The function of breaker is to cut off supply when load draw is higher then the breaker capacity.
please clarify the breaker connection is : over the wall socket or at the out put load connection.
circuit breaker will trip only if the identified load is higher then the breaker capacity. i.e 5 amp breaker at output will trip if draw is over 5.25 amps it will cut off supply.
remove power plug from wall socket open up the top cover of stabilizer note down the rating of circuit breaker and replace with same rating. Better brands are Bosch, Terasaki, & National buy from a store which sell quality products. Rural areas of Pakistan are rich market of bootlegged stuff.