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600V 3-phase motor (milling machine) --> 240V operation

Discussion in 'ELECTRICAL ISSUES - POWER YOUR MACHINES & SHOP' started by slow-poke, Apr 20, 2017.

  1. slow-poke

    slow-poke Canada Steel Registered Member

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    I have been on the lookout for a bench top mill for occasional use (should be a good compliment to my Emco 8 lathe). I found a local one for a reasonable price ($500) however it is powered by a 3 phase 600V motor. So I would either need a converter or replace the motor to single phase 240V.

    Has anyone done this?

    Converter or swap the motor?

    Estimate $ for the conversion?
     
  2. markba633csi

    markba633csi United States Active Member Active Member

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    You could shop around for 600 volt variable frequency drives and compare the price vs a single phase motor- The VFD would give you some speed control but at what cost?
    Mark S.
     
  3. CluelessNewB

    CluelessNewB Active Resistor H-M Supporter-Premium

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    Unless it is some weird frame size motor I would suspect finding a replacement single phase motor would be the least expensive option.

    I don't know of any 240V single phase input VFD's that output 600V 3 phase.

    You could build a rotary phase converter to convert from 240V single phase to 240V 3 phase and then add a 3 phase step up transformer to get it up to 600V. I don't think that would be very cost effective for just one machine.
     
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  4. hman

    hman Active User H-M Supporter-Premium

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    A benchtop mill with that huge a motor??? Sounds like the seller or a previous owner went way overboard on power! And I can almost envision a huge motor scabbed onto a small mill and overbalancing it to the rear :)

    I'd agree with changing out the motor for a single phase 240V (1 ½ to 2 HP) as the most economical solution. Round column mills (which I'll suppose your candidate is) come from the factory with such motors. Often they're wired for 120/240, but the current draw at 120V is pretty high. So 240 is the way to go. You'd have to rewire the switch, of course.
     
  5. CluelessNewB

    CluelessNewB Active Resistor H-M Supporter-Premium

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    Just because it is 600V doesn't mean it is all that powerful. It might be only 1hp.
     
  6. slow-poke

    slow-poke Canada Steel Registered Member

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    I spoke with the seller, he will send me a picture of the motor plate, he said he does recall it being 1.5HP Mill.JPG
     
  7. tq60

    tq60 United States Active Member Active Member

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    Do not waste time here.

    The 600 volts may be wrong data as this looks like typical hf or other low end mill.

    Get photo of actual motor to confirm as it is likely single phase native voltage of where first sold.

    If it is some odd 3 phase voltage the cost to convert to single phase house voltage more than mill is worth.

    If price is real cheap the motor can be replaced as they just mount to plate at real like normal drill press which these mills are almost...

    Sent from my SAMSUNG-SGH-I337Z using Tapatalk
     
  8. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    In the Canadian area that he's in, it is very likely the motor is set up running off of 575 volts, not 600 volts. That is a common voltage for that area. I have a surface grinder that had a 575 volt motor on it that can from that area. Guess what, it got pulled and chunked into the junk pile, and a 230 volt 3 phase motor put in its place. I operate it off of a VFD on 230 volt 1-phase now. Ken
     
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  9. Chipper5783

    Chipper5783 Active User H-M Supporter-Premium

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    Sure. Not really a big deal (been there done that). I assume that you have 3 phase power (RPC, or what ever). When faced with the same issue, I got a 240-600V 3 phase transformer (found a good used one), plugged it into my 3 phase (RPC) distribution and it works great. I now have 3 machines on this (having 600v - 3 phase has opened up some nice opportunities).

    I was fortunate to get the transformer for $100. However, powering things up was just so easy (no issues with motor mounts, shaft size, controls) - the changes are external to the machine. Of course it is possible to change motors - depending on all sorts of factors whether it is easy or hard. All I am presenting is that plugging in a transformer is easy.

    If I were to do it again and I had to pay $1000 for the transformer - I would still go with the transformer option (quick, easy, works great - sometimes those considerations are worth paying for).

    Let us know how you make out. Regards, David
     

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  10. Keith Foor

    Keith Foor Active Member Active Member

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    Be advised about running equipment above 440 volts.
    For some reason the 400 volt threshold is a level not to be crossed by the faint of heart.
    240 volts if it shorts will typically just make a bang, melt some wires and blow a breaker.
    The higher voltage stuff will create sustainable arc's and plasma balls that will burn for a longer period of time and tend to really roach things before it gets done cooking.

    I am not trying to indicate that it's not safe. It's used every day in industry and works well. But it has to be respected more than the low voltage stuff for the reason mentioned above.
    Be safe and have fun
     
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  11. slow-poke

    slow-poke Canada Steel Registered Member

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    Thanks for the advice.

    Yes 600V definitely needs to be treated with respect, I recall from an electrical safety course (many years ago), that this is the most common voltage responsible for serious accidents and fatalities.

    I have a few pictures of the motor.
     

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  12. slow-poke

    slow-poke Canada Steel Registered Member

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    Making progress........

    Managed to get the mill home in my wife's mini-van, disassembled it into three pieces. Loading was easy, four "He-man" at the pick up location man handled it into the van , and then I pulled it up and out the side door with a chain lift. Then built a rolling base to get it to its new home location. I'm not sure how much it weighs but must be in the ballpark of 450-500lbs. I have a used 1.5HP, "Inverter Duty" 240V, 3-phase motor with the same frame size as the original on order. I also picked up a used but supposedly good Altivar 31 VFD which is now wired (less the motor side).

    I would like to perform a preliminary function test of the VFD, test: forward, reverse, speed etc. If I were to try powering the original 600V motor (no load) with the 240V, VFD do you think it will spin with the reduced voltage?
     
    Last edited: May 11, 2017
  13. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Nope! Got to have the same voltage from the VFD to the motor. You more than likely will fry the VFD trying. Ken
     
  14. British Steel

    British Steel United Kingdom Active User Active Member

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    I've tested VFDs without frying them by putting three lots of 240V bulbs across the motor terminals, keep adding bulbs for more load...

    Hard to tell whether it's in forward or reverse, or what the speed is though ;)

    Dave H. (the other one)
     
  15. hman

    hman Active User H-M Supporter-Premium

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    2.99793E10 cm/sec :)
     
  16. Chipper5783

    Chipper5783 Active User H-M Supporter-Premium

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    It won't hurt the motor. It is very common for service shops to no-load test motors at reduced voltage (talking good sized motors - such as a 13.8kV run at 4160V). I understand in the motor world, 600V is still considered low voltage - so they wouldn't test that at a reduced voltage, but only because 600V is readily available. I also don't think it would hurt the VFD - the full load current draw of a 1.5 HP - 600V motor is probably less than 2 amps (with the actual motor winding sized accordingly) - it will not suddenly draw big current (beyond the typically expected inrush). Can you program a current limit into the VFD? No-load means remove the v-belt.

    If you were going the other way, with a 240V motor and running on 600V through the VFD (expecting the VFD to protect itself and the motor)? That would be ill advised!

    Let us know how you make out. David
     
  17. slow-poke

    slow-poke Canada Steel Registered Member

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    I paralleled the 2nd and 3rd phase on the input of the VFD and connected it to 240V, and then hooked it up to the original 600V motor for a reality test. Unloaded it works just fine, forward, reverse and from very slow to > 1800RPM.

    VFD was a great suggestion, thanks to all.

    Can't wait to get my 240V motor, it might arrive today.
     

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