Alternator Q's - PM Thickness and Magnet Wire etc

[gsk2005uk]

Hello Everyone,

I am new to all this renewable energy stuff so please forgive me if I ask any silly questions!

I want to start designing and perhaps one day, after a lot of experimentation) build a small wind turbine to help reduce the amount of electricity that I spend. I don't have much expectations mainly because I live in a well populated area (Athens, Greece) and even thought I am up on the 5th floor I imagine that turbulence will downgrade any attempt that I make.

Nevertheless I keep my hopes high and will ask my first question:

• I read in another post in this forum (http://www.fieldlines.com/story/2005/9/6/43131/19329) few equations that help calculate the produced voltage from a 3 phase (star) alternator. It does not mention any effect that magnet thickness might have in the results. Is it important? I am asking this so I know more or less what magnets to buy.
  
• In the same post  the total coil turns are calculated as:
  
  

Total coil turns n =turns per coil*Total no. of coils in series per phase*1.73

...by "Total no. of coils in series per phase" what does it mean? ie. if I had a 24 magnet alternator (3-phase/star) would it be 24(no of PM's)x3(phase)?

• Also in google i found a lot of references to "magnet wire". Is this a special wire or is it just the phrase used to describe the wire used for the coils?
  
• While searching for info on alternator design I bumped onto a very nice site called windstuffnow.com where the guy there uses wedged magnets instead of rectangular onces. As he explains this gives more magnet area hence better performance. Even though he sells wedge magnets I was wondering if there are other people that sell these so I can compare prices not only for the magnet cost but also postage. I need to find a seller who can send these cheaply!
  
• Irrespective of whether the magnets are wedged or rectangular, which are the best places to buy online such magnets?
  
  

Sorry for the looong post and sorry if any of these questions have been asked before. I am surfing on a 56k modem and I cannot really read every post or info on the web.

Thank you in advance!

[finnsawyer]

A 24 magnet 18 coil three phase alternator will have 6 coils per phase.  

Doubling the thickness of your magnets will not double the voltage.  The reason is they will not result in double the flux.  The magnets must stick out into the air, and for the three phase alternators they are quite close together.  The flux flows from a north pole to a south pole by the shortest path, and such a path can be from the side of the magnet.  A thicker magnet would have longer sides and lose more flux that way.  Flux that doesn't pass through the coils doesn't contribute to the voltage and is said to be "leakage flux".