Question 245Electricity & Electronics - Assistant Engineer

The correct answer is D) The trip point should be set above but as close as practical to the maximum asymmetrical short circuit current available. This is because 46 CFR Subchapter J, Section 111.12-1(a) states that the instantaneous trip setting of the ship's service generator circuit breaker should be set above, but as close as practical, to the maximum available asymmetrical short circuit current. This ensures that the breaker will trip quickly to clear a short circuit, but without setting the trip point so high that it could inadvertently trip during normal generator operation. The other options are incorrect because A) setting the trip point exactly at the maximum short circuit current is too precise and could lead to unwanted tripping, B) setting it below the maximum is unsafe as it may not clear a short circuit quickly enough, and C) setting it considerably above the maximum could allow a short circuit to persist for too long before the breaker trips.