2 * 700 watt 24v three phase turbines

KefalonianmanKefalonianman Solar Expert Posts: 60 ✭✭✭✭
Hi Everyone

I have just arrived back from my place abroad and i have been monitoring my turbines,

Although the solar i am very happy with in summer it loses about 60% in winter although the winds pick up,but even on a gusty day my two turbines were showing max occasional at 40 amps between them. If i wire the turbine in series after the rectifier this will double my voltage there start to charge the batteries sooner or would this sacrifice top end on the windy days

Would i be better buying larger turbines which wil produce more even when breezy.

Finally i have the xantrex xw4024 am i right in presuming i cannot change the settings to 48v and then re configure my battery bank to 48v as this would bennifit me i believe.

look forward to your help

paul

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 2 * 700 watt 24v three phas eturbines

    it would not be advisable to wire those turbines in series even if you could easily do so (remember they are 3 phase) as what happens when there's inequality between the outputs? a bigger turbine would probably be the answer over a seriesed wiring of the turbines and i'm not one who has been advising going wind power much for many reasons and i'm not advising you to do it either. low output from 2 smaller turbines is still going to be low output from a larger turbine as it needs the wind to up the outputs. even with the lowered winter output from solar it may be cheaper to try and get the power from more solar than to opt for another turbine. you will still have the output of the 2 turbines and you just supplement with solar to get it where you want it to be.

    a 4024 is only suitable for 24v. inverters aren't as versatile on battery voltage options as controllers are for they work with only 1 battery voltage input range usually centered on one of the 3 major battery voltages of either 12v, 24, or 48v. you presume correctly that 48v is out of the question for that inverter.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: 2 * 700 watt 24v three phas eturbines
    If i wire the turbine in series after the rectifier this will double my voltage there start to charge the batteries sooner or would this sacrifice top end on the windy days

    I'm not sure you can wire them series at the rectifier and get it to work. Although it is theoretically possible, I have never tried it.
    --
    Chris
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: 2 * 700 watt 24v three phas eturbines
    niel wrote: »
    and i'm not one who has been advising going wind power much for many reasons and i'm not advising you to do it either. low output from 2 smaller turbines is still going to be low output from a larger turbine as it needs the wind to up the outputs.

    Neil, this is not accurate. If you double the rotor size of a wind turbine the output increases by 4x. A single 4 meter turbine will produce 4x more power than a 2 meter machine, and 2x more power than two 2 meter machines. The limiting factors for off-grid wind power are the support structure (tower) for larger turbines, and the amount of amps they put out. Large turbines can deliver way more amps in high winds than most battery banks and wiring can take. With better than a decade of experience with wind power for off-grid systems I recommend limiting the size to no more than 3.5 - 4.0 meters and using multiple turbines where one or more can be shut down in high winds to prevent over-amping your battery bank. A single 3.5 meter turbine can make 3.5 kW of installed solar capacity look pretty lame on a windy day.

    For the month of December up here in Wisconsin, 33.0% of our power came from the generator, 51.1% from wind power, 15.9% from solar. Installing more solar capacity don't work. So we increase our capacity from 3.5 kW to 7.0 kW - and instead of 100 watts on an average day we get 200 watts from solar. A wind turbine just toying with a light breeze on the tower makes that much - and it does it for 24 hours a day instead of just 6 hours.

    For somebody who already has installed wind capacity, upgrading to bigger turbines is cheap, assuming the towers can handle the bigger machines.
    --
    Chris
  • BB.BB. Super Moderators, Administrators Posts: 31,907 admin
    Re: 2 * 700 watt 24v three phas eturbines

    It is possible to rewind alternators to run at a different voltage (thinner wire, more "turns", will give more voltage).

    There used to be quite a few local motor rewinding shops around--Perhaps you can find one... Or if you are a do it yourself person--You could try it yourself after a bit of research on how to do it.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: 2 * 700 watt 24v three phas eturbines

    The WG700 cannot be rewound for 48 volt. It is just a cheaply built little 1.7m Chinese turbine and has 18 AWG windings in it to begin with in the 24V model. It's a 350 watt turbine, not a 700 watt. There's not enough room in the core, between the stator teeth, to wind double the volt turns with 20 AWG. Wind it with 22 and the stator resistance will be so high you'll barely get 125 watts from it at 30 mph. I got a burnt out one laying in the junk heap. After I took it apart to see what's in it I laughed and tossed it. It's nothing but a Air-X that somebody strapped bigger numbers on the sticker.

    Chinese watts are different than American watts.

    Edit:
    To clarify what I mean, a 1.7m rotor running at 40% efficiency @ 25 mph wind speed develops 700 watts at the shaft at 1,100 foot elevation. So the generator and wire run has to be 100% efficient to get 700 watts at the battery. While it's possible the Chinese manufacturers have defeated Ohm's Law, I have my doubts.
    --
    Chris
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: 2 * 700 watt 24v three phase turbines

    The original size wire is not used to wind an alternator for higher voltage. Smaller wire must be used to get in the required # of turns. The voltage goes up, the current comes down, but the wattage stays roughly the same. Yes higher resistance, but with that, is higher voltage and lower current.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: 2 * 700 watt 24v three phase turbines

    That's right. I've wound and rewound so many of them over the years that I've lost track of how many I've done. There's a thing called "packing density" when you go to more turns in the same space and you run out of room to stuff the coil groups in the stator. 18 AWG is .0404 and 6.386 ohm/Kft. 22 AWG is .0253, which is the largest wire that will fit at 1.8 packing density in the stator core of a WG700 at the required turns, and 16.20 ohm/Kft. All you have to do is saw the winding heads off and measure the core and I can tell you exactly what will fit and what won't. And I'm telling you the core in the WG700 turbine is not suitable for a 48V winding.
    --
    Chris
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 2 * 700 watt 24v three phase turbines

    chris,
    are you saying for him to just upgrade the turbine blades to a larger size? it may work if it doesn't harm the turbine.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: 2 * 700 watt 24v three phase turbines

    No, he can't do that either. The tip speed ratio for the larger blades will be way too high. Assuming the towers can handle larger turbines, the logical choice is to simply swap them out with bigger machines like a couple Bergey XL.1's or something. There's any number of hobbiests that will buy those little pinwheel turbines if you advertise them on eBay. As long as they're running fine it's not too hard to get your money back out of them.
    --
    Chris
Sign In or Register to comment.