Exam Question

### (a) Concept of Fail-Safe and Fail-Set Systems
A fundamental principle in marine automation and control is designing systems to behave predictably and safely upon the failure of their control medium (e.g., control air, hydraulic pressure, or electrical signal). This leads to two primary design philosophies: fail-safe and fail-set.
**(i) Fail-Safe System**
A **fail-safe** system is designed to automatically revert to a pre-determined 'safe' position upon failure of its actuating power or control signal. This action is typically achieved by a stored energy source, like a spring or compressed gas, which drives the final control element (e.g., a valve) to the designated safe state without needing external power or operator intervention. The 'safe' position can be either fully open or fully closed, depending on the system's function.