justafink
Industrial
- Mar 20, 2008
- 2
Bright idea: Replacing pulleys on an AHU w/VFD. AHU normally runs at 67%, so I thought adjusting the ratio of drive to driven to put the motor closer to it's more efficient speed. Ok, increased the drive to driven by 20%. Motor speed is up to 76% (didn't go quite as far as I had hoped), current draw is down from 12.5 to 10.6 amps at 492v (Nice! Down 18%). I know how to calculate single phase energy consumption (amps to watts), but am not sure if there's a trick to calculating 3 phase. Any takers here? I understand Ohm's law isn't hard and fast on motors, I'm just looking for somewhere of a ballpark estimate of reduction in wattage. --Ray
