Target Material Impact on Inductive Sensing Distance Reduction Factors
Target material conductivity and permeability set inductive sensing distance reduction factors, reducing nominal operating range by up to seventy percent.
Complex Coil Impedance
Electromagnetic Parameter
Opposing force to alternating current in an inductive sensor consists of both a resistive and a reactive component. Measuring the complex coil impedance provides a complete profile of the sensor’s interaction with nearby metallic targets. When the sensor coil is excited by a high-frequency current, the resulting magnetic field generates eddy currents in the target.
These induced currents alter the effective resistance and inductance of the coil, causing the impedance value to shift along a characteristic curve.
Signal Separation
Plotting the real and imaginary components of the voltage on an impedance plane allows the separation of target distance from material properties. High-frequency impedance analyzers measure the phase angle to determine whether the target is magnetic or highly conductive. This distinction is critical for sensor systems that must ignore distance changes while monitoring material composition.
Calibration Routine
Baseline evaluation of the sensor coil occurs in free-space conditions away from any metallic objects. Factory procedures measure the complex coil impedance at reference temperatures to establish the start point for all subsequent measurement cycles.
External Influence
Operating temperature alters the winding resistance of the copper wire and causes the impedance vector to drift. Compensating for this drift requires the integration of dual-coil designs or reference elements. The residual temperature error must not exceed the specified drift limits.