ABOUT MAGNETIC PROXIMITY SENSORS

As with inductive proximity sensors, amgnetic proximity sensors have an LC oscillating circuit, a signal strength indicator and a switching amplifier. They also have a core (strip) made of amorphous, highly permeable and magnetically soft glass-metal.

This strip attenuates the oscillating circuit using eddy-current losses. The core quickly becomes magnetically saturated if a magnetic field is applied, e.g., if a magnet is brought closer, the eddy-currnet losses attenuating the oscillating circuit are reduced and the oscillating de-attenuates. The power consumption of a magnetic proximity sensor therefore increases as a magnet is brought closer, in contrast to inductive proximity sensors where the power consumption reduces as the switching trigger is brought closer.

A major advantage of this technology is that large sensing ranges are possible even with small sensor types.

Permanent magnets are usually used to trigger magnetic proximity sensors. They comprise magnetically hard substances, such as steel alloyed with other metals such as aluminum, cobalt and nickel. Magnetically hard ferrite with similar properties can also be produced from sintered compounds containing iron oxide and other metal oxides.



LINKS
Magnetic Proximity Sensors Product Information (PDF)