Virtual sensors are sensors that result from the application of a mathematical formula to the data collected by sensors, allowing to relate data from different sensors or to apply a constant over a certain measured value.

Let's see the following practical cases of virtual sensors applications:

Case 1: Calculation of the temperature difference of water at the inlet and outlet of a circuit.

    Sensor 1: Inlet water temperature.

    Sensor 2: Outlet water temperature.

These two measurements, when considered individually, have no meaning if you want to know the energy dissipated in the water circuit.

By creating a virtual sensor that relates these two parameters, we obtain, in real time, the difference between the water temperature in the circuit as an output of the virtual sensor created.

    Mathematical Formula: Value measured by sensor 2 - Value measured by sensor 1

Case 2: Finding out whether a room is under positive or negative pressure.

    Sensor 3: Static pressure in a room.

    Sensor 4: Static pressure in the adjacent room.

By creating a virtual sensor with the mathematical expression below, we can know directly if the room is in positive or negative pressure.

    Mathematical formula: Value measured by sensor 3 - Value measured by sensor 4

If the output of the virtual sensor is a positive value, the room is under positive pressure. If it is negative, the room is under negative pressure.

Case 3: Calculate the air renewal rate per hour in a room.

    Sensor 5: Air speed at the supply duct.

To know the air renewal rate per hour in a room, in addition to the air speed at the supply duct, we need to know the sectional area of the duct and the room volume. Note that these two data are constants, characteristic of the infrastructure of the room.

By creating a virtual sensor with the mathematical formula below, its output will be the renovation rate per hour in the room.

    Mathematical formula: ( Value measured by the sensor 5 * Sectional area of the duct ) / Volume of the room

All the configurations and settings for the physical sensors are also available for the virtual sensors.

Find out how to create a virtual sensor through the following article: How to create a virtual sensor?