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How capacitive sensors shine in industrial environments

01 February 2023

Capacitive displacement sensors are still deemed to be primarily suited to clean, dry environments. However, capacitive sensors can also achieve peak performance in harsh industrial applications, explains Glenn Wedgbrow, Business Development Manager at Micro-Epsilon UK.

Capacitive sensors measure changes in an electrical property, described as ‘capacity’. This is a body’s or a conductor arrangement’s ability to store electrical charge.

Micro-Epsilon’s capacitive sensors are based on the principle of the ideal plate capacitor. The electric field is only located between the two conductive objects in the active measuring range, i.e. between the sensor and the conductive measurement object.

The sensor electrode is fed with alternating current of constant frequency and amplitude, which means the amplitude of the resulting voltage is proportional to the distance between the two objects.

More precision with triaxial design
Unlike conventional capacitive sensors with coaxial designs, Micro-Epsilon’s sensors have a triaxial design. This means that the capacitor is not simply surrounded by a housing, but also has an extra-fed guard ring located between the capacitor and the housing, which generates an electric field. This creates a homogeneous field between the measurement electrode and the object surface.

The protective field around the measurement electrode prevents this field from spreading to other close conductive objects, preventing them from influencing the measurement. This triaxial design makes the sensors more robust and considerably more accurate. 

Read the full article in DPA's February issue

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