Exam Question

### Working Principle of a Differential Pressure (DP) Transmitter (Pneumatic Force-Balance Type)
A Differential Pressure (DP) Transmitter is a device used to measure the difference in pressure between two points and convert this measurement into a standardized output signal (typically pneumatic 3-15 psi or 0.2-1.0 bar, or electrical 4-20 mA). The pneumatic force-balance type is a classic and robust design that operates on the principle of balancing forces to achieve a stable and accurate measurement.
**Core Principle:** The fundamental principle is that the force generated by the process differential pressure acting on a sensing diaphragm is continuously balanced by a counter-force generated by a negative feedback system. The magnitude of the feedback signal required to maintain this equilibrium becomes the output of the transmitter, directly proportional to the measured differential pressure.
**Construction & Operation:**