why wind needs dump load?

unyalli
unyalli Solar Expert Posts: 121 ✭✭
in Solar Beginners Corner #1
Power will not flow without a load. Power is not pushed it is drawn. If I'm all charged up and barely drawing why dump load to draw power not needed?

- Jeff
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,175 ✭✭✭✭
    #2
    To avoid critical over speed of the blades.
    I always have more questions than answers. That's the nature of life.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    If the wind turbine sees a full battery, and stops charging, it will spin freely in the wind and either burn out it's bearings, or the high RPM will cause rapid dis-assembly of the spinning blades. (flies to pieces)
    both are bad outcomes
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,664 admin
    #4
    To add to Mike's and Marc's explinations... The overspeed problem is usually only with horizontal axis wind turbines overspeeding with no load and high winds (HAWT).

    Vertical Axis Wind Turbines (VAWT) generally do not overspeed with no loads (However, have not seen many that will harvest much electricity, or run with any sort of reliability (frequently VAWT are installed on building roofs and as "quasi-art" installations).

    There are other methods to limit overspeed on HAWT units... Feathering blades, tilting/turning blades out of wind, mechanical brakes, etc...

    One reason (from what I have read) the Dutch got a lot of large/commercial wind turbine contracts early on was because they had multiple/redundant methods to control/shutdown turbines (prevent overspeed) in their designs/products.

    One of the most scary things is when a turbine goes out of control. One happened during installation... Somebody took out the shaft lock during the install, before the rest of the electronics/brakes/turning out of wind controls were installed/operational... Wind started to pickup and all they could do was backup and watch the unit self distruct.

    This thread has pictures and links to several commercial HAWT failures:

    https://forum.solar-electric.com/discussion/5517/large-windmill-collapse-in-nh

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