Wanting to change 3 phase motor to single phase motor on a Coltri MCH-16 Compact

[rhwestfall]

See if Tony (ajtoady) chimes in... he's a "sparky"....

Anyhow, not a compressor, but we use a VFD[VSD?] (variable frequency/speed drive) to run three phase pumps where two phase is the only source available in sewage pumping applications. These are much more reliable than the true phase converters.

 

[ajtoady]

VFD can be a little pricey when compared to a rotophase unit, however they give you all kinds of extra's. Overload protection, speed variable, torque adjustable, soft start capability and they really do well. The soft start is a feature that will considerably reduce the wear and tear on whatever you are controlling, thus it's a win win with the VFD. Check out ebay and also, google variable frequency drive, to find a whole truck load of vendors. As far as using your motor starter on single phase instead of three phase, not a problem as long as you size the heaters for the motor amperage and voltage you are using. The amount of control you get with a VFD by far exceeds any rotophase converter. This however is my opinion and based on observations that I have had in the past 40 yrs in the manufacturing plants.

 

[dchango]

Ron, good point do you have the specs on the motor? That was I can make sure it fits.

Thanks
Damon

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

 

[frogman62]

I am of the old school also I took a 15 HP three phase motor and added the necessary capacitors to bring the wild leg up to capacity. Only issue is I need to spin it to about 1200rpm before I turn on the switch.I have less than $120 in it -- salvage motor ,new bearings, capacitors and wire - easily runs 10 HP three phase for several hours.
The leeson you linked to (213 frame )is a good motor for your conversion
Jim

 

[lowviz]

Frogman62 & Oldschoolto,

I admire that.

Looking back, I should have done the same. If I did it again, I'd build my own and spend the money on switching and capacitor banks that would allow for really good load matching. I wired the rotary converter into the shop through emt so I can have 3Ph for several other odd machines.

 

[maniago]

I'm going down this road currently myself, but I came up with a different answer than a Rotary, a VDF, or a static - a transformer+caps. Wind it yourself. This is what I''ll be doing once I finish the rebuild on my Rix.

Unique3phase

That said, if this stuff gives you the willies, stick with one of the purchased solutions....

 

[roastbeef]

Stay away from those 3550 rpm motors there cheaply made and don't last get your self a nice 1750 rpm motor and adjust your pulley sizes accordingly. You roughly need 1 hp to produce one cubic foot of air. Run your compressor slower and reduce wear.

 

[dchango]

Thanks everyone for you input and help. I purchased the 213T frame motor and now I have another question. Maybe Ron can chime in on this, along with everyone else of course. I am trying to get the correct pulley ratio the get the RPM of 1550 at the compressor (what the specs call for) the motor specification is 3520 RPM. From what I have found on different pulley ratio calculators sites the drive pulley should be 8” if the compressor pulley is 18.7/16” OD (that’s what I measured). But where do you measure it form, the OD or inside the groove? I think it will be the BK85 pulley, but no sure. I am just afraid to get the RPM to high on the compressor. Is it okay to go a little over, like 20-30RPM over? Here are the specs on the puleys.

Part# OD PDa PDb
BK80 7.75 7.00 7.40
BK85 8.25 7.50 7.90
BK90 8.75 8.00 8.40

Thanks
Damon

 

[maniago]

But where do you measure it form, the OD or inside the groove?

you tube is your friend. VbeltGlobalSupply has several videos to help you out. For example: How to Measure V-Belts - YouTube

 

[BRT]

The only thing is the added cost and higher amps to run the single phase over the three phase..

I built a rotary phase converter for my Bridgeport..... It works like a charm.... just had a leg that was 170 volt that I needed to bring down..... The easy way is spend the money and enjoy the diving...

Jim....

This is wrong. The amperage will be higher but the kilowatt hours will not be higher. You pay for kilowatt-hours.