Draw-wire sensors, also known as draw-wire encoders, are equipped with a highly flexible stainless-steel measuring cable which is attached to the measured object. The measuring cable is wound on a drum, which is pretensioned by a spring, the spring force of which acts against the cable being pulled out. If the measuring cable comes loose, e.g. due to sudden release when pulled out manually or due to faulty fastening, the cable will snap. This snapping is similar to the snap of a whip and can lead to injury to persons, damage to property or destroy the sensor.
To prevent this, WayCon has developed snap protection for the 10 to 25 m measuring ranges of the SX135. By using the principle of an eddy current brake, the snapping protection increases safety by reducing the speed of retraction in the event of a sudden drop in pull-out force, thus preventing the snap effect.
An eddy current brake makes use of the Lorentz force acting on an electrical conductor transverse to the field lines of a magnetic field. This results in induced eddy currents, which in turn generate a magnetic field that ultimately slows down the moving object.
SX135 series draw-wire sensors can be adapted precisely to customer-specific applications thanks to a wide range of options and special designs. The linear sensors are used, for example, in automated warehouse management, e.g. in port facilities or warehouses. Draw-wire encoders measure the travel of cranes and transmit the information to the control system. This ensures safe and precise operation of the plant. Especially in situations where people and machines are working closely together, the safety provided by the WayCon snapping protection is of particular importance.