The liquid level detector described here is an advanced micro controller based design capable of detecting level of even distilled water. Most liquid level detectors use a technology which measures the resistance of the liquid. This resistance depends upon the presence of electrolytes in the liquid. The liquid in some areas is too clean, therefore the resistance is high and the typical liquid level detector will not work.
When you need to measure multiple levels, multiple probes are required increasing the number of wires required to the tank and sump from the main controller. This increases the cost of cabling. Our capacitance method needs only 2 wires to the tank and 2 wires to the sump from the main controller. A small sensor board has to be mounted near the tank and the sump. The power to the sensor board is provided by 2 wires and the data is also sent back through the same wires.
The capacitance can be of any value say X when the tank or sump is empty or partially filled. When the water increases, there will be a capacitance Y. Then Y - X will provide the change in capacitance. The change in capacitance will be of a significant value since there will be a difference between capacitance of air and water. This change is linearised and displayed.
The WLC that we have designed can be field calibrated for any tank size.
When you need to measure multiple levels, multiple probes are required increasing the number of wires required to the tank and sump from the main controller. This increases the cost of cabling. Our capacitance method needs only 2 wires to the tank and 2 wires to the sump from the main controller. A small sensor board has to be mounted near the tank and the sump. The power to the sensor board is provided by 2 wires and the data is also sent back through the same wires.
The capacitance can be of any value say X when the tank or sump is empty or partially filled. When the water increases, there will be a capacitance Y. Then Y - X will provide the change in capacitance. The change in capacitance will be of a significant value since there will be a difference between capacitance of air and water. This change is linearised and displayed.
The WLC that we have designed can be field calibrated for any tank size.
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