How Does the Regulator on a Wind Genreator work to slow the speed of rotation?

[Mark Turner]

On Saturday my son and I installed a new "old stock" Rutland 913 on my boat (first learning - it would be nigh on impossible to do this on your own if there is any breeze blowing - its a hefty piece of kit). I also installed a Marlec Regulator that allows me to add solar later and to charge two battery banks. In the wind (F4/F5) the generator started work as soon as it was freed off, and mindful of the forecast for gales coming through on Sunday morning I turned the generator off at the regulator. Immediately the generator slowed to a much lower rate of rotation.

Now, it should be obvious from the title of this thread that my knowledge of how these things work is very limited, and I have four questions in respect of which I'd appreciate "an idiot's guide" level of response, if anybody who has the knowldge also has the time and the inclination to reply, please:

1) How does the regulator slow the generator?
2) Is it bad for the generator to be left switched off for a couple of weeks? (The manual says not to tie it off for extended periods)
3) Is the regulator drawing current from the batteries (which are not being otherwise charged) at a significant rate in slowing down the generator.
4) Was I being over cautious in switching it off in the light of the forecast (F8/9)?

Thanks for any help,

Mark

 

[Spirit of Glenans]

1)With absolutely no technical knowledge in this area, I would hazard a guess that the regulator provides a load which will absorb the excess energy being produced. The increase in magnetism thus produced in the field coils causes an increase in the wind energy required to turn the generator. In the absence of an increase in wind speed, the speed of rotation will be slower. The only example I can think of is the effect you experience when switching on the A/C in a car; the engine note changes as it has to produce more power to turn the alternator.
2)Dunno
3)Definitely not
4)I'd say not. People on neighbouring boats will be grateful

 

[Mark Turner]

4)I'd say not. People on neighbouring boats will be grateful

Some wind generators on neighbouring boats were spinning very fast, others slowly - don't know whether the latter just had full batteries or were switched off. If they are all going at full pelt together it would be quite a racket, I suspect. On my midstream pontoon we don't get many overnighters!

 

[Giblets]

One point when turning the genny off is that you have to feather it into the wind so that the blades stop turning before you turn off the regulator. There is a small hole in the vane for attaching a cord to so that you can pull the head round for feathering.

 

[Storyline]

1. Not sure, have an idea but do not want to make myself look stupid as others will be along in a minute to explain it properly.
2. Do not think it would be very bad but the very helpful guy at Marlec said it is much better for the bearings if the generator is allowed to rotate and not be stationary and exposed to the elements.
3. Do not know (see answer 1) but guess none as it is using the power of the very powerful magnets/coil (like an electric motor).
4. No, the generator automatically free wheels when the wind gets too strong but as you will find out one day in a gale it produces the most unpleasant screaming noise. Edit : this is nothing like the normal noise at high speed - it is a scream and quite alarming the first time it happens.

Just to add that you should not stop the generator using the regulator in anything much over a gentle breeze. Use a broom handle/boat hook to (carefully) turn the vane part across the wind until it slows and then either get someone to turn off the regulator or tie it off (which I do overnight) if gales are forecast. There is a hole at the bottom of the vane that some people tie a short loop of line to. I don't, I use the hole to stop my broom handle slipping off.

 

[JumbleDuck]

1)With absolutely no technical knowledge in this area, I would hazard a guess that the regulator provides a load which will absorb the excess energy being produced. The increase in magnetism thus produced in the field coils causes an increase in the wind energy required to turn the generator. In the absence of an increase in wind speed, the speed of rotation will be slower.

It may well just short circuit the output, which does the same thing but more so. I have a Bosch cordless drill which "locks" that way, and it's standard to short analogue meters when carrying them around to prevent the needle thrashing around too much.

 

[jerrytug]

Marlec will themselves answer your questions.

 

[Storyline]

Also meant to say I understand the effort it took you to install it. The only ommission from the otherwise excellent documentation was some tips as how to lift it into position and then lower it square onto the pole. In my case it also took two of us and some brain power to ensure I did not go plunging off into the water complete with generator. Think we used a halyard and a line attached to the backstay with a running caribiner but cannot be sure.

 

[Giblets]

Can I claim a "Lakesailoring" against Storyline?

 

[john_morris_uk]

Our wind generator is slowed by shorting it out. The back emf as it drives a short circuit makes the blades slow down. You don't need to feather ours before you throw the switch, but ours is a different make (Superwind)

 

[GrahamM376]

Our wind generator is slowed by shorting it out. The back emf as it drives a short circuit makes the blades slow down. You don't need to feather ours before you throw the switch, but ours is a different make (Superwind)

Same with our Aerogen4, just insert a switch to short the wires. In strong winds it does continue to rotate although much more slowly and I wonder how much power is being fed to the shorted wires, maybe able to generate heat. LVM instructions are to tie it off if leaving the boat for some time or if very strong winds expected.

 

[john_morris_uk]

Same with our Aerogen4, just insert a switch to short the wires. In strong winds it does continue to rotate although much more slowly and I wonder how much power is being fed to the shorted wires, maybe able to generate heat. LVM instructions are to tie it off if leaving the boat for some time or if very strong winds expected.

No instructions to tie our Superwind off but I expect other manufacturers have different guidelines. You need a changeover switch to apply the 'short' as otherwise (obviously) you're shorting the batteries!

 

[GrahamM376]

No instructions to tie our Superwind off but I expect other manufacturers have different guidelines. You need a changeover switch to apply the 'short' as otherwise (obviously) you're shorting the batteries!

The switch goes across the feed between the genny and the split charge diodes/controller so no chance of shorting the batteries. The outputs from the diodes are fused anyway so additional safeguard.

 

[Mark Turner]

Marlec will themselves answer your questions.

Sounds so obvious when I see it written down!

Thanks

 

[silver-fox]

1) How does the regulator slow the generator?
2) Is it bad for the generator to be left switched off for a couple of weeks? (The manual says not to tie it off for extended periods)
3) Is the regulator drawing current from the batteries (which are not being otherwise charged) at a significant rate in slowing down the generator.
4) Was I being over cautious in switching it off in the light of the forecast (F8/9)?

Thanks for any help,


I have been using the equipment you describe since 2008. As previously stated Marlec will provide you with precise answers but here are mine for 2-4

2 Yes, the rotations of the generator helps prevent the ingress of water into the bearings
3. No it does not draw current from the battery
4, Yes you are being over cautious mine has never been switched off in 6 years and has been in wind speeds of 55-60 knots on several occasions

BTW - When your batteries are fully charged you will notice the genny slows down as the regulator prevents overcharging

 

[john_morris_uk]

The switch goes across the feed between the genny and the split charge diodes/controller so no chance of shorting the batteries. The outputs from the diodes are fused anyway so additional safeguard.

Aha, all understood. It's wired in a very different way to ours where the diodes are built into the generator that feeds the controller that feeds the batteries. (No splitter; I only charge the domestic bank from the wind generator.)

 

[pampas]

Regarding the amount of power when switched off. Will be the max i.e. the rated full load of the generator if simply shorted. Those that slow down progressively have a control system that is related to the battery voltage and/or the max rotor speed the manufacturer has allowed for.

 

[JumbleDuck]

Regarding the amount of power when switched off. Will be the max i.e. the rated full load of the generator if simply shorted.

<polite cough>

Actually, if it was shorted the generator would be producing no power, as there would be no volts. In practice there will be a small voltage across the output, but the power produced will still be very low.

 

[john_morris_uk]

<polite cough>

Actually, if it was shorted the generator would be producing no power, as there would be no volts. In practice there will be a small voltage across the output, but the power produced will still be very low.

Quite.

A function of the resistance of the shortcircuit and various factors involving losses in the coils etc of the generator. A tiny amount of 'power'.

 

[rob2]

I had the smaller model and would use the electrical "brake" to make it easier to turn it across the wind and tie it off. I used to tie a mailbag over it so that it wouldn't vibrate in the airflow, which is what makes the bearings wear.

Rob.