Generator project help

Discussion in 'The Projects Forum' started by amilton542, Apr 9, 2011.

  1. amilton542

    Thread Starter Active Member

    Nov 13, 2010
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    For my college project I am making a generator. So far I have made my rotor but have not yet made my field windings. For my rotor I have got two pillow block bearings with two neodymium ring magnets mounted on the 20mm shaft and then I have connected a drill to the shaft for it to spin. I wound about 30 coils of copper enammeled winding wire round the palm of my hand connected it to a multi meter and put it near the magnets when they were spinning from the drill. I didnt have an induced emf what so ever :confused:. The multi meter is automatic and was only picking up a resistance reading but the resistance reading did shoot up when near the spinning magnets. I'm thinking maybe an automatic multi meter isn't sensitive enough and perhaps connect it to a galvonemter instead
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    I think you probably obtained axially magnetized ring magnets instead of diametrically magnetized ring magnets - either that, or you have diametrically magnetized magnets with the N and S poles aligned so that they cancel each other's fields out.

    See here:
    http://www.kjmagnetics.com/magdir.asp
     
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  3. amilton542

    Thread Starter Active Member

    Nov 13, 2010
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    There axially magnetized, i did turn one ring magnet around so the magnets oppose each other to create more radial flux and not parallel flux but nothings happening. I could use a length of steel trunking and mount the magnets onto the trunking with there own force so theres radial flux cutting the conductors at all times
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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  5. amilton542

    Thread Starter Active Member

    Nov 13, 2010
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    Ive removed the magnets and laid them flat and just kept flicking the coil across the flux by hand and it works!! The voltage symbol is flickering on and off on my multimeter :). Time for a redesign
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    If you try to use the axially magnetized ring magnets spinning perpendicular to their axis, you will have a good deal more atmospheric drag, and you will not be able to get the windings aligned optimally, as the ends of the magnet are not radiused.
     
  7. amilton542

    Thread Starter Active Member

    Nov 13, 2010
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    Im not sure what im doing wrong but earlier the multimeter was flickering with a voltage in the minus to indicate I had my leads back to front but im not getting anything again. I had a look at those pages, but making something like that would be a complete redesign and i don't have long left. My field winding design is a 110mm soil pipe with an internal diameter of 100mm, and i've got 6 bolts for each side, so if you were to look down the pipe each bolt is seperated by an equal arc length for both sides, then im going to wind my coils round the bolts across the pipe, with a 2mm air gap for rotor. I dont no wether to just scrap the ring magnets and by some rectangle ones and make a permanent magnet squirrel cage?
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Can you obtain diametrically magnetized ring magnets of the same diameter as your axial magnets?

    I don't know why you are not getting a voltage from your coil now - unless you may have shorted the ends of the coil.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    I know you don't have much time left, but have a look at this design anyway:
    http://www.otherpower.com/steamengine.shtml
    It's far larger than what you're trying to build, but if you have a number of axially magnetized rings, you might glue them on to the face of a rotating disk, and make a group of stationary inductors as they did. You would of course need a way to precisely control the end play; just simple pillow blocks would not work very well. If you had some collets and washers, you could capture the shaft between the pillow blocks, perhaps spring-loading it to one end.
     
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