Generally speaking, capacitive level switch functions as sensors at a liquid, solid, or powder level with an electrical output. Traditionally they are used for sensing the non-metallic materials and used in the plastic industry, wood industry, chemical industry, ceramic industry, packing industry, and glass industry.
The capacitive level switch provides reliable measurements of materials stored in vessels or bins. They are available in the market in different models, with various features. There are capacitive sensors that can detect both metallic and non-metallic objects. They appear with non-movable parts and allow mounting on required surfaces.
One must mount the capacitance level switches in a vessel or tank along with an electrode attached to it. When the material touches the electrode, be it in solid, liquid, or in powder form, the level switch will detect the presence of the material and produce a signal through the system attached to it.
The electrode can be mounted in any position. Be it horizontally, vertically, or in any comfortable way. The principle of capacitance level measurement mainly depends upon the change in the capacitance of the capacitor—an insulated electrode functions as one plate of the capacitor in this type of level switch.
The capacitance depends on the level of the material. An empty vessel has lower capacitance, while the filled one has higher capacitance.
One can operate the capacitive level switches by using two electrodes, in turn, form the capacitor, mainly in the form of two metal plates which are held parallelly, with an insulating material separating them, which is non-conductive or dielectric.
The switch detects the quantity of the material inside the vessel by analyzing the difference in electrical status. The switch does this by detecting the difference between the electrical status of detecting and the grounding electrodes.
When the vessel is full of the material, the electrode will be in full status (filled). Then the capacitance value and resistance value between the grounding electrode and detecting electrode changes from Rs to Cs.
Through its sensors, the switch can capture this change and bring the output. When the vessel becomes empty, the electrical status of both the detecting and grounding electrodes will change, and the resistance (Ro) becomes infinite.
The capacitance (Co) then becomes the specific capacitance value, which is determined by the installation status. Also, the electrical status varies depending on the type of material filled in the container.
- a) If a material is not a conductive one, no change will occur in the electrical status of the capacitive level switch, because the resistance will be almost infinite. The capacitance will change in such situations. After that, the switch will detect the level of change in the capacitance and then produce the output.
- b) If the material is conductive, there is a change compared to the case of non-conductors. Here, the resistance value will not be infinite, but it will have a smaller resistance value. Then the switch will check the resistance value to detect the level of the material present.
- c) For semiconductors that are neither isolative nor conductive, there will be a change in both the resistance and capacitance. The capacitance level switch captures both these changes and detects the level of the material present in the container.
Advantages of Capacitive Level Measurement
In addition to the regular functions, capacitive level switches have some other advantages too. They are a cost-effective solution for checking or detecting the level measurement of materials of solid, liquid, and powder forms.
Their measurement has point level precision. They are reliable and trustworthy substitutes for the traditional measurement methods and need minimal maintenance and management. Since there are no moving parts for them, it is comparatively easier to manage the working process.
These capacitance switches are relatively smaller in size and make it easier to install and operate them in different types of containers of various sizes. It is easy to clean them and use them for measuring the levels from small sizes to large ones.
They are adaptable in both high and low temperatures and manageable in high and low pressures if appropriately designed.
The icing on the cake is that they can perform along with multiple materials and applications. They are mechanically simple without any moving parts, which requires minimum maintenance. Also, they are well suited for continuous level measuring and checking.
Capacitive level switches function as all-time favorites for level measuring purposes, as the best solution for the same.