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Electronic ballasts

  1. Sep 17, 2008 #1
    hi guys tell me something

    i have seen electronic ballasts for florecent tubes,
    they come in different wattages as well as the florecent tubes,
    what i need to know is the following...

    1. if i get an electronic ballast that states 15watts and buy a florecent tube that is 20watts
    would the tube work?

    2. now if i get an electronic ballast that states 15watts and then use a florecent tube that is 11 watts would it work ?

    thanx
     
  2. jcsd
  3. Sep 17, 2008 #2

    berkeman

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    As with most power supply specifications, the supply (ballast in this case) needs to be sized to supply at least the power that will be drawn by the load. Having excess power supply capacity is fine (maybe wasteful in cost).
     
  4. Sep 17, 2008 #3

    NoTime

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    The electronic ballasts for florescent tubes have a label that say which lamp types they will work with.
    Most will support different bulbs with different wattages, but you don't want to use one that isn't listed on the label.
     
  5. Sep 17, 2008 #4

    berkeman

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    That's interesting, I didn't know that. Is it a variation in output voltage, or startup characteristics or something that leads to the different types of ballasts?
     
  6. Sep 17, 2008 #5

    dlgoff

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  7. Sep 18, 2008 #6

    NoTime

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    I know that only because the ballast in the kitchen ceiling light burned out last month and I had to find a new one. :smile:

    When I was in High School I built a battery powered strobe light out of a small 10" florescent tube.
    It got quite a bit of use in the physics class they had.
    From what I can remember there was a specific run voltage (about 70v).
    Filament voltage and about double the run voltage were required for startup.
    For the strobe, I left the filament voltage on since it would go out at low pulse rates otherwise.

    My guess is that a range of tubes have the same run voltage.
    Not a problem for an active voltage regulator to work with different currents.
    The magnetic ballasts use an inductor to limit current and apparently are designed to a specific tube.
     
  8. Sep 18, 2008 #7
    hi guys, thanx for the advise and help, ok so i understand that if the tube is a higer wattage rating than the ballast it would work but its a waste in cost, the reason i asked this is should there not be any florecent tubes that is matched to my ballast that my local supplier has then i could use a wattage higher, so i needed to know if it would work and the price between wattages isnt much of a difference too:) , but guys does this mean that if my ballast is like 40watts and the florecent tube is 20watts then the tube wont work and can burn out because of the high 40watts load that would run through the 20watts tube?
     
  9. Sep 18, 2008 #8

    NoTime

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    First I'd check with a different supplier.
    J got mine at the a big box home center, mostly because it was the weekend and I needed it NOW.
    They had three electronic ballasts.
    One for single pin tubes (no filament)
    One for midrange bulbs.
    And one for smaller bulbs (like your 20w).
    Magnetic ballasts are different, but they had ones for different bulbs.

    I think the units use a buck regulator. Some designs might have an issue with reduced currents. In which case the ballast could overheat and self destruct. Reduced efficiency means more heat gets produced.

    I would not use the ballast unless your tube is listed on it.
     
  10. Sep 18, 2008 #9

    stewartcs

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