TRIPPING OF THE INCOMER ON THE SWITCHGEAR.

[Edward s]

Hello, everyone . have got a situation at hand of which i need a clear understanding on the operation of this switchgear(11kv).
The switchgear has seven breakers feeding different units ,of which 1(the CB) is for the incomer ,the other breaker is for the overheard line(11kv) and the other five breakers feeds individual transformers.
Now what happens is that whenever the over headline line breaker trips usually on phase fault ,the incomer trips on earth fault at the same time and the settings on these two breakers are not the same .when ever i try to reset the switch gear using the SFT 2841 sepam software i cant reset the incomer first not untill i start with the overhead line thats when i can succesfully reset the incomer.Now what type of operation or coordination is this???i need clear understanding






























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[RRaghunath]

The scheme drawings for the overheadline feeder and Incomer panels as well as respective protective relay internal programmable logics give a clue to what is happening.
Without a detailed study, it won't be possible to conclusively say what is happening.
Problem could be with BF protection scheme that may have been enabled or/and could be in the intertrip and interlocking schemes between the two feeders or/and in protection coordination issues etc.

 

[jghrist]

Are there any outputs from the OH line relay to the incoming relay inputs? This could explain both the trip and the inability to reset the incoming relay before resetting the OH line relay.