Interesting data. Do you know what the max specified operating temp =20 was on these? And I assume the power to these resistors was higher =20 than rated right? This answers a lot. Cheers, -Neil Quoting Antonio Benci : > We've done similar things with 20W and 100W resistors. > > The most consistent failure was the soldered joint from resistor =20 > tabs to wires. At any elevated temperature above 80degC we noticed =20 > that the joints, over time, would fail and become open cct. This was =20 > cured by either bolting or crimping wires to the resistor tabs. > > We've run 20W resistors (ceramic casing) up to 100degC for up to 10+ =20 > hrs before element failure. 100W up to 160degC for close to 40+ hrs =20 > before element failure (ceramic/aluminium casing). > > Nino. > > On 3/10/2011 2:14 PM, RussellMc wrote: >> On 3 October 2011 02:30, PICdude wrote: >>> How do these things fail? This is not a volume or commercial product, >> I used commercial white ceramic 5W and 10W resistors to "power" a >> Fluidyne Stirling Engine (small and for fun). These were run at about >> rate wattage with the aim of being "as hot as possible". From memory >> these were placed in contact with a metal tube, possibly layered over >> with high temperature silicone rubber and wrapped in fibreglass >> insulation (intended for in-wall insulation). These lasted "for a >> while". Given that the engine only got occasional use I'd suspect they >> lasted 10's of hours of run time. This was OK for the application. >> Temperature unknown. Failure O/C. >> >> If you used Nichrome and brought the ends out to a cooler location >> you'd not have the problems that Bob mentions. >> >> >> Russell >> > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .