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Tomsic[_2_] Tomsic[_2_] is offline
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Default What's inside of these modern electronic ballasts


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What's inside of these modern electronic ballasts for florescent shop
lights and other straight tube fixtures? I know these ballasts are
being sold more and more to replace the old iron core magnetic types,
but what's going on inside of them? Obviously there are semiconductors
and other electronic components. I would suspect that a capacitor
discharges to start the bulbs.

I tried to google a schematic, found several showing how to wire them
(same as the old style ballasts), but none show the innards or a
schematic that explains how they work.

I also wonder how durable and reliable they are compared to the old
ones? Electronics are often more likely to burn out from power line
surges caused by lightning and load surges. Since surges occur in all
electrical systems, are the electronic types as durable as the old coil
wrapped around iron ("transformer") types.

Thanks


The circuitry is fairly basic: RF filter, surge protection, ac-dc power
supply, inverter (dc to high-frequency ac), current limiter (fluorescent
ballasts are constant-current devices) and starting circuitry.

The surge protection feature has been included since the 1980s when the
first electronic ballasts were used in buildings. Whole buildings were
converted, lightning struck and whole buildings went dark with ballast
failures. One manufacturer went bankrupt trying to honor warranty
replacements. Doesn't take too many of those to get the attention of the
industry.

No, the new electronic ballasts don't appear to be as durable as the old
"core-and-coil" types -- not much to go wrong with a wire wrapped around a
few steel plates; but just like a TV or any other electronic device, the
circuitry is reliable depending upon the manufacturer. A bonus is that
lamps are more efficient and last longer on electronic ballasts. I built a
house 10 years ago with indirect fluorescent lighting in most of the rooms.
There are 20+ ballasts. So far, one lamp has failed -- no ballast failures.
And, last year set a new record for rain and lightning storms in the area.

Just like any other electronic device, I think heat and capacitor wear out
are or will be the cause of most electronic ballast failures. CFL bulbs are
good examples of that.

Tomsic