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Using DC motors underwater

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  • mvharish14988
    Hi, I have this regular small 12V 500 rpm DC motor which I tried to run underwater, with no special waterproofing work, i.e., the motor was immersed as it is
    Message 1 of 4 , Jan 11, 2008
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      Hi,
      I have this regular small 12V 500 rpm DC motor which I tried to run
      underwater, with no special waterproofing work, i.e., the motor was
      immersed as it is into water with no special covering, and run. I was
      surprised when it worked perfectly well(i.e., it did not burn out or
      anything). Can anyone please explain this? Is it possible that there's
      some sort of covering on the core?

      - Harish
    • Triffid Hunter
      ... Of course, or the windings would short to the other windings. Also, water isn t a perfect conductor, certainly nowhere near copper. In fact, pure water is
      Message 2 of 4 , Jan 11, 2008
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        On Sat, 12 Jan 2008, mvharish14988 wrote:

        > Hi,
        > I have this regular small 12V 500 rpm DC motor which I tried to run
        > underwater, with no special waterproofing work, i.e., the motor was
        > immersed as it is into water with no special covering, and run. I was
        > surprised when it worked perfectly well(i.e., it did not burn out or
        > anything). Can anyone please explain this? Is it possible that there's
        > some sort of covering on the core?

        Of course, or the windings would short to the other windings. Also, water
        isn't a perfect conductor, certainly nowhere near copper. In fact, pure
        water is an insulator! It only becomes conductive when you add stuff like
        salt or minerals. It conducts well enough to stop most low power signals
        like logic, but not things like motors.

        However, it's likely that the water will remove the grease from the
        bearings, and corrode the commutator so I doubt it would last very long at
        all. Brushless motors are far better suited to underwater environments,
        and even those should be sealed as much as possible to prevent corrosion
        and lubricant migration.
      • Rob Purdy
        The coils on the stator are coated. The place you run into problems eventually is the comutator. Eventually the impurities in the water will destroy the
        Message 3 of 4 , Jan 12, 2008
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          The coils on the stator are coated. The place you run into problems eventually is the comutator. Eventually the impurities in the water will destroy the copper faster than it will in the air. The other draw back is it has to move all thatwater through the motor.


          To: SeattleRobotics@yahoogroups.comFrom: mvharish14988@...: Sat, 12 Jan 2008 03:44:07 +0000Subject: [SeattleRobotics] Using DC motors underwater




          Hi,I have this regular small 12V 500 rpm DC motor which I tried to rununderwater, with no special waterproofing work, i.e., the motor wasimmersed as it is into water with no special covering, and run. I wassurprised when it worked perfectly well(i.e., it did not burn out oranything). Can anyone please explain this? Is it possible that there'ssome sort of covering on the core?- Harish







          [Non-text portions of this message have been removed]
        • John Palmisano
          Try it in sea water and watch how fast your motor lasts ;) John societyofrobots.com ... -- John Palmisano Robotics Specialist Naval Research Laboratory,
          Message 4 of 4 , Jan 13, 2008
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            Try it in sea water and watch how fast your motor lasts ;)

            John
            societyofrobots.com



            2008/1/12, Rob Purdy <kb7wnz@...>:
            >
            >
            > The coils on the stator are coated. The place you run into problems
            > eventually is the comutator. Eventually the impurities in the water will
            > destroy the copper faster than it will in the air. The other draw back is it
            > has to move all thatwater through the motor.
            >
            > To: SeattleRobotics@yahoogroups.comFrom<SeattleRobotics%40yahoogroups.comFrom>:
            > mvharish14988@... <mvharish14988%40yahoo.comDate>: Sat, 12 Jan
            > 2008 03:44:07 +0000Subject: [SeattleRobotics] Using DC motors underwater
            >
            > Hi,I have this regular small 12V 500 rpm DC motor which I tried to
            > rununderwater, with no special waterproofing work, i.e., the motor
            > wasimmersed as it is into water with no special covering, and run. I
            > wassurprised when it worked perfectly well(i.e., it did not burn out
            > oranything). Can anyone please explain this? Is it possible that there'ssome
            > sort of covering on the core?- Harish
            >
            > [Non-text portions of this message have been removed]
            >
            >
            >



            --
            John Palmisano

            Robotics Specialist
            Naval Research Laboratory, Washington, DC
            B.S. Mech. Eng., Robotics, Carnegie Mellon University
            www.societyofrobots.com


            [Non-text portions of this message have been removed]
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