sure I can find a $200 VFD to work if I switch the motor out to 3phase for another $300. $500 isn't terrible. But then I get to multiply that by 16 buildings and the time it takes to rewire all of them and hook up a control system.
In a perfect world, I would just have 5-36" fans along the side wall for cold weather, but that's not easy (or cheap) either.
Edit:
We have some 3/4hp single phase fans on a variable speed controller in our brooderhouse. Ironically the power usage increases as you slow down the motor. I believe they are just reducing the voltage to the motor, but haven't ever looked into it that serious.
Edited by nhermanson 10/20/2012 16:24
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