If a Breaker fail happens at any outgoing feeder what should we trip (Incomer & Bus Tie only) or (Incomer , Bus Tie & All the outgoing feeders)?

It should trip Incomer, Bus Tie & All the outgoing feeders, so the trip of all the outgoing feeders desingned to protect next switching incomer to be load free. 

SIMPLY TRIP INCOMER CHECK THE TRIPPING MECHANISM OF UN TRIPPED FEEDER THEN START FORWARD PROCESS

In the order of the distribution in the parallel circuit first is 2 incoming or incomer hv circuit breaker, second is 2 hv transformer, third is  2 outgoing mv cb, fourth is 2 isolation switch and  fifth is a bus tie or a tie breaker which is in line with the feeders (this is just an example). If one outgoing cb fails half of the circuit are out. Trip the incomer cb of the failed outgoing cb for safety. Switch off the isolation switch for safety also.  Now if that half circuit need power supply you have to switch on some of the feeders which is important & the rest should be off. On the other side of the outgoing the one that is still in operation. switch off some feeders and remain switch on feeders that are important. Because there will have an overload in the  hv transformer if the feeders of the 2 outgoing are all switch on. Also switch on the bus tie or tie breaker. Now check the status in the protection device and start troubleshooting.

Incomer adn bus tie breaker

It was overload . any short circute the mal pungson.

concern bus incomer and out going feeder will trip as well if bus Tie closed condition same will trip

Under breaker fail condition on an outgoing feeder we must cut all the sources of fault currents. The sources could be all going feeders, all incoming feeders, bus coupler and bus sections and also the remote end of the faulted feeder.

Incomer & Bus TIE only and check relay setting & mechanism of Outgoing feeder breker

only trip the incomer breaker responsible for outgoing feeder & then check why outgoing feeder has not tripped. In case there are two sources then also trip teh bus tie breaker

We should trip incomer only.

The transmission power lines will enter a distribution substation ... Distribution Bus ... Outgoing LV ... Faults occurring on overhead and underground distribution feeders ... Security is maintained throughtime and pickup coordination ... No change in the primary ... This type of sympathy trip occurs when a fault occurs