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WindMill

 Created: 12-07-02, Revised: 06/10/2014, 17/05/2014
 
Power at Brickhurst Farm

Design Notes on a Wind Turbine for electrical power generation

    

Solar pannels seem more practicle.

The system Wind Turbine power generation, storage and distribution

The existing Wind Turbine power generator (picture above) uses a 12V dynamo includes a power diode and storage is with a 12V Milk float Lead Acid Battery. The problem with this is that the voltage output is probably inadequate, and any case the wind speed required to turn the prop is very high, which rarely occurs at Brickhurst.

We hope to provide power for a couple of PCs and lighting and battery charging e.g. phones - about 3kWhours/day. Advice received is that we will need a back up source such as a few pv panels - or construct a very large wind turbine. At the present time we shall not be including photo voltaic panels though.

We considered two sites, one was where the existing wind turbine is situated near the chickens, alternatively the higher site is near the office and the path, but this second site has more trees around it. The second site has the major advantage as far as cabling and control electronics of being near the office, but we shall pursue the existing site. The plan is to construct a three blade turbine, to produce an average 100 Watts. If the batteries at Brickhurst are not beyond use then these will be used to store power giving you at least a few kilowatts a day.

The first stage being to charge batteries and optimize the generator. We have got quite a lot of information from the web. There is a list of things we need. We will also need some help.

The pole for the wind generator has some rotten wood at the base that needs replacing then the existing dynamo may be connected up to at least keep the batteries in a reasonable state of charge. I shall mount the blocking rectifier diode (MR1215YL?) to a heat sink, though this will be under sized, ready to put back with the dynamo. The termination's have turned to isolating rust. There will need to be some sort of shed to protect the equipment and batteries.

Other links
 

The system Wind Turbine power generation, storage and distribution

System diagram;    Standards

        Wind Turbine.  
                |
          Coupling
               |
           Gearing
               |
   Main Generator.  Low Power Generator.
        |                           |
        |    -------------    | -  Flexible cabling for power and control.
        |                           |
   Junction at the top of the pole
        |                           |
        |  ----------------  | -  Non flexible cable.
        |                           |
   Fuse, Over Voltage protection, and Rectifiers (At the bottom of the pole).
           |    |    |    |
           |    |    |    |
  Wind turbine power output optimization and battery charge regulator cut-out .
        |
        |-------- Storage battery's + other battery which may occasionally need charging.
        |
        |                                                                                            Alternative power supply
        |                                                                                                           |
   Inverter 250W ----------------------------------------------------------------------------'
        |
        |_______________ 100 - 400V DC Distribution to office, kitchen etc.
        |                   |
        |                   |
        Office         Kitchen _____>
        |
        UPS (1 kW) + extra Batteries + input power limiting
        |
        Equipment.     (Low power lighting, and Laptop PC's)
 

WIND TURBINE

A three blade turbine is the best practical design, although multi blade high strength turbine is most efficient. This mounted using a vehicle front wheel hub assembly has a strong bearing assembly. Making a variable pitch turbine seems impractical, but such a design could accommodate high wind speed protection. A Folding Delta shaped turbine as used on a model girocopter is another variable pitch possibility. We have decided to make are own fixed pitch turbine.

A solution Hugh Piggott's reproduced was to construct variable pitch prop. The pitch starts steep and a governor mechanism moves the prop pitch to normal position, when the prop turns. It has a further refinement in that at high speed the governor works against a heavy spring which continues to change the pitch to a flat position to slow it again. My refinement would be to keep the starting governor as before, but pivot the blades at the leading edge and allow high wind pressure to push the blades back to a very steep angle to let the wind blow through.

Coupling - the constant velocity coupling + another coupling to the generator needs to insure vibration is minimized at the generator. Alternatively if a two bearing rear wheel hub were found from a rear wheel drive vehicle this would give a fixed shaft extension for mounting, for toothed belt drive

Gearing - with a low friction toothed belt. This gearing could make the turbine starting difficult, although a low ratio toothed belt of 1:4 should be ok. A vehical timming belt is 2:1 coupling, but might also provide other ratios if water pump is also included (such as a VW Golf engine).

Using a toothed belt or cycle chain drive should be more efficient than the V belt normally fitted in cars. The problem is that  advice received is that there would be little drag from a direct drive brake drum permanent magnet alternator compared with resulting from an up-ratio belt drive to an alternator even without field.  Advice was that 1:8 gearing, at 3m/s wind, and 2.5m turbine would stand no chance of starting, but 1:4 should be ok with other advice but that may be with a variable pitch turbine.

Drew says The average wind speed at Brickhurst is about 5m/s (European Wind Energy Atlas), which is about 11 mph, which in wind generating terms is not much. Also the wind will only be above 20 mph / 10 m/s for 10% of the time. The energy that the wind contains increases with the cube of the speed, so that there is a major difference between 10 and 20 mph. But we also want to generate a reasonable amount of power, about 3kWhours/day in order to provide lighting and power PCs. The existing dynamo and small ( 0.9m ) 2 bladed propellor are great for the West of Ireland, where there is a constant high average wind speed. The small 2 bladed propeller is very good at converting wind speed into dynamo revolutions - it probably has a tip speed ratio of about 6, meaning that for every metre a second of wind the prop tip moves 6 metres, and because it only has a diameter of 0.9m, this corresponds to 2 revolutions of the dynamo. Thus a 20 mph wind equals 1200 rpm. And the wind has sufficient energy to be generating significant power most of the time - something like a Kilowatt at 30 mph, allowing for aerodynamic and mechanical inefficiencies.

An effective generator for Brickhurst needs to
a) have a large enough diameter prop to capture enough energy from the wind at 5 m/s or so
b) operate reasonably efficiently, to convert the wind energy into electrical energy
c) be reasonably simple to build, given lack of experience and time ( and money? ).

Drew did some calculations how big the propeller needs to be to capture enough energy and 2.5 metres / 8 feet in diameter seems about right, based on an average wind speed of 5m/s having about 130 watts / square metre of energy - thus about 640 watts. Because the wind above 5 m/s has a lot more energy than below the power potential of an average 5m/s wind speed is significantly more than if there were a constant 5 m/s wind. Once aerodynamic and mechanical inefficiencies have been included the electrical power output this means an average power output of about 200 watts, enough for 3kWhours/day with a bit to spare - very roughly!

The choices in technology are between multi bladed and 2 or 3 bladed props and retaining the existing dynamo with gearing or building a new one that operates more efficiently at low revs. Multi bladed props capture the wind more effectively at low speeds but are generally less aerodynamically efficiently ( 30% ) than 2 or 3 bladed props ( 45% )  - there is more turbulence, which means less energy to the dynamo. There is a company in Denmark that has made very efficient multi bladed wind generators ( www.windmission.dk ) but they have used a lot of aerodynamic knowledge to design the prop blades that they mould out of fibreglass - for us to do this would be a lot of work.

Use the existing dynamo? To get enough revs would mean designing and building a gearing system - maybe a 5 to 1 ratio - to get the 1000 rpm plus that the existing truck induction dynamo needs. Something else that comes to mind is that this option would need considerable energy to start it rotating, to overcome the inertia in the dynamo which will be multiplied by the gearing.

Drew had been looking at Hugh Piggott's designs for small wind generators on his web site (www.scoraigwind.co.uk ). He has been building props and dynamos for 20 years plus and his most recent examples (see descriptions of the Seattle and Scoraig courses on his web site ) seem to be definitely in the right direction. They are quite low tech and easy to make with low cost components, but also efficient and tough. The most recent ones have 3 bladed wooden props of 8 feet or so
connected to axial flux "air gap" alternators that are home-made and use transit axles for the prop to rotate on. They seem to produce about the right amount of power at low winds - apparently 100 - 200 watts at 10-15mph, whilst working efficiently at higher wind speeds. They also have a built in rectifier and turn out of the wind automatically at high wind speeds. There is also plenty of information available about how to construct them and Hugh is an email away. The only question I have is about optimizing them for 5m/s winds - how much wind do they need to start? Hugh Piggott's Brake Drum Alternator seems far superior in that it's efficiently is improved by using iron, and therefore very much less copper wire is required.

Another variant I have have seen is to have lots of small generators and turbines e.g. 100mm dia.

The design being talked about is from the Hugh Piggott generator built at the May 2002 Scoraig wind generator building course. It seems that even though it has a permanent magnet dynamo it will start working at 3m/s and stop at about 10 m/s (working on basis of tip speed ratio of 4) - 150 to 300 rpm. The Drew says design seems more optimized to light winds than he would expect for a Scoraig design... but very good for us.
 

Generators

Probably the most suitable type of generators are brush-less permanent magnet generators. Stepper motors, motorbike generator (magneto), and Hugh Piggott's brake drum alternator, or air-gap are examples. The latter being less efficient in resources used, but both Hugh Piggott's alternator's are most suitable in that there is no turbine resistance when it's not generating. Similarly a vehicle alternator, dynamo, or, induction motor offer no turbine resistance when they are not generating, but only the induction motor has similarly very low servicing requirement, due to it being brush-less, and is commonly used in higher power wind turbines.

ELECTROMAGNET TYPE GENERATOR
- Alternator:
The battery provides important protection for the alternator in that when over generation occurs, due to speed or load change, the battery clamps the voltage to a safe level. I found experimentally that the battery sense wire provides a second function of preventing alternator from generating unless a battery is connected this is obviously is intended to protect the alternator.

I found experimentally that for the generator to generate power by providing 10V, 2A to the field winding, which made the rotor very stiff, the inertia was heavily damped. The output hand turned at 50 RPM was 0.5A short circuit and 2V open circuit, much less than power needed by the field. I also found that if you wire the main and the secondary outputs together and supply them from 10V once again the Alternator draws current and the rotor becomes stiff, as you would expect. In this case the main output continues to draw 100mm from the battery.

The Alternator regulator is quite easy to rewire, and it would be possible to add components so that it can be turned off remotely or the regulation voltage increased and varied according to the battery voltage on the ground, it is therefore only necessary to have two very heavy sets of cables to the ground and a small number of control wires. A second permanent magnet type generator such as a magneto or stepper motor is still necessary as this can be used to monitor prop speed and
would generate 10-100W where the main alternator would not be efficient, that power would also be used to control the main alternator.

The advantage I see with an alternator is that the shaft turns freely, when not generating as there is no magnetic holding force, it has more poles (12). Rewinding an alternator, would be effective and should mitigate loss of efficiency if more copper is used. A car alternator runs to hot to touch at full power. Using a 24V Alternator would also be effective, it may start generating 12V at 500 RPM. Therefore gearing should be more reasonable at 1:4 or less.

Following what I have read (see below) on induction generators, that similarly a dynamo or alternator with field winding wired directly to the output produces power output proportional to the cube of RPM when operating below it's rated voltage and RPM. This is very handy, the alternator seem to produce at 60% of full power at 1000 RPM, I guess below this RPM the Alternator's output will conveniently fit a cubic law.

Estimation of m/s at 1000 RPM if we assume that an alternator produced 500W at 1000 RPM. From Drew's arithmetic above 200W would be produced at 5m/s. 500W would be produced at 6.8m/s, and this would be at 1000 RPM.
 

INDUCTION GENERATOR
Induction motors with capacitors are said to be very suitable for wind power generators, you need to add a capacitor to magnetize the rotor. The capacitor(s) must be fitted close to the generator to minimize power loss. Although only a few hundred watts a fridge compressor motor is fairly ideal in that they are low RPM, and weather-proof. Because of higher voltage produced power could be cabled to where it's need to charge batteries. This type of generator like permanent magnet types are very long lasting as only the bearings will wear, but like the dynamo or the alternator it uses it's own power to create the magnetism it needs to generate power though. A good source of suitable capacitors could be from old fluorescent light units.

I read that Induction Generator output power matches a cubic power law. This makes the load management very simply a current limit proportional to the voltage. Therefore compared to a PMG, or alternator with voltage limited by core saturation, no squaring or cubing circuit is required.
 

PERMANENT MAGNET GENERATOR
- Brush motor:
Using a washing machine motors as generator is unlikely to work as they are two pole for very high RPM .

A couple of wind generator 200W/500W in Wales use gearing and a very large permanent magnet computer tape drive motors. These 200W generator uses 1:5 gearing and start easily in a light breeze. But the author of this design says 1:4 gearing would work better.

- Non brush (synchronous motor or generator):
A two phase, 200 step, stepper motor. This is identical to a permanent magnet alternator, such as the brake drum type, except it may be an order of magnitude more efficient. The output voltage would be very low at 10V, 3A at 150 RPM (guess no testing done). The particular maker Sanyo-Denki http://www.sanyo-denki.com/ makes very efficient ones. The output voltage rises proportionally to RPM the platues the maximum RPM is 3,000RPM. I have new information that a stepper motor will generate a decent power at 30 RPM, there will not be a very high voltage e.g. levelling at 10-20V? The inertia is very low, but the turning force needed is high, but drops once started to turn. This is because the magnets are very strong, and the output is 100 cycles per phase per revolution. Incidentally don't be tempted to look inside a stepper motor at it could  seriously demagnetize the rotor.

I have looked further at the Scoraig generator. It is about 50% efficient at full power is quite poor and is due to copper losses, but no iron or eddy current losses as there is no iron in the power coils. There are commercial motors designed this way exist (Portescap), there are brush motors which have coils formed in to a tube, which looks like stiff woven copper, and they rotate between permanent magnets. These motors therefore have exceptionally low inertia, but it is the heavy magnets with move in the Scoraig design.

The Scoraig air core generator:-
    Air Gap: coil thickness 13 mm + resin covering + at least 2 * 1 mm gap to magnets. The total air gap could be 17 mm.
    Each phase comprises: 2 * 100 turns of 1.7mm diameter copper wire.
    The mean length of one turn is: 320mm = 4 * 80 mm.
    The total length of both coils (per phase): 64m = 2 * 100 * 320mm.
    Resistance of 1.7mm dia. (16 SWG) copper wire is:  0.008R/m.
    Total resistance of each phase is: 0.512R = 0.008 * 64m.
    The Scoraig generator produces 40A at 12V maximum in May 2002. This would be delta connected in which at one instant 1/3 of the current flows through two windings in series which are in parallel with the 3rd winding carrying 2/3rds the current. Therefore 40A total comprises 13.3A + 26.6A. Voltage drop is therefore 13.6V = 0.512 * 26.6A.

    Efficiency is: 50.7% = 100 * 14V / (14V + 13.6V).

The Scoraig brake drum generator design improves on this by:-
     Each coil comprises: 24 turns of 0.8mm diameter copper wire 20AWG/21SWG. (assumption)
     The mean length of one turn is: 160mm = 4 * 40 mm. (assumption)
     The total length per coil: 3.84m = 24 * 160mm.
     Resistance of  0.8mm dia (21 SWG) copper wire is: 0.034R/m.
     Total resistance per coil is: 0.13R = 0.034 * 3.84.
     There are 10 coils per phase, and 30 coils total. I suspect these are connected in a combination of series / parallel.
     The coils are laid and stuck to the back of a stator - possibly a fridge motor would provide suitable materials.
     Air gap magnets to stator is 4 mm allowing 2.5mm for the windings. Therefore total air gap is 8 mm.
     20 Magnets are 20-25mm thick, and 32mm wide. This is variable between implementations

     Efficiency for one example of a 20 pole machine can produce over 1 kW at 320 rpm with approximately 70% efficiency.

Comparing the Air core V the brake drum Generator's:-
1) It has more coils and magnets (phase and poles), 8 magnet pairs are increased to 20 magnets. This should reduce the amount of copper required which is high. The design is also improved by reducing the comparatively large air gap. But this would require more accurate work. It has more optimally (conventional) 3 phase arrangement. losses due to mismatching in winding voltage and phases could be mitigated by fitting more rectifier diodes, one for each winding, these would be cheap convenient low current types.

2) The advantage of this design is that there are no magnetic force from the permanent magnets to overcome initially is maintained. This is Like the car alternator with the field wind turn off. This is achieved by using an iron core (out side of a motor stator) that does not have high points for the magnets to be attracted to. In any case a nudge over the initial magnetic resistance and the magnetic forces diminish greatly. In any case large, 2 mm, air gaps are required to accommodate movements in the bearing due to forces on the turbine blades.

3) The output power limit of 400W is due to the coils being potted in resin. Allowing air to flow around them and allowing iron stator which can also conduct heat is a benefit of the Brake Drum design. In any case thermally conductive resin is available which would improve the power output in both cases.

4) The both designs may be improved if the shape of the magnets were wedge is the air core design and curved in the brake drum design. Pieces of sheet mu metal could be cut in to the optimal shapes and placed on the magnets. Mu metal is highly magnetic conductive sheet, it is used to magnetically screen CRT's such as in a TV.

5) The air gaps have been made large to accommodate play in the bearing, this play is a disadvantage which indirectly driving a generator would not have.
 

Power Control
The generator load should be very light to allow the prop to start turning. The controller would limit the power to the cube of prop rpm, or wind speed. Another factor often not included is that the power out is proportion to square route of air density (note added 2010).

The output power generated from an induction generator with capacitors follows a cubic law, when loaded with a resistive load, conveniently. It is possible the below normal voltage vehicle dynamos and alternators do the same. The power control is therefore simply to limit the current drawn from the generator to a fixed proportion of the voltage generated. This means the control system does not require compensation. At low RPM the the induction generator will need extra capacitors added to extend the power generating RPM range. My plan is to switch the extra capacitor out when generator starts to generate, the loading in the case won't be matched and the power generation will operating in a discontinuous mode.

Alternative 1:
Any of the alternators would need either squaring circuit (e.g. RC4200) to limit the current to the square of the voltage generated. But the advantage would be that the power supply would not need to operate over such a wide voltage range as the induction generator above.

Alternative 2:
Vehicle Alternator can be controlled by varying the field current. The control could be by variation of the tacho IC suggested on High Piggott's web site, and in addition a cubing circuit with compensation. The cubing circuit would be somewhat unwieldy. A second Generator such as a Stepper motor, or magneto would generate low power for the controller with the surplus light wind power generating. This may also be beneficial with the induction generator.

My electronic design requires a small modification to the alternator. One of the connections to regulator is disconnected and then re-connected to some new circuitry. The new circuit limits the output power. This is so that the prop speed does not drop below the optimal 1/3 rd of that expected from the air speed. The optimum quoted in Hugh Piggott's notes.

Controller conclusion:-
The advantage of the brake drum or induction generator's is that voltage output is proportional to RPM, but there is a disadvantage in that the power supply efficiency would be severely compromised because it has to accommodate a wide input voltage range. I guess power supply efficiency could be 70% - 98%, but that is a lot of power that would need dissipating. In order to accommodate the range in the case of the induction generator I'm working on a design using a IGBT's. 

WIND POWER STORAGE - GUSTs OF WIND

Ideally the voltage should be high. we have 10 new but seriously deteriorating 12V batteries. These could be pared up to form 24V pares. The batteries can be charged in parallel. By there nature lead acid batteries don't equalize there charge, when connected in parallel. Therefore a discharged battery won't discharge a charged battery very much, unless it's faulty. This is a very useful feature.

The 12V Milk Float and other batteries may also be included as I plan to make the distribution up inverter draw most current from the 12V side which is at the highest voltage. Therefore not only will all batteries contribute to gusts of wind energy store, but will also be the place to keep spare batteries charged.

The batteries at Brickhurst though good quality are deteriorating badly. I have found such a battery and have been able to restore some capacity after five days. This 12V, 48Ah battery remained drawing less than 5mA after a few days charging, in other words seemed well beyond recovery. I more than doubled the charging voltage to 32V and the current drawn increased to 25mA then to 500mA after 4 hours. Returning to 14V charging the charger current increased 20 fold to 100mA. After another 4 hours of charging at 32V then 24 hours latter the battery was charging at 400mA, and the terminal voltage is 11V. It recovered as much as possible after two weeks and has been holding a charge for a number of months.

I think the best strategy for charging these batteries will be to charge them in parallel properly at 14V. As batteries become fully charged we should disconnect them. I shall include a modification in the charger so that when the charging current is very low the voltage rises above 14V. This should recover the batteries which are deeply discharged.  

POWER STORAGE TO DISTRIBUTION

A Up inverter - would run all the time that there is wind or the battery is in a reasonable state of charge. This produces a low continuous 250 Watts for distribution. The inverter would protect there batteries by shutting off when the battery charge drops to low point, and restart the inverter when the battery has recharged enough.

I have some PC power supply parts now and plans to make a 200W inverter for 24V to 300VDC. The inverter uses
power from two sets of 12V Batteries in series, drawing current from the set of batteries which are in the best state of charge. Once I am more certain about voltages I shall purchase other components such as the power transistors. There is a variation of this Half bridge design with produces more power and better efficiency from 48V.
 

POWER DISTRIBUTION

The copper losses in 500M of cable are quite high at 8 V/A to 20 V/A for 2.5 mm2 (squared) and 1 mm2 cables respectively.

* For 1 mm2 stranded cable the resistance is 20 R/KM (ohms per kilometres), this is the similar to lighting cable. 1 amp load would give a 20V drop.

* For 2.5mm2 stranded cable the resistance is 8.2R/KM, this is the similar to 30A ring main cable. 1 amp load would give a 8V drop.

Evidently increasing the current to 10A (2.5KW) gives ridiculously high losses, this is a biggest problem. The solution is to carry 1A, 24 hours and use up to 10A from batteries and a local UPS for two hours a day.  

POWER USE

The main power would be stored where it is needed with local UPS's and additional batteries. This could give you a few hours a day of up to 2.5KW, and once again the UPS will protect its batteries.

The local UPS's will need to be modified so that they progressively draw less current as the input voltage reduces, rather than shut-off. I think this may not be practical, it may be necessary to either charge batteries or run equipment from local batteries. Therefore the UPS's may need to be rewired so that direct output from input power is not permitted. This is because the input power is only 250W maximum, and one bypassed UPS will steal all the power from the wind generator.

The additional Batteries could be 72V.

International Standards

Additional radio interference filtering should be added, this can be done by winding the output cables around a piece of ferrite material. Ciricuit stability and noise should be tested and measured. These measures should be written down (technical construction file) along with any tests we do and kept as our reasoning why we thing the generator conforms to EU standards for electromagnetic compatibility.
 

Dynamo

The dynamo is said to be a Lucas dynamo, presumably for a lorry, and has been used on the wind generator since 1922/3, in a windy north coastal part of Ireland. It was decommissioned in the (1950's ?) 20 years ago. This four pole dynamo only has two not four brushes I had expected to find in a four pole dynamo. I could see no sign that another pair of brushes had ever been fitted. I can only guess that the opposite segments of the commentator are wired together, instead of having four brushes. The field winding is directly connected to the power generation at the brushes, there is no regulator, or cut-out. I suspect that there never was a regulator, because of its age, and being a more less state-of-the-art lorry. It is also possible that there was no battery either if it was a steam lorry. The dynamo has been maintain It needs engine oil for the front bearing once every six months, there is a oiling point for this and a grease point at the back. The grease point should be greased about once a year. The dynamo is said to be rated at 12V, 90A (1 kW), and it has had radio interference suppression added. The Dynamo probably should rotate at 1000 RPM to generate at full power, and the maximum may be 5000 RPM.

I looked at some 1930's car manuals, most cars had dynamos with both a regulator and a cut-out. The exception was the cheapest model such as Austin 7, which had a cut-out, and a high and low charge rate switch. As the dynamo is pre 1922 it is probably wound to generate about the correct voltage over most of the engine speed range. It must have had a cut-out though, as we found no other mechanism to disconnect it from the battery. There have been modifications I would like to see what voltage and current it now produces.

Maintenance - Commentator type generators require cutting of the insulation to just below the copper segments with a hacksaw blade, but avoid scratching the copper segments. The commentator and brushes are in good condition.

There is a rectifier diode fitted in line with the cable at the bottom of the pole it provides the cut-out function. This would introduce an unacceptable voltage drop of 0.5 to 1V.

The diode may be: MR1215SL

300 Vr   (400V non repetitive).
100 A at 135'C
0.4 Vf at 150'C
15 mA leakage 150'C at Io & Vr.
0.4 'C/W junction to case.
 

The Pole

Perhaps a taller telegraph pole could be planted for a high power generator.

1) I suspect there would few planning issue if the height is no more than a communications tower (15M) - though they have special dispensation. There may be planning dispensation for wind energy.
 

ALTERNATIVE POWER SUPPLY

The 5 kW 240 v ac Lister diesel driven generator set. Is it possible to run it using vegetable oil derived diesel substitute or methane.
Also have a solar panel.

Things we are looking for:

1) Generator: -
    a) Large Induction motor 1 - 2 HP low RPM (185RPM say) Ideally three phase.

        - we now have a dual speed 375/3000 rpm 240V washing machine induction motor ("SOLE Made in Italy. Type 20571/1.277 Cl.F, 12403661/1 *3.38.M*") as(e) - we have discovered how it is wound, but have been unable to get it to generate any power. We also have another dual speed induction motor which we have not been able to get to generate power.

    a) Large 200 step stepper motor such as Sanyo-Denki 103H89223-0941 or -0911, http://www.sanyo-denki.com/. This is a size 42 motor (4.2" flange mount), 106 mm X 163 mm. The motor is typically used in milling machines to move the work in X, Y, and Z directions, one motor per axis. This particular make is probably the most suitable for power generation, but other makes include; Moore-Reed, Papst, Stebon, Philips (Impex), Berg-lar, Unimatic, Portescap, all 6 or 8 wire type.

    b) Permanent Magnet Brush Motor such as: - not keen on this option.
        A "trolling motor" as used on small fishing boats.  These motors have bearings that are specifically designed for thrust loading,
        A servomotor, such as a drive motor from tape transports in old mainframe computers,

    c) 24V or Higher voltage vehicle alternator.

    d) Parts for the Brake drum design:
        Induction Motor (this low speed motor should as it stands make quite a good generator - we may already have a suitable motor).
        Vehicle Brake Drum Hub and wheel assembly, must have two bearings, such as a front wheel. Transit van is recommended.

    e) A low RPM, 2HP induction motor. Induction motor electronic power efficiency controller. This might be difficult to adapt but the benefit is very good reliability and no gear box is required.

2) Wind Turbine Bearing:-
    a) A generator (motor) with suitably strong bearings.
    b) Small vehicle wheel hub.
        A rear wheel drive hub with two bearings for stability,
        A front wheel drive hub.
        The preferred type would have three wheel mounting bolts.

3) Power factor correction capacitors, such as from old fluorescent lamp units.

4) Moped/motorbike magneto.
    2:1 to 4:1 tooth belt and sprockets.

5) The other things we will be looking for are:
    - High current cable for low voltage, and battery terminals,    ** I have some cable but still require the termination's
and
    - cable for power transmission.

 - I now have a Compaq UPS that looks suitable for about 0.5 or 1KW though said to be rated at 3KW. The Invert runs from 48V (24 lead acid cells) can be turned on/off by pressing a button, and a buzzer conveniently sounds whilst it is running (that can be canciled).

Useful Links

http://www.scoraigwind.co.uk                             Hugh Piggott's webpage is not avaliable
http://www.windmission.dk
http://users.aber.ac.uk/iri/
http://www.southcom.com.au/~windmill/
http://www.otherpower.com/
http://seabenergy.com/ 
                            Vertical Axis Wind Turbine will provide sellabe Power to the grid. I have been working for SEaB Energy since 6/2010
Wind speed calculator for the UK
http://www.energysavingtrust.org.uk/  The original link is not available so please look around this host site link.

Discussion on green energy see; http://gatecrashenergy.ideascale.com/

My page on Electronics