48-volt heating controller

Posted on 06/03/2012 by hugh

Here is a diagram for a simple 48-volt heating control system for a 3 metre ‘recipe‘ turbine.  I did this design for Dr Francis Greaves in Ireland.

circuit diagram for heating controller including LDR circuit by Solar Converters

Notes:

  • There is no battery but the voltage is stabilised by the bank of capacitors (recommended minimum 20,000 microfarads ,by connecting multiple capacitors in parallel).
  • The main heating load (lower right) is controlled by an LDR controller from Solar Converters (I can supply these too).  It’s important to connect the sensing terminals or it will not work.
  • The heating load can be resistors (such as 2 of these in parallel) or a water heater from TP Fay for example.
  • Use a rectifier to convert the 3-phase AC to DC.  Here is a nice simple one or you can use multiple single phase ones to do the job for lower cost.  Mount the rectifier on a heatsink.
  • A string of small resistors feeds the over-voltage trip relay.  You could use a potentiometer to adjust the tripping voltage if you want to spend more.  Or simply add resistors until it just stops tripping.  This relay protects the LDR against excessive voltage in gusts.  It will remain closed until the voltage drops right down.
  • When energised, the trip relay connects a dump load to the AC source.  This can be via another rectifier as shown, or you could use 3 such resistors connected in delta.  It’s easier on the relay to switch AC rather than DC.
  • I also show a brake switch that can for example be a big 2-pole mains voltage switch like this.  This is for parking and safety.  It stops the turbine.

It’s tricky to use a thermostat to control a DC load and it might damage the LDR if you were to turn off the heater but you could contrive a way to trip the relay on using a thermostat, thus stopping the wind turbine.

You could probably get better performance and higher peak power by adding another heater just after the main rectifier (in series with the DC stuff) before the trip relay wires branch off.  This would allow the blades to run a bit faster and give more power without adding to the current in the windings.   But it complicates the installation a little bit.

I see no need for fuses or circuit breakers here since there are no dangerous sources of high current, but be aware that the wind turbine could produce dangerous voltages if allowed to run without a load.  This is partly why it’s a good plan to have a trip relay.

Posted in construction, products/technical, wind systems tutorial | 7 Comments

Servicing the 6kW Proven on Scoraig

Posted on 02/03/2012 by hugh

I have just done a service on our local Proven 6kW (aka Proven 11, aka Kingspan Wind KW6) at the Council’s School here on Scoraig.  First time it has been taken down since 2006.  Installed in 2003 by Sangsters.

Nothing much goes wrong with this particular turbine.  The covers blew off in 2005, and this happened again last November (2011) and I finally got the go ahead to put them back on so I took it down yesterday, and sorted out a few minor issues.  Greased the bearings, and replaced some plastic bits and bobs.  Renewed the cable-ties and added a few to the covers.  Cranked it back up on its 15 metre free standing pole today (took about 45 minutes with a 3200kg Tirfor).

Click on a photo to see it full size, with extra comments in some cases.

 

Posted in my own projects, products/technical, Scoraig, UK small wind scene | 59 Comments

International wind turbine builders’ forum

Posted on 22/02/2012 by hugh

The Windempowerment web page has settled into a good stride, with interesting posts and lots of reference tools such as the World Map, Calendar and Member Organizations pages.

The forum is also worth watching for the latest questions and discussions amongst groups all over the world who are building turbines based on my designs or variations on them.

Posted in construction, developing world | 2 Comments

Some new web pages for homebrew windpower

Posted on 11/02/2012 by hugh

Here are some pages that are new, or at least some are new to me.  There are a lot more links on my old scoraigwind.com page.

Otherpower have a new page and a new web shop here.  Also buckville.com is the Dans’ new web site for workshop courses.  Their discussion board at fieldlines.com remains popular

A new arrival on the discussion board scene is anotherpower.com

Here is a Romanian web site for homebrew wind enthusiasts SIA electric offers a range of useful stuff including controllers that boost the voltage in low winds, allowing you to use a winding that has fewer turns and lower resistance.

For vertical axis fans in the USA here is a source of kits and parts

In the UK, V3 are offering parts of wind turbines, custom made and wind-turbine-supplies are offering all the bits and pieces you need to build my recipes.

Posted in construction, People, products/technical | Leave a comment

Engineers Without Borders conference small wind session video

Posted on 31/01/2012 by hugh

I went to Birmingham on 28th to meet EWB and to share experiences about using small wind turbines for international development work (and for having fun).  Lots of good chat.  This was the launch of their national small wind community of practice group.  They made a video.

www.windempowerment.org

Engineeers Without Borders

Posted in developing world, People, UK small wind scene, Video links | 1 Comment

Workshop Course on Scoraig in May

Posted on 28/01/2012 by hugh

WHAT
A hands-on wind turbine building workshop with Hugh Piggott.  These courses have been held since 2001, with small groups around 5-8 people building a wind turbine over a period of six days and testing it.  Activities include carving blades out of wood. winding and assembling alternators from scratch, arc welding the steel frame.  No previous workshop experience is required.  There is some informal discussion and explanation of the theory behind the design and wind energy for stand-alone situations.  During the week we shall tour some of the many wind and solar systems on the Scoraig peninsula.

WHEN
This year’s workshop course will run from Saturday evening 5th May 2012 and run to Friday evening 11th May with departure the next morning.

WHERE
The Scoraig Peninsula
About 70 miles west of Inverness in the north of Scotland, with no road access.  The easiest way to arrive is by small boat across one mile of water from Badluarach Jetty, but it is also possible to walk in around the cliffs.  The course is timed to fit the arrival and departure of the Westerbus service from Inverness at approximately 1700 on Saturday, returning the following Saturday morning.  Transport will be arranged to and from the Westerbus at ‘Badcaul Road end’.
More travel information – how to get to Inverness

ACCOMMODATION
Part of the package is bunkhouse accommodation with meals provided for the week at a cost of £280 each payable to Scoraig Teaching Group, a local charity that runs the bunkhouse.  You are welcome to bring a friend or partner if we have sufficient space.  Please let us know of any special dietary requirements although there may be a small charge for special meals.  The bunkhouse is about 10 minutes walk from the workshop location.

COST
The total cost for the workshop will be £320 for tuition and lunch (including VAT) plus £280 for accommodation for a total of £600 including £53.33 VAT (tax).  If there are sufficient participants then a student discount is sometimes negotiable.
DEPOSIT
A deposit of £100 has to be paid in advance to secure a place in the workshop.

WHAT TO BRING
Bring suitable clothing for workshop activities and wet weather.  Wellington boots recommended.  With any luck it will turn out dry – the weather is often wonderful in May.  Other suggested items are a camera and insect repellant.  Should you wish to bring tools of your own, that will be welcome, although tools are provided.

 

Posted in courses, Notices, Scoraig | 5 Comments

Inventor Doug Selsam

Posted on 27/01/2012 by hugh

This one is for inventors.  I mostly do not have time for them because they think they have got something new and I know they have just reinvented something old that never could work.  Doug’s inventions will probably never work either, but at least he has something new, and has studied the subject enough to understand it before telling the world that the designers who use old stuff that actually works have got it wrong.

or something.  Anyway his stuff is fun to watch.

more

Posted in People, products/technical, Video links | 1 Comment

Simple tower

Posted on 18/01/2012 by hugh

Thanks to Jan Wolstenholme (on an Irish coastal site) for this ultra simple tower design for those with very open, high wind sites and plenty of scaffold pipe.

“The main tetrahedron is made of  six poles which are two scaffold poles together. The base triangle is bolted properly in each corner, it has disappeared into the grass which only anchors it more, along with some rocks in the corners.
The other corners/joints are bolted or if the angles don’t work out, just lashed.
I have a small cross bar at the top to lean a ladder against for checking the pulley system.  The base of the tower rests on a flat rock and is tethered to the base to keep it in position when lowering and raising.
I tie on another rope to guide the tower when lowering. I can raise it and lower it single-handed in any weather and land the turbine neatly on the trestle really softly.
With more elegant steel tubes and a bit of engineering the whole thing could look better. And it could take a bigger load with just a stiffer pole and more gearing on the block-and-tackle. All parts re-usable and it barely cost me €100 on top of the old scaffolding, for pulleys and good marine rope.

The Ampair 300 can’t do much when the solar is whacking 900w into the batteries at 28v etc. But it excels in storms which is when we need its output.  I really take my hat off to David Sharmann and Co., excellent support (for the blades which they now have sorted) and the unit itself has run flawlessly for years. It has outlived all other small turbines in the area and even the big Vertical Wind Energy egg-beater up the road I think. ”

 

Posted in construction, People, wind systems tutorial | 9 Comments

Completísimo manual para el autoconstructor de equipos de energía eólica

Posted on 08/01/2012 by hugh

Thanks to John Furze in Denmark I found this lovely manual for building small wind turbines  “Energia Eolica” – Juan Ignacio and Sebastian Urquia Lus, published in 1982.

You can download it here

Unfortunately I don’t know Spanish so I can only skim through looking at the pictures but some of them are truly lovely, for example this one:

If anyone can lay hands on any of my old publications from the 1980s I’d be very grateful for scans.  There were some nice cartoons by Cathy Dagg in some of them.

 

 

 

Posted in Books, construction | 2 Comments

All readings are based on open current voltage and shorted load

Posted on 03/01/2012 by hugh

This is just a word of warning for those who are thinking of buying modified car alternators from http://www.hurricanewindpower.com/ or http://www.prestowind.com/

—-             I did have rather a nice photo of some alternators and parts here but Tim at Presto asked me to remove it.  Fair enough.  Click on the above links to see the nice photos and plausible sales talk.

Dear Hugh,

Please remove any pictures and content from your blog/website that are the property of Presto Wind(TM). You are free to exercise your opinion, but not to use our pictures and data, without permission. So called “car alternators” are absolutly fine and offer the customer an affordable alternative to building a RF alternator. Thank you Sir.
Best Regards,

Timothy Moeller, MSME, P.E. Ohio, Nebraska
Engineering Dept.

———

The specifications are not always completely clear on these web sites.

You will come across tables of figures like this

50 RPM- 18 volts x 0 amp = 0 watt

80 RPM- 24 v. x .25 amp = 6 watt

100 RPM- 32 v. x .50 amp = 16 watt

200 RPM- 72 v. x 1 amp = 72 watt

etc…

The watts figures cannot be simply used to predict the power that you will get from the alternator at a given RPM.  “All readings are based on open current voltage and shorted load ” means that these are not taken at the same time (as you would do to measure power) but under two separate artificial conditions.

In reality the alternator will not produce any power with an open circuit or a short circuit.  The useful data would be what actual power it can produce charging at 12 volt battery but you need to try and figure this out for yourself.  The results will be a lot lower than you might think.

In the above example the alternator can cut in at a very low rpm and produce 12 volts for battery charging, but its internal impedance is evidently very high which means that the output current is pitiful.  Current in amps to charge a 12 volt battery will be lower if anything than the tiny short circuit currents quoted in the above list.

These permanent magnet alternators can be useful for home-brew projects and a lot of people have fun fitting them with small blades made out of bent bits of metal.  But beware of the hype because these guys are out to sell you stuff, and not to make it completely clear whether it will actually work well for you.  A small turbine on your garage rooftop is not going to be able to catch much energy, and one of these alternators is not an efficient energy converter (any more than the bent metal blades) so don’t get high hopes of powering your house but you can have a lot of fun with them if you are realistic.

Posted in construction, products/technical, Rooftop madness | 17 Comments