# VFD Inverter or 1Phase Motor on a compressor that would normally be 3phase



## ScottJohns (10 mo ago)

I live in Indonesia and had settled on buying a Swan brand (everyone says that’s the best quality available here), 5HP, 3 Phase (380V), 8 bar, belt drive, reciprocating air compressor with an FAD of 619L/min (22 CFM). 

I’ve been getting into building custom motorcycles and metal fabrication as a hobby, so planning to run things like a plasma cutter or die grinder continuously at times, as well as do some painting and probably some sand blasting of engine parts. From the research I’ve done, that seems like it should be sufficient for my needs most of if not all of the time. Worst case scenario I take brakes while sandblasting.

As it turns out, I can’t get 3 phase power, so I’m stuck with single phase 220V. I don’t really understand why, but compressors above 3HP all come with 3 phase motors here, with the exception of a couple of resellers that are buying 5HP compressors without the motor and strapping a single phase motor on it for resell. Obviously I’m not the only person with this problem here.

I’m leaning toward buying my compressor of choice without the motor and putting a single phase motor on it myself, as that will come out to about the same as if I had just gotten it with the 3 phase motor.

The other option would be buying a VFD inverter on top of the compressor, so that I can run the 3 phase motor.

I don’t know much about any of this stuff, other than from the research I have been doing. So, here are some questions:

1) What’s the problem with a 1 phase motor that has the compressors above 3hp usually coming with a 3 phase motor instead?

2) Is the VFD route actually going to save me money in the long run, because I’m going to go through 1 phase motors so much quicker?

3) If the 1 phase motor is indeed the way to go, what do I need to know to make sure I get a motor that will work?

I already know it should be 4 pole/1500RPM. We don’t have any of that NEMA sizing label stuff here. Pretty sure I just need to get one that’s “foot mount” and worst case scenario I have to drill my own holes or fabricate a new bracket for the compressor.

4) Is there any information that will help me decipher the quality of a motor when I’m looking at them?

5) What am I not aware of or thinking about that I should be?

Thank you very much to anyone who takes the time to read this and had the knowledge to respond.


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## stevon (Mar 5, 2019)

ScottJohns,

My advice is to buy a single phase 5HP compressor from the start, unless you can buy a used 3 phase unit for 1/3 or less than the price of new. Converting single phase to 3 phase is A) very expensive, B) inefficient and C) another thing to fail. I strongly suggest that you _*do not go*_ down the conversion route. If you are buying a new unit you will void the warranty by switching out the motor or using a converter anyways.
3 Phase motors are cheaper to build, use less power and simple (no capacitor start mechanism) and more efficient than a single phase (lower power bill). That's why commercial users always prefer 3 phase.

Stephen



ScottJohns said:


> I live in Indonesia and had settled on buying a Swan brand (everyone says that’s the best quality available here), 5HP, 3 Phase (380V), 8 bar, belt drive, reciprocating air compressor with an FAD of 619L/min (22 CFM).
> 
> I’ve been getting into building custom motorcycles and metal fabrication as a hobby, so planning to run things like a plasma cutter or die grinder continuously at times, as well as do some painting and probably some sand blasting of engine parts. From the research I’ve done, that seems like it should be sufficient for my needs most of if not all of the time. Worst case scenario I take brakes while sandblasting.
> 
> ...


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## stevon (Mar 5, 2019)

ScottJohns, 
I believe this electric motor would meet a real 5HP compressor load:

WEG model number 00518OS1CCD184T

Stephen



stevon said:


> ScottJohns,
> 
> My advice is to buy a single phase 5HP compressor from the start, unless you can buy a used 3 phase unit for 1/3 or less than the price of new. Converting single phase to 3 phase is A) very expensive, B) inefficient and C) another thing to fail. I strongly suggest that you _*do not go*_ down the conversion route. If you are buying a new unit you will void the warranty by switching out the motor or using a converter anyways.
> 3 Phase motors are cheaper to build, use less power and simple (no capacitor start mechanism) and more efficient than a single phase (lower power bill). That's why commercial users always prefer 3 phase.
> ...


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## ScottJohns (10 mo ago)

@stevon thanks for your response, but as I said in my original post, the only 5HP single phase compressors here in Indonesia are ones that resellers have already converted anyway.

Far as I can tell, there are only a couple single phase 5HP motors available, meaning I would be using the same motors as the resellers to do my conversion.

The reason I can not buy a single phase 5hp compressor as you suggested or the 5hp motor you suggested is that the tax on importing any product here is ridiculously cost prohibitive.

Are you able to answer my question about the VFD option vs the single phase conversion option?


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## stevon (Mar 5, 2019)

ScottJohns,

OK 5 HP single phase motor is not a option for you. If you choose to use a VFD on single phase input, you will introduce problems that a VFD was not specifically designed for. There is a good article about this:





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Can a VFD Convert Single-Phase Power to Three-Phase? | VFDs.com







vfds.com





A simpler solution would be a phase converter. Contact the sellers of VFD or phase converter to make sure you buy the correct model for your application and also what warranties are available. Get the longest warranty you can on your selection, please let us know how you make out

3 phase converter: https://www.amazon.com/Single-Converter-MY-PS-7-5-200-240V-200V-240V/dp/B07F243HLG

Stephen




ScottJohns said:


> @stevon thanks for your response, but as I said in my original post, the only 5HP single phase compressors here in Indonesia are ones that resellers have already converted anyway.
> 
> Far as I can tell, there are only a couple single phase 5HP motors available, meaning I would be using the same motors as the resellers to do my conversion.
> 
> ...


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