Cable Long Runs.Experience,Theroy

Hey....It is a water wheel running a regulated Alternator from a car. I have learned I can trick the alternator into giving off more volts by removing a diode or so. Maybe 18volt....also the possibility of running in AC,then regulating it back to 12vDC for an inverter.....thats if I can get enough power to the destination.

I think my distance was more like,150m-200m however playing it safe. As it is a costly exercise to experiment over this distance....technical information or personal experience is a plus. This is supposed to be a quick and dirty way to get some power..lights...maybe a TV.

300W at the destination would be a good start.

Most people that are doing this are based close to their water wheels. I

Close...Fossil fuel costs money......Water in a river is free...strapped to a car alternator.

Are you suggesting that at the power source(water trubine) convert it to AC 240V via invertor,conduct it a couple hundred meters .....I do want AC 240V at the destination....I can live with a slighly dodgy AC power supply....been there many times over 100m with extenstion cords...?

You could probably experiment with some older Fisher and Paykel washer motors driven as alternators to get some higher voltages, they are three phase though.

They claim 0 to 300V unloaded at 2-3 amps for an unmodified winding. You could probably bung a few on the one shaft and transmit high voltage low current on three wires and use a 3 phase transformer at the far end.

if its a normal 3phase alternator you should be able to get a usable ac voltage from it , push it through a suitable transformer to step up and deliver to site.

even more by removing the regulator.

I'm guessing it's running at a few thousand RPM in which case 50Hz transformers aren't going to work with it really well.

BTW what sort of car altenator puts out 150A ? I'm guessing that you have a 35A altenator and batteries right next to it.

here's an idea that could work at 12V ...

If you could put the batteries beside the house and a regulator there too and run 100A wires from there to the altenator (for battery + and - ) and a thinner wire from the regulator to the field terminal of the altenator you'd probably have something that'd work.

(if you leave the regulator in the altenator it'll only see the voltage at its end of the wires and that'll be higher than the voltage at the other end. conseqently the batteries won't get fully charged. The built-in regulator can be easily bypassed and an after-market external regulator is less than $20)

There'd be losses in the wires but the altenator would just be asked by the regulator to "work harder" to compensate.

a thermal switch cponnected in the field line, mounted on the body of the altenator (or the heatsink of the rectifier) could be a good addition too. (eg jaycar cat# ST-3825) I killed the diodes in an alttenator once by running it non-stop at full power for too long.

With the batteries next to your house you'll have upwards of 400A on demand. use plenty of apropriately sized fuses. That sort of current can make fires real well, and I'm guessing the firemen out there are volunteers.

Bye. Jasen

Yes I am saying use an inverter to convert 12 volts dc to 240v ac

If the turbine produces a regulated 12 volts, then a 12v dc to 240v ac inverter, such as the jaycar pn MI5088 1000watt inverter is the ticket. 10 or 15 amp 3 core wiring over 400 meters is no problem at all if done properly, forget extension leads, use 3 core flex from the electrical shop with connector boxes, will be cheapest to buy 4 drums of 100 meter flex I think, but enquire.

If the turbine's output voltage follows rpm, its not going to be so easy. Do you have any data, pics, etc of the turbine?

Regards, Mark

What turbine??, the OP's turbine?. Even using 240V flex will lose you

87.9 Volts based on the original poster's power requirements, 14 AWG 15A copper wire and 800M round trip distance, this is 37% power loss. If he could go as high as say 480V at half the current to 240V the power loss would be 9% using the same resistance wire.A couple of 240V transformers wired together could bring it back to a lower voltage suitable for batteries and an inverter at the far end.

DC that varies over time has an AC component.

thats a common misconception; it applies for all AC, e.g. mHz to GHz

the skin depth in 25C copper at 50Hz is d = 9.34mm. go look at some huge AC busbars.

This means that for all but the largest transformers, the conductor thickness is a small fraction of d, so the ac-dc resistance ration Fr ~

1 and both skin and proximity effect can be ignored.

Cheers Terry

So what is it you are farming that you want the power for 24hrs/day and dont want a big increase in your power consumption from the mains?

Sorry....couldn't resist with the OP's name :)

James

Calculations based on what load ?

What were the OP power requirements. They only wanted lights and power and maybe a TV. This maybe as little as 300 Watts if they are careful with what is installed.

Well, He said 12 volts at 130 Amps = 1560 Watts which I think is optimistic for a car alternator. 14 AWG is 1.69 Ohms per

100 metres

**Wrong. ALL AC is subject to skin effect.

--
Trevor Wilson
www.rageaudio.com.au

True, but pretty hard to measure at audio frequencies though! Do YOU really worry about it Trevor?

MrT.

**Nope. A trivial exercise to measure at 20kHz. More difficult as the frequency gets lower. **Of course not. That, however, is not what you stated.

--
Trevor Wilson
www.rageaudio.com.au

Just how much signal loss do you usually measure at 20kHz due to skin effect Trevor? Trivial would apply there as well!

True, and I admitted that, but if you weren't being simply pedantic, you would have clarified what you actually meant for the benefit of others.

MrT.

**That would depend on the constrution of the wire and the impedance of the load. That, again, is not what you stated. You stated:

"True, but pretty hard to measure at audio frequencies though!"

I suggest you study up on electrical theory. Sadly, the equations surrounding skin effect are not trivial ones. Measuring skin effect, however, is pretty straightforward.

**Not necessarily. Unless you know all the factors, you can't say. **I don't need. I am merely stating fact. Anyone who cares to dispute what I say, need only refer to the appropriate text, to see that I am correct. I'll say it again: Skin effect takes place on ALL AC signals. Whether it is significant or not, depends on a variety of factors. At 50Hz skin effect can be a significant loss factor. That does bother electricity supply companies.

--
Trevor Wilson
www.rageaudio.com.au

I wonder why they use stranded wire for loudspeakkers then...

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Bye.
   Jasen

To make it flexible.

MrT.