HI Drake I don't know if this could apply to your situation, but I've seen the QO/QOU fail from debris getting into the breaker itself. Around here there are insects that deposit mud into small openings, like on those breakers. I've seen this cause the breakers to fail.
jay peltz power On May 17, 2010, at 7:02 AM, Drake Chamberlin wrote: > The QO breaker I saw fail was a disconnect switch for an Air 303. The run > from the battery bank was substantial, and the wire was number 10. At the > time, I calculated the amperage available (I -V/R) and the short circuit > current available was not close to the 5000 amp AIC of the breaker for its DC > rating. > > At 06:13 PM 5/16/2010, you wrote: >> Voltage is not the issue here, it is current, and battery fault currents can >> be staggering - far more than one would ever encounter in a typical AC >> system fed from a distribution transformer. I have seen a 200A Class T fail >> to act on an 48V inverter fault which resulted in welding the metal tabs of >> the fuse holder (which had been greased with copper-laden Penetrox E) to >> their sockets. That indicates a fault current well north of 200,000 amps, >> quite possibly sseveral times that. A fire ensued, which triggered the gas >> protection system and fortunately resulted in almost no peripheral damage. >> It did cost about $10k to recharge and recertify the Inergen system. The >> inverter manufacturer was quite cagey on warranty replacement until they saw >> the photos - at which point a replacement miraculously arrived by overnight >> air. >> >> >> >> On May 15, 2010, at 9:43 , Drake Chamberlin wrote: >> >>> I did see a QO breaker fail to trip on a 24 volt DC system with only >>> battery voltage behind it. It burned a #12 wire completely in two. >>> >>> >>>> The 48v is a max rating not a nominal rating. >>>> So yes only good for 12 and 24v systems. >>>> >>>> However with CBI breakers I don't understand why the need for QO for DC >>>> anymore? >>>> >>>> jay >>>> >>>> peltz power >>>> On May 15, 2010, at 6:28 AM, Rebekah Hren wrote: >>> >>> Drake Chamberlin >>> Athens Electric >>> OH License 44810 >>> CO License 3773 >>> NABCEP TM Certified PV Installer >>> Office - 740-448-7328 >>> Mobile - 740-856-9648 >> >> ___
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