The term automation supplier usually describes an inductive proximity sensor or metal sensor – the inductive sensor is considered the most commonly utilised sensor in automation. You can find, however, other sensing technologies that use the phrase ‘proximity’ in describing the sensing mode. Some examples are diffuse or proximity photoelectric sensors designed to use the reflectivity of your object to modify states and ultrasonic sensors designed to use high-frequency soundwaves to detect objects. Most of these sensors detect objects which can be in close proximity to the sensor without making physical contact.
Just about the most overlooked or forgotten proximity sensors on the market today is the capacitive sensor. Why? Perhaps it is because there is a bad reputation going back to whenever they were first released years ago, while they were more vulnerable to noise than most sensors. With advancements in technology, this has stopped being the situation.
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 recognized by the flush mounting or shielded face of your sensor. Shielding causes the electrostatic field being short and conical shaped, similar to the shielded version in the proximity sensor.
Just seeing as there are non-flush or unshielded inductive sensors, there are also non-flush capacitive sensors, as well as the mounting and housing looks exactly the same. The non-flush capacitive sensors have got a large spherical field that allows them to be used in level detection applications. Since capacitive sensors can detect virtually anything, they can detect amounts of liquids including water, oil, glue and so on, and they also can detect quantities of solids like plastic granules, soap powder, dexqpky68 and just about everything else. Levels might be detected either directly where the sensor touches the medium or indirectly the location where the sensor senses the medium by way of a nonmetallic container wall.
With improvements in capacitive technology, sensors have already been designed that could make up for foaming, material build-up and filming of water-based highly conductive liquids. These ‘smart’ capacitive sensors are based on the conductivity of liquids, and they can reliably actuate when sensing aggressive acids including hydrochloric, sulfuric and hydrofluoric acids. In addition, these sensors can detect liquids through glass or plastic walls approximately 10 mm thick, are unaffected by moisture and require little if any cleaning in these applications.
The sensing distance of fanuc module depends on several factors for example the sensing face area – the greater the better. Another factor may be the material property of the object to be sensed or its dielectric strength: the larger the dielectric constant, the greater the sensing distance. Finally, the dimensions of the marked affects the sensing range. Just like with the inductive sensor, the objective will ideally be similar to or larger in proportion compared to the sensor.
Most capacitive sensors have got a potentiometer to enable adjustment of your sensitivity of the sensor to reliably detect the objective. The maximum quoted sensing distance of a capacitive sensor is dependant on a metal target, and consequently you will discover 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 best for detecting nonmetallic objects at close ranges, usually below 30 mm as well as for detecting hidden or inaccessible materials or features.