air circuit breaker not opening

[sivagurunathan]

this is one of the question i was asked during my oral examinations.... the scenario is we are offloading the generator when the load is 20 kw we are opening the acb from main switch board ( the open/ close handle) but the acb is not opening.
my answer is i shall operate the open close button on the acb (manual operation).the reason for the mal function could be the failure of the solenoid inside the acb.

cross question for this answer is if in case the contacts are stuck like micro siezure ( is it possible? ) what could be the solution for opening the breaker. if the breakers are not open then it will reverse power and over load the other generator. is black out is the only solution? doing black out and pulling the defective breaker out.

is it possible to pull out the acb when the breakers are in closed condition because coz in the manual its mentioned we use a handle to turn and pull out the acb but when the breakers are closed the turning is not possible some internal safety to prevent this .

correct me if i have mentioned anything wrong.

share ur solutions. thanx in advance

[Big Pete]

It is possible for the contacts to weld together, in which case the safest option is to black out and withdraw the breaker completely from the switchboard. It will then be possible to power up the switchboard again and then repair the Breaker by fitting new contacts, and finally refit the Breaker.

BP

[sivagurunathan]

thank u mr Big pete