Checking the function of dust collectors or cyclone separators dust concentration is measured on clean gas side. The sensor uses the tribo-electric effect. Transported dust particles in the gas stream bear an electric charge and transfer it to the sensor. The amount of charges is a parameter of amount of dust. The basic version of the dust measurement sensor has a two-way contact, which switches reaching a set value. This is the typical application of broken bag detection. Using an additional converter the measured signal is transferred to 4 … 20 mA signal, for example to monitor the trend of dust concentration in the gas stream.