Quote:
Originally Posted by MrBungle
Everything has a design lifetime. Planning that is part of engineering.
The job these capacitors do is a sacrificial one and basically to break down on any transients. The lifetime is a function of the transients.
Arguably this isn’t even a trade off between cost and lifetime. All the plastic replacements are unknown at this point. After 25 years, do we really know what will happen to suntan X2’s? Nope!
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While I do to some degree agree that X2 capacitors break down at transients, that is not the normal mode of operation only the normal mode of failure. A cheap polyester one is more likely to exhibit failure than a polypropylene from a more reputable brand. As Station X says, a non-X2 polyprpylene of a sufficient rating just won't fail (but has a minor chance it will fail a bit more destructive if it ever fails).
That said, while we don't know how the Suntans will hold up in 25 years, we DO know that the RIFAs are already defective (not by breaking down at transients but by other failure modes) at the very moment when we mount them so it's probably best to skip that step altogether and bin them.