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Can I handle a 3 phase machine?

Discussion in 'ELECTRICAL ISSUES - POWER YOUR MACHINES & SHOP' started by silverforgestudio, Jul 8, 2017.

  1. silverforgestudio

    silverforgestudio United States Active Member Active Member

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    OK so I am in a position to get a 3ph mill with 3hp motor... but I have residential wiring (max 220v single ph 20 amp circuit)...

    Mill is good price, low mileage (only driven to church on Sundays- or was that sunny days? HA!) and in decent condition...

    So my questions are:

    1- Do I invest in the rotary phase converter (And how loud are they)
    2- What are the pros/cons of the 3ph starters that convert after starting to single phase?

    I will be doing aluminum and stainless with brass/bronze mixed in- Im a hobby jobber for now so nothing ultra industrial is needed.

    Gotta convince myself I can DO this before I toss the $$$ and drag home a beautiful piece of machinery that is- well, a doorstop. (And along the way- my wife is all for it if the price is right for the solution as well so SWMBO is on-board!)

    Thanks in advance and I hope everyone had a great and jolly Fourth! For all who have served to protect my rights- I SALUTE YOU!

    Kerri
     
  2. NCjeeper

    NCjeeper United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I have two American Rotary phase converters. They are very quiet and made here in America with awesome support.
     
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  3. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Quite a lot of 3 HP three phase machines are operated in residential spaces. They can be made to work using either a VFD or a rotary (or static) phase converter.

    Edit: Full load current at 220v for a 3 HP, 3 phase induction motor is around 10 amps.
     
  4. RandyWilson

    RandyWilson United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I have a RPC, but the wife wouldn't let me run it at night due to keeping the neighborhood school kids awake. I have the parts to rebuild it and hopefully quiet it down some, but it's now low priority. All of my equipment is now on VFDs. The RPC will be sold off whenever I get it rebuilt. For a single machine, I would go VFD before RPC, and would never consider a static starter.

    Would this be that round ram BP that's been on Craigslist?
     
  5. mksj

    mksj Active User H-M Supporter-Premium

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    Another vote for a VFD, buy the mill if it is in good condition and what you want. Static converter essentially derate the motor by 50% and they can overheat the motor, I would not go that that route. I have heard very quite RPCs if done correctly, but I think it is easier and more cost effective to go the VFD route for a 3Hp setup. I would not worry about 3 phase, overall it will operate much nicer than a single phase machine.

    If using a vari-speed head, you may want to have the VFD set at a fixed frequency and use the mechanical speed control, if a pulley setup, then definitely the VFD route adds a lot of flexibility to the machine speed.
     
  6. markba633csi

    markba633csi United States Active Member Active Member

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    I would be more concerned with the mill itself and how worn it is rather than how to power it
    Mark S.
     
  7. f350ca

    f350ca Canada Active User Active Member

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    Another vote for a VFD. I have a Phase Perfect solid state converter, basically a VFD with out the variable frequency but it will handle switching loads and 10 hp. I recently bought a 3 phase radial arm drill press. It sits on the opposite side of the shop from the rest of the equipment. Rather than run 3 phase wire to it I bought a VFD to feed it from 220 v single phase which was close. The solid state supplies use virtual no power in standby and the Phase perfect is 95% efficient at full load so big power bill savings. Both are visually silent too.

    Greg
     
  8. tq60

    tq60 United States Active Member Active Member

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    3 hp is 750 watts X 3 which is about 2250 watts or just shy of 10 amps as mentioned above but starting current a bit more.

    Do go with a vfd but it will need derating at single phase input and different models are different so after you select the model type of unit then download the manual and verify exactly which one you need for your mill.

    The vfd can cheat a bit in that it converts ac to dc and uses filter caps to make better dc before making the 3 phase output and these caps help out with short periods of higher current.

    Sent from my SAMSUNG-SGH-I337Z using Tapatalk
     
    Bob Korves likes this.
  9. silverforgestudio

    silverforgestudio United States Active Member Active Member

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    Not the one on Craigslist in hampton roads Randy- its actually near Richmond. Cool to see another HR fellow around here- Deep creek or Great Bridge area?


    THAT is true Mark- it is an as-is sale. I will be getting my hands on it for a bit of a tester look-see (its not under power) Tuesday- Ill know a LOT more about it then!


    THANK you for the tidbits on the VFD functionality- If you havent guessed Im a home shop guy still learning all the stuff... this is cool info!

    Thank you guys to every one who replied! Ill post more on Tues when I get to put my voltage tester to the motor and a few switches... I know its missing the XY table feed handle- so no telling what ELSE was scrapped/swiped/pulled off it.

    The NEXT adventure is getting the thing home... lift gate rentals here I come! HA!
     
  10. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Lift gates suck for lifting milling machines. They are slippery, often not level, and there is nothing to keep the mill from sliding off onto the ground. You can also get badly hurt. I recommend a low trailer, preferably a drop deck (drop bed) trailer. All you need beyond the trailer and something to tow it with is a come along, some 3/4"pipe sections for rollers, a few short 2x4's and 4x4's, a pry bar, and some good ratchet tie down straps for securing the mill for the road.
     
    Last edited: Jul 10, 2017
  11. RandyWilson

    RandyWilson United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I'm a bit farther around. Some call it Western Branch. I call it the Great Dismal Swamp.


    As Bob said, full sized mills and lift gates are not a good combination. Mills are very top heavy, and right at or above the weight capacity. I moved mine (2500#) with a low trailer and 2ton Harbor Freight engine crane.
     
  12. Eddyde

    Eddyde Active User H-M Supporter-Premium

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    Bob is spot on, I moved my mill with a lift gate truck, the gate was rated at 3,800 lb. and the mill weighs around 2,500 lb. So I thought it would be okay, Not so... It was very dicy getting it down (it was loaded with a forklift) I had to roll the mill on pipes to get it onto the lift gate at which point the gate sagged and the mill wanted to roll off the back of the truck, fortunately I had a line attached to the mill and was able to stop it. I would consider alternate means of transport.
     
  13. f350ca

    f350ca Canada Active User Active Member

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    I spoke to a tech at Automation Direct before buying my VFD from them. He said if the VFD is rated for single phase input you don't need to derate it.
    As a side note he also clarified whether you can have switching between the VFD and the motor. (everything I've read said NO). Im using a two speed motor. As long as the output from the VFD is off, (as in stop bottom pressed) I can use the switch to change windings without powering down the input to the VFD.

    Greg
     
  14. silverforgestudio

    silverforgestudio United States Active Member Active Member

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    Thanks Bob and Randy and all the info there as well- I work over in the Suffolk side of W Branch off 17- beautiful area (mostly)...

    Goood to know Greg- assuming I get this thing I will probably have a few threads to read and jump into about these VFDs-
     
  15. silverforgestudio

    silverforgestudio United States Active Member Active Member

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    OK so UPDATE- I did NOT get the machine... nothing wrong with it, even know the fellow who bought it... its a great machine. Had a few things crash that ate the cashflow for it... Oh well.

    For those who chimed in- THANK YOU! I am now wiser and more educated on the what and whys... and think a Teco VFD is the way I will head should I meet this opportunity again!
     
  16. tq60

    tq60 United States Active Member Active Member

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    Not quite.

    Just because a VFD is single phase rated means nothing about derating.

    ALWAYS get a copy of the manual and read it.

    Most like our AB have a compatibility chart showing the assorted model numbers and their capabilities.

    They often will require a larger unit for single phase input pulley due to the way the dc power supply works.

    The single phase compatibility usually is just the device not alarming with only 2 lines supplying power.

    Sent from my SAMSUNG-SGH-I337Z using Tapatalk
     
  17. Smithdoor

    Smithdoor United States Active User Active Member

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    I have made 3 ph converters they are low cost and simple to build
    See if motor is start would motor and this is even simple to install and a mill motor new around $30.00 for all parts

    Dave
     
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