Selecting an Inductive Proximity Sensor
To selecting an Inductive Proximity Sensor you need to consider several parameters to suit the particular application.
The lowest-cost sensors can be found in the APS4 rectangular, and 8mm / 12mm round standard sensing distance ranges, which provide 1.5mm to 4mm sensing distance, with a switching hysteresis (differential travel) of typically 10% of distance, and repeat accuracy of typically 2%. Once set, the switching position, of a sensor with 4mm sensing distance, will be accurate to 0.08mm (2%), and require return travel, or lateral movement, of typically 0.4mm to allow for the 10% hysteresis. These figures apply when sensing steel, and will be less when detecting aluminium or brass. Target size and direction of travel (in/out ot lateral) will also affect the switching point and hysteresis, see the Selection Guide for full information. A high switching frequency must also be selected, if detecting gear teeth, and a small time delay before availability (tv) is required for accurate positioning of a fast moving target.
Applications for basic low-cost sensors include the detection of moving parts on machinery, guards, doors and dampers. When the object is hot, or there is a large amount of mis-alignment or wobble it will be necessary to choose larger diameter sensors, or sensors with extended and triple sensing distance. IP68 sealed sensors are also available for use in wet conditions.
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