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DC Motor connected directly with solar panels

  1. Mar 17, 2010 #1

    I have many time thought about AC & DC Motors, but have not yet find out. Example. if a motor of 4HP 48VDC. We give it power 48VDC but 1HP power, so what happens? And what if we connect it directly with solar panels of 48VDC and 4HP power.

    So when sunshine is lower how it will affect motor? Will the motor burn up if it is lower current than it is rated on motor?

    Best Regards
  2. jcsd
  3. Mar 17, 2010 #2


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    Science Advisor

    We need to use watts rather than horsepower. HP is a mechanical unit but watts can be mechanical or electrical.

    1 HP = 746 watts output from the motor. 4 HP = 2984 watts.
    These are loads on the motor.

    If the motor was 100 % efficient, you would have to supply 2984 watts into the motor to let it rotate a 4 HP or 2984 watt load at the right speed.

    If the power source isn't capable of supplying 2984 watts (62 amps at 48 volts) the supply voltage would drop below 48 volts and the motor would either run slower or stall with a 2984 watt load.

    If the motor stalled, the power supply fuse might blow or the motor would get hot and possibly burn out.

    Properly designed systems would run motors off a battery bank which would supply power when the sun wasn't shining.
    The motor would also not be connected to a reduced voltage if this would damage it and it would be protected from excess current by current cutouts.
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