Originally Posted by
smile4shy
thanks Zog
We sted the bottles and they passed the test. we also conducted semulation on isolated switchgear and observed 5 out of 15 breakers changed status to closed position when moved from test position (T).
Would you explain to me what happened during the racking-in process? Does the breaker close and then open instantly after the Test position?
Sounds like you have some serious issues. No breaker should ever change status to close while racking, there are interlocks to prevent racking a closed breaker.
We have seen a few different issues with Siemens GMI breakers, one is a failure of the trip free interlock roller in the cell, we saw one of these at a plant, looked at all the cells and saw nearly 30% of these rollers were damaged. This device is what prevents racking in a closed breaker. Luck for the plant they were remotely racking the breaker when this one occurred and no one, besides our "robot" was injured.
THe other GMI failure we have seen is broken push rods, this allows the indicator on the breaker to say open when the phases with broken push rods are actually closed.
Both of these are coverd briefly at the end of this power point
http://www.cbsnuclear.com/downloads/...mitigation.pdf
I can send you more detailed info if you like, you can contact me at
Nuclear Safety-Related Servicing of Safety Related Class 1E Circuit Breakers - 10CFR50 Appendix B Qualified - CBS Nuclear Services, Inc. - Scott (Zog)