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IndustryArena Forum > CNC Electronics > Phase Converters > Trying to decide - vector drive on Okuma or RPC
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  1. #1
    Join Date
    Nov 2013
    Posts
    23

    Trying to decide - vector drive on Okuma or RPC

    Hi. I just hD a moment of sheer insanity and bought an Okuma MC-4VA mill for my home shop. 10hp spindle.

    Machine manual lists power requirements of 26kVA which works out to about 65A at 230 3ph, presumably at full load.
    I initially thought about using a vector drive to drive the spindle, but I'm not sure if that would work or not. Would you retain the stock spindle drive or replace it with the vector drive? If replace, would the vector drive interface with the Okuma control system (OSP 5020)?

    If i go the phase converter route, I was planning to use an American Rotary DIY panel with a 40hp 3ph motor, 1750 rpm, delta, per their specs.
    One guy on this forum with the same machine seemed to think a 20HP would work.
    But a 30hp would probably be a lot better.
    How big do you I really need to go?
    Would you recommend American Rotary or another brand?
    Their DIY panel is supposed to have the digital voltage control and soft start like their CNC complete kits, the AD series.

    Because i have a 3hp hydraulic pump, they are telling me I have to use an ADX (extreme) model, even though the hydraulic pump is fairly small compared to the spindle and total RPC capacity.
    I suppose I could replace the hydraulic pump with a single phase, or a dedicated vector drive to avoid this issue, but I really wonder if this really would cause a problem requiring the ADX version.
    Most appreciative of any replies!
    Thank you
    Bryan
    Simsbury CT

  2. #2
    Join Date
    Jan 2005
    Posts
    15362

    Re: Trying to decide - vector drive on Okuma or RPC

    Quote Originally Posted by bryanbdp View Post
    Hi. I just hD a moment of sheer insanity and bought an Okuma MC-4VA mill for my home shop. 10hp spindle.

    Machine manual lists power requirements of 26kVA which works out to about 65A at 230 3ph, presumably at full load.
    I initially thought about using a vector drive to drive the spindle, but I'm not sure if that would work or not. Would you retain the stock spindle drive or replace it with the vector drive? If replace, would the vector drive interface with the Okuma control system (OSP 5020)?

    If i go the phase converter route, I was planning to use an American Rotary DIY panel with a 40hp 3ph motor, 1750 rpm, delta, per their specs.
    One guy on this forum with the same machine seemed to think a 20HP would work.
    But a 30hp would probably be a lot better.
    How big do you I really need to go?
    Would you recommend American Rotary or another brand?
    Their DIY panel is supposed to have the digital voltage control and soft start like their CNC complete kits, the AD series.

    Because i have a 3hp hydraulic pump, they are telling me I have to use an ADX (extreme) model, even though the hydraulic pump is fairly small compared to the spindle and total RPC capacity.
    I suppose I could replace the hydraulic pump with a single phase, or a dedicated vector drive to avoid this issue, but I really wonder if this really would cause a problem requiring the ADX version.
    Most appreciative of any replies!
    Thank you
    Bryan
    Simsbury CT
    The RPC needs to be twice the rating of what it is driving, (Name Plate Rating) you will not drive this with a Vector drive 7.5Hp is the max for any Single Phase to 3 Phase, 26KVA 230v =113A using Single Phase, 65A 3Phase you will need a good single-phase supply to run this.
    Mactec54

  3. #3
    Join Date
    Jan 2013
    Posts
    474
    Quote Originally Posted by bryanbdp View Post
    Hi. I just hD a moment of sheer insanity and bought an Okuma MC-4VA mill for my home shop. 10hp spindle.

    Machine manual lists power requirements of 26kVA which works out to about 65A at 230 3ph, presumably at full load.
    I initially thought about using a vector drive to drive the spindle, but I'm not sure if that would work or not. Would you retain the stock spindle drive or replace it with the vector drive? If replace, would the vector drive interface with the Okuma control system (OSP 5020)?

    If i go the phase converter route, I was planning to use an American Rotary DIY panel with a 40hp 3ph motor, 1750 rpm, delta, per their specs.
    One guy on this forum with the same machine seemed to think a 20HP would work.
    But a 30hp would probably be a lot better.
    How big do you I really need to go?
    Would you recommend American Rotary or another brand?
    Their DIY panel is supposed to have the digital voltage control and soft start like their CNC complete kits, the AD series.

    Because i have a 3hp hydraulic pump, they are telling me I have to use an ADX (extreme) model, even though the hydraulic pump is fairly small compared to the spindle and total RPC capacity.
    I suppose I could replace the hydraulic pump with a single phase, or a dedicated vector drive to avoid this issue, but I really wonder if this really would cause a problem requiring the ADX version.
    Most appreciative of any replies!
    Thank you
    Bryan
    Simsbury CT
    I've been into shops with underpowered supplies, even when stepping up the spindle speed gently the lights dimmed and trips blow.

    The starting load of a motor can be 2.5 times it's maximum running load.

  4. #4
    Join Date
    Nov 2013
    Posts
    23

    Re: Trying to decide - vector drive on Okuma or RPC

    FWIW, phase converter vector drives seem to be available to 20hp

    https://www.ato.com/single-phase-to-three-phase-vfd

  5. #5
    Join Date
    Jan 2005
    Posts
    15362

    Re: Trying to decide - vector drive on Okuma or RPC

    Quote Originally Posted by bryanbdp View Post
    FWIW, phase converter vector drives seem to be available to 20hp

    https://www.ato.com/single-phase-to-three-phase-vfd
    And a 150A single phase supply to run it, a Phase Perfect would be a perfect match for what you want to run.

    This will not run your whole machine, the VFD Drive can only be used to run the Spindle Motor and any other AC 3Phase motor.

    It also may not run your spindle motor depends on if it is just an AC 3phase motor, which if it is would already have a VFD Drive driving it, so if it has a regular 3Phase Ac motor then you would not be able to use another VFD Drive to Power it.
    Mactec54

  6. #6
    Join Date
    Nov 2013
    Posts
    23

    Re: Trying to decide - vector drive on Okuma or RPC

    I ended up buying an American Rotary DIY panel which has the better electronic voltage control built in. I hooked it up to my used 40hp delta motor, and it started right up. Hooked up to 125A single phase. Haven't run machine yet, but was really worried about starting that big motor! Added another contactor and start/stop switches to allow me to start mill after RPC is on. Going to add voltage/amp meters next for three L-L readings.

    Click image for larger version. 

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