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Is conventional commutator DC motor still in use?

  1. Jul 10, 2013 #1
    I think most of them are replaced by brushless types or Induction Motor with VFD (variable frequency drive). Is there some industries where they are still preferred today?
     
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  3. Jul 10, 2013 #2

    Simon Bridge

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    ... you could look up commercial suppliers of DC motors and look through their catalogs to get an idea of how common commutator motors are.
     
  4. Jul 10, 2013 #3

    nsaspook

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    In most industries you don't replace perfectly good equipment unless there is a very good reason so there are millions of large to small conventional DC motors in commercial use and maybe billions in toys and household appliances.

    http://www.anaheimautomation.com/manuals/forms/brush-dc-motor-guide.php
     
  5. Jul 10, 2013 #4

    jim hardy

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    automobile starters, fans, electric windows, windshield wipers

    treadmills

    take some stuff apart and see !
     
  6. Jul 10, 2013 #5
    Thanks for the response.
    I think the reasons they are used for automobile starters, Electric Windows (automobile) and Windshield Wipers is because 12V is the only available supply.
    But why do they use it in Treadmill ?
    Perhaps because of their high stall torque and easy speed control mechanism.
    I am planning to do a project on regenerative braking of DC motor. Can someone point a nice industrial application except uses in traction.
     
    Last edited: Jul 10, 2013
  7. Jul 11, 2013 #6
    For new applications not too many , but in older steel mills ( 10+ years ago) , I used to see a lot that the mill owner would not justify replacing with the options above. The issue being the wearing out of the shoes.

    I believe hand tools still use many because the weight and intermittent use eg: http://servicenet.dewalt.com/Products/Detail/DC925KA
     
  8. Jul 11, 2013 #7

    nsaspook

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    I can't think of any that try to store the recovered mechanical energy on equipment using normal utility power. The energy from regenerative braking must go somewhere so most circuits with large motors use a dump load when spinning down quickly.
    http://electronics.stackexchange.co...-implement-regenerative-braking-of-a-dc-motor

    I've designed a few controllers for DC brushed servo motors to replace some obsolete parts in a few fab process tools. This controller uses relays to supply stepped voltages, insert series resistors and dump-load controlled braking to position a track or arm. I could have used modern electronics for the outputs but I needed to drive the motor in a similar fashion to the original controller for testing.

    http://www.flickr.com/photos/nsaspook/8121852614/in/set-72157630632759744
     
  9. Jul 11, 2013 #8
    Hand tools use universal motors which works on both AC and DC. They are in fact series field DC Motors so they just by chance happen to work on AC as well. The battery powered tools should use DC though, so as to obviate the need to convert DC to AC.
    I am looking for Bigger application though.
     
  10. Jul 11, 2013 #9

    Averagesupernova

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    I believe at one time some machine tools (milling machines, etc.) used a DC generator to sense the speed of the spindle. The higher the speed of the spindle the higher the DC voltage that came out of this generator. The one machine I worked on I believe had this part integral to the main motor. I recall a discussion between a coworker and I about what the tach signal was coming back to the main controller once when this machine was down. I thought it was AC but it was not. It was DC coming from a commutated permanent magnet generator.
     
  11. Jul 11, 2013 #10

    Simon Bridge

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    How much bigger?
    Did you have a particular industry in mind?
    What do you need the information for: idle curiosity?

    Perhaps it would be simpler to ask if there is any industry where commutator DC motors are no longer used instead - it should get you a shorter list? i.e. brushless AC motors tend to be used where power transmission is a factor (i.e. electric locomotives).

    The short answer to you question is that commutator DC motors are still used for all kinds of purposes.
    If you pick some routine work where commutator-less tech has been used, I suspect you will be able to find someone, probably many someones, using commutator tech for the same purpose ... what's the problem?
     
  12. Jul 12, 2013 #11
    Bigger to the scale that implementing regenerative braking is sensible.
    If AC motors and DC motors are so interchangeably implemented in industries, then perhaps better question would be: Any industrial example that benefits from regenerative braking? (except transportation)
    I appreciate the time you took to make the reply.
     
  13. Jul 12, 2013 #12

    Baluncore

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    Industrial applications usually balance the loads wherever possible. But there are situations such as drag-line open cut mining equipment or construction tower cranes where unbalance is part of the process. Loading or unloading shipping containers is an obvious application.

    Storage of energy by pumping water up hill into a higher reservoir could use a regenerative motor on the pump to recover the energy later.

    Wheel balancing machines accelerate, detect the imbalance and then brake heavily once per cycle. I believe they sometimes put a DC current through the motor to act as the brake. It would be more economic in the long term to use regeneration.

    Look for unbalanced operating cycles and you will find regenerative applications.
     
  14. Jul 12, 2013 #13
    As you look to larger and larger applications - finding an existing motor design that can handle the application becomes the center of the overall effort. Large custom motors become expensive. Since the regen mode will require electronics, this can typically be done for any large motor.
    Using Regen is an application specific case - and has nothing to do with the motor type. Does the application have enough energy and does it start and stop frequently enough to justify the cost of buying or developing a regen system. You can buy a regen drive - these are typically active front ends and have the added benefit of low harmonics and good power factor (reducing costs eleswhere) - but cost more.
     
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