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Thread: 5 Hp 3 Phase

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  1. #1
    Join Date
    May 2005
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    92

    5 Hp 3 Phase

    I would like some guidance on the wiring of my mill. I have a 1984 hurco KMB1 bx w/o tool changer. My question is the only thing that is 3 phase is the 5 hp spindle motor, I'm sure that is all that is 3 phase this machine also has a parajust (not sure what that is) but would it be a good choice to get a 5hp 3 phase converter since the only thing that needs it is the spindle motor. On more thing I do not want a vfd.

  2. #2
    Join Date
    Dec 2005
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    3319
    I"m not an expert on 3 phase Hurco's, BUT I do have some experience with connecting single phase equipment to a 3 phase lathe (IE: PC for tape reader replacement).

    In a simple sentence, if it was designed to run on a common source 3 phase, buy a suitably sized phase converter and run it that way. YOu can create some real headaches trying to interface 3phase to single thru a phase converter if you're not careful.

    I suspect someone will advise otherwise but we had troubles mixing single and 3 phase equipment due to ground loop current issues. Got real co$tly.

  3. #3
    Join Date
    Dec 2003
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    24216
    If you decide to build a rotary converter there are a few links here if you do a search, I built my own sucessfully.
    Make sure however that you put the single phase fed control on the main two-wire 240, not the artificial leg.
    I assume it is set up for 220~240 three phase.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #4
    Join Date
    Apr 2005
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    31
    drill,

    It's highly unlikely that the machine would be single phase. Rotary phase converters are an obsolete method for generating three phase power. Most variable frequency drives (VFD) will operate on single phase current and produce three phase current, however there's 33% reduction in output so a 5HP application would require a 7.5HP VFD. Variable frequency drives convert AC current to DC current and then redistribute it as three phase frequency modulated AC current.

    Servo

  5. #5
    Join Date
    Dec 2003
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    24216
    Quote Originally Posted by Servo Wizard
    drill,

    Rotary phase converters are an obsolete method for generating three phase power.
    I would not say it obsolete for the hobyist, You can build your own for ~$200.00 against $2K for a decent 7.5HP VFD. Also if you happen to pick up other three phase motorized equipment, the Rotary converter can be used to feed up to double its HP rating due to other motors acting to assist the converter, as long as the largest motor is no larger than the converter.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  6. #6
    Join Date
    Aug 2003
    Posts
    8
    I have to disagree with Servo Wizard and All_the_man. I have had great success with the Hitachi VFD's I have purchased and would recommend them to anybody that wants an affordable solution to 3phase. You can't beat the variable speed controls and the braking (great for tapping). Check out this months "The Home Shop Machinist" mag. It has a great article in the back. Also, if you have a 5hp motor, you buy a 5hp VFD. the 33% reduction is for static phase controllers, not VFD's. I bought one of my VFD's fro my Index Mill on driveswarehouse.com and they were helpful. When you look at the prices you will find them very good. The only negitive about a VFD is that you cannot run multiple machines on one VFD. That is where a Rotary Converter is nice.

  7. #7
    Join Date
    Dec 2003
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    24216
    Quote Originally Posted by gtd107
    I have to disagree with Servo Wizard and All_the_man. I have had great success with the Hitachi VFD's I have purchased and would recommend them to anybody that wants an affordable solution to 3phase. You can't beat the variable speed controls and the braking (great for tapping). Check out this months "The Home Shop Machinist" mag. It has a great article in the back. Also, if you have a 5hp motor, you buy a 5hp VFD. the 33% reduction is for static phase controllers, not VFD's. I bought one of my VFD's fro my Index Mill on driveswarehouse.com and they were helpful. When you look at the prices you will find them very good. The only negitive about a VFD is that you cannot run multiple machines on one VFD. That is where a Rotary Converter is nice.
    No1, I was not knocking VFD's as I have used them extensively, the poster specifically said he did not want a VFD.
    Also the derating DOES apply to VFD of some makes when using them on single phase, You have to check with the individual manufacturers recomendations, also there is a practical size limit when using single phase.
    Also, many people buy the economy version of VFD which is not Flux Vector control, If you want nice spindle control, this is the only way to go, but cost more.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  8. #8
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    Aug 2003
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    8
    Sorry, Missed the part about not wanting the VFD. I will bow out I just love the VFD's though, I will never go back to a rotary or static. I love to be able to program and control the machine.

  9. #9
    Join Date
    Apr 2005
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    31
    Al_The_Man,

    I cannot believe that you would think that I was recommending a solution that would cost $2K. I purchase new Yaskawa and Mitsubishi VFDs through eBay auctions and I have not paid over $500.00 for any one of them.

    gtd107,

    Why do say that you disagree with Servo? Sounds to me like you are an advocate for using variable frequency drives for the purpose of generating three phase current which is exactly what I recommended.

    Servo

  10. #10
    Join Date
    Aug 2003
    Posts
    8
    Servo,

    I just disagreed with the 33% power loss on and manification of the VFD needed. Everything I have read to date on modern VFD's for HP under 10 states that Power is not reduced. Both my VFD's, one is a 3hp and the other is 1/2 hp, have full rated power and work excellent... I have actully been told by a friend that rebuilds glass bottle machines, that I should not over rate the VFD's. Although in the settings you can adjust for the exact motor you have. I just feel that VFD's are the way to go because of the programming you are able to do. I was amazed at how easy it was to set up and operate. Anybody that messes around with CNC programing would be more than able to program one.

  11. #11
    Join Date
    Mar 2004
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    369
    Why are you sure you don't want a VFD? Do you have 3-phase power there? As for power loss,
    that is totally wrong. Most VFDs have a "torque boost" mode that allows the motor to
    provide MORE than rated torque for a few seconds at a time. Also, hard-starting a 5 HP motor
    on residential service will definitely cause every light in your house to blink, rotary converter
    or not. The VFD has a soft-start that eliminates this. Also, you get very effective braking for
    free, as well as electronic reversing and variable speed. How could this ever be wrong?

    The only thing that will give a 33% power loss is a "static" converter, which is really a starting capacitor and a relay, in a $150 box. (Ie, a big ripoff.)

    Jon

  12. #12
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    May 2005
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    92
    OK, OK what type of VFD do I get and can anyone show a pic or drawing of the wiring process. and will I be able to get one for less then $475.00
    and if so where might that be. also the spindle rpm is already programable
    thru g and m code and also conv.. also that the only thing that is 3 phase is the spindle motor and the rest runs thru a parajust wich I was told was already a VFD in many ways and that is what "seperates" the power from 3 phase to single.

  13. #13
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    Apr 2005
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    31
    drill,

    It's a money over time matter. If you have the time and patience then you can shop eBay for a VFD that meets your needs. If you're short on time and long on money then a VFD will cost you more. My personal preferences are Mitsubishi, Omron & Yaskawa drives. If you have an eBay account then e-mail your user name to me and I will not bid against you.

    Servo

  14. #14
    Join Date
    Mar 2004
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    369
    There are literally thousands of different models. You need a 230 V model, rated for
    5 - 7.5 Hp. It needs to have analog speed input, which may be missing on some very
    low-end models. I've never heard of a "parajust". If that truly is a VFD, then just hook
    up 240 V single phase power to two of the inputs, and don't make long runs above 4 Hp
    and you should be fine. You don't need any special device to run single-phase loads
    from a 3-phase source, you just connect that device's input to any two phase wires and
    it is supplied. So, any time you have a single-phase 240 V device, hook to any two
    hot wires of a 240 V 3-phase supply, and it will work fine.

  15. #15
    Join Date
    Sep 2003
    Posts
    552
    If you can program your spindle speed by S word and there are no gears or variable speed transmission you probably allready have a VFD in this machine. If so check to see if it will run on single phase.

    Darek

  16. #16
    Join Date
    Feb 2006
    Posts
    171
    Drill
    I sent you a private note, so check your mail.
    Next
    The servo drive and the computer drive both have transformers. You can feed these with 220 Volt single phase. No Problem. I have done it for the past 6 years on my Hurco.
    Next item, Rotary convertors.. i have a 3 HP spindle motor, that I powered with a home made rotary. Used a 5 HP motor that had a static starter FOR IT !
    This fed the spindle contactors.
    Then 3 years ago, I put a 5 HP VFD on on Hurco and got rid of the noise of the rotary.
    There is some misconceptions in my opinion here.
    VFD do not need to be "downrated" if they are powered by 3 phase power....however,
    when they are powered by single phase, you must derate them. here is why.
    the three phase generator circuts each have a power capacitor, which must be charged between each cycle. this is not a problem when 3 phase comes in, as each leg powers it's own capacitor. However running the same unit on single phase means that the capacitors are getting charged only 1/3 of the time ( logically, but in real life they get about 2/3d's charge) This lower charge means that they cannot handle the full load expected of them.So you must reduce the HP.
    If you look at any site with Mfg'rs spects, you will see a dual rating for dual feed VFD's
    So for my 3 HP spindle, I use a 5 HP Mitsubishi,that I paid 240 bucks for, brand new. ( I just found the BOS)

    Now Drill for your Hurco.
    A "Parajust is a VFD !
    Some Hurcos have built in spindle speed control (Mine does not ! )
    They used Parajust and other brands to do this.
    You do NOT want to power your Hurco with another VFD !!
    You will blow out both units.
    Go with a rotary convertor made with a motor at least 50 % greater than the spindle motor rating ( Hurco has 2,3 and 5 HP motors?? so I don't know what you got.

    Summary. split off the 2 transformers and power the spindle drive with a rotary...no problem
    Rich

  17. #17
    Join Date
    Mar 2004
    Posts
    1542
    Condsidering the year of manufactuer, 1984, This is likely a DC servo spindle. You'll need the three phase if it is this.

    A VFD will do you no good. A phase converter is easy to build. Cheap if you can scrounge used components. Here's some advice: http://www.metalwebnews.com/electric.html

    Karl

  18. #18
    Join Date
    Apr 2005
    Posts
    31
    Rich,

    You are providing drill with a bunch of misinformation. If the frequency is set at 60Hz then the current will be as pure as if it came right off of the pole.

    drill,

    Did you receive my private message regarding the VFD?

    Servo

  19. #19
    Join Date
    Feb 2006
    Posts
    98

    your hurco kmb1 will run on single phase power,period.

    drill...i have worked for hurco since september of 1984, i know the kmbx1 well...actually, the only requirement for three phase power on a kmb1 is for the three phase flood pump motor if it is so equipped...the spindle drive (parajust model a 5hp) requires single phase 230 volt power, the servo drives (most-likely cmc randtronics servomate) also require only single phase power, as does the cnc power supply...why get all involved in three phase generators or vfd's if you can simply replace the three phase flood motor with an inexpensive single phase flood pump...better yet, if you do not require flood, but can use mist coolant instead, disconnect the flood motor and you are good to go...if you take a close look at the parajust a drive, you will see labeled input power, and you will see only two power lines...the kmb1 will simply run on single phase, actually, it is the only hurco model that would, and it was a popular pole building\garage mill, you will need to connect your single phase power to the proper two wires on the three wire disconnect lugs,a good electrician can help, or get ahold of your local hurco rep, we would love to help,do not forget your ground wire connected to the ground lug...regards...john

  20. #20
    Join Date
    Dec 2003
    Posts
    24216
    Welcome John, It now looks like we have a Hurco expert in the Forum. :banana:
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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