Test Coil, Country flag and Turbine blades

I made a test coil winder earlier and today i made one coil with 37 turns. I didn't add any varnish coat but the coil is difficult to remove from the fixture ... I shall make another simple jig tomorrow that will ease up removing the coil without destroying it.

"Roman" at cnczone posted a helping post in my thread about Coil winding , following are his words for everybody who need to wind the coils:

"About your coil winding jig, I have done many coils and even worked in an electrical motor shop that had a few commercial coil winders.

Suggestion 1; Put the jig on the end of a portable electric drill (with a speed control) and then it can wind automatically. A lathe is also good if it has a low speed.

Suggestion 2; You can paint the coil with varnish or nail polish every layer as you wind it, which will then be a reliable solid coil when done. However this will stick badly to your coil former. If you made the coil former from polyethelene (like food chopping board) the glue will not stick and you can make solid coils then pop them off the former. You might need a small taper on the middle round part, to slide out of the coil.

The magnetic forces on the windings will be high, so somehow they need to be set in resin or varnish. Otherwise if there is any air in the coil the windings will flex and rub because of the magnetic field and soon wear through the insulation and fail.

If putting a dry winding in resin we would put in a vacuum chamber to make sure the resin goes through the coil and no air is present. It is easier to varnish the coil as you wind it, every layer, so I would go for the polyethelene former and do that. Varnish type is not that important, quick dry nail polish is an acrylic and will be strong and bond well later when you set the hard coil into the former with resin."

I hand rotated the magnetic plates and got 1.5Volts (don't know about the RPM) with single test coil. Tomorrow i shall borrow a stroboscope and will plot a graph between RPM and Voltages. following is the formula to get estimated cut in voltages.

Required Cut in Voltages= VAC(of test coil at cut-in speed) x No. of coils/phase x1.732(multiplication factor for 3 phase)x1.414 (DC conversion factor) - 1.4V (diode drop)

The cut-in speed i shall keep around 150~200RPM. You can see pictures of furling flapper that is turned into flag of my country.

Three PVC blades 6feet each worked out by my brother one year back . The blades are big you can see pen kept on the center blade for comparison.

Wind Mill Charge Controller arrived

At last i received the wind mill charge controller. It took about 15 days to reach at my door step from Hong Kong port :).. It seems very solid and i have also recieved the software CD to monitor various parameters of the wind turbine.
I also completed the furling tail flapper.

Birthday of My son

Coil Winder Jig completed

I have completed the coil winding jig. Meanwhile, i purchased the copper laminated wires SWG 17 number for making coil. The price of laminated wire per Kg is 11US dollar. I purchased 5.5Kg of laminated wire.

Fiber Glass Resin Casting of magnetic Plates

Yesterday, after two failed attempts of fiberglass resin casting of magnetic plates i at last succeeded.

Alternator mount Frame and Furling completed

Today i have completed the Alternator mount frame and furling design. I cut the 55 degree triangular jig which make the whole assembling process very easy and timely.

Beware of Advertisements- Chinese Wind Turbines

Recently I spent some time going over ads for micro turbines, and there's lots of interesting claims out there. So before anybody parts with their hard earned cash some wind math is in order.

A case in point is an ad for a micro turbine:
"We build these wind turbines to provide 1200watts of power. They are suitable for charging 12/24/48 volt battery systems....in winds over 4-5mph (6.4-8kph or 1.7-2.2ms)...Brand new 24” (.61m) blades."

Wow, 1.2kW from a 48" (1.22m) diameter blade. Unless you live in a wind tunnel you'll never see that kind of an output.

The most energy you can extract is 59.3% of the total kinetic energy contained in the wind. Most small scale turbines operate much lower then that, while industrial turbines approach it, but still can't get there.

According to the Bertz co-efficient you would need a sustained wind of 27mph (43kph or 11.9ms) to get 1200w from a 48" (1.2m) or 4ft blade (Wind turbine diameter=8ft). To come to this number we need to use some wind math;
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First we need the swept area of the rotor;
Area = π x (blade diameter x blade diameter) / 4
Using the above ad - 3.1416 x (1.22 x 1.22) / 4 = 3.1416 x 1.4884 / 4 = 1.17m2
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Power in watts = .5 x air density x swept area x wind velocity³
Where - air density (@ sea level) = 1.23kg/m3
            - swept area in m2
            - velocity in meters per second
So.......... .5 x 1.23 x 1.17 x 5.5ms3 (5.5ms is my areas average wind speed)
               .5 x 1.23 x 1.17 x 166.37 = 117.91 watts
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Now lets try doubling the blade area;
.5 x 1.23 x 2.34 x 5.5m/s3 = .5 x 1.23 x 2.34 x 166.37 =  239.42 watts
*Doubling the blade diameter roughly doubles the power output.
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Now lets use the original swept area and double the wind speed;
.5 x 1.23 x 1.17 x 11m/s3 = .5 x 1.23 x 1.17 x 1331 =  957.72 watts
*Doubling the wind speed roughly increases 8x the original power output. Yet we're still not at the 1200watts from the original ad.
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Using 43kph wind speeds;
.5 x 1.23 x 1.17 x 11.95m/s3 = .5 x 1.23 x 1.17 x 1706.49 = 1227.9 watts
Wind speeds like this happen very rarely in most areas of the world.


Below is a spreadsheet showing output at different wind speeds using the above 3meter (9ft) diameter wind mill.

More CNC and Metal work

Today i machined the template for marking the position of Stator Holes on the structural frame. This template shall also be used for Resin casting. Moreover, the metallic structure for mounting the wheel hub and magnetic plate is also fabricated. Some snap shots of today's work.

 The picture shows an Antique drill machine in local workshop where the structure being fabricated.

Precision Parts and Progress Updates

As the drawing development in progress so the parts coming out from my home made CNC machine.

Some MDF template along-with actual metallic parts.

 
You can see how accurate  the MDF part produced with my home made CNC router compared to a metallic part produced with a precision industrial CNC machine.

CNC Machining of Coil winder

Today completed the coil winder on my CNC machine.

the CNC machining process.

 Checked the fitup of the coil winding mockup on the magnets and its perfect.

Wind-Solar Hybrid Charge Controller on its way

Today i purchased the Wind Solar hybrid charge controller with following parameters:

Rated Battery Voltage	24V
Rated Wind Turbine Power	600W
Wind Turbine Maximum Input Current	40A
Wind Turbine Maximum Input Power	1000W
Unload Voltage(factory default)	28V
Unload Current(factory default)	25A
Rated Solar Power	300W
Battery Over Discharge Voltage Shutoff	22V
Battery Over Discharge Recovery	24V
Output Protection Voltage	32V

Display Mode	LCD
Display Parameters	Wind Turbine Power, Wind Turbine Voltage, Wind Turbine Current, PV Voltage, PV Charge Current, PV Power, Battery Voltage, Over Voltage, Under Voltage, Over Load, Short Circuit, Night. Etc