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At what tempature should you shut down a baldor motor for cooling?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Dan Seaver, May 29, 2009.

  1. Dan Seaver

    Dan Seaver

    Jun 25, 2007
    Well for my hammer I'm just going to leave my new motor running rather than shutting it off between heats. The only problem is I don't know when I should shut it down for cooling off? Is there a general temperature that a motor should not exceed?

    For now I'm only going to have a fan blowing air past it to keep it cool but I'm building a piping system that will transfer the motor heat to water and then the water will be sent to a water to air heat exchanger to keep it cool.

    Thanks guys!
  2. ONeill

    ONeill KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Nov 15, 2007
    most motors have a duty rating , continues or intermediate .
  3. rfrink


    Aug 1, 2000
    Dan, My first thought is that you are overthinking this....

    Baldor makes industrial motors..nearly bullet proof. I would just leave it running. If there no load on the machine, then it's drawing very little current...and generating very little heat. These motors are industrial motors designed for continous use. The nameplate wll have some info on the duty cycle, or thermal rise... But for starters just use your hand..if it feels hot then you'll need to address the issue. Hot is hot! it will be uncomfortable to keep your hand on it. If this is a single phase motor..does it have a built in thermal overload? If so, then it will automatically shut off when it gets too hot. If this is the case, then I wouldn't worry about the heat unless it shuts itself off.

    If it's a 3ph motor...you should be using a motor starter with overload heaters properly sized for that motor. I'm guessing that it is not 3 ph though.

    For me, I prefer the KISS concept and not fixing it if it's not broken.

    Have fun with your new hammer!!

  4. Dan Seaver

    Dan Seaver

    Jun 25, 2007
    Ahh I never under stood what the duty rating meant. So I would assume that "40C amb-Cont" means 40 degree Celsius ambient temperature for continues running. So I should shut the motor down for cooling before it reaches 104F or 40C.

    Thanks ONeill!

    Edit- thanks rob! I was having fun till the old motor stopped working properly; its most likely a short in the motor but why waste my time with a 50 year old motor when a baldor will do the job better with less hassle? Yea its single phase.
  5. rfrink


    Aug 1, 2000
    That's a reasonable assumption...but no. AMB refers to the temp of the air in the room. This is the temp that the max air temp that the motor was designed to run in at full load continously. If the room temp is hotter...then the motor cannot keep itself cool enough...and teh temp will rise out of controll....hypothetically at full load. Less than full load...and the motor makes less heat...so it can run in hotter environments without overheating.

    The key is "Temp Rise" which may not be listed on the nameplate. This is how much the motor temp rises at full load.

    Back when I had a corp job in industry...I was forced to run some motors at scalding hot temps just to keep up with production demands. It was much cheaper to replace these motors due to premature failure than to shut down production. It was then, that I learned how tough "real" industrial motors are built. Baldor is one of them.
  6. 69_knives


    Nov 20, 2008
  7. ONeill

    ONeill KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Nov 15, 2007
  8. sunshadow


    Oct 2, 2006
    Rob is right, industrial motors run stinkin' hot which is why chinese copies of industrial motors burn up. Baldors are damn near indestructable (and rebuildable should they fail)
    give it flenty of free air clearance and bolt it to something metal that will help heatsink it, and have fun

  9. Dan Seaver

    Dan Seaver

    Jun 25, 2007
    Thanks for the help guys! Its being bolted down to 6000lb of hammer so its got quite the heat sink attached to her. :)

    Thanks again fellas.:thumbup:
  10. WadeH


    Apr 24, 2006
    If you are still worried Dan the motor starter that Rob was referring to can be done on a single phase motor to. There are what we used to call heaters in the starter that you get rated for the amp pull of the motor. When that amp pull is reached it will generate a cetain amount of heat and anything about that amount will cause the heaters to trip turning off the motor. Hope that gives you some idea of how it works.
  11. R.C.Reichert


    Jul 26, 2008
    I work in a flour mill that runs Baldor motors continuously 24-7. They will literally run for years, even covered in layers of dust and flour.

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