how high RPM can you make an electric motor go?

Discussion in 'General Electronics Chat' started by stanman11, Aug 17, 2012.

  1. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
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    I kinda want to make en electric dredge motor. I hate using petrol motors. Im thinking a propane conversion but id rathee use clean electric.
    si either it would have to run of 24v dc or run off a convertered 115v inverter.

    Also what altercations would the motor need to have to take the heat?

    Can this be done?
     
  2. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    I men't 12v
     
  3. #12

    Expert

    Nov 30, 2010
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    Well, given that the motor type, horsepower ratings, operating conditions, and load are unknown, I don't know.
     
  4. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    its 400w not sure the amps and barely makes coffee.
    can I boost the power outing in this thing to give me more like 1000w?
    do some component changes?
     
  5. #12

    Expert

    Nov 30, 2010
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    Not a chance.
     
  6. stanman11

    Thread Starter Member

    Nov 23, 2010
    230
    4
    yeah did some googling. didnt think so. gunna have to pick one up cheap some where.
     
  7. cork_ie

    Member

    Oct 8, 2011
    348
    58
  8. #12

    Expert

    Nov 30, 2010
    16,345
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    Are you going to dredge something or drive the boat that has a dredge on it?

    Be aware the op changed the question from a motor to an inverter.
     
  9. cork_ie

    Member

    Oct 8, 2011
    348
    58
    Why do I think of an armature and a stator belting the crap out of each other?
     
  10. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
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    What is the main control for the speed of a series wound motor? Scroll for answer


















    The load
     
  11. DMahalko

    Senior Member

    Oct 5, 2008
    175
    14
    An unloaded DC motor will spin as fast as possible. With no load the speed limit is air drag on the rotor and friction in the bearings.

    The actual limit on how fast it can go is how well the spinning rotor has been assembled. The faster it goes the more angular force on the spinning parts.

    At some point the rotor windings may start to dislodge and move outward until they start hitting the stationary frame, then the insulation is rubbed off and the exposed wire starts sparking and burning.


    You may be able to increase the voltage above a motor's design spec, to increase power output, but there's a point where the insulating ratings are exceeded or bare metal components inside are too close together for such a high voltage, and it starts arcing and sparking inside the motor until it burns up.


    Also increasing the voltage increases the thermal dissipation -- it runs hotter. Too hot and insulation starts melting ... leads to sparking and burning again.



    In "short", you can't cheap this out. It's going to cost money for a properly rated motor. If you try overvolting a motor for more power, then you have to deal with possible smoke and fire, work stoppage, ripping out the fried part to put in another that also eventually blows up due to your abuse, etc.

    Or you could do it right the first time and the correctly-rated motor runs for years, with minimal maintenance. (I know, I know, this is a ridiculous line of thinking..)
     
  12. matty204359

    Member

    Apr 6, 2011
    105
    3
    I have in the past destroyed an expensive motor by running it at a higher than rated voltage. I believe with a well balenced load that it might not be so bad but in my application with a pulley and belt, well the motor's brass sleeve bearing wore out pretty quick. I'm sure with a well balanced load the bearing would wear more evenly but with the pulley it made a pretty deep groove in the bushing pretty quick till the thing was making horrible noises and sounded like it was gonna blow up into a fiery ball of shrapnel.
     
  13. maanga

    New Member

    Aug 20, 2012
    12
    3
    Petrol engines are lighter in weight compared to electric motors. That is why these are used for many many years. You will need a powerful low weight magnet motor to use. Output kw is proportional to torque and speed. Since the field is permanent magnets, the torque is constant. You have to operate at twice the speed to get twice the power. But your propeller or any load is increased (power demanded) to nearly 4 times of what was at normal speed.If you reduce propeller size, you can achieve twice the power. Heat generated will be more, sparking and commutation problems will occur. You also may eventually loose the power on the magnets.

    regards,
    Maanga
     
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