A basic magnetic level sensor is a type of device used to determine the level of a liquid inside a container or tank. It relies on the principle of magnetism to detect the position of a magnetic float within the liquid. The float moves up and down with the liquid level, and the sensor interprets this movement to provide level measurements.
Here's how a basic magnetic level sensor operates:
Components: The sensor consists of two main components: a magnetic float and a sensor housing. The magnetic float is typically a buoyant object made of a magnetic material, such as a small metal cylinder or a sealed plastic capsule containing a magnet. The sensor housing contains a reed switch or Hall effect sensor, which is an electronic component sensitive to magnetic fields.
Mounting: The sensor housing is installed at the desired level on the outside of the container or tank, while the magnetic float is placed inside the tank, free to move up and down with the liquid level.
Principle: When the liquid level rises or falls, the magnetic float also moves accordingly. As the magnetic float moves, it brings the magnetic field closer to the sensor housing mounted outside the tank.
Sensor Detection: The sensor housing contains a reed switch or a Hall effect sensor that is activated by the presence of a magnetic field. When the magnetic float approaches the sensor, it triggers the reed switch to close (in the case of a reed switch) or causes a change in the Hall effect sensor's output voltage (in the case of a Hall effect sensor).
Signal Output: The closure of the reed switch or the change in the Hall effect sensor's output is then interpreted by associated electronics. This change in the sensor's state is used to generate a signal that corresponds to the liquid level. This signal can be further processed, amplified, or converted into various output formats, such as analog signals (4-20 mA, 0-10 V) or digital signals (RS-232, RS-485, etc.).
Measurement Interpretation: The electronics interpret the signal based on calibration parameters to provide an accurate measurement of the liquid level. The relationship between the float's position and the corresponding liquid level needs to be determined during calibration, where the sensor is adjusted to accurately represent the range of liquid levels in the container.
Output Display or Communication: The sensor's output can be used to display the liquid level on a local indicator or can be integrated into a control system for monitoring and automation purposes.
In summary, a basic magnetic level sensor operates by utilizing the movement of a magnetic float within a liquid to trigger a sensor housed outside the tank. The interaction between the magnetic field of the float and the sensor's magnetic-sensitive components generates a signal that is interpreted to provide an accurate measurement of the liquid level inside the container or tank.