Static phase converter



Well, if I use the 10 HP motor, I would want the pulley sized so that I get more or less all 10HP out of the motor. (my pump is rated 5-10 HP).

It does not seem to hurt, so I will try. I will use the 10 HP reliance motor, first I will run it with phase converter just to verify the basics, and then I will buy run caps and will go from there, using 24 uF per HP. The motor may well start from these caps, actually. My phase converter's 10 HP idler starts from 194 uF every time.
At first I will use the pulley that would demand 7.5 HP out of this motor, which is a pulley that came with this compressor that matches the 10 HP motor's shaft as well, but if all goes well, I will try to up-size the pulley to get all 10 HP out of this system.
(the compressor had a 7.5 HP motor, I got the tank, pump and pulley but not the motor as part of the bargaining procedure).
Thanks a lot. I will hopefully get it to run today from RPC, proceeding from then on.
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On Fri, 06 Feb 2009 16:23:08 -0600, Ignoramus7868

Myself, I'd use the VFD for one very important reason: Compressors normally are setup on a pressure switch and run unattended. And you have to think through the possible failure modes.
Sometimes you are at the other end of the shop when they start, sometimes you are up on the roof with a nailer placing new shingles, or in bed. Or miles away.
When the motor fails to start, and Murphy's Law says sooner or later it will... You probably can't get there fast enough to kill the power. And electrolytic caps go off like fireworks when they go - a Party Popper with tons of foil chaff confetti and some power behind it, with perhaps a flaming oil chaser on the old ones.
The VFD is smart enough to fault and stop, hopefully before anything blows up.
A homemade phase converter, not so much... The breaker might trip out before the fire reaches self-sustaining levels, but I wouldn't bet on it - remember, the breaker has to be heavy enough to hold Locked Rotor Amps during a normal start cycle without a false trip, so the motor has to stay stalled and drawing LRA current for a while to trip.
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This is what overloads are for?

I start my phase converter manually, it does not have any facility for automatic starts. And it is not something that I would want, for the above reasons.
The caps on it are oil filled, not electrolytic.
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in

Um... yeah, that's be it, Iggy. And the heaters always trip out before the breakers do on my compressors.
But then, maybe _somebody_ hasn't heard about adjusting the motor starter timers (or selecting _and_installing_ appropriate heaters on non-adjustable ones).
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