Thermal Parameter
Fractional change in the electrical resistance of a material per degree of temperature change is a fundamental property of metals. The temperature coefficient of resistivity determines how much the electrical conductivity of a sensing target shifts as the operating temperature rises. This change directly affects the intensity of induced eddy currents and the resulting sensor signal.
In inductive proximity sensors, this thermal dependency can cause major measurement drift if left uncompensated.
Physical Mechanism
Heating causes increased lattice vibrations within the metal, which obstructs the flow of free electrons. This rise in resistance reduces the magnitude of the eddy currents that can be induced in the target. The sensor must be calibrated to account for the temperature coefficient of resistivity of the target material.
Metrology Calibration
Measuring the thermal shift requires placing the target and sensor in a temperature-controlled chamber. The sensor output is recorded at multiple temperature steps to generate a multi-point correction curve.
Compensation Design
System controllers use the correction curve to mathematically adjust the sensor readings in real time. This adjustment relies on a dedicated temperature sensor positioned close to the target. The remaining measurement error must not exceed the specified tolerance limit of the system.
