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OT electrical question

Discussion in 'Off Topic Threads' started by blkcloud, Jun 6, 2010.

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  1. blkcloud

    blkcloud Active Member

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    I'm trying to buy a air compressor with a baldor 20 hp 200 volt 60 hz motor on it, my shop is wired for low voltage 3 phase, will this run or will it burn up? thanks!
     
  2. Kooz25

    Kooz25 TS Member

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    I,M SURE THE COMPRESOR WILL RUN FINE, LOOK AT THE NAME PLATE ON THE MOTOR AND THERE SHOULD BE MORE THAN 1 VOLTAGE ON THE NAME PLATE. IS THE COMPRESOR SINGLE PHASE OR THREE PHASE?

    KOOZ
     
  3. Trapshooter

    Trapshooter Well-Known Member

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    Look at the tag on the motor to see what the amperage draw is. I am guessing you have at least 200 amp service there at your shop.

    Todd
     
  4. 221

    221 Banned User Banned TS Supporters

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    <em>"low voltage 3 phase"</em>

    Do you mean 208 3 phase?

    It will work, may run a little fast, or just have the internal wiring switched to the correct voltage.
     
  5. Pull & Mark

    Pull & Mark Well-Known Member

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    air compressors use alot of power. My 2 hp. contractor grade needs a dedicated 20 amp. breaker and plug and needs to be plugged directly into the plug or maybe a short 25 ft. 12 ga. cord at the most. Your 20 hp. motor may need a 60 amp dedicated breaker??? Is it a plug in or wired directly??? Do the plugs match up??? I would have a lic. elect. contractor look at it and hook it up. I'm sure you can find one locally who could do the work for you on the side. Good Luck and Break-em all. Jeff
     
  6. ABH

    ABH Member

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    BLKCLOUD,


    Your motor will be 240V single phase or 208V 3-phase.The name plate will tell you which it is.If it is 240V,you will need an 80amp feed to it.If it is 208V 3-phase,(most likely),you will need a 50 amp feed to the motor.Either way, you should run the feed to a disconnect and then to the motor itself.A disconnect with overload protection would be ideal.Hope ihis helps.

    ART H.
     
  7. Leo

    Leo Well-Known Member

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    The original post said it was a 200 volt only motor. There is such a thing used in foreign countries, both in single phase and three phase. He didn't say if it was single phase or three phase. That will make a lot of difference, as well as the exact voltage of his service. There are three phase matching transformers that can be tapped to get what he needs, but generally the cost of the transformer and proper installation far exceeds any savings of buying the odd ball equipment. The suggestion for a combination starter/disconnect with properly matched overload heaters is not optional, it is mandatory. You cannot mickey mouse with a 20 hp compressor, it is a full load start and run condition, it has to be right or you will smoke it right away.
    Code requires a minimum of a 60 amp disconnect and 4 gauge supply wire for a 3 phase 20 amp motor no matter what the exact overload rating is for a 230 volt application. 200 volt load would be a little higher, which means a 100 amp combination starter. I think it will work out cheaper to find a motor that matches your available service.
     
  8. blkcloud

    blkcloud Active Member

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    It is 3 phase 200 volts only as per the baldor tag
    221..all i know is that i have low voltage 3 phase..I have a high voltage surface grinder I run off of a transformer..
     
  9. Shootrman

    Shootrman Member

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    LEO hit it on the money, If your manufacturing tag says 200v 3-phase you should be good with the proper fuse and safety features.
     
  10. M-16

    M-16 TS Member

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    If you need to ask the question have a electrian come in
     
  11. 221

    221 Banned User Banned TS Supporters

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    blkcloud.....your 200v 3phase should be fine, but you need proper onsite assistance to be sure you will have enough supply for your loads.

    Around these parts we have 208Y/120v 3phase 4wire .....then theres 277/480 3phase, with no 120 1ph...... we consider 208y low volt 3ph here and 480 and up as high voltage.

    I'm sure what you have will work, just seek out someone to guide the process.
     
  12. blkcloud

    blkcloud Active Member

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    I have the 208.. I called a motor shop.. the guy said because it was 60 hz and not 50hz that it would start and run ut it would burn up...?? must be a foreign motor.. thanks!
     
  13. halfmile

    halfmile Well-Known Member

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    We use 60 cycle in America.

    The above URL shows the various countries voltage schemes.

    Your motor shop guy must be trying to get some business...........

    HM
     
  14. tom-n8ies

    tom-n8ies Member

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    Try to contact Baldor direct.

    tom
     
  15. 221

    221 Banned User Banned TS Supporters

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    It will work....as long as the Hz is 60......8 volts ain't gonna burn it up. That's only 4%..... Unless you are planning to do some serious sandblasting, it should outlast you......as long as the motor is in good shape.

    Does the name tag on the Balbor motor have the available voltages stamped on it?

    Whats the tag/model #.......someone here can look it up and find out for sure.......or trust your luck to a motor shop.
     
  16. Catpower

    Catpower Molon Labe TS Supporters

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    If it's a 200 volt motor, it can run on any voltage between 180-220, and the frequency doesn't mean much either it will run slower on 50 Hz than 60Hz, we have been using variable frequency drives for many years, and have run motors from 10 Hz to 120 Hz with no problem, execpt that at real low rpm we have had to put cooling fans on some older motors as the internal didn't move enough air to cool the motor

    But what you are looking at will work
     
  17. BerettaJ

    BerettaJ Member

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    Blkcloud,

    I am an electrician with 20 years experience.

    3 phase 208 volt should be fine. Most power companies only supply power with a variable of +/- 10%. Check your power output with a good meter to be sure. your actual voltage can be as high as 216-218 volts or as low as 196 volts.

    Otherwise a buck/boost transformer may be needed. It may be a little spendy, but some motors can be a little finicky.

    John
     
  18. JEB

    JEB Active Member

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    Beretta J is correct, just know that the motor will run about 4% faster at 208 volts as opposed to 200 volts. Full load amperage for 20 hp at 208 volts is 59.4, but figure on a 25% overload. A 60 amp breaker is really not adequate. I do not know your local codes, but you will probably have to use a 100 amp breaker.

    JEB
     
  19. Scott Morris

    Scott Morris TS Member

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    In the USA we generate at 60 hertz ( 60 cylcles per second) so.. you are good there. What exactly is your service? Low voltage three phase? Wye/Wye or Wye/Delta...that's 208 three phase or 240? Or...beleive it or not 120 three phase. I've never heard of "low voltage three phase". It is what it is. What's your definition of "low voltage"? Mine is anything under 600 volts. But then again I work on lines up to 345KV.
    If you are unsure of your service voltage/current capabilities then I would highly recommend that you seek out a liscened, IBEW member, electrician. Otherwise you could easily run into very regretable & preventable problems. I could go on & on, but will save you the headache. Grab a phone book.
    Scott
     
  20. halfmile

    halfmile Well-Known Member

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    Scott, good advice.

    HM (IBEW loc. 158 ret.)
     
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