What is the role of instrumentation calibration in preventing incorrect trips?

• A. Calibration is optional and rarely affects trips.
• B. Ensures sensor accuracy to avoid nuisance trips or missed trips; regular calibration keeps measurements within tolerance.
• C. Calibration only affects non-safety devices.
• D. Calibration is performed after a trip.

Answer: (B)

Maintaining accurate measurements is what prevents incorrect trips. Protective trips rely on sensor signals to decide when to act, and sensors can drift over time due to aging, temperature, and environmental factors. If a sensor drifts high, the system may trip when there isn’t a real fault—a nuisance trip. If it drifts low, a real problem might not trigger the trip—missed protection. Regular calibration keeps readings within specified tolerance, so the trip setpoints match the true process conditions and the protection logic operates as intended. Calibration involves checking the instrument against a known reference, adjusting if needed, and recording the results, then verifying the system response. This matters for all monitored parameters and safety devices, not just non-safety components. Without routine calibration, drift can lead to unnecessary trips or failure to trip when required, compromising both reliability and safety.