Hello Piclisters ~

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We are prototyping a product which requires a pair of 36" fluorescent tubes
to be turned on frequently for a short period.  Specifically, it could be a=
s
frequently as once every 2 or 3 seconds with an ON duration of perhaps 1
second.  This level of use is sporadic however, and probably would not last
more than a few minutes at a time. =20

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We have built up this device using a standard ballast (ICN-2P-32N) and two
36" F30T8CW tubes.  We turn it on and off simply by controlling the 120 VAC
input to the ballast with a relay.  It seemed to work fine, but the lamp
life has proven to be extremely short, i.e. the tubes blackened on the ends
and failed after only a few days of use.

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I have been trying to research this problem, and as far as I can tell, ther=
e
is no spec on how frequently you can cycle the ballast on and off, nor is
any minimum on-time specified.   However, reading between the lines (again,
I can't find any real spec on this,) I am getting the impression that there
is a limited number of "starts" available from a given fluorescent tube
before the electrodes are used up.  I don't know what that number might be,
but let's say arbitrarily that it is 1000 starts.  In that case, bulb life
in a normal lighting application  might be a year or two, but I could reach
that limit very quickly.  (This is only an assumption on my part; I don't
really know what the failure mechanism is for sure.)

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One thing I have discovered is that there is a kind of ballast which is
designed for "programmed start."  This seems to extend lamp life, but the
turn-on time is about a second and (I should have mentioned this,) I need
the light to come on more or less instantly, i.e., 200 mS max.

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I'm sure there are people on the list who know a lot more about this than I
do, and any ideas about this problem, or better yet practical suggestions a=
s
to how I can solve it, would be very much appreciated.

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Thanks,

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  Foster

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