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Motor Stall Current

  1. Aug 7, 2014 #1

    I am currently doing my Master project and unfortunately did a rookie mistake.
    My DC motor is mechanically linked to a loaded PMA (wind turbine generator) and I need to run it at a variable speed. All this is built, however when choosing my PSU, I forgot to take into account the stall current (which was unfortunately not indicated in the motor's datasheet. My motor is rated at around 600W (3/4 HP to be precise) with 24V (so a current of 25A). My PSU is the same, 24V and 25A rated. My whole system is built, the motor starts for 1 second and then the PSU stops working (very probably due to overloading). I am therefore unable to start my motor at all.

    Would any of you have a solution for me to jump-start my motor without having to replace the whole PSU (which is quite expensive)? I still do not have a measurement of stall current, but I ordered a meter shunt to help make my measurements.

    OMPMDC34-18-24V-56C :

    Thank You for your help.

  2. jcsd
  3. Aug 7, 2014 #2


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    The quick and dirty solution would be a 1 ohm series resistor rated about 600 watt. Instead of a resistor, I would consider using 24V 100W truck headlamp globes, maybe 4 to 6 of them in parallel. That will limit current during start-up, globes will then go dim and low resistance once motor is running. Maybe a parallel switch to short the globes for maximum power.

    Alternatively, make a switching current limiter.
  4. Aug 7, 2014 #3

    jim hardy

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