On 12/3/2014 9:27 AM, andy pugh wrote: > On 3 December 2014 at 13:38, Marcus Bowman > <marcus.bow...@visible.eclipse.co.uk> wrote: > >> I don't believe 1500 Million hours. It is, in any case, a calculated value >> (not that there's anything wrong with that). If the unit contains large >> capacitors, 1500 hours is a much more realistic figure. Short; yes. But >> realistic. > 63 days? That doesn't seem _that_ much more plausible than 170,000 years. > > Given that (statistically) only 38% of parts would be expected to get > to the MTBF time it looks even worse. > > The background here is a 24V supply for a pulse clock. The clock has > been running since 1957 and still would be were it not that the master > clock was in a demolished building. I would like to think that the PSU > I choose would last for 10 years or more. (I plan to put a > hot-swappable replacement in the case too)
I buy and install and replace a lot of switcher power supplies. I would expect a decent industrial 24 volt switchers to last over 10 years, with some failing in the first few years and some making it to 15 years but that is about it. If you push it to near capacity expect it to have a much shorter life.. maybe 5 years. The brand does seems to matter much. Expensive Siemens switchers seem to last about as long as cheap Meanwell switchers. They are all trying to sell to the same market and the downward price pressure is fierce. If you want a power supply that you can install, power up and have a fair expectation of it lasting 25+ years I would go with an Acopian linear power supply. Back in the 80's I was involved in a expansion of a distillery that had been in operation in the same location for over 150 years when I worked there. Their perspective is that everything should last. Their buildings are all brick with copper flashing and many are over 100 years old and still in very good condition. That was 27 years ago. That building that they put up 27 years ago is still considered the "new" tank room building. I still do work at that distillery ocassionally and work and rework the same equipment that I helped install and program 27 years ago. When they put up the "new" building 27 years ago and installed new state of the art instrumentation and controls (since replaced 2 times) they installed Acopian instrument grade power supplies which were expensive and seemed like an over kill. Although they have replaced the controllers twice since the build, the same Acopian linear power supplies power the controls and instruments. NOW I understand why they spent the cash on the Acopian power supplies. :-) They NEVER planned on replacing them. I believe the super reliable Acopians are the Gold Box units. But you should contact them and ask them what is their most reliable power supply design these days. http://www.acopian.com/ Dave --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
