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CFL's and oscillating inverter

Discussion in 'Home Power and Microgeneration' started by Scott Willing, Aug 11, 2004.

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  1. I helped a friend upgrade an extremely modest cabin system, and while
    I was at it, threw in a refurbished Samlex 600W isolated output MSW
    inverter to replace a non-isolated Statpower 250W.

    The inverter primarily runs a string of four CFL's. One bulb is OK,
    but when a second bulb is turned on, the additional (non-linear,
    highly capacitive of course) load is seen by the Samlex as an
    overload. It limits the current, tries again, limits the current,
    tries again et cetera ad infinitum. Net result is a very lousy strobe
    effect.

    Not surprisingly, throwing a single incandescent bulb (or just about
    any other load) into the mix swamps the effect of the ugly CF bulb
    loads and we can turn 'em all on no problems.

    We could simply switch back to the other inverter but the idea was
    that I wanted my friend to have enough inverter juice to run a few
    small kitchen appliances. Annoying to put in a larger inverter only to
    have a problem running 26W of light.

    I'm looking for a cheap and simple fudge that does not compromise
    safety or use significantly more power.

    As in the past, Samlex was very helpful and forthcoming with my
    original inquiry, though all they've done so far is confirm my
    suspicions. I'm awaiting a response to this follow-up question that I
    thought I'd post here as well:

    Mightn't we resolve this with a little series inductance, and if so,
    what would a good experimental value be? I don't have the junk
    collection that I used to, so I'd probably have to order something. I
    might have something with a PI RFI filter on the AC input...

    BTW, the bulbs in use at present are 13W Sylvanias. We're going to go
    over their next time with a bunch of our no-name generic brand CFL's
    to see if we get lucky with a different ballast design. This is very
    much "on the edge" e.g. just the manufacturing variables between the
    different Sylvanias is enough to cause inverter cycling or not
    depending on the order you turn them on.

    (Wiring's good BTW.)

    -=s
     
  2. Danno

    Danno Guest

    My Kill-A-Watt meter doesn't work on my MSW inverter, but it does work on
    utility power and a SW inverter.
     
  3. The irony here is that my real problem is the surge from charging the
    capacitor in the CFL that -- at least according to one source -- they
    added to the circuit to try to improve the power factor.

    MSW driving non-linear switch-mode converter... I'm not sure that
    power factor per se -- i.e. a steady-state issue -- is really the
    problem. It's more of a transient behavior issue.

    I'm also highly skeptical that a meter like the Kill-a-watt could make
    sense of non-sinusoidal input either.

    La la laaa.... still haven't gotten over there with a pile of
    alternate brand CFL's to try that, but I'll bet it will be different.
    Like maybe she'll be able to turn on two bulbs and the third one will
    start the light show. We'll see.

    Thanks for your thoughts lads.

    -=s
     
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