Mag-Probe Testing an Inductive Proximity Switch

Mag-Probe Testing an Inductive Proximity Switch on a Boeing 737-300 Aircraft Landing Gear

A basic inductive proximity switch has virtually become a commodity. Over the last 15 years its price has dropped from about $100/device to less than $15 (see Figure 1). This cost reduction has been driven by the evolution of sensor technology and …

It senses the down and locked Position of the landing gear which is critical to the safe landing of the aircraft.

Inductive Sensor – Wikipedia

A proximity(inductive) sensor is an electronic proximity sensor, which detects metallic objects without touching them.

The sensor consists of an induction loop. Electric current generates a magnetic field, which collapses generating a current that falls asymptotically toward zero from its initial trans when the input electricity ceases. The inductance of the loop changes according to the material inside it and since metals are much more effective inductors than other materials the presence of metal increases the current flowing through the loop. This change can be detected by sensing circuitry, which can signal to some other device whenever metal is detected. .

Common applications of inductive sensors include metal detectors, traffic lights, car washes, and a host of automated industrial processes. Because the sensor does not require physical contact it is particularly useful for applications where access presents challenges or where dirt is prevalent…. read more….