Sunday, August 15, 2010

Making a stator

Stator is center part of a PMA (Permanent Magnet Alternator). It is in the stator that a current is formed. The stator consist of a number of copper coils resin casted into a circle. The number of coils in a stator depends on the number of magnets on a rotor. To make a 3phase alternator the number of magnets divided by the number of coils has to equal 1 and 1/3-ds.
The easiest way ro make coils is by using a coil winder. It consists of 4 main parts and is easily manufactureable at home. The copper wire that is used to wind coils is chosen upon the voltage requirement for the system. The copper wire can be bought at different thickensses, measured commonly as #XX (x-means numbers)gage. A wires cross section roughly halves everytime the wire size goes up 3 times. The voltage of the turbine directly relates to the number of turns in a coil. If you double the turns in a coil you double the current. If your planning to make a 12V system you should know that for that you need the thickest wire, it is resolved with using two strands of wire and connecting them as one.

Saturday, August 14, 2010

Alternator

A common misconception about wind turbines is that they are generators, as in wind generators, in fact most of the turbines produce alternating current or AC not direct current as in DC. The main reson that AC is used in wind turbines is that it is much simpler and reliable to build an alternator than the same rated output generator.
I am building a PMA type alternator ( Permanent Magnet Alternator ). I made my decision to choose to build a PMA mostly because of it's simplicity, the way a PMA works is just so foolproof that even a child could understnd it.
3phase alternator
If you have even the slightest imagination you could visualise that the magnet ( white with N and S labels) turns and by doing that it's magnetic field turns with it. When a magnetic field moves thorough a coil it generates electricity in the coil ( marked as red green and blue, the violet is earth or ground).

But by generating alternating current it should render itself useless as a DC source? Actually no because as you know from the physics class the AC is a wave that flips between positive and negative. When we eliminate the wave from the negative side we have been left with a wave on the positive side, but the minus wave is missing. For thet we can use full wave rectifiers, they convert the minus wave to a plus wave thusby keeping the voltage wave on the one side of 0 line, and so by making AC into DC.

Friday, August 6, 2010

Planning to build a wind generator

Things that are needed to build your own wind generator:

First of all the most common generator type is the 3-phase generator for that you need the number of magnets divided by the number of coils to be exactly 1 and 1/3-ds. For example 16 magnets divided by 12 coils. Also the coils can be wired mainly in 2 distinct formats first a star format that is used mainly in low wind speeds and delta format or configuration that is used in higher wind speed. The different wiring configurations allow the generator to achieve higher efficiencies in different winds.

1.-Magnets

N50 2" x 1" x 1/2" Block, Package of 24 Rare Earth Neodymium Magnets
Magnets are the core pieces of a generator, the stronger the magnets the stronger the generator. I suggest that you should get the largest you can afford, but for the starters you could choose magnets accordingly. Preferably they should be about these dimensions, 2 inch by 1 inch by 0.5 inches. But they could be a bit thinner, depends on what you can afford. 
Magnets are glued to a rotor that spins and when magnets move the magnetic field moves with them, that creates electricity in the stator.

2.-Copper wire
Tarnish Resistant Bright Copper Wire 24 Gauge 30 Yards (27.4 Meters)Second essential thing is the copper wire that is used to make the stator. Stator doesn't move, it relies on the rotor to spin instead. The copper wire has to be in an ellipse or molded to represent a sector. The thickness of the wire dictates the current (measured in amperes) that generator produces.The number of spools in one coil dictates the voltage that the generator makes. 
3.-Resin and hardener
Castin' Craft Clear Polyester Casting Resin - 32 OuncesThis is used to cast the stator and rotor. Most of the times they sell you only resin without hardener or catalyst. So always check that when you buy they are sold either together or it is said what kind of hardener is supposed to be used. Beware that this resin could be unsuitable for a wind turbine. Because it may not wet glassfiber. 
4.-Steel tubeing
It is essential to own or buy some steel. It doesn't matter if it's new or used, or even scrap steel. To make towers for the wind turbines, ususally the metal pole, with guy wires for safety, route is used. Also the furling system that helps the small and big wind generators to survive high winds that are out of the safe operating limits of those units, is made of metal mostly.
5.- Tools

One essential tool that you most probably can't do without is a welding machine. An anglegrinder for smoothing out welds and cutting steel is probably a good idea to own too. A drill for attaching screws and drilling holes should already be in every homeowners garage or toolbox.

Windenergy in Estonia


Estonian government is planning to sell AAU's (Assigned Amount Units-meaning CO2 emissions) in 23 million euros worth to Spain. Most of the money is planned to be spent on new wind farms in total output of 25-30MW.
If only the government would subsidise mi plans on building a wind genny. In mi opinion this is a grateful news to Estonians because electricity in Estonia is mainly produced by burning oil shale, which is a big pollutant if burned, also the power stations where the oil shale is burned aren't very efficient.
Currently there are several wind farms in Estonia, which are producing according to the manufacturer in excess of 78MW  of electric energy. Even though current production should be 70+ MW there are still plans in development for more then 570MW worth of wind farms to be developed in Estonia. But still on average whole of Estonia requires about 1100MWh of electricity every hour, so in the best of winds all of the build and developing wind farms would not feed the need for electricity.

Tuesday, August 3, 2010

Solar water heater


I just finished building mi 1tonne solar heated water reservoir project. I used an old USSR era radiator that I had laying around at home. From a local hardware store i acquired some fittings and voila a days work was guaranteed.
The work was quite straightforward cut 3 holes, 1 for hot water from the radiator in 1 for cold out and one tap for getting the water out. The first time i filled it with tap water i had some issues with the radiator because the spirals needed to be level, but once i figured that out all went well. In just 15 seconds the power of sun became obvious the cold in was 8'C and hot out was 47'C that's a 39'C increase in water temperature with no carbon spilled to the atmosphere.
Now that I have proved to myself that this concept works I think its time to start planning for the sun water heater to be used to heat mi tap water in the house.