Tag
#control
3 topics across all disciplines.
Valve actuation and fail position — deciding what happens when everything stops
Pneumatic, electric and hydraulic actuators, why a spring is what makes fail-safe possible, how fail open and fail closed are chosen per service, and what a positioner actually does.
What a transmitter is, and why it sends 4–20 mA
How a field instrument turns a physical quantity into a number the control room can use, why the signal starts at 4 mA instead of zero, and how to pick a measurement principle.
Safety instrumented systems and SIL — the layer that acts on its own
Why protection is kept separate from control, what a SIL number actually measures, how voting trades spurious trips against missed ones, and why a bypass left in is the classic failure.