Quantitative Sensitivity
Measurement of the change in the zero-point output of a sensor per degree of temperature shift defines the stability of the device across its operating range. A low thermal coefficient offset is necessary for sensors used in environments with wide temperature swings, such as outdoor industrial plants. This value is usually expressed in units of percent of full scale per degree Celsius.
Adjusting Bridge
Modification of the resistance in the network with temperature-sensitive components can negate the inherent drift of the sensing element. To minimize the thermal coefficient offset, manufacturers include a compensation circuit that counteracts the expansion and resistive changes of the main gauges. This process is performed in a temperature-controlled chamber during the final calibration.
Testing Range
Verification of the sensor at the minimum and maximum rated temperatures reveals the extent of the zero-point shift. The thermal coefficient offset is calculated by dividing the total change in the zero signal by the temperature range. If the drift exceeds the specified tolerance, the unit is rejected or the compensation is reworked.
Stability Factor
Zero-point consistency is the primary factor in the accuracy of low-pressure measurements. This ensures the signal is not lost in the noise.
