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  1. #21
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Fluffy View Post
    uumm 220V three phase is 380V three phase.

    The difference is in the Star and Delta wiring.

    Nice choice of inverter BTW.

    In the pic below all motor wirings are in fact 230V. Its the same motor just connected differently.
    Not always the case .

    But luckily for the home user it's common for electrical 3 phase motors rated 5.5 kW and smaller to have the 230 V delta / 400 V star rating.

    But on larger motors you also get 400 V Delta / 690 V Star rated motors.

  2. #22
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by 12richardk View Post
    Would it not be cheaper to just change the motor ?
    No. For the price you can pick up a Variable frequency/ Vairable voltage drive for in the 2.2 kW range you will be hard pressed to buy a single phase motor for the same price. And you lose the capability to change the speed without moving belts / changing gears.

    Getting a VFD is the way to go.

    I changed the single phase motor on my lathe to a 3 phase motor and VFD.
    I wish mine came with a 3 phase motor.

  3. #23
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Here is one for a good price and reasonable delivery.

    https://www.banggood.com/220V-or-380...6&rmmds=search
    Cheers

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  4. #24
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Tiaan Pot View Post
    Not always the case .

    But luckily for the home user it's common for electrical 3 phase motors rated 5.5 kW and smaller to have the 230 V delta / 400 V star rating.

    But on larger motors you also get 400 V Delta / 690 V Star rated motors.
    Well yes, naturally.

    The point being though, to identify exactly what the motor is from its name plate, and buy an appropriate Inverter - VSD - VFD - Converter - (insert preferred term here)
    Cheers

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  5. #25
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    Default Re: Running a 3-phase machine on 220 via a VFD

    On a lathe or milling machine, you rather want the motor running on 3-phase 220V than single phase 220V. (surface finish on machined parts is better with a 3phase drive than a single phase drive)

    So no, I would not recommend changing the motor to a single phase, but rater just get a VFD, and change the windings on the motor (if the motor is compatible).

    I got my Lathe VFD from Neels... Very helpful guy.
    Last edited by SinWolf; 2021/06/09 at 03:33 PM.
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  7. #26
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    You have misunderstood me. Wish has an inverter for R790 .00.Sounds too cheap.By the way his lathe is an emco super ll. Far superior to any emco vp 10 which has powered crossfeed.
    Haha! I have indeed.

    Where is the "embarrassed" icon when you need it .

    At least I thought you were being tongue-in-cheek, as the comment seemed unlike you.

    Just concerned in my misunderstanding that other readers may also misunderstand.

    So, apologies.
    If my post insulted you, wonder where the smiley went .

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  9. #27
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    Please explain to me Fluffy how this works. Yes Im an electrically challanged plumber. Mosty little motors under 2,2kw can be changed from star to delta. But their name plate actually states that it 3 ph 240v . Ive tried running some 3 phase motors 380v motors through a vfd like my bandsaw motor and no problem. It does not have the ability to be changed from star to delta.
    But some growl and grunt but it is possible they are damaged as they are second hand. I always thought you should aim to use a power source close to what is recommended. I see they do a 220v in 380v out but thought this was done through trickery by doubling up on the power somehow.
    Like Fluffy has said in the diagrams in both star and delta the windings "see" the 230 V across their terminals.

    When your supply voltage is 230 V single phase your can use VSD (South African naming) or VVVF drive ( variable voltage variable frequency) drive to generate a 230 V 3 phase output. Then you will use a delta connection on the motor in order for each phase winding to see 230 V

    When you have a 400 V 3 phase supply then you can either connected it directly to the motor with the motor windings in a start configuration or trough a VVVF drive if you want to be able to control the speed of the motor

    In star you will notice that you basically have 2 windings in connected in series between the phases. Now normally in a DC circuit the voltage would be split evenly between two loads in series circuit. So if you have 400 V DC each winding will see 200 V

    But in 3 phase AC circuits the phases are out of phase by 120deg , and voltage that each motor winding will see is 400 V/ √3

    400 V / 1.732 = 230 V

    I have seen motors where the nameplate only states 400V 3ph .

    I have been luckily in that I was able to reconnect them in delta and use 230 V 3ph supplies on them.

    In cases where the motor is rated 400 /690 V then you will need to get a VSD that can increase the voltage or use one of the methods that you have mentioned.

    I have never played with this or seen in used first hand but have read up on it.

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  11. #28
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Peter Connan View Post
    Looking at buying a milling machine, but all the good ones seem to have 3-phase motors.

    Can anybody tell me whether it is possible, what is necessary and roughly how much it would cost?

    Motor power on the one I am currently looking at is 1.5 HP.

    I have a copy of a Grizzly G1006 milling machine - beefed up drill press - with a 2hp (1.5kW) single phase motor. Seeing as you get more torque due to increased flux in the 3-phase motor, they should have equivalent torque. Could someone pse confirm this? I can't remember.....

    If it is, I'll swop you motors.

    Guess what my next purchase would be.......
    If my post insulted you, wonder where the smiley went .

    Johnie
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  12. #29
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by JJJ View Post
    I have a copy of a Grizzly G1006 milling machine - beefed up drill press - with a 2hp (1.5kW) single phase motor. Seeing as you get more torque due to increased flux in the 3-phase motor, they should have equivalent torque. Could someone pse confirm this? I can't remember.....

    If it is, I'll swop you motors.

    Guess what my next purchase would be.......
    No for the same motor type, and kilowatt rating the torque for the single phase and three phase will be the same at the same speed. Torque is a moment of force or the energy required to rotate the shaft, power is a measure of the speed at which energy is applied .


    I think what you want it a motor with a higher moment of inertia - in that case you will look at a motor with more poles. But the more poles a motor has the slower its speed. for 50 Hz - 2 pole = 3000 rpm, 4 pole = 1500rpm 8 = 750 rpm ...

    This is an awesome WEG document of motors explains everything in simple terms:

    https://static.weg.net/medias/downlo...nglish-web.pdf


    Also why a VSD also has to bring the voltage down as the frequency goes down and why a motor will overheat when you reach 50 Hz and max voltage and then overspeed it to higher frequency but the VSD is already at max of the supply voltage..

    3 phase motors do have a higher starting torque than 1 phase motors
    Last edited by Tiaan Pot; 2021/06/09 at 06:57 PM.

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  14. #30
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Fluffy View Post
    An lo-and-behold, you will find your single phase induction motor has a starting capacitor anyway and is rather unsuited to a milling machine with variable speed control. Ever noticed all those different diameter pulleys in a drill press.
    This is an elegant way to get around the problem. Works like a CVT gearbox. Infinitely variable spindle speed from 450 to 2500rpm
    Unfortunately the price has gone up substantially since the beginning of last year.

    https://leroymerlin.co.za/bench-dril...AaAisHEALw_wcB

  15. #31
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Woolf View Post
    This is an elegant way to get around the problem. Works like a CVT gearbox. Infinitely variable spindle speed from 450 to 2500rpm
    Unfortunately the price has gone up substantially since the beginning of last year.

    https://leroymerlin.co.za/bench-dril...AaAisHEALw_wcB
    Now I need somebody to teach me what speed to use when.

    I'm too lazy to change the belt on my bench drill so I just use the same speed for everything.
    Cheers

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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Fluffy View Post
    Now I need somebody to teach me what speed to use when.

    I'm too lazy to change the belt on my bench drill so I just use the same speed for everything.
    Try the G-Wizard Demo. Works quite well to learn feeds and speeds
    GaryG


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  18. #33
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Woolf View Post
    This is an elegant way to get around the problem. Works like a CVT gearbox. Infinitely variable spindle speed from 450 to 2500rpm
    Unfortunately the price has gone up substantially since the beginning of last year.

    https://leroymerlin.co.za/bench-dril...AaAisHEALw_wcB

    I have the Eurasia version. I was bloody awesome! Until the belt wore out and no replacement is available. I've tried various belts with no luck.

    So now I am talking to Neels about a VFD and 3 Phase motor to replace the motor that I currently have on it.
    Everything is a hammer.
    Unless it is a screw driver.

    Then it it a chisel.

    083 399 2046

  19. #34
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by faniedup View Post

    The other option is to convert 1 phase to 3phase using a 3 phase motor and capacitor.
    This works fantastic for the cooling water pump as it runs at full speed all the time. No need to use the VFD for it. Just ensure that the caps used give a close to 220V on each phase.

  20. #35
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by ekkekan View Post
    This works fantastic for the cooling water pump as it runs at full speed all the time. No need to use the VFD for it. Just ensure that the caps used give a close to 220V on each phase.
    Ive done this on my coolant pump as well. But I wonder if he is not referring to using an idler motor that is powered up by single phase and then creating the third leg of the three phase to power up the machines motor. The caps are used to try balance the power so each leg has little variance between the phases.,.

  21. #36
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Uys View Post
    I have the Eurasia version. I was bloody awesome! Until the belt wore out and no replacement is available. I've tried various belts with no luck.

    So now I am talking to Neels about a VFD and 3 Phase motor to replace the motor that I currently have on it.
    But remember, the pulley system (or CVT) will give more torque at low speeds than a motor running at lower speed...
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  22. #37
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by SinWolf View Post
    But remember, the pulley system (or CVT) will give more torque at low speeds than a motor running at lower speed...
    Is this the same as variable speed drive where the pulley is adjustable or is it the motor speed that is adjustable.?

  23. #38
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    Is this the same as variable speed drive where the pulley is adjustable or is it the motor speed that is adjustable.?
    That CVT systems the guys are talking about, works on the same principle as adjusting pulleys... so you can refer to that system as speed adjustment using pulleys....

    With a pulley system, the motor runs a constant speed and you change "gear ratios"... With a VFD, you have a fixed 1:1 ratio, but motor speed changes... Thats why you'll have more torque with a puley/gear system than a VFD alone...

    Best of both worlds is if you combine the two... Like I did with my lathe... I have a gearbox and VFD...
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  24. #39
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by SinWolf View Post
    But remember, the pulley system (or CVT) will give more torque at low speeds than a motor running at lower speed...
    Not if the motor has a VSD

    With a VSD the motor can always produce it's rated Torque.

    At half the speed it will only produce half its power as power is a factor of speed and torque.


    https://www.pumpsandsystems.com/pump...-vfd-frequency

  25. #40
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    Is this the same as variable speed drive where the pulley is adjustable or is it the motor speed that is adjustable.?
    I don't understand what you mean 100 ,%

    But with a motor and VSD you can reduce the speed , still have the full Motor rated Torque but with reduced motor output power

    With pulleys you can reduce the speed of the drill and still have full Motor rated torque and power

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