wiring strategies for multiple DanB style 11' or 17' turbines

[BullCreek]

Hello,

I'd like to have redundant turbines so I can still have power if one fails or needs to be serviced.  At the moment, let's say 3 DanB style turbines going into a single 48 volt battery bank using the AUX out of an MX-60 to trigger diversion control.  Turbine1 is approx 125ft from battery, Turbine2 200ft, Turbine3 275ft.  Would it be better to have 3 seperate cable runs for each turbine (say #1 AWG or maybe even #1/0 for Turbine3) or could a single set of larger cable be used for all of them?  The reason I ask is that I already have enough salvaged #4/0 to make the longest run one time - but not all three.

If using just one run of #4/0 for all three turbines would work - my next question is more practical than technical.  The boxes I'm using as a kill switch have enough room in them for also mounting the heatsink and rectifiers and I think could also be fitted with some bus bars or some such which would make combining the small guauge wires from the rectifiers and the large #4/0 clean.  Does anyone know of a source for such an item - or how would others recommend handling this?  Also, for all but the turbine on the very end, there would be #4/0 coming in and going out both so it seems some sort of substantial combiner would be needed.

Turbine3               Turbine2               Turbine1

   |                      ||                     ||

   -----------------------  ---------------------  ---------------------Battery

Thoughts?

[drdongle]

I believe that using one set of cables would be just fine as long as you have a combiner box with isolation diodes and a circuit breaker/ fuse for each machine, you could also have the kill switch for each machine there as well. Just a suggestion you could have a remote kill switch at the house by running a smaller multi conductor cable back out to the combiner box to operate relays in the box.

I think that a small QC ( 6 breaker positions) circuit breaker box would work fine and have room for some additional components as well as the circuit breakers.

[wooferhound]

Using my favorite Voltage Loss Calculator

http://www.electrician.com/vd_calculator.html

I came up with these figures . . .

Using a length of 275 feet and a wire size of 4/0

and using different amperages for charging, you will get these losses

 300 amps = 10.1 volts drop

 200 amps =  6.7 volts drop

 100 amps =  3.4 volts drop

  50 amps =  1.7 volts drop

Of course not all of your generators will be at the end of the cable so your total losses will be less than what is stated above, you could condider this a `worst Case' scenario.

I work in the entertainment business and 4/0 cable is the standard wire size for getting the power from the Building (or generator) to the stage. it's always 3 phase power so there are 5 wires needed including the neutral and ground wire. Ever so often, we will use runs up to 300 feet. I'm going to tell you that it is a REAL JOB to run out 300 feet of 4/0, 5 wire cable.

[commanda]

He's talking about a 48 volt battery, so 50 amps equates to some 2500 watts.

And he only has to run the cable out once.

Amanda

[BullCreek]

Thanks for your feedback (especially since somehow I posted this in controls rather than wind).  I found some 150A four post busbars on eBay for around $8 each that will fit in my existing enclosure nicely.  Does this look right to you (assuming my first attempt to post an image works)

Regarding the remote kill switch, that would be nice too - as I have a ultimeter 2000 weather station with heated anemometer that in time I might hook into some sort of controller/logger.  That way if I wasn't at home or asleep, and the wind got extreme, the computer could shut the turbines down automatically.  I already have a bunch of PoE (power over ethernet) adapters and cat5 cable from other projects, which should work ok just to toggle a relay no?

A few last questions:

1.  If I just stick with the manual kill switch for now - I don't really need the diode since the short happens on the other side of the rectifiers, correct?
   
2.  If I do go with the relay, I'd place it between the two outer busbars and I need the diode in there to prevent shorting the batteries.  I'm a relative newb when it comes to analog electronics - so would something like http://www.allelectronics.com/cgi-bin/category.cgi?category=205100&item=1N1190AR
   
   

be what I need?  What is the difference between anode and cathode case diodes and when I get it, how do I tell which way the current is suppose to flow so I don't install it backwards?  What sort of relay would you recommend?

[drdongle]

The resolution on this image could be better, but I think I have it doped out.

The diode you indicate is in series with the circuit breaker is not really necessary as the 3 bridge rectifiers will perform the same function. As for a relay to act as a shut down, All's RLY 458 would do the job, just add some high wattage resistors to limit the current, you don't want to burn out the contacts. The POE stuff probably won't help in this application but you could us the 4 pair Cat 5 cable between the load location and combiner box. One pair of # 18/16/14/12 wire will work fine. Cat 5 is over kill for this application but if you have it you can use it. Keep in mind that it is 24 gage power limited wire and that you might have to double up some of the conductors. Also a resistor in series with the relays coil to drop the 48 volts to something closer to 24 when you activate it.