Soft Start vs Hard Start for Compressors/Motors?

[Industrial Toys]

I never really did know or ask if AB, AC-Tech and the like, VFDs made true sine wave. Interesting question. I know lathes and milling machines do whine at slow speed when running off these.

I couldn't even justify putting in a small fountain, for the thought of how much time one spends enjoying it VS it's overall run time, drives me crazy. And to shut it on and off, spoils the mood.

I know a guy that works for "rich" people at their "cottage" (cottage is a multi story concrete structure with an elevator) where there is an outdoor swimming pool kept at bath tub temperature year round. For the most part, it's never used!

 

[ultrarunner]

you put an oscilloscope on that, and you'll see why it's not really clean, true 3 phase!.. the motors must whistle or hum..

Since 1982 I've been running my Bridgeport Mill from a 1 hp 3 phase motor that simply idles after I give it a spin by hand.

The spinning 3-phase motor provides power to run my milling machine motor.

Never scoped it but no issues in 38 years.

 

[radios1]

Since 1982 I've been running my Bridgeport Mill from a 1 hp 3 phase motor that simply idles after I give it a spin by hand.

The spinning 3-phase motor provides power to run my milling machine motor.

Never scoped it but no issues in 38 years.

that's the only way you can generate true 3 phase power from a single phase source.. however, you won't get the full 1 hp from that, and it's not as efficient as a VFD..