The expression automation supplier usually identifies an inductive proximity sensor or metal sensor – the inductive sensor is the most commonly utilised sensor in automation. You can find, however, other sensing technologies which 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 alter states and ultrasonic sensors that use high-frequency soundwaves to detect objects. All of these sensors detect objects which can be in close proximity on the sensor without making physical contact.
One of the most overlooked or forgotten proximity sensors available today is the capacitive sensor. Why? Perhaps it is because there is a bad reputation dating back to to after they were first released yrs ago, since they were more prone to noise than most sensors. With advancements in technology, this is not really the situation.
Capacitive sensors are versatile in solving numerous applications and can detect many types of objects for example glass, wood, paper, plastics and ceramics. ‘Object detection’ capacitive sensors are often recognized by the flush mounting or shielded face in the sensor. Shielding causes the electrostatic field to be short and conical shaped, just like the shielded version from the proximity sensor.
Just because there are non-flush or unshielded inductive sensors, in addition there are non-flush capacitive sensors, as well as the mounting and housing looks a similar. The non-flush capacitive sensors possess a large spherical field that enables them to be employed in level detection applications. Since capacitive sensors can detect virtually anything, they are able to detect degrees of liquids including water, oil, glue or anything else, and so they can detect levels of solids like plastic granules, soap powder, dexqpky68 and all sorts of things else. Levels might be detected either directly where sensor touches the medium or indirectly the location where the sensor senses the medium via a nonmetallic container wall.
With improvements in capacitive technology, sensors happen to be designed that will compensate for foaming, material build-up and filming water-based highly conductive liquids. These ‘smart’ capacitive sensors are derived from the conductivity of liquids, and they can reliably actuate when sensing aggressive acids including hydrochloric, sulfuric and hydrofluoric acids. Furthermore, these sensors can detect liquids through glass or plastic walls as much as 10 mm thick, are unaffected by moisture and require little if any cleaning during these applications.
The sensing distance of fanuc module is dependent upon several factors such as the sensing face area – the greater the better. Another factor is the material property of the object to get sensed or its dielectric strength: the greater the dielectric constant, the higher the sensing distance. Finally, how big the target affects the sensing range. Just as having an inductive sensor, the marked will ideally be equal to or larger in dimensions in comparison to the sensor.
Most capacitive sensors have got a potentiometer to allow adjustment in the sensitivity from the sensor to reliably detect the objective. The utmost quoted sensing distance of a capacitive sensor is founded on metallic target, and so there is a reduction factor for nonmetal targets.
Although capacitive sensors can detect metal, inductive sensors should be used for these applications for optimum system reliability. Capacitive sensors are best for detecting nonmetallic objects at close ranges, usually lower than 30 mm and for detecting hidden or inaccessible materials or features.