Recent Posts

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21
Hydro / Re: 5kw Poncelet Wheel Project
« Last post by keithturtle on January 19, 2018, 10:53:17 PM »
I bought some of this for the underwater part of my reaction turbine

https://www.vesconite.com/vesconite-hilube/

but the dam washed out before I could try it.

Not sure if the weight of your wheel is more than it could handle, but they say it's pretty tough

Turtle
22
Wind / New build- 20 foot diameter variable pitch windmill
« Last post by windy on January 19, 2018, 09:17:00 PM »
 I am in the process of building a 20 foot diameter variable pitch windmill and may need some help in designing the stator and rotor. I have attached a file using the Axial Generator Calculator that was posted a few years back. Could someone look at this and let me know if this looks right.
 I will be using this generator for resistance heating only,(water and space heating). There will be no batteries or DC voltage involved. Controlling speed will be with a Arduino microprocessor  using solid state relays.
 The blades that I am using are the GOE 222 profile that I carved myself and read a few posts back that when using  the 222 profile, the stator should be wound accordingly.
 I designed the stator and rotor using Solidworks and used these dimensions in the file. I will be using 20 poles with 15 coils. Not sure if I have the wire gauge right.
Take a look and leave any comments or questions and will reply as soon as possible. When I get a little farther with the build, I will post some pictures.

windy
23
Wind / Re: Torque value on blade design
« Last post by SparWeb on January 19, 2018, 05:53:44 PM »
9% less at 3000 feet above sea level.

My "pressure altitude" is 91% of sea level, given the same temperature.  But it's often so friggin' cold here that maybe it comes out even!

24
Wind / Re: Torque value on blade design
« Last post by SparWeb on January 19, 2018, 05:48:19 PM »
26%? I don't think it's that bad. But density is lower... I can work it out...  stand by...
25
Hydro / Re: Hey all
« Last post by SparWeb on January 19, 2018, 05:38:15 PM »
Below is something I grabbed from Powerspout (no endorsement intended) just because it was convenient and seems to be a good starting point.
You can pinpoint your site's area by head and flow rate.  You could say that you are in reach of all 3 types of wheel shown - with some compromises.
You have the flow for a large wheel, but may not take advantage of all of the head you could have.
Or you have the head for a faster Pelton wheel, but you would need several to capture all of the flow in your stream.

If the aesthetics of the open wheel really appeals to you (and I have to agree, it does) then there are many ways to make it work.  Generally you will still need to have a "pumphouse" building beside the wheel to house the structure and generator out of the elements.  Some excavation work is unavoidable to concentrate the water's approach to the wheel, make space for the wheel to spin, a spillway, and you might also need a holding pond.



Attachments: Powerspout.png * Powerspout.png ( - downloaded times.)

26
Hydro / Re: 5kw Poncelet Wheel Project
« Last post by SparWeb on January 19, 2018, 05:20:33 PM »
Cool.  Some new problems are really old problems - and there's an old solution for it.
27
Lighting / Re: State of the art LED
« Last post by dnix71 on January 19, 2018, 12:53:47 PM »
The strip they are mounted on is the heat sink. It's like your laptop computer now. The entire shell is a heat sink. That's why better laptops are made of aluminum instead of plastic. It conducts heat well, so the entire laptop will be the same temperature even with no air flow.
28
Lighting / Re: State of the art LED
« Last post by Bruce S on January 19, 2018, 06:54:33 AM »
The heat you're feeling is the electronics keeping those diodes on. The cooler you keep them the longer they will last.
29
Wind / Re: Active Pitchcontrol
« Last post by mbouwer on January 19, 2018, 04:30:34 AM »
To twist the blade the necessary torque power is not that huge. Also because the blade itsself is suspended in the line of gravity.

Also see reply #907

Attachments: kop aanz..JPG * kop aanz..JPG ( - downloaded times.)

30
Solar / Re: "Tricking" a GTI?
« Last post by clockmanFRA on January 19, 2018, 12:10:07 AM »
Hi petect,

GTI's have in built codes that follow a particular Nation/Country specifications.

 Most need to see a good HZ and a good stable AC voltage that is between certain voltages.

 But there is a time lag where the GTI has to see good parameters before it will start working, and begin AC Coupling.

The time lag for start up can be from just 10 seconds to several minutes, so your batteries must take the load for that short time.

The below is my usual AC Coupling comments.
   

I do the OzInverter, 6kW-15kW, 48vdc to 230vac Pure sine wave 50HZ. Its taken 3 years to get to a published kit design that is now perfected and now operating all over the World.

The below relates to the OzInverter only.

With 'Oztules' help, one of my criteria was to allow the OzInverter to back charge from its 230vac Mini Grid when standard GTI's are connected into that created Mini grid and therefore charge the batteries. And to handle DC sources directly charging the batteries ie, DC coupling at the same time.

However their are parameters that must be met.

1. Max GTI input should not exceed the OzInverter upper working output. Its an H bridge design so voltage can go either way.

2. Basically ......... We can control the GTI's 4 ways,
 A. ..... We use the AC Voltage push back as the batteries charge, this higher AC trips out the GTI's, however the latest OzControl board No12 has a rock steady AC output voltage.
 B ....... We use a DC comparator on the batteries to trip out, simple AC disconnect, the GTI's when the batteries are at a charged state.
 C ........ We control the DC on the DC input side of the GTI's before it goes into the GTI, again comparing the batteries voltage state of charge.
 D ..... We can connect in dump loads or diverting loads, so no RE generation is lost.

(Note, we do not use the HZ increase to back off the OzInverter, this method is foolish and leads to domestic appliances failing).

3. It is preferred to use smallish GTIs rather than one big one, as the smaller ones can be switched in and out sequencially.

4. The Ozinverter must stand alone and be the master, and importantly, it must have sufficient batteries to take the loads asked for the short time before the GTI's kick in. Ie for the 6kW OzInverter a minumum of 500ah of batteries is satisfactory.

At present the LF GTI's all work well, and work is progressing on the HF types of GTI, although there are serious spike issues with HF types.

Other folk are working on a Inverter design that connects to a GTI with minimum batteries. "The design shows great promise".

MPPT DC chargers are very expensive, so AC Coupling using used/second hand GTI's where most have MPPT built in are very cost effective.

PLEASE REMEMBER, High Voltage is dangerous, please seek a competent persons advice with GTI's and Inverters.
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