An inductive proximity switch is based on the principle of the resonance circuit quality changes. The switch consists of the following basic units: an oscillator, a detector, a trigger circuit, a power amplifier stage and protective circuits. An incorporated LC resonant circuit of the oscillator generates an electromagnetic scattered field. The field forms around active face a spatially limited zone that is considered to be the active switching zone.

If an electrically conductive object is placed within the active switching zone, the eddy currents induced in the object extract energy from the oscillator. As a result, a reduction in the oscillation amplitude occurs and the oscillator becomes damped. If the conductive object is removed from the active switching zone, the oscillation is restored. Two states are possible: the oscillator oscillates (no conductive object present in the active switching zone), or the oscillator does not oscillate (a conductive object present in the active switching zone). These states can be electronically evaluated.

Depending on the switch mode (normally open/normally closed), the output closes or opens, when the conductive object approaching the active switching zone.