All factory post mortems stated failure of the electronic trip portion of the breaker. They were all more cost effective to replace v.s. rebuild. All breakers are 10 years old and are in a clean, temperature comtrolled environment.
Having no experience with large Circuit Breakers, may I still introduce some ideas?
How do the trip modules receive power? Is it possible that the control power source is providing "dirty" power which results in failure of the trip modules?
Is the "clean, temperature comtrolled environment" the area where the switchgear is installed, not necessarilly the environment of the trip modules? If so, could the modules see significantly higher temperatures due to outside air being introduced thru unused conduits or floor penetrations?
Larry C
