What is the measuring principle of eddy current sensor?

Among inductive displacement sensors, the eddy current principle occupies a unique position. Measuring via eddy current is based on the extraction of energy from an oscillating circuit. This energy is needed for the induction of eddy currents in electrically-conductive materials. Here, a coil is supplied with an alternating current, causing a magnetic field to form around the coil. If an electrically conducting object is placed in this magnetic field, eddy currents are induced which form a field according to Faraday’s induction law. This field acts against the field of the coil, which also causes a change in the impedance of the coil. The impedance can be calculated by the controller by looking at the change in the amplitude and phase position of the sensor coil.




High precision

For many years, Micro-Epsilon has been a pioneer in displacement measurement using high precision eddy current technology. The eddyNCDT displacement sensors are designed for non-contact measurement of displacement, distance, position, oscillation and vibrations. Considered as extremely precise and robust, they are preferably used in industrial environments.



  •  Wear-free and non-contact measurement
  •  Highest precision and resolution
  •  High temperature stability
  •  Ferromagnetic and  non-ferromagnetic materials 
  •  For demanding, industrial environments: dirt, pressure, temperature
  •  Fast measurements up to 100 kHz
Eddy current sensor with integrated controller pages
     Measuring ranges 2 - 8 mm
     Resolution ≥ 3 μm
     Frequency response 5 kHz
Compact eddy current measuring system
     Measuring ranges 1 - 6 mm
     Resolution ≥ 0.5 μm
     Frequency response 5 kHz
High-performance inductive measuring system
     Measuring ranges 1 - 8 mm
     Resolution ≥ 0.02 μm
     Frequency response up to 20 kHz
High-performance inductive measuring system
     Measuring ranges < 1 mm
     Resolution ≥ 0.02 μm
     Frequency response up to 20 kHz
High precision eddy current displacement measurement
     Measuring ranges 0.4 - 80 mm
     Resolution ≥ 0.02 μm
     Frequency response up to 100 kHz
Turbocharger speed measurement
     Measuring ranges 0.5 - 1 mm
     Speed range from 200 to 400,000 rpm
     Sensor operating temperature up to 285 °C
Spindle growth measuring system
     Measuring ranges 250 - 500 μm
     Resolution ≥ 0.5 μm
     Frequency response 2 kHz


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