Brent

I can add to this if needed but

- If you value WT survival and if it is in a site where it can be
potentially "overpowered" then be sure it has shutdown / loading / braking
/ feathering / stalling / off-winding mechanisms to protect it. SAs you no
doubt know, energy into the WT disk increases with velocity cubed. So a WT
rate to deliver 300W at say 10 m/s is  notionally being delivered a
deliverable 2^3 x as much =3D 2400 W at 20 m/s. This will be modified by
stalling and other mechanisms but disk pressure rises with velocity squared
so you are liable to get significant loading increases even if power into
the alternator does not rise at Vcubed rate.
- In some designs hard shorting of the outputs can provide enough braking
to slow or stop an overspeeded WT but in some/many cases high enough wind
speeds will not be able to be overcome by electrical braking.
- A common method of power reduction is to have the WT head tilt off wind
or sometimes tilt-up under wind pressure. Some Chinese designs have
mounting holes designed to allow the head to pivot accordingly. Some have
these in the wrong place :-). The intention is that the weight forms a
torque to hold the head into the wind and pressure on the disk overcomes
this causing slewing. An alternative is to spring or gravitationally ramp
the "tail" so the WT is not held into the wind and as before turns cross
wind.
- In large commercial units blade pitch control is the norm but this is
liable to be unavailable on your unit.

Several loanable items listed below. I want to use them (again) longer term
but they are available for loan for some to quite a few months:

- I have a currently unused small (250W?) grid tie 24VDC-230VAC inverter
intended for (according to label) wind turbine use. It works but quality
and true capability is unknown and lack of legal certification for
connection to the grid is guaranteed :-). You are welcome to borrow it for
a while to play if of use. More details on request. (I have used it
successfully for trialling PV input. Long term it may end up islanding on a
caravan).

- Controllers often offer "load dump" outputs where excess energy is
shunted to. How and how well is TBD in each case.  A good load for WTs are
available low voltage water heater "spears" - these may have two or 3
separate elements which can be either switched sequentially or PWMd.  Don't
let them run dry for too too long :-). I have a friend who may have some
for sale and have one unit which may or may not still be usable if you wish
to play.

- Surplustronics in Ak used to be an OK source of large wattage resistors
suitable as loads. I may have some (used by me as exercise bike loads that
MAY suit your use. Resistances and wattages and findability tbd and may not
suit.

- You can also buy large diameter high current rating nichrome wire suited
for low voltage elements. I have a coil rated at 500W + air cooled - free
form self supported spiral wound (also used as exercise bike load - 500
Watt or more at ??? V* and easily tapped.  (* Vin the 10's of V range
normally but would rise with user testosterone level and enthusiasm).

- More ...

           Russell
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.