On Thu, 19 Jul 2018 23:06:54 -0400, Ralph Mowery
wrote:

I guess it is my time to be educated. Those start capacitors are
common but a special case for electrolytics. Good for a short time, but
will let loose if AC is applied for very long at one time.

Maybe. There are different levels of quality in such capacitors.
Since the heat generated is mostly from the ESR (equivalent series
resistance) of the capacitor, a low ESR would heat up less and
theoretically last longer. However, that's not what causes caps to
die:
https://youtu.be/OMd9QkinXz4?t=345
He starts out putting a run capacitor across 220VAC and leaves it
connected. It stays cold and nothing happens. Somewhat later in the
video, he does the same to a large value start capacitor. It belches
hot steaming electrolyte and then blows the end off. If the
centrifugal start switch sticks or is delayed in opening, for example
by line undervoltage, the switch stays closed for too long and cap
dies. Part of this is ESR and ripple current heating, but the real
culprit is junk centrifugal start switches with partly welded
contacts. If the switches were good, methinks that even the lowest
cost motor start capacitor would last forever.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558