Diversion Load Issues

99 Posts
Jun 22, 2009 12:18 pm
Diversion Load Issues

I own a Bergey XL.1 turbine rated at 1kW.  Bergey specs from their website indicate that a diversion load connected to their controller should have a resistance greater than or equal to 0.5 ohms and draw 60A or less at up to 30 VDC (1800 Watts max).

AltE's "Low Voltage Water Heating Element 24/48V" says that for 28VDC, if the two sub-elements are wired in parallel the resistance should be 0.62 ohms and draw 45.2A (1265 Watts).

From my understanding of the electrical properties of these two products, this element should work for this turbine/controller.  Does anyone know of a reason why it wouldn't?  I don't want to cause any damage by hooking this up.

Also, this being a custom water tank, I'll have to design the interface for the element.  Does anyone know if the element has to be 100% completely submerged or if some part of the element can be exposed to air?  E.g. the first inch or two.

Thanks in advance for any answers.
 
97 Posts
Jun 22, 2009 03:24 pm
Re: Diversion Load Issues

Hi Thomas A.  I am currently doing this.......heating water with a wind turbine and using a water heating element as a diversion load.  I am using the lower element in a conventional water tank where it is side mounted and completely submerged except for the element flange and wiring.  The size of wiring from the turbine controller to the element may be of issue, depending on how much distance it must run.  But, with adequate wire size to minimize voltage drop on the wiring, I experience no problems with this concept.  I am thinking that you would not want to expose any portion of the heating element to air, and risk a burnout.  If the element should burn out though, you know what the danger is to the wind turbine.......A runaway condition of the turbine with possible self destruction?  Best of luck with your project. :-)  Jon C.
 
99 Posts
Jun 23, 2009 12:04 am
Re: Diversion Load Issues

Thanks Jon.  As I understand it, if the element were to blow, it would break the circuit and create the same condition I currently have -- no diversion load connected.  In that case, the turbine goes into "slow mode" when the batteries are full.  I can't imagine it would create a short since if the water were a better conductor than the metal, the exposed metal would short in the first place.  The water must present a higher resistance than the element.

Good point about the wire size.  Do you know what gauge is required for a short run (about 10 feet) at 28VDC/45.2A?

I was hoping to get an informed opinion about the suitability of the element I described for my turbine.
 
97 Posts
Jun 23, 2009 10:51 pm
Re: Diversion Load Issues

Ah, ok, Thomas.  I was not aware that the Bergey would self regulate with no diversion load.  I am accustomed to the old bare bones turbines that require a dump load to avoid self destruction.  Without a load, mine would begin to throw parts, make smoke, followed by running and screaming, etc.  Your calculations on the water heater element stats sound close enough to be doable, and sounds like you are good to go on this project. The appropriate wire size can be found on a table showing wire size and typical current ratings.........I love Google for this.  I settled on a hardware store heating element designed for 120v at high wattage....entirely adequate and a fraction of the cost of the low voltage ones.  The heater element really doesn't care if it is supplied with AC or DC voltage......only that it operates within parameter of wattage. I was not concerned about exposure of the low voltage to water, since water is hardly conductive unless it is contaminated with a conductive chemical, but rather the fact that the heating element must be allowed to dissipate its heat by direct thermal conductivity into the water, or it may overheat......air is not very conductive this way.  Again, best of luck and let us know how it works for you?  Jon C.
 
6 Posts
Jul 23, 2009 02:50 pm
Re: Diversion Load Issues

Hi Thomas,

I have the same setup (Bergey XL.1 and 24/48v heating element) going into a custom made tank.  It's been working fine for over a year but the threaded connections and little insulators are pretty fragile.  In my setup the element is fully immersed.  I wouldn't be worried about burning out the element so much as ensuring the you can most effeciently transfer the heat and water/glycol solution is much better than air. It can get extremely hot (120 F +) so make sure that you use good wire as well. Make sure that you put in a breaker between the Bergey control panel and the element too.

Cheers,

Ben

 
99 Posts
Jul 23, 2009 04:01 pm
Re: Diversion Load Issues

Thanks Ben.  Do you have the elements wired in parallel?  How did you mount it to your custom made tank?
 
6 Posts
Jul 23, 2009 04:30 pm
Re: Diversion Load Issues

I don't have mine wired in parallel.  I have a standard threaded insert welded to a 3 ft. piece of 8 inch pipe.  The pipe sits flat at a slight angle with both ends welded closed.  A 2 inch piece of pipe is welded at the upper end for filling.  I have a vented cap on that so that steam can escape if it gets too hot.
 
99 Posts
Jul 23, 2009 05:49 pm
Re: Diversion Load Issues

So you have them wired in series then?  Doesn't that put the resistance and amperage outside of Bergey's recommended range?

 
97 Posts
Jul 23, 2009 06:42 pm
Attn. Wind Turbine Owners

I was recently interviewed by Public Radio, and was surprised to learn that some people are disappointed with their wind turbine performance.  It seems that we soon will have data from a new government Small Wind Certification Council to help with selection of wind turbines currently on the market. Personally, I had no unrealistic expectations of turbine performance, so I experienced no disappointments either, but I would be interested to find out what others here think about their particular turbine.  This might make a good topic for the forum.  http://minnesota.publicradio.org/display/web/2009/07/22/home-turbines/
Smiles :-) Jon C.
 
99 Posts
Jul 23, 2009 07:28 pm
Re: Diversion Load Issues

Jon, I'm not disappointed at all.  That's why I'm installing a diversion load.  More often than not, the red diversion load light is lit, but I have nothing to do with that energy currently.  Heating water with it will improve my overall performance from my turbine.  My main limiting factor currently is my battery bank, at about 12 kWh capacity (roughly two days of demand).  But still, I have no complaints. 

My wind (rated 1kW) and solar (rated 0.74kW) components complement each other perfectly.  I tend to get more sunlight than wind during the day and during the summer, but every evening, during storms, and throughout the winter, the wind is strong.  Since I installed the system, I've always had power in my off-grid house.  That includes running well and septic pumps, lights, radio, television, power tools, vacuum cleaners, etc.

I can understand how others might be disappointed though.  It's not because of manufacturers, but due to a complete lack of any research on the part of homeowners.  I keep seeing these Skystream turbines go up on 30 foot towers lower than nearby tree lines.  Of course they're not generating their rated amounts -- there's no wind!  My site is on the top of a hill, and I have an 80 foot tower.  Wind is generally not a problem.  Of course there are still calm periods, but diurnal temperature swings generally ensure at least a few hours of wind per day. 

People down in valleys should look to solar or microhydro, especially if they live in tight suburbs.  On hills or flat plains, towers should be at least 80 feet unless there are literally no obstructions for like a mile.  Turbulence can seriously degrade turbine performance if it's too close to the ground.  It really doesn't cost much more to go from 30 feet to 80 feet.  A grand or two maybe... but without the height, the whole thing is worthless.  And if people bothered to even do a Google search before buying one, they'd know that.

 
6 Posts
Jul 23, 2009 09:15 pm
Re: Diversion Load Issues

Hi,

Went and checked when I got home.  I'm not sure that I have the exact model that you do after all but it's pretty close.  The options for my model are 24 volts in parallel for 40 amps (2 jumpers), in series for 20 amps at 48 volts (1 jumper) or wired without jumpers for 20 amp at 24 volts (which is how I have mine).  The fitting is a standard 1 inch pipefitting.

Ben
 
6 Posts
Jul 23, 2009 09:19 pm
Re: Diversion Load Issues

I agree. I have no disappointments with my turbine except that the wind doesn't blow as often or as hard as I'd hoped.  But that's my issue, not the turbines.  My 1.5 kW of solar and the Bergey keep us power up 95% of the time.  I'm limited by battery capacity, not power input.
 
97 Posts
Jul 23, 2009 10:49 pm
Re: Diversion Load Issues

Thank you for your feedback, Thomas A. and Ben R.  I am pleased to hear that others have success stories as well, and also pleased to be in the company of innovative people such as you that do the ground work, do the math, and most importantly......just do it!.  Like everything in life......it all comes back to us, and our choices, and any errors land on our shoulders, as it should be. It's better to lead the sheep herd than to walk in the aftermath of the herd.  Wink ;-).  Best of continued good fortune to you.  Jon C.
 

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