The expression automation supplier usually describes an inductive proximity sensor or metal sensor – the inductive sensor is easily the most commonly utilised sensor in automation. You will find, however, other sensing technologies that use the word ‘proximity’ in describing the sensing mode. Included in this are diffuse or proximity photoelectric sensors which use the reflectivity of your object to change states and ultrasonic sensors designed to use high-frequency soundwaves to detect objects. Every one of these sensors detect objects which are in close proximity to the sensor without making physical contact.
Just about the most overlooked or forgotten proximity sensors currently available may be the capacitive sensor. Why? Perhaps this is due to they have a bad reputation dating back to once they were first released years back, since they were more susceptible to noise than most sensors. With advancements in technology, this has stopped being the way it is.
Capacitive sensors are versatile in solving numerous applications and might detect various kinds of objects for example glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors can be identified by the flush mounting or shielded face of your sensor. Shielding causes the electrostatic field being short and conical shaped, just like the shielded version from the proximity sensor.
Just as there are non-flush or unshielded inductive sensors, there are also non-flush capacitive sensors, and also the mounting and housing looks exactly the same. The non-flush capacitive sensors have got a large spherical field that enables them to be used in level detection applications. Since capacitive sensors can detect virtually anything, they may detect levels of liquids including water, oil, glue and so forth, plus they can detect degrees of solids like plastic granules, soap powder, dexqpky68 and almost everything else. Levels can be detected either directly the location where the sensor touches the medium or indirectly in which the sensor senses the medium by way of a nonmetallic container wall.
With improvements in capacitive technology, sensors have been designed that could make amends for foaming, material build-up and filming water-based highly conductive liquids. These ‘smart’ capacitive sensors derive from the conductivity of liquids, and they also can reliably actuate when sensing aggressive acids like hydrochloric, sulfuric and hydrofluoric acids. Furthermore, these sensors can detect liquids through glass or plastic walls up to 10 mm thick, are unaffected by moisture and require virtually no cleaning during these applications.
The sensing distance of fanuc parts is determined by several factors such as the sensing face area – the greater the better. The following factor will be the material property from the object being sensed or its dielectric strength: the greater the dielectric constant, the higher the sensing distance. Finally, the actual size of the target affects the sensing range. Just as with an inductive sensor, the objective will ideally be similar to or larger in size compared to sensor.
Most capacitive sensors possess a potentiometer to permit adjustment of the sensitivity from the sensor to reliably detect the prospective. The most quoted sensing distance of a capacitive sensor will depend on metallic target, and therefore there exists a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors must be used for these applications for max system reliability. Capacitive sensors are fantastic for detecting nonmetallic objects at close ranges, usually lower than 30 mm and then for detecting hidden or inaccessible materials or features.