dumpload/ generator matching

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sbassman
sbassman Registered Users Posts: 4
in Wind Power Generation #1
How can I best match gen. to dump load. I dont think mine is working right. When dump load is directly connected to turbine (pma) it slows down to about 60 rpm. When connected to 3 -12v deep cycle batteries it spins normally fast. I am concerned about too much wind resitance during high winds. Resistors are 1 0r 2 ohms designed for 300w at 12v each. I have 3 in parellel equaling 900w. Tried with only one in parellel with same result. They never get warm. I think generator is not puttng out much current however with only multimeter connected voltage goes up to 20 volts dc. I am a using 10 ga. wire 80ft. lead in. Have not invested in 30a+ current meter or dc clamp meter yet. Also, what combo wind and solar controller would you suggest. Some recommend a unit with wind input. I currently have seperate dump and solar controllers and they are competing with each other.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: dumpload/ generator matching

    "I currently have seperate dump and solar controllers and they are competing with each other. "

    Then they are either wired wrong or programmed wrong.
    Three 50 Watt panels shouldn't be much "competition" for a 500 Watt turbine (which probably doesn't come close to that in output because they rarely do).

    Can you post a diagram of how what you've got is connected together? Can you include specific information about what controllers are used? Also the capacity of the batteries (sounds like three in parallel, which is not the best plan).

    Another thing; you're trying to diagnose with Volts, Ohms, and Watts but the all-important Amps is being left out. That the turbine can put out 20 VDC with nothing connected isn't surprising. To know if it's doing anything you've got to be able to measure the current from it to the batteries. The fact that having the dump load connected directly to the turbine slows it down shows that some output is there, but unless its Voltage is higher than battery Voltage with current flowing it doesn't mean much.

    Example: if you have three 100 Amp hour batteries in parallel that's 300 Amp hours @ 12 Volts. Putting 30 Amps to that would be good charge current. This will only happen if the batteries are discharged and there's a source of power capable of providing the charge current. Three 50 Watt panels won't; they're only about 3 Amps each maximum. But 30 Amps @ 12 Volts is 360 Watts. If you have a 20 mph wind blowing the turbine might come up with that.

    Ignore the dump load problem for the moment and see if you can get the charging going. The dump load should only be active once the batteries are charged and the turbine needs to be loaded to keep it from free spinning out of control.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #3
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    Re: dumpload/ generator matching

    There are folks that will have a switch to connect the dump load directly to the turbine (switch out the battery and connect the turbine alternator to the dump load resistor bank, or behind a blocking diode to the battery bank).

    The theory is that some turbine alternators will overheat in high winds with a zero ohm shunt on the alternator output in high wind (I2R heating)--Instead, they use a resistor bank to limit maximum current and yet still provide load on the turbine to prevent over-speed.

    Zero Ohm (dead short) or Resistor Bank for a shunt load (to control/stop turbine rotation in high wind/when not needed)--I don't know. It probably depends on size of stator winds vs rotor area anyway (large enough rotor and/or very high winds will overpower any "simple" shunt brake anyway).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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