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Quick Grinder Motor question

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by KillerGriller, May 30, 2019.

  1. KillerGriller

    KillerGriller

    158
    Sep 4, 2018
    I’ve found a 3 phase, 4pole, 200v, induction motor for sale but I can’t find a hp value for it online?

    60hz
    1410 rpm @200v
    1750 rpm @220v

    I found a website to give a quick estimate which said ~1/3hp, does that sound right?
     
  2. Rhinoknives1

    Rhinoknives1 KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jul 1, 2013
    I really can’t answer your question other than I never buy a motor that doesn’t have tin plate on it that states, ————110 or 220 volt, 3500 or 1750 Rpm and a HP rating so I’ll know what the heck I’m buying! :)
     
    Ken H> and 12345678910 like this.
  3. Lieblad

    Lieblad

    Jul 24, 2015
    An experienced motor guy could estimate by seeing its physical construction. Shaft size, wires within its peckerhead, hook up and take electrical measurements, etc.
    But there is no way to know without its factory dataplate.
     
  4. JTknives

    JTknives Blade Heat Treating www.jarodtodd.com Knifemaker / Craftsman / Service Provider

    Jun 11, 2006
    That’s a weird one. Normaly with ac motors rpm is tied to HZ not voltage. You see rpm change with voltage on DC motors. If you drop the voltage on an ac motor by half you reduce HP by a factor of 4.
     
    kmf600 and KillerGriller like this.
  5. KillerGriller

    KillerGriller

    158
    Sep 4, 2018
    There is a data plate, with everything I gave above, but no hp value.

    For clarification, it says;
    200v - 50hz - 1410rpm 1.3a
    200v - 60hz - 1700rpm 1.2a
    220v - 60hz - 1720rpm - 1.2a

    Sorry for the confusion
    Going by the conversion website I found, and info on other motors I’ve seen it looks like 3hp tends to run in the 13amp zone?


    Moving on, can you run a 575v motor on a 220v service?
     
    Last edited: May 30, 2019
  6. Drew Riley

    Drew Riley

    Oct 17, 2007
    Do you have a link or some pics to the motor? There's really no way to tell based on the info given.
     
  7. KillerGriller

    KillerGriller

    158
    Sep 4, 2018
  8. Drew Riley

    Drew Riley

    Oct 17, 2007
    According to the nameplate, it's a .2kw motor. That comes in at around 1/4hp which isn't nearly enough power for a grinder.
     
    kmf600 and KillerGriller like this.
  9. KillerGriller

    KillerGriller

    158
    Sep 4, 2018
    Cheers, thanks for the feedback
     
  10. Ken H>

    Ken H>

    Dec 31, 2011
    That depends on how the winding are in the motor. No way to tell from that limited info
     
  11. KNelson

    KNelson

    99
    Jan 9, 2019
    Agree with drew, about a 1/4HP which is useless. Voltage and amps relates to a hp rating
     
  12. KillerGriller

    KillerGriller

    158
    Sep 4, 2018
    Agreed, I was hoping a 220v motor would be more likely to have more hp than a 130 furnace motor.

    Hypothetically: If you managed to wire a 120v motor with 220 plug you’d blowup the motor, but what would be the fallout of trying to run a 575v motor on a 220v system?
     
    Last edited: May 31, 2019
  13. Lieblad

    Lieblad

    Jul 24, 2015
    It would run at greatly reduced power, and at such reduced power, take forever to get up to speed if at all.
     
    KillerGriller likes this.
  14. kmf600

    kmf600

    82
    Jul 2, 2018
    Basically, you multiply volts times amps, that gives you watts, then divide by 746, that gives you horsepower, 746 watts is 1 hp.
     
    KillerGriller likes this.
  15. JTknives

    JTknives Blade Heat Treating www.jarodtodd.com Knifemaker / Craftsman / Service Provider

    Jun 11, 2006
    In an electric motor if you cut the voltage in half you reduce HP by 4 times. So if you ran a 240v 1hp on 120v it would put our 1/4hp. So that 575v motor would put out 10-1/2 times less hp on 220v. If it was 10hp motor you would end up with less then 1hp and it probably would not have enough torque to even get started.
     
    KillerGriller likes this.

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