Capacitive sensors are a type of proximity sensors. They are used to detect the presence of loose materials, liquids, glass, wood or other physical objects that cannot be detected in any way by inductive sensors. These types of sensors are often used to detect the minimum or maximum state in a tank, for counting objects on a conveyor, or for proper alignment. They also signal sticking together or wrong arrangement of various details.
Capacitive sensors: construction and principle of operation
Capacitive sensors are those whose main task is measurement of parameters , distinguished by high precision. Each capacitive sensor has a sensitivity adjustment to such an extent that the user can adapt its scope to the environmental conditions in which specific measurements take place. In construction, capacitive sensors resemble proximity sensors, although they are distinguished by the fact that on the front side they have an electrode that is a capacitor's cover, and the other cover is an object close to the sensor's operating zone. The sale includes sensors in sizes M18 and M30, although there are also miniature, rectangular and pass-through sensors. The sensor output can be PNP, NPN or can be two-wire. Then it is connected in series with the coil of a relay or an executive contactor.
During activities such as detection of electric field changes , the sensors work with DC or AC voltage. You can also find five-wire versions, with universal power supply and relay output. They have a built-in SPDT contact. The output of each electric field checking sensor can be normally open or normally closed. The output status is indicated by the built-in LED indicator. The sensor face may be built-in or exposed. An important parameter that is checked is the maximum connection frequency. In addition, before the purchase, users pay attention to such issues as: construction type, housing material, size, supply voltage, operating zone, output system, output type, output function or connection. The sensor connection may be a built-in wire or a standardized M8, M12 or square connector. Thanks to this structure, the indicated devices are perfect for detecting electrically conductive materials and you can be sure that all measurements will always be correct.
Capacitive sensors: application of
Capacitive sensors can be used in harsh environmental conditions, because apart from the standard version, they can be available in many special versions. Each time they are tailored to the specifics of the industry in which they will be used. Special features such as non-contact detection of package contents can be associated with an increased zone of operation, high operating temperature or the addition of an additional coating. ATEX certificates are also taken into account, which are responsible for the admission to circulation of a product that will be used in potentially explosive areas. You just need to remember to replace the indicated sensors periodically or use additional covers. Then they will be characterized by high reliability as well as resistance to work in difficult environmental conditions related to humidity, temperature or vibrations. Checking for the presence of liquid in bottles or other hazards will no longer be complicated in any way. That is why, among other things, such sensors are ideal for level control in flat-walled tanks and for flow control in plastic pipes. Compared to inductive or optical sensors, these sensors can be used everywhere. However, you have to be careful when using them, because they are sensitive to dirt and obstacles. It cannot be denied that these components are extremely precise in detecting excess liquid or bulk material, or in measuring the thickness of wood.