The word automation supplier usually means an inductive proximity sensor or metal sensor – the inductive sensor is the most commonly utilised sensor in automation. There are actually, however, other sensing technologies that utilize the word ‘proximity’ in describing the sensing mode. Some examples are diffuse or proximity photoelectric sensors that use the reflectivity in the object to change states and ultrasonic sensors that use high-frequency soundwaves to detect objects. All of these sensors detect objects which can be in close proximity for the sensor without making physical contact.
Probably the most overlooked or forgotten proximity sensors available today is the capacitive sensor. Why? Perhaps this is due to they have a bad reputation dating back to when they were first released in the past, because they were more prone to noise than most sensors. With advancements in technology, this is not really the way it is.
Capacitive sensors are versatile in solving numerous applications and will detect various types of objects for example glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are typically recognized by the flush mounting or shielded face from the sensor. Shielding causes the electrostatic field being short and conical shaped, much like the shielded version from the proximity sensor.
Just seeing as there are non-flush or unshielded inductive sensors, in addition there are non-flush capacitive sensors, as well as the mounting and housing looks the same. The non-flush capacitive sensors possess a large spherical field that allows them to be used in level detection applications. Since capacitive sensors can detect virtually anything, they are able to detect levels of liquids including water, oil, glue or anything else, and so they can detect amounts of solids like plastic granules, soap powder, dexqpky68 and almost everything else. Levels might be detected either directly the location where the sensor touches the medium or indirectly in which the sensor senses the medium through a nonmetallic container wall.
With improvements in capacitive technology, sensors happen to be designed that may make up for foaming, material build-up and filming water-based highly conductive liquids. These ‘smart’ capacitive sensors derive from the conductivity of liquids, and so they can reliably actuate when sensing aggressive acids including hydrochloric, sulfuric and hydrofluoric acids. Additionally, these sensors can detect liquids through glass or plastic walls around 10 mm thick, are unaffected by moisture and require little if any cleaning over these applications.
The sensing distance of fanuc module depends upon several factors like the sensing face area – the larger the better. Another factor is definitely the material property from the object to get sensed or its dielectric strength: the larger the dielectric constant, the higher the sensing distance. Finally, how big the target affects the sensing range. In the same way with the inductive sensor, the target will ideally be similar to or larger in proportions in comparison to the sensor.
Most capacitive sensors use a potentiometer allowing adjustment of your sensitivity of the sensor to reliably detect the prospective. The highest quoted sensing distance of any capacitive sensor will depend on a metal target, and thus there is a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors should be employed for these applications for max system reliability. Capacitive sensors are fantastic for detecting nonmetallic objects at close ranges, usually under 30 mm and for detecting hidden or inaccessible materials or features.