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  1. #1
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    Default Powering a 3 phase VMC at home?

    I'm trying to power a https://www.machineryhouse.com.au/m905 at home. It has a 2.2kw spindle, 650w coolant pump, three 1.5kw servos (from my research). I have 30 amps of regular 240v single phase power from two 15amp outlets run in parallel. I cannot find info on the total peak power draw of the machine, but my friend who speaks German is going to find out later....

    1st option/question:
    If I could get my hand on a large enough powerwall, how much would I need to spend to get a 415V inverter and other equipment to power the cnc mill? I would charge it with 240v (somehow)

    2nd option:
    I can get a rotary phase converter, but would I need an 8kw phase changer one? They are like $6500. Phase changer are an awesome company im sure but i just need to get this thing going....

    3rd option:
    Generator - just for home hobby use - what sort would I need? I did some googling and Im confused what is and whether I need AVR, pure sine wave, $2000 generator, or $8000 generator. Not knowing power requirements of mill makes it harder.

    Thanks for any help *projects a large batman like symbol into the sky in the image of BaronJ asking for help*

  2. #2
    Join Date
    Sep 2012
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    Default

    Hi J3dprints,

    I saw the mental image of the penguin projected on the clouds

    Just add together all the watt ratings and do the P/V=I to get the current draw.

    It looks like you have 7.35 Kw there, so 7500/230=32.5 amps. Your two outlets are going to be right up to the max.

    HTH.
    Best Regards:
    Baron J.

  3. #3
    BobL is offline Member: Blue and white apron brigade
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    Default

    The biggest 240v single-three phase VFDs are about 4kW. But for not much about $500 you could by 3 vfds and power all motors independently AND have a MUCH better device. Eg have better motor protection, be able use speed control, jog, fast/slow start, braking separately. But it would require the motors to be compatible with 240v vfds and am almost a complete rewire of the mill. I did this for just 2 motors on my little mill and it was a fairly big job but we’ll with it on the end but I would not like to be doing that on that mill. Too much automation, interlocks etc.

  4. #4
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    Default

    Thanks Baron, but the 1.5kw servos are highly unlikely or not able to operate at peak power together, you would need to be doing a heavy cut diagonally UP as all axis would be turning. The spindle of course would need to be drawing 2.2kw too.

  5. #5
    BobL is offline Member: Blue and white apron brigade
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    Default

    Thought it was 3 motors but now see it’s 5 so <$1000.

  6. #6
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    Default

    Just to add, my estimate based on peak power requirements. All these motors have surge current requirements !

    3rd option:
    Generator - just for home hobby use - what sort would I need? I did some googling and I'm confused what is and whether I need pure sine wave
    It is very likely that you would need a pure sine generator depending on how the servos are controlled. Probably something around 10 Kw
    Last edited by BaronJ; 4th Feb 2020 at 07:01 PM. Reason: Added info
    Best Regards:
    Baron J.

  7. #7
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    Default

    Thanks Baron, any rough idea on price for a generator that could be relied upon to not fry my electricals?

  8. #8
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    Mar 2014
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    Default

    why not just get 3phase connected to your house? Be very careful running cnc machines off phase converters and generators, some controllers don't play nicely with dirty power. Running off a phase converter may also affect your warranty, assuming it is new.

  9. #9
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    Default

    I got this data from the manual they sent me:


    Total Connection:
    3 x 400V ~ 50Hz 12 KVA
    ( 3 x 400V ~ 50Hz 14 KVA )

    Power of spindle drive S1 operation 2.2 kW( 3.7 kW )
    Power of spindle drive S6-30 % operation 3.2 kW( 5.5 kW )


    Not sure why the second is in brackets.

    Does that mean I need a 12kw supply? Or 14kw supply?

  10. #10
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    Quote Originally Posted by snapatap View Post
    why not just get 3phase connected to your house? Be very careful running cnc machines off phase converters and generators, some controllers don't play nicely with dirty power. Running off a phase converter may also affect your warranty, assuming it is new.
    Rental property. Dont think its under warranty, got it 2nd hand

  11. #11
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    I did a bit of price research last year around generators for backup purposes at work. Worked out around $1000 per KVA for quality generators in the 1-10kva range. That was single phase but a quick look online just now looks like its about right for 3 phase too.

    In your situation I'd definitely be hiring one first for proof of concept.

    Thinking outside the square and along your lines of a powerwall, you might be able to pick up a cheap used 3 phase UPS (backup power supply). My understanding is that they are essentially a 3 phase inverter, supplied by the internal bank of batteries when input power is out of limits.
    Sort out a way to charge the batteries either externally or possibly they will charge from one phase anyway.
    Even if the batteries are a bit suss, it would make a great power conditioner for a less than perfect 3ph generator.
    Just a thought.

    Steve

  12. #12
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    A 5kva inverter charger is about $3k, plus wiring etc say 10k.
    Then batteries, assuming an average load of say 5kw, you'd need say 15kwh of batteries to give 2 hours running. Maybe another $2500
    With single phase charging, at 5kw, you'd need 2 hours charging for 1 hour running.
    So all up under $15k?

  13. #13
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    Default

    You must have very compliant neighbours

  14. #14
    Join Date
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    Quote Originally Posted by j3dprints View Post
    I got this data from the manual they sent me:


    Total Connection:
    3 x 400V ~ 50Hz 12 KVA
    ( 3 x 400V ~ 50Hz 14 KVA )

    Power of spindle drive S1 operation 2.2 kW( 3.7 kW )
    Power of spindle drive S6-30 % operation 3.2 kW( 5.5 kW )


    Not sure why the second is in brackets.

    Does that mean I need a 12kw supply? Or 14kw supply?
    The figures in brackets are the peak values that will occur when a motor starts.
    Best Regards:
    Baron J.

  15. #15
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    Hi J3dprints, Steve, Guys,

    Quote Originally Posted by OxxAndBert View Post
    I did a bit of price research last year around generators for backup purposes at work. Worked out around $1000 per KVA for quality generators in the 1-10kva range. That was single phase but a quick look online just now looks like its about right for 3 phase too.

    In your situation I'd definitely be hiring one first for proof of concept.
    That is probably a good idea ! See my note below.

    Thinking outside the square and along your lines of a powerwall, you might be able to pick up a cheap used 3 phase UPS (backup power supply). My understanding is that they are essentially a 3 phase inverter, supplied by the internal bank of batteries when input power is out of limits.
    Sort out a way to charge the batteries either externally or possibly they will charge from one phase anyway.
    Even if the batteries are a bit suss, it would make a great power conditioner for a less than perfect 3ph generator.
    Just a thought.

    Steve
    NOTE:
    I would be very wary of UPS supplies. I am not aware of any that produce clean sine wave output. Not that they couldn't. They output what is known as a "modified sine wave" which is actually a series of square wave steps. Computers and a lot of equipment have their own, usually switch mode power supplies built in. These tend not to care about the quality of the feed power, simply because of the way they work.
    Best Regards:
    Baron J.

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