Wind Turbine: Air density question

Calahonda52

Am reading a book on same which says that in Canada, when turbines designed for working in Texas were installed in the colder climate in Canada, they "burned out" due to the colder air being 27% denser that the Texan air.

Trying to understand why:
the math is
Kinetic Energy =1/2mv^2

Area of Circle: A=πr^2

Wind Turbine Energy, in Joules: = 1/2ρAtV^3
where
ρ is density
A is swept area
t is time and
V is velocity
^ is to power of

So if just the density went up by 27%
the Joules go up by 27% for same air speed
but it it is a fixed magnet revolving in a wound stator at the same speed, how can it burn out?

Is it the horizontal thrust on the bearings thats the issue?
Thanks

Winding gauge too small usually. Bearings should be able to take it.

Calahonda52

Sir Liamalot wrote: »

Winding gauge too small usually. Bearings should be able to take it.

so just more "flywheel type" momentum on the rotor?

I don't understand what you mean.
There's no clutch/crank

The magnets are usually spinning on the commutator and the windings are coiled on the stator according to the nominal power curve.

The only friction is on the bearings which should be thrust. Some cheapo turbines use commutated brushes and the better ones of those use 2 brushes per phase.

The four common ways of dealing with overspin are furling, active blade pitch control, electric loading or fitting smaller blades.

Calahonda52

Back to my original question
If the only difference is air density, then how can the increased energy " burn out" the turbine?
The denser air will deliver more energy to the blades which will not rotate any faster.

Afaik the turbine is converting the kinetic energy in the wind to mechanical energy in the blades then electrical through flux.

If the blades aren't spinning faster my guess is it's torque meaning it's not losing RPM to electrical load. There's nothing in the head bar coils to burn.

quentingargan

My guess is that this might be an ASYNCHRONOUS generator. Directly connected to the grid. On the smaller stuff (and now some larger ones) there is a permanent magnet generator rectified and converted through an inverter. The inverter would have a power curve keeping the current constant.

In an aysnchronous generator, it is slip that enables power to flow - the generator runs slightly faster than its natural frequency pushing energy into the grid. That could burn out because there would be 27% more slip at the same rotation speed. These generators run at a fairly constant speed.

Calahonda52

Thanks guys, this all makes sense. Case closed!