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Default very low wind and wind turbines turning

Am I correct in thinking that large wind turbines do not produce power when the wind speed is below 12mph?
Why on some days do they stop altogether and others they keep turning, even though there is hardly any wind at all?

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misterroy wrote

Am I correct in thinking that large wind turbines do not
produce power when the wind speed is below 12mph?


Nope, you are wrong about that.

Why on some days do they stop altogether and others they
keep turning, even though there is hardly any wind at all?


The wind can be surprisingly variable, particularly
when there is hardly any wind at all.

Just been out on a mates 2 ton yacht, testing the launching
system and its surprising how variable the wind can be.
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Default very low wind and wind turbines turning

On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy wrote:

Am I correct in thinking that large wind turbines do not produce power
when the wind speed is below 12mph?


Varies.

Why on some days do they stop altogether and others they keep turning,
even though there is hardly any wind at all?


Those blades are big, heavy and flexable. They motor them round to
prevent damage to the bearing(s) and to not have the blades take a
set. If you see a turbne going slow watch a blade and how much it
flexes as it goes past 12 o'clock.

--
Cheers
Dave.



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Default very low wind and wind turbines turning

On 08/08/2017 00:18, Dave Liquorice wrote:
On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy wrote:

Am I correct in thinking that large wind turbines do not produce power
when the wind speed is below 12mph?


Varies.

Why on some days do they stop altogether and others they keep turning,
even though there is hardly any wind at all?


Those blades are big, heavy and flexable. They motor them round to
prevent damage to the bearing(s) and to not have the blades take a
set. If you see a turbne going slow watch a blade and how much it
flexes as it goes past 12 o'clock.


Oh dear, these must be well and truly f**ked:
http://www.bbc.co.uk/news/uk-england...shire-27393177

They haven't moved in years!
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Default very low wind and wind turbines turning

On Tuesday, August 8, 2017 at 12:18:41 AM UTC+1, Dave Liquorice wrote:
On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy wrote:

Am I correct in thinking that large wind turbines do not produce power
when the wind speed is below 12mph?


Varies.

Why on some days do they stop altogether and others they keep turning,
even though there is hardly any wind at all?


Those blades are big, heavy and flexable. They motor them round to
prevent damage to the bearing(s) and to not have the blades take a
set. If you see a turbne going slow watch a blade and how much it
flexes as it goes past 12 o'clock.

--
Cheers
Dave.


There is a wind farm here and a few years ago there was storm force wind, and then a power cut. The wind changed direction, still storm, and because there was no power the turbines could not turn the blades to the desired angle, the bearings were finished by the time the storm had passed. They turbines were only four months old.


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Default very low wind and wind turbines turning

On Tuesday, August 8, 2017 at 5:09:32 AM UTC+1, misterroy wrote:
On Tuesday, August 8, 2017 at 12:18:41 AM UTC+1, Dave Liquorice wrote:
On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy wrote:

Am I correct in thinking that large wind turbines do not produce power
when the wind speed is below 12mph?


Varies.

Why on some days do they stop altogether and others they keep turning,
even though there is hardly any wind at all?


Those blades are big, heavy and flexable. They motor them round to
prevent damage to the bearing(s) and to not have the blades take a
set. If you see a turbne going slow watch a blade and how much it
flexes as it goes past 12 o'clock.

--
Cheers
Dave.


There is a wind farm here and a few years ago there was storm force wind, and then a power cut. The wind changed direction, still storm, and because there was no power the turbines could not turn the blades to the desired angle, the bearings were finished by the time the storm had passed. They turbines were only four months old.


There are three turbines up from my house, somewhere between 0.5 and 1 MW, there is no wind and they are turning at 17 rpm. There is also a 50kW turbine which is stopped.
Since the load on the 50kW turbine is so much smaller, it does not need to turn.
Would that be correct?
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"misterroy" wrote in message
...
On Tuesday, August 8, 2017 at 5:09:32 AM UTC+1, misterroy wrote:
On Tuesday, August 8, 2017 at 12:18:41 AM UTC+1, Dave Liquorice wrote:
On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy wrote:

Am I correct in thinking that large wind turbines do not produce
power
when the wind speed is below 12mph?

Varies.

Why on some days do they stop altogether and others they keep
turning,
even though there is hardly any wind at all?

Those blades are big, heavy and flexable. They motor them round to
prevent damage to the bearing(s) and to not have the blades take a
set. If you see a turbne going slow watch a blade and how much it
flexes as it goes past 12 o'clock.

--
Cheers
Dave.


There is a wind farm here and a few years ago there was storm force wind,
and then a power cut. The wind changed direction, still storm, and
because there was no power the turbines could not turn the blades to the
desired angle, the bearings were finished by the time the storm had
passed. They turbines were only four months old.


There are three turbines up from my house, somewhere between
0.5 and 1 MW, there is no wind and they are turning at 17 rpm.


Its more likely that there is more wind up there than at your place.

Unlikely to be worth running them at 17 rpm for the bearings.

There is also a 50kW turbine which is stopped.
Since the load on the 50kW turbine is so much
smaller, it does not need to turn.
Would that be correct?


More likely its got a different bearing design
which doesnt need to always be turning.

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Default very low wind and wind turbines turning

Well maybe some are broken in the brake department. Seriously though, I
suspect each has a detector and uses that to decide. There has to be
something that turns them and if the wind is that something I see no harm in
them rotating even if off line.
Brian

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"misterroy" wrote in message
...
Am I correct in thinking that large wind turbines do not produce power
when the wind speed is below 12mph?
Why on some days do they stop altogether and others they keep turning,
even though there is hardly any wind at all?



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Default very low wind and wind turbines turning

On 07/08/17 21:56, misterroy wrote:
Am I correct in thinking that large wind turbines do not produce power when the wind speed is below 12mph?


More like below 5mph Id say.

Why on some days do they stop altogether and others they keep turning, even though there is hardly any wind at all?

Because motors keep them turning to save the bearings from flat spots.


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No Apple devices were knowingly used in the preparation of this post.
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Default very low wind and wind turbines turning

On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy
wrote:

Am I correct in thinking that large wind turbines do not produce power when the wind speed is below 12mph?
Why on some days do they stop altogether and others they keep turning, even though there is hardly any wind at all?


It could be the wind gradient: the wind speed drops off quite a bit as
you get close to the ground. So depending on how high the blades are,
the wind velocity could be higher than at ground level.


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Default very low wind and wind turbines turning

On Tue, 8 Aug 2017 01:08:20 +0100, Fredxxx wrote:

On 08/08/2017 00:18, Dave Liquorice wrote:
On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy wrote:

Am I correct in thinking that large wind turbines do not produce power
when the wind speed is below 12mph?


Varies.

Why on some days do they stop altogether and others they keep turning,
even though there is hardly any wind at all?


Those blades are big, heavy and flexable. They motor them round to
prevent damage to the bearing(s) and to not have the blades take a
set. If you see a turbne going slow watch a blade and how much it
flexes as it goes past 12 o'clock.


Oh dear, these must be well and truly f**ked:
http://www.bbc.co.uk/news/uk-england...shire-27393177

They haven't moved in years!


I reasonably frequently go past them and noticed they were finally
working. Seems as though the radar issue has been resolved:

https://www.s****er.co.uk/news/news-...wer-full-time/



--
AnthonyL
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Default very low wind and wind turbines turning

On Tuesday, August 8, 2017 at 12:29:58 PM UTC+1, Caecilius wrote:
On Mon, 7 Aug 2017 13:56:27 -0700 (PDT), misterroy
wrote:

Am I correct in thinking that large wind turbines do not produce power when the wind speed is below 12mph?
Why on some days do they stop altogether and others they keep turning, even though there is hardly any wind at all?


It could be the wind gradient: the wind speed drops off quite a bit as
you get close to the ground. So depending on how high the blades are,
the wind velocity could be higher than at ground level.


there are calculators on the web for the wind gradient, and the effect is quite small, at low speeds anyway.
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