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Old 06-08-17, 09:42 AM   #1
jeff5may
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Default Alternative variable speed drives

I am looking for ideas on variable speed drives that can run phase change compressors. I don't necessarily have to use a dedicated steel pot hermetic compressor. The main goal here is cheap and reliable. Something that can drive a belt or shaft is fair game. If it is electric and can drive a 3 phase compressor or inverter compressor without major modification, that might work if a common source of these types of compressors could be discovered.

One idea I have been tossing around lately is the motor and drive inside the new front load (HE) washing machines. They are showing up in salvage yards and landfills every day with problems like bad hinges and latches. The vast majority of these units don't have drive motor failures. They seem to do a pretty good job tossing around a big drum filled with wet clothes and water for years, so they shouldn't have much trouble running an auto AC or shop air compressor. I just so happen to have a guinea pig unit to look at right now...

Another one is the drive inside all those treadmills found at garage and yard sales every weekend. Watching all the youtube and facebook videos of people being thrown by them, I would think they have enough torque to start and run a compressor. Plus they have an automatic soft start built in...

I don't mind devising a belt drive with pulleys and sheaves to match RPM requirements if needed. But what RPM ranges do the previously mentioned candidates operate? And how is that power factor? Do these motors gobble up VA while not running at full HP?

I have read that commonly available VFD units can run refrigeration compressors, but where can these compressors be found on the cheap? Once a suitable pot is found, how much fun is matching the VFD to the compressor?

Feel free to educate me on the holes in any of these ideas. I get told every week how what I am doing will never work. I'm a "Git-er-done" type of person, not a "Go buy a new one". There you go, run it til it breaks. Or not, I hope...

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