Homebrewed Electricity > Controls

About to get started.. Just a few more questions...

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jondecker76:
Ok, I've posted a few questions over the last week or so to help me decide on my system layout. This board and the people here have been very patient and helpful to get me to this point.
First, what I am building is a 16' dual rotor axial using 32 2" x 1" x 1" magnets, grade N42. It is going to be a 48 volt system. Not sure what AWG/turns I'm going to use for the windings, but i'll get there soon. Also, the blades are being built like OtherPowers's 17' machine - a straight taper blade with a straight twist (3 degrees at tip, 6 degrees at mid radious and 9 degrees at the root). I'm hoping for output in strong winds to be in the 2kw-3kw range.
I have all parts etc. that I need for fabrication, minus the tower and cable run from the tower to the house. Here is where my questions start:
Lets assume high end - 3.5kw 48v output. What gauge of wire should I run from the tower to the house? (at a distance of 300-500 feet)
Also, to save on wire costs - would it ba advisable to put up a power shed near the tower, with the inverters and batteries inside the shed and run the 300-500 feet of wire as 120v AC wire, which would be cheaper. Only question would be - would I suffer huge losses on the 120vAC side of things if I ran say 500 feet of wire from the shed to the house?
thanks for the help
Jon

jondecker76:
One more note.. Thought I would give some insight on my plan to slowly add my RE system.
At first, I'm going to have just the windmill, one inverter and a charge controller. Eventually i will add another windmill and some solar.
What I am going to do is run the bathroom and 3 bedrooms off of the RE system, with the rest of the house connected to the grid. After seeing how things go, I'll add or subtract rooms from my RE system to suit my average generation of power. As my system grows, I'll be putting more and more of the house on my RE system. Also, the RE system will be backed up by the grid - when batter bank charge level goes low enough, a transfer switch will fire and put those house circuits on to the grid while the battery bank charges again. Once a decent charge level is reached, transfer switch puts thos house circuits back to the RE system.
Eventually I want to make a "priority" system for charging/grid power. First, each house circuit (i envision each room being a circuit, with the exception of high load appliances also being their own circuit) would be assigned a priority.. For example:

priority 1: Refrigerator

Priority 2: Water Heater

Priority 3: Living Room

...

Priority 10: Washing Machine

Last Priority: Dump Load/Shunt
The first priorities will be always considered first. Priorities nearer the end of the list are more like shunts or dump loads.. I want to design a circuit to do this automatically...

For example..

Priority 1 (Refrigerator in my example) is always connected to the battery bank/Inverter.. While charging, if full battery bank voltage is reached, then switch next priority circuit (water heater) from the grid to the RE system. Now if battery voltage is still high, switch the next priority house circuit from the grid to the RE system, and so on until if all else fails, the shunt load is turned on and energy is wasted out. ANd on the reverse end, if battery voltage is dropping, take priority 10 off of the RE system and back to the grid, followed by priority 9, 8, 7 etc... THis way, the individual house circuits act as the dump loads/charge controller. The more power you make, the more of the house circuits are put onto the RE system.. DOing it this way, the real dump load should rarely come on and wasted power should be minimal. And of course, each priority house circuit would fall back to the grid, so it should happen pretty seemlessly. I would also add the ability to not fall back to the gird (for instance, if it is detected that the grid is down, or by manual trip). THe circuit for such a charge controller would be pretty easy for a DIYer to make.
What do you think?

willib:
that sounds like a real workable plan to me

the only thing i would add ,is the dumpload could be your  water heater or a few of them

i like the idea of the shed next to the wind mill with the inverters inside.

since the current transferred in 120v line is much less than say a 48v line ( for the same power)..

hvirtane:
priority 1: Refrigerator

Priority 2: Water Heater
I think that the priority list should

be done carefully to include first

such things, which really need electricity

and don't consume too much.

For example water heating

is a very much energy consuming task,

which maybe would be better done

with some solar air panels.
Concerning the wire size from the wind turbine to the house.

That depends on some factors

such as the distance, the voltage of your wind turbine,

possibilities of installing the batteries outside etc.

There certainly are available catalogues

about the resistance of the different size wires,

available from the manufacturers of wires.

In my opinion the best way to avoid unnecessary losses

is to install the inverter and the batteries

on the base of the tower (, if your plan is to use an inverter).
- Hannu

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