How to figure wiring for transfer of 3 phase AC [CLOSED]

[Oregonorganic]

 Hello, I am trying to construct my own hydro system for my remote home, I have a post here already concerning using automotive alternators for generating DC power.

 Now I have a new question since I am considering building the system at a more distant location with more reliable water flow. Now insted of being near to my battery bank, I am wanting to place the system 300'-700' away, this of course would reqire some fairly heavy cables if I used low voltage DC for transfering power.

 Previously I was advised to look into converting a 3 phase motor into a power source, but after buying a good book on the subject I can see it is pretty advanced for my current abilities.

 But I recently came across a company called Wind blue that builds alternators specificly for use with wind, and low volume hydro. Some of the alternators come with both a conventinal DC output, and 3 phase AC output jacks(only one or the other can be used). They also sell rectifiers that can be mounted at the battery bank for converting the power to 12VDC.

 What I am currious about is how do figure the cable requirements for transfering the AC power? I am familier with figuring DC cable requirments, but I am assuming it is different for the AC?

 It looks like the alternator I am looking at can produce up to 100 volts at the RPMs I'd be operating at, which would be around 2000.

 Here is a link to the alternator I am looking at- http://www.windbluepower.com/Permanent_Magnet_Alternator_Wind_Blue_Low_Wind_p/dc-540.htm

 Thanks!

Closed because the original poster seems he/she/it would rather complain and argue than address the problem.

[bob g]

"the following is in the opinion of himself only, yours as well as others might vary"

1. forget going 300 to 700ft with low voltage dc, it just is not going to happen

the cable size needed to transfer any significant amount of power over these distances would be many times that of the generation system.

2. start thinking about 3 phase ac, at in my opinion a minimum of 208vac Y connected

for 300 ft and maybe 400 plus vac if nearer 700ft. now these voltages allow much smaller and more economical copper cables, but at these voltages you can kill yourself or others.

3. you might consider the use of transformers to step up for transmission and back down at the load end, you will take a bit of an efficiency hit but it opens up some other possibilities too such as even higher voltages i suppose if you got big you know whats

how big of a water resource do you have? i guess my question would be is it big enough to warrant the cost not only to harvest but to transport those distances.

bob g

[DanG]

Clues their 'package' may not be in your best interests...

From the link:

"90 day full replacement warranty on all units"

"Warranty void if PMA has been opened or tampered with"

"Replace that broken or worn out case with this Brand New case"

"Bearing Kit for Delco... ...alternators"

An automotive style alternator was never designed for continuous duty.

There are 8,760 hours in a year - a vehicle that gets 15,000 miles a year on it may see 300-600 hours operation in that whole year. Something more robust is definitely called for as even one day a week usage is 1238 hours a year.

A 90-day warranty should be warning enough to the wise - unless you need it yesterday and then only for a week or two a year you should be looking elsewhere.

[Oregonorganic]

 Well, its my only option to generate power in the winter time here, so I guess its a hearty yes!

 Where would I find suitable trasformers? And how will they help me specificly?

[Oregonorganic]

 Well, the most popular Hydro system in North America(the Harris turbine) uses a automotive style alternator modified for this use, just as the Wind blue alternators, so I guess I have to respectfully disagree with your comment.

 Thanks for the concerns and criticism guys, I know you mean well, but......

1. Yes I am sure this installation is worth the cost and time to install, it will satisfy my meager household power needs.
   
2. I have confidence that a Alternator will work for my meager power needs.
   
   

 If anybody has a response to my originally asked question, I'd like to hear it.

[Oregonorganic]

 Oh and let me make it known that I am only looking for 100watts per hour, not 1000w or anything like that, this is a small system for a small family very much into simple lifestyles and consumption.

[Oregonorganic]

LOL! One more thing, this system will only be in use from late November through late April, my solar power system takes care of ours needs fine in between.

[ghurd]

I thought I posted something earlier...

About look into AL US or USE wire.  Cheaper.

And frequency, and distance,

And math,

http://www.paigewire.com/volt_loss_formulas.htm

G-

[wdyasq]

Mr OregonOrgmazic,

I just read through this and saw some very good suggestions. That in itself is remarkable as you gave so little information.

The fact you are asking wire size and "Where would I find suitable trasformers? And how will they help me specificly?" leads me to believe you know very little about electricity.

Do yourself a favor and get enough education in the matter to understand and use "Ohm's Law". It is a simple mathematical relationship that can help one solve a lot of problems and is a tool you will find use for as long as you play with electricity.

As far as the analogy that a particular object is the most popular and therefore good, I suggest thinking of the No. 2 lead pencil. It is a writing tool. It is far more popular than the "Parker 51" I use daily. Guess which one is a better writing tool?

Remember, you can get yourself killed very dead messing with electricity.

Ron

[bob g]

a few further comments if i may

having worked with delco, leece neville, motorola/prestolite and various other

automotive alternators i would not recommend any delco product for this application

for the following reasons.

1. they are internally regulated, which can be worked around, but why?
   
2. they have typically very small brgs relative to other heavier automotive alternators.
   
3. they don't have external posts to tap directly to the stator, which again can be worked around, but why?
   
   

if you are set on using an automotive alternator, take a look at the much heavier truck alternators such as the leeceneville/prestolite 110-555 unit. it uses much larger ball brg up front and also a ball brg at the rear instead of needle brgs.

it also has AC posts connected directly to the stator to tap output. the regualtor is a piggyback unit that is easily removed and replaced with something more suitable in my opinion and the brush set is externally servicable as well.

for the power levels you are talking about, i might rewind the stator as a single phase at as high a voltage as i could get, not knowing what rpm your turbine will turn it i have no idea what that might end up being. i do know that one can rewind a leece neville jb2600 series to make around 480vac single phase at 2400rpm so i would expect you could get as much as 240 single phase from a 110-555 at least.

the jb2600 produces this power at 2400 rpm at 240hz which is acceptable for a good 60hz transformer without significant losses.

so if it were me i would generate at 240vac transfer it to your load and step it down to 12/24/48 for battery charging with rectification and some large filter caps to smooth down the ripple to an acceptable level. you will then need some form of regulation at the point of charging and not send i signal back to the alternator, which can be done with a charge controller such as an mx60 i would think (if the resultant dc is clean enough) you might even be able to just use a transformer that steps down from 240 to 120 then rectify, filter and feed an mx60 if the resultant dc voltage is below the max input of the controller.

if you only need a hundred watts or so the alternator will run cool and at 2400rpm or so will run a very long time.

this is at least one of probably several things that one might do to get power over those distances.

again i don't like the delco in this application, i too just don't think it is up to the long term use and if you are going to go to all the trouble to attempt such an installation you might consider all the options available.

bob g

[oztules]

At 2000 rpm as you suggest, the blue alternator should be around 280vac. This at your 100w requirement will be only 3-400 milliamps.

Normal building wire will carry this the distance you need without too much trouble.  Provided you transform at your battery end. This will keep the current in the three phase  part to minimul levels, and match the high impedance to your battery bank. Without the transformers, transmission of the 280v (ac or dc) rectified and then tied to the battery will give poor performance

Microwave transformers with total rewind will do the transforming at the battery end. It will require three transformers. Probably at these modest power levels, you could build three out of two.

New primaries and new secondaries will be required. With this setup, it would probably match the system better than up close direct battery tie would do at these speeds. The data sheet claiming a 350v 2500rpm direct tied to a 12v battery for 15A is pretty sad. Even with all the losses of transmission and transforming, I think this would do better than up close direct battery tie in.

When working out your primary turns, my first guess would be about 1v per turn for around 3.5 to 4 square inches of of core cross section area. ( I'm guessing a 6 pole alternator @2000rpm.)

A second simpler way would be to rectify the 280vac to dc at the turbine end, with some capicitors to filter it, and the new voltage to transmit will be 280 X 1.414 = 395vDC. This will transmitt over your 700 feet with only 2 modest wires quite well.

At the battery end you can use a normal offline pwm to bring it back down to 12vdc, or modify a computer power supply to do the same thing. You should walk in your 100w this way.

The transmission loss in this case would be very small. (At 400vdc, the current to transmit is only 250ma for your 100w at the battery for conversion) Losses in the converter will probably be greater than the transmission losses.

The second version (DC transmission @400v) would be the best way to go, and you may find you have well over the power you wanted. Finding an off the shelf converter is easy now days as well, if modifying a psu is out of your interest.

.........oztules

[Ungrounded Lightning Rod]

At 100 watts per hour after 10 hours you'd be running at a kilowatt, after 100 hours at ten kilowatts, and by the end of July of next year you'd be running at a megawatt.  That must be some water source you have.  B-)

Are you sure you didn't mean that you want to run at 100 watthours per hour, i.e. 100 watts?

If you want coherent answers here you really need to use the units correctly.

[Ungrounded Lightning Rod]

Why the heck would you want to rewind a transformer?  You can scale the voltage by the operating frequency relative to the transformer's rated frequency and pick something off-the-shelf to do the job.

How many poles does the genny have, what will be its operating RPM and AC output voltage, and are you measuring between two of the three-phase terminals or between the center and one end of a Y?

[Oregonorganic]

 Well my question was about figuring cable size needs for long distance AC transmission, I already have a pretty fair understanding of everything else, so I guess you misunderstood.......don't you have something better to do than pick on people who aren't as "smart" as you???

[Oregonorganic]

 Well, I'm not asking about the system itself, I was asking about formulas for figuring cable needs for long distance AC transmission so I can work out the problem myself, what little info I provided about the system itself was just to explain why I did not need anything larger than a "automotive" alternator.

 So as you can see there is no need for giving more info..........

 I currently am running a off the grid PV system that I desinged and built, I have a pretty good understanding of low-voltage electricity, what I am looking for is information on AC, which I have little experience with outside of household wiring, FYI.

[Oregonorganic]

 Thankyou for your post!

[oztules]

Well ULR,

Fair question I guess.

I rewind throw-out transformers (microwave ones are both plentiful, and a decent size to start with) because they are available to me (at the dump).

I actually enjoy building something out of nothing, and as I am on a very sparsely populated island, there is no shelf to pick one off, so I guess it's a mind-set I have evolved from being here. If you cant build it, you may have to wait forever, and it will cost a fortune... and probably be the wrong one when it gets here.

The man claims to be using a delco conversion (6 pole?), at 2000 rpm is his design speed. Output figures are in the link he provided in his introduction/question. (claim 350v@2500 rpm... doesn't seem to match the graph)

Whilst it is true that the graphs provided do not quite match up with their claims printed beside the graphs, it should give a feel for what the product is.

The delta / star bit is of no real relevance apart from giving a larger range of off the shelf matches. I assume star for a normal car alt basket.

............oztules

[bob g]

of the two, rewinding a transformer or rewinding an alternator

i would rather do it to the transformer myself!

but i guess that is beside the point

and if it is readily available at an affordable price?

makes sense to me.

gotta get one of those microwave transformers and take a look at it.

bob g

[DanG]

I'm not supposed to say anything bad, but I will say this...

My above comment was not necessarily meant for your eyes alone now was it? This forum of DIY RE is readily accessible to ANY English speaker on the planet and your post will be coming up in text searches for a long time to come.

Putting out comments like "the most popular micro-hydro system in North America" without accepting peer review looks like taking advantage of our host's forum for a free advertising opportunity (from my perspective only).

How about if someone said the "NairX wind turbine was the most popular wind turbine in North America" because they have made 200,000 of them? Is that popular because of the sexy design, sleek marketing and profit margins for the vendor, or is it the superb power and thunderous noise it has proven to make in hurricane force winds?

A 460V fractional or 1 horsepower motor in a wash-down style frame with a few of our hosts neodymium magnets on the rotor will easily outrun any automotive style alternator - you would have to match the correct wheel to it and accept a little trial-by-error... OR have you already bought the Harris?

[Oregonorganic]

 Well the point is I'm trying to replicate the design of the time proven Harris turbine, I'm obviously not a Electrical engineer, nor do I want to be(I'm not trying to make a living doing this), so I'm not into trying to build a system totally from scratch. I can't afford to spend money on a complete Harris system, because the price has been inflated because of the worsening energy crisis.

 The problem is that both times I've tried to tap into this website for info, I've had a bunch of elitest geeks looking down their noses at me and telling me I'm not smart enough to do it, I've never encountered so much arrogance in a online forum of any subject. Perhaps some folks around should learn how to treat ignorant newbies, belittling and teasing is not constructive to effective teaching. for example it insults my intellegence to be informed that electricity kills, like it isn't obvious already, LOL!

 Anyways, I'll abandon this unfreindly website like a bad habit.

[Stonebrain]

Oo,

If you say '100watts/hour',that means you don't know the difference between power(watts) and energy(watthours).

ULR is very kind to point out your lack of understanding.

If you don't understand this,indeed,you're not very 'smart'.

cheers,

stonebrain

[TomW]

Mister Oganic;

Uh, well, maybe you should bail out. It certainly beats growing up for ease.

All we know is what you told us which was not much. You also made assertions of "fact" that are not so. Are we expected to accept you as our savior and all knowing newest member or can we assert truth into your misunderstandings stated as fact?

Accuracy counts so you get lots of blunt info here.

Should I disable your account and refund your costs of joining?

I would suggest you don't let the door hit you where the Lord split you as you leave.

You will be missed.

TW