Hello, breakers are thermal-magnetic the current heats the breaker; if the current is high enough for long enough, a solder pot inside melts; this current and excessive heat causes other breakers to open Are you sure the string current is less than 80% of the breaker rating and the wire connecting to the breaker is ampacity 120 percent of the current? I have seen several of these events when the cabinet is in the sun or in other hot locations. Also, excessive breakers in a panel board can cause heat build-up and premature breaker tripping. If a breaker trips from heat several times, the bus bar clip can soften or distort, this can damage the bus. I hope this has some value.
On Thu, Aug 4, 2022 at 1:12 PM Jason Szumlanski via RE-wrenches < [email protected]> wrote: > I have a commercial 208 volt job where four of 11 fully populated strings > of IQ7A had breakers that were tripped as reported by the client. They were > able to reset two of them. They also reported that the two they were not > able to reset we're very hot. The other two were warm. By the time I got > to the site, all four breakers had permanently failed. > > Once I got replacements, I was able to install them and they turned on > without any faults. I gave it about 15 minutes and then put my infrared > camera on it. To my surprise, the breaker immediately above two of the > failed breakers and across from the other two failed breakers was clearly > hot. I'm thinking this might have been the bad breaker all along causing > the heat issue on the bus bar which made adjacent breakers fail. But this > hot breaker did not fail. > > Does this seem like a plausible scenario, and if so, any ideas on what > might have caused it? All of the breaker bolts were tight, but a couple > were not torqued to spec. I just find it strange that one breaker that > didn't fail would cause other adjacent breakers to heat up enough to fail. > > Flir image attached. This was after I replaced the four failed breakers. > > Jason Szumlanski > Florida Solar Design Group > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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