How many switches are involved in sensing low lube oil pressure for a single MFP trip?

In the context of sensing low lube oil pressure for a single Main Feed Pump (MFP) trip, the correct answer involves two switches due to the redundancy requirement in many systems for safety and reliability. Typically, these systems utilize two separate low-pressure switches to monitor the lube oil pressure. This design serves to ensure that if one switch fails or provides an erroneous signal, the other can still function correctly to indicate low lube oil pressure.

The first switch acts as the main control point, while the second serves as a backup. This redundancy is key in industrial applications where the consequences of low lube oil pressure can be severe, potentially leading to equipment damage or failure. Having both switches helps prevent false trips due to minor fluctuations in pressure while still protecting the equipment through vigilant monitoring. In summary, the use of two switches enhances the overall reliability of the trip mechanism, ensuring that critical parameters are continually monitored and maintained within safe operational limits.