My supervisor asked me Friday if there were any way to determine the operating reliability of a large circuit breaker in a Substation. Now, to me (just having thought about it a little over the weekend), it would seem that breaker reliability of operation would really have to be something that would have to be tested since it relies on too many factors to reliably calculate. The reason this came up is we (the power company I work for) give out yearly breaker operation reports to all of the towns/municipalities that we serve. We use the number of operational events there were and how many operational events that lead to lockout or events that went straight to lockout on each breaker for that cities' substations. This gives the city some idea of distribution lines that may have some too much tree growth around them, or if there's some other kind of reoccurring fault that can be fixed. With this in mind, I'm thinking her question is more along the lines of system reliability and not breaker reliability, which is a whole different ball game. I was wondering if anyone had any decrypting articles or e-books handy regarding high power circuit breaker reliability (Jim Hardy, I'm looking at you ) : How it could be quantified; what is it, and how does it tie into system reliability? among other questions I'd like to know. I spent some time today and yesterday trying to find things on Google with no success. Much obliged, -Tyler Glenn.