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Old 02-17-17, 10:57 PM   #12
Elcam84
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The best way would be to use a three phase motor with a soft start vfd which can be had for around $100 these days depending on size. Then you should also use a centrifugal clutch on the motor or an electromagnetic clutch. That way you can not only soft start the motor but get it up to speed before the load is introduced.
Now if you don't use the clutch make sure your unloader works properly and find a way for it to stay open longer so the motor can get up to speed before it gets a load on it. Or use another valve as an unloader.

Soft starting a single phase induction motor doesn't work well. You end up burning up the start windings which aren't meant to run long and are frail.

Oh and old washers used to have centrifugal clutches on them because their motors were way undersized for the job. Just enough to spin the tub but not enough to get it going without burning up. And for electric there are the ones on riding mowers however neither is going to like the beating they get on a compressor. Lots of cycles and lots of heat.
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