28-pole PM-generator design by Kragten (plus added rectifier papers)

Adriaan Kragten writes:
Report KD 730 can be copied for free from my website: www.kdwindturbines.nl at the menu KD reports. The title of this report is: “Ideas about a 28-pole, 3-phase permanent magnet generator using the housing and winding of a 4-pole asynchronous motor frame size 80”. This generator is using 28 neodymium magnets size 40 * 7 * 3 mm and the magnet costs only about € 25. It is expected that this generator can be used with the original 230/400 V winding for 24 V battery charging if the winding is rectified in delta.
I have added figure 1 out of this report as an attachment and you can use this figure in a blog about this message.
Nice days
Adriaan Kragten

ADDED 16th January:

Hereby I want to draw your attention to two KD-reports about rectification of an AC current.
Report KD 340 describes 1-phase, 3-phase and 2-phase rectification. Originally only star en delta rectification of a 3-phase current were described but recently I have added chapter 3.2.3 about rectification with three separate 1-phase bridge rectifiers. This way of rectification results in a somewhat higher voltage and power than star rectification but the rectifier losses are higher as the current always flows through six diodes.
Report KD 712 describes 5-phase and 9-phase rectification. Originally only 5-phase rectification was described but recently I have added chapter 6 in which rectification of a 9-phase winding is described. It appears that there are two ways to rectify a 9-phase winding and the way which is described in chapter 6.2 is favorable because this results in the highest power. The winding is split into three, 3-phase windings which are rectified separately. The three, 3-phase rectifiers are connected in series. The advantage of 9-phase rectification is that there is almost no fluctuation on the DC voltage and the DC current. This is of interest if the wind turbine is grid connected by a 3-phase inverter because it eliminates the need of using capacitors to flatten the fluctuations.
Both reports can be copied for free from my website: www.kdwindturbines.nl at the menu KD-reports.
Adriaan Kragten
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Details of Ivan’s paint job

Several people have admired the finish on the turbine in my recent post about Ivan Juretic’s turbine, so I asked for details.  Here is what he told me:

Hi Hugh!

The blades and wooden parts of the tail are painted with a transparent polyurethane bi-component glossy varnish “Wood gloss” of Veneziani company.
I have been using this product for many years and I have a really great experience with it. It intensifies the beauty of wood and is extremely resistant to atmospheric agents over years, but is quite demanding for the application.
It is recommended to be applied in many coats, we’ve applied 10 times with brush, and in between coats the surface need to be over and over abrade with fine sanding paper.
All metal parts are galvanized and then yet protected with two layers of high quality coating based on modified epoxy “Hempel’s Selecta Metalni Efekt DTM”.
This paint is easy to aplicate with air spray, and the painted surface looks great with some twinkling sheen. We applied this paint also on the plywood part of th tail.
Some may say it’s all together too much, an exaggeration, but like what you said, and I believe, attention to the detail is always paying off.
In the attachment I’m sending to you Data sheets of both paints what we used and some additional pictures of the painting job!
All the best.
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Mountain top turbine still going strong

In 2108 I reported a turbine build in Croatia by Ivan.  It’s based on my ideas but Ivan added some engineering refinements.  He just wrote to report that it is still going strong without problems.

That turbine works perfectly, for the third year in a row. And as I report to you in the mountains where it works there are really extreme conditions.
Cold, snow, ice, rain, hail, extreme turbulent wind, I don’t think it can get any worse.
But, no problems at all! It is just working.
After almost 20 months of constant operation we put it down this spring, because we just wanted to check everything and make regular maintenance.
There was little damage just on the blades leading edge, actually in the beginning I stick too short 3M protective tapes (just 30 cm) and now I repainted everything with 3 more layers of the amazing Veneziani Wood Gloss PU protective paint (use to be used for yachts) and sticked twice longer tapes.
Overall, the blades were in very very good shape, you can see it on the attached photo taken before I start reparation. The blades were made from larchwood.
The only other thing we had to change was the bronze bearing ring (blue in the drawing / bronze in the photo) on the bottom of the head because it was quite worn out. Now we’ve made it out of Teflon, and we’ll see how it behaves.
Also, the electrical system and control with your Tristar follower works really great, stable, reliable!
Again, thank you very much for all your help, and support for this amazing project.
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Comparing plastic turbine runners with cast metal ones

I had a message today from a customer who has 3 turbines from 3 manufacturers.  After a few years running he has this observation to make:

I have been very pleased with the PS and its nylon spoons which, even after almost 10 years at 70M head seem barely worn and I’m still on the original bearings. Both the Harris and Stream Engine needed a new runner and bearings.

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Eoltec turbine for sale in England

Eoltec 6kW wind turbine complete with tower and inverter for grid connection for sale in Lincolnshire LN13 9TL.  It has worked well for ten years but needs some servicing.

Alan writes:

It is most likely that the Yaw bearing on top of the tower will need to be replaced as there is a bit of tail lift.  Also, the little yoke rollers and possibly the slewing rings on the blade pitching mechanism may need to be replaced.  All spares are readily available for the Eoltec 6KW wind turbine.

Unfortunately, we have been unable to service our turbine due to our age and poor health.  We have been continually let down by another engineer who said he could do the job but has now disappeared.  We don’t know what else we can do and think that it is probably best if we just dispose and sell our wind turbine system.

Installation date was Feb 2011 by Brian Randall.

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New 3.6m ferrite windmill on Scoraig

Posted in ferrite magnets, my own projects, Scoraig | 1 Comment

A couple more PowerSpout turbine installations where customers have sent photos

These are both budget systems.  Installed since my last post in February.

The first is a low head site in the UK.  160mm PVC drainage pipe works well if properly supported.  This one is grid connected using a Ginlong Solis inverter.  The “twin pack” is a very cost-effective way to buy a pair or TRG turbines like this with free shipping.

Next is a PLT turbine using 63mm PE pipe for a long 300m run to achieve a 30m head.  This one charges a 12V battery using a low cost Tracer MPPT controller, and a Tristar for load management to keep the turbine under load all the time.

It’s great to see photos of turbines up and running, but most times I just have to be happy to hear that everything is going fine.


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User experience with evacuated tube water heating

Nathan Jowett asked me to publish his article that he wrote about his solar hot water system.  I have to agree with him that evacuated tubes are brilliant, having had my own system for fifteen years now.

Nathan’s Article V3.0

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Kragten update again

Dear Hugh

I have written a new report KD 723 which can be copied for free from my website: www.kdwindturbines.nl at the menu KD reports. The title of this report is: “Ideas about an 18-pole, 2-phase permanent magnet generator using the housing of a 6-pole asynchronous motor frame size 100 for driving a 0.55 kW motor of  a centrifugal pump”. In chapter 6, an alternative 6-pole armature is described which can be used in combination with the standard 6-pole, 3-phase winding.
Adriaan Kragten
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New Kragten paper on asynchronous motor conversion

Report KD 718 can be copied for free from my website: www.kdwindturbines.nl at the men KD-reports. The title of this report is: “Ideas about a 16-pole, 3-phase permanent magnet generator using the housing and winding of a 4-pole asynchronous motor frame size 100”.

This report describes a way how to modify a standard 4-pole, 3-phase asynchronous motor such that it can be used as a PM-generator for a wind turbine for 24 V or 48 V battery charging. Manufacture of the new armature is rather easy as the magnet grooves are wide and shallow and in parallel to the armature axis. The magnet costs are low as only a rather small magnet volume is used. Mechanically the armature has sixteen poles but physically it has four poles and therefore it can work together with the standard winding of a 4-pole motor. The flow pattern is given in figure 2. The armature pole angle is 2.5° larger than twice the stator pole angle and the fluctuation of the sticking torque is therefore almost flattened. A front and a side view of the armature and the stator is given in figure 1.
Adriaan Kragten”
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