Breaker Failure Clearing

[operplan]

Hi All,

The utility that I work for has as a standard practice to open the disconnects of a failed breaker ASAP in order to restore the bus or other breakers that needed to clear the failed one. We have been hearing recently that some of our neighboring compnanies have been electing to leave the cleared bus/bkrs open during this process. I am wondering if anybody has experience doing this and what the pros/cons are? To me it makes sense to restore the cleared bkrs as soon as realistically possible.

Thanks in Advance!

 

[Kyle2022]

Are you saying that neighboring companies have elected to leave the cleared breakers open while the disconnects are opened on the failed breaker? Are the disconnects motor-operated? Do the disconnects automatically open on a failed breaker as a result of a BFI timeout and after checking for no current flow?

Assuming this is a breaker-and-a-half scheme with motor-operated disconnects and a relaying scheme that operates the disconnects automatically, the bus cannot be reenergized while the disconnects are being opened.

 

[AusLee]

All i can share with you is that once there was a fault on an MV cable, a large explosion, a minute after, everything was clear so someone decided to go down see what was the story. Before he got there, another explosion happened due to reclosure: the network's automatic diagnostic system required in this case one more reclosure to identify the faulty circuit and reconfigure. This could have cost a life. From that moment, no automatic reclosures anywhere.

 

[operplan]

Kyle2022,

I should have clarified myself after re-reading. Yes the switches are motor-mech operated. Our current practice is to automatically open the switches in order to clear the stuck bkr and then reclose the bkrs that opened to clear the bus. The resultant is that the fault bkr is isolated by the automatic switches. It seems our neighbors have been electing to not open the switches automatically and reclose the bus but rather leave the bus open until personell have arrived at the station.

AusLee,

I can see this as a definite problem. The operations I am talking about would be over in 90seconds so unless people were working in the station at the time of failure then that would not apply. Am I understanding that your company operates on one-shot and do not reclose anything? Or is this just for Bkr failure?