Magnetic field sensors
Things to know about magnetic field sensors
Magnetic field sensors have a current flowing through them, and can detect magnetic fields of a certain strength. If a magnet (magnetic field) is brought to the sensor, it delivers an output voltage. For this purpose, a magnet is integrated into the piston; this magnet can then be detected from outside. This allows unproblematic flexible, individual adjustment of the sensing points. However, when magnetic field sensors are used the cylinder housing has to be non-magnetic so as not to influence the magnetic field being detected.
The operational limits of these simple position sensors are at 105 °C (221 °F). AHP Merkle also offers a solution that goes up to 130 °C (266 °F); this is implemented through the use of switches with displaced electronics. Here the evaluation electronics are not located directly on the sensor element, but rather at a distance of up to 0.5 m (1 .64 ft) via a cable connection.
Caution: Due to their measurement principle, magnetic field sensors are especially vulnerable to electromagnetic interference pulses, such as those that may occur in industrial environments. Therefore it should be checked ahead of time whether this type of sensor is suitable for the specific application.
As a basic rule, ferromagnetic components have a negative influence on the functionality of magnetic field sensors, and should therefore not be placed closer than 30mm (11.8 inches) form the sensor.