The wind turbines were turned off...

[Man at B&Q]

...to avoid fanning the flames

Heard during a report on R4 this morning about countryside fires.

WTF?

Are people really that stupid?

MBQ

[John Williamson]

Do you really need to ask?

Or do you just not meet the great unwashed on a regular basis?

[The Natural Philosopher]

IN what way? for sure turbines increase ground level wind.

You get a lot of wind shear, and the turbines 'stir' the layers..

But I'd expect it to be a safety if firefighters were around, or there was a chance the turbines could catch fire (I wish)

But is it a true story?

I dont listen to radio 4 PC lefties any more..

[Dave Liquorice]

Do you have to ask?

There might be an element in truth in that to stop damage to bearings when sat still for long times they are motored round. There is f'all wind ATM, 300MW from wind when I looked a few minuets ago. About 1% of the total installed wind capacity...

[The Natural Philosopher]

ITYM 10%...

In fact that's a fairly normal figure and reflects a medium breeze.

Wind farms seem to spend most of the time between 5 and 15% output, with occasional excursions above 50% to 'make the figures look good' and occasional excursions below 5% which don't overall make a lot of difference to the averages, anyway.

To put it in simple terms, the 25% average is actually more or less

10-15% most of the time, with a few days of >50% and a few more days of less than 5% interspersed.

[Allan]

I didn't hear the report on R4, but if it's Ovenden Moor near Halifax, there are currently moorland fires up there, and there's also a wind farm on the moor too.

Allan

[Nightjar]

A few pictures of them doing so here:

Bignell

[The Natural Philosopher]

yep. fires are very common. Generally if the mains frequency stops them over speeding, if the wind is too strong they should feather to keep the torque down. If the feather fails either the generator will overcurrent or the gearbox will overheat and catch fire, or the bearings will fail and the same thing happens. If they lose connection to the mains as the windings burn out, then the thing will overspeed and shake itself to pieces.

It is rumoured as little as a .22 round in the right place can cause this.

[newshound]

I particularly liked the video of the one which either failed to feather or had lost its brake

[The Other Mike]

Have you got documentary proof of that?

[The Natural Philosopher]

I've seen the video yes.

yes and overspeeding turbine will disintegrate.

That takes in general a cascade of failures..the feathering mechanism has to fail, and then either the gearbox or anything else that keeps it as a certain speed. Earlier fixed speed turbines are synched to the mains I think. Modern ones use inverters. But anything that takes the load off the turbine without it feathering will cause it to disintegrate in a strong wind.

There is for that reason a safety exclusion region that is broadly as wide as the turbine is high.

There is some evidence that lightning strikes can remove a blade as well..that leads to disintegration as well if it also takes out the feathering system.

Too high seas in a marine locale will result shutdown as well, as will sufficient blade icing. Note that ice that does not seriously unbalance the turbine will simply be thrown off. Up to 200 meters estimated, at speeds of up to 150mph. .

But the most common cause of drastic failure is overheating gearboxes, and especially bearings. Fluctuating strong magnetic fields together with water - especially salt water - are the perfect way to induce electrochemical corrosion in metal bearings. Secveral times a year...;-)