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  1. #41
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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.
    This is a concern but I'll cross that bridge when I have to

  2. #42
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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...
    Yes. So I am changing from a 0.75 kW motor to 1.5 kW - the difference is only R700. Also adding 2:1 reduction pulleys on the motor and the spindle drive.

    This also gives you a forward and reverse option, and with that the ability to tap on this machine.

    SO for R4700 on top of my existing drill press. I get much more than the new Einhell Wolff posted. I also need a motor for one of my compressors - so there is an additional saving because I can use the one that I remove from the drill press.

    Do not challenge me to justify tools! I will always find a way!
    Last edited by Uys; 2021/06/10 at 10:38 AM.
    Everything is a hammer.
    Unless it is a screw driver.

    Then it it a chisel.

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  4. #43
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Uys View Post
    Do not challenge me to justify tools! I will always find a way!
    No justification should be necessary when the subject is tools.

    Thanks gentlemen, this has turned into a fascinating thread. Just wish I could understand more than one word in three. Electrics are on the mantelpiece for me.
    Last edited by Peter Connan; 2021/06/10 at 10:58 AM.
    Beat-up rat rod of a '96 Nissan Patrol that bears the evidence of many wonderful adventures (and a few stupid indiscretions).

  5. #44
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    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.,.
    Yes that is correct if using a 3 phase motor to be the generator. Using the 2 caps is actually simple for 1 phase to be used on a 3 phase small motor.

  6. #45
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Sorry, I want to add an element of complexity:
    The machine I am looking at has at least three motors (spindle, feed and coolant pump), as well as a DRO.
    I did not take enough notice, but expect that the DRO probably runs off single phase and probably plugs in separately.

    However, the three motors are probably all three phase and take their power from the same source currently.
    Assuming that the combined current drain does not exceed the rating of the 220V power supply and the VFD, and assuming I leave the frequency set at 50 Hertz, would it be possible to operate the whole machine off one VFD, or will that cause problems?

    Since the spindle and feed mechanisms already have multi-speed gearboxes built in, I don't really need to change motor RPM's

    Thanks again.
    Beat-up rat rod of a '96 Nissan Patrol that bears the evidence of many wonderful adventures (and a few stupid indiscretions).

  7. #46
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Peter Connan View Post
    Sorry, I want to add an element of complexity:
    The machine I am looking at has at least three motors (spindle, feed and coolant pump), as well as a DRO.
    I did not take enough notice, but expect that the DRO probably runs off single phase and probably plugs in separately.

    However, the three motors are probably all three phase and take their power from the same source currently.
    Assuming that the combined current drain does not exceed the rating of the 220V power supply and the VFD, and assuming I leave the frequency set at 50 Hertz, would it be possible to operate the whole machine off one VFD, or will that cause problems?

    Since the spindle and feed mechanisms already have multi-speed gearboxes built in, I don't really need to change motor RPM's

    Thanks again.
    My 3-phase coolant pump runs straight of 220V... I just installed a Capacitor between 2 of the phases... It's a small motor and should be fine running off a single phase with capacitor...
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  9. #47
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    Default Re: Running a 3-phase machine on 220 via a VFD

    If it has a dro i would assume it has table feeds . These are normally 110v running through a transformer. I done the same as sinwolf with regards to the pump. When you have vfd you will definitley want to run the motor with the vfd . Belt changing is a pain in the arse.

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  11. #48
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    Default Re: Running a 3-phase machine on 220 via a VFD

    There is an auction coming up with a couple of three phase motors of about 2,2kw. I would like to try build another knife grinder and need a motor. Trouble is the name tag states they are 525v/550v .Whats up with this .How would they have been used and what would happen if you try run them on a 240v in single phase 240v out three phase vfd.

  12. #49
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    Default Re: Running a 3-phase machine on 220 via a VFD

    I have just found out that 550v and even 690v is available in this country off the grid from eskom.

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  14. #50
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    I have just found out that 550v and even 690v is available in this country off the grid from eskom.
    After replacing stolen cables the municipality swapped a neutral with a phase when replacing, it blew cell chargers of the walls downstream before it tripped.

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  16. #51
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    There is an auction coming up with a couple of three phase motors of about 2,2kw. I would like to try build another knife grinder and need a motor. Trouble is the name tag states they are 525v/550v .Whats up with this .How would they have been used and what would happen if you try run them on a 240v in single phase 240v out three phase vfd.
    Hi Plunger

    We use 525 V / 550 and 690 V three phase motors in the mining sector.


    Higher voltage means less current and therefore smaller cable for the same power.

    I wouldn't not buy them as you require a transformer with the correct output voltage to run them.

    Additionly the odd voltage used in mining makes them less attractive to theft as you can't use them in domestic or factory setups that uses 420 V without getting a suitable transfermer as well.

    The 525 V is very much a South African mining environment standard .

    The rest of the mining sector in Africa is moving to 690 V

    (400 V x sqrt3 = 690 V )

    So if the motor is rated 400 V delta / 690 V star then you can use it if you have a 3 phase supply
    Last edited by Tiaan Pot; 2021/06/17 at 09:09 AM.

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  18. #52
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Yes... 525V on mines and industrial plants... very common in SA...
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  20. #53
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by faniedup View Post
    After replacing stolen cables the municipality swapped a neutral with a phase when replacing, it blew cell chargers of the walls downstream before it tripped.
    Phase to neutral voltage is 230 V
    Phase to Phase voltage is 420 V so double the rated voltage will cause some issues :-)

  21. #54
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    There is an auction coming up with a couple of three phase motors of about 2,2kw. I would like to try build another knife grinder and need a motor. Trouble is the name tag states they are 525v/550v .Whats up with this .How would they have been used and what would happen if you try run them on a 240v in single phase 240v out three phase vfd.
    Holy cow. A 2.2kW knife grinder. What kinda knives, you sharpening.
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  22. #55
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Fluffy View Post
    Holy cow. A 2.2kW knife grinder. What kinda knives, you sharpening.
    It would make a nice 4 inch grinder and not the usual two inch grinder. It can use the extra oomph of a bigger motor but I have my answer . All these beautiful motors will be useless to me at this auction.
    They have a nice oxy acetylene porta pack going at this auction as well.

  23. #56
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Plunger, my brother is a knife-maker (as a career, not a hobbyist) He gave his 2" belt grinder to me several years ago and moved to a 1".

    The issue with going wider (specifically in terms of knife grinding) is heat. You can burn the steel very quickly on a wide belt.

    He also has a setup to apply cooling water to his grinder. But he does extremely thin edge geometries as he makes a lot of straight razors. On those, the blade profile for the first 4-5mm behind the edge is less than 0.1mm thick. So thin that if you run your thumb-nail along the bottom of the blade you can see the metal flex on the other side. I have seen him split a hair along it's length with one of these blades...
    Beat-up rat rod of a '96 Nissan Patrol that bears the evidence of many wonderful adventures (and a few stupid indiscretions).

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  25. #57
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Peter - I've seen Jack's work first-hand. It's excellent. That is off-topic and I don't want to derail this thread so I won't say any more on that matter. But he really makes fantastic blades.
    Ian de Villiers
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  27. #58
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by plunger View Post
    It would make a nice 4 inch grinder and not the usual two inch grinder. It can use the extra oomph of a bigger motor but I have my answer . All these beautiful motors will be useless to me at this auction.
    They have a nice oxy acetylene porta pack going at this auction as well.
    Where is the auction please.
    Cheers

    ZS5KAD
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  28. #59
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Quote Originally Posted by Fluffy View Post
    Where is the auction please.
    Fluffy they have two sets there . The online bid for the first one is R2000 and the second one which is much nicer is sitting at R3000. There is also a bigger set the full size going for R2000.
    Problem with these auctions is you get fools there bidding crazy prices. Ive seen drilling machines beaten up go for more than new. Its Dales bros auctioneers . They porta pack will go for more than the standing bid is for the moment.

  29. #60
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    Default Re: Running a 3-phase machine on 220 via a VFD

    Plenty porta packs on FB market place.

    The issue is just if it's Afrox bottles refilling becomes an issue


    Cheapest one

    https://www.facebook.com/marketplace...ok_story_share

    Nice ones are all R5k

    https://www.facebook.com/marketplace...ok_story_share

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