5. a) Describe the circuit breaker for an a.c. generator using a sketch to show how arcing controlled.(6)
b) Explain the sequence of events that might occur if the breaker opens on a short circuit and state the check you would require following such event.(5)
c) Give a safe procedure to follow should a main circuit breaker fail to open under fault condition.(5)
Reference Answer
### Part a) Circuit Breaker for an A.C. Generator and Arc Control An Air Circuit Breaker (ACB) is commonly used for the protection and switching of main A.C. generators on board ships. It is a mechanical switching device capable of making, carrying, and breaking currents under normal circuit conditions and also making, carrying for a specified time, and breaking currents under specified abnormal circuit conditions such as short circuits. **Construction and Operation:** * **Main Contacts:** These are typically silver-plated copper contacts designed for low resistance to carry the continuous load current with minimal heat generation.
Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.
