What this 30mm inductive proximity sensor is
The XS630B4NAL2 is a 30mm-diameter inductive proximity sensor from Schneider Electric's Telemecanique Sensors line, part of the Proximity Sensors category. Inductive proximity sensors like this one detect the presence of metal targets without physical contact, using a high-frequency oscillator that changes state when a conductive object enters the sensing field. The 30mm barrel size is a standard industrial form factor for mounting in brackets or through-hole holders.
