Buddy works at a machine shop under new ownership. They're "making changes" which means we've had multiple opportunities to pick up tools and equipment that don't fit with the new shop owner and layout. One of those things that ended up in my garage last night was a one-year-old Ingersoll three phase compressor. For real short money.
Either one of us could make the argument for using it at one of our houses, but neither of us has three phase service. It seems to me that the market for three phase equipment is smaller, so would we take a hit trying to flip it for some actual cash? Would we be better off either putting an appropriate single phase motor on it, or perhaps phase conversion via rotary converter or VFD?
What should we be thinking about here?
zordak
Reader
12/15/22 10:10 a.m.
Anything over 1-1/2 hp can't be done on 110v 15 amps. You would have to go 220v single phase to get more hp. I would look at the cost difference between the 220v single phase motor and a VFD. As for selling I would look at ebay for comperable pricing, if deciding to sell.
I used a phase converter that I got for ~$200 off of craigslist or Facebook. It's enough to fire up the wayyyyyyyy oversized dual motor 2-stage 100gallon Quincy compressor I got for $300 8 years ago or whenever it was.
The 5hp phase converter models seem cheap and available used, cheaper than VFDs last I checked, but they are heavier and take up more space.
At the time I spent 200 on the 5hp phase converter, switching to a 220V motor that could drive my compressors would have cost somewhere in the ~$900 range if remember correctly.
I just picked up a nice American Rotary ADX-20 phase converter to run a CNC I just got, but I scored a great deal @ $1200 used, and it would run 5 of your compressors, probably.
I'm a big fan of 3-phase power.
I have a 7.5 HP rotary phase converter....new about $1100. It will run any 2 machines at once, for the rare moment I'm not working alone.
With the RPC, you'll lose any efficiency gains of the 3 phase, but...
3P motors are physically smaller for same HP output.
Instant reverse....useful tapping on mill or Lathe, or just stopping quickly
No capacitors to fail
No start windings to overheat...which I did with my 1P 3HP tablesaw, ripping lots of pieces (adjust, start, cut, repeat).. Cap start split-phase motors are designed for less than 20 starts per hour...to allow the start winding to cool. I burned mine up. I replaced motor with a 5 HP 3P...same physical dimensions. Cheaper than the 3HP 1P motor.
If a new 3P lasts a month, it will go for decades...until the bearings fail. They are super reliable.
Smoother torque output....rarely significant for us, but smoother finish with precision cutting machines.
Nikola Tesla, father of 3 phase and my childhood hero....
BTW, VFD is used for varying speed and maintaining torque. Not needed for compressor.
RPC mounted on wall;
3P breaker panel just below
On-off for RPC
Hlavni vipinac=Master Switch in Czech
Bottom of breaker panel just visible above..
Mill with 3 single pole switches ganged to make 3P emergency cut-off switch...
