Electrostatic particle filtering

An electrostatic air cleaning device, comprising:

• a particle charging section;
• a particle precipitation section, comprising parallel electrode plates;
• a source of electric potential for applying a voltage between adjacent electrode plates in the particle precipitation section;
• a current sensor for measuring an electric current flowing through the electrode plates;
• a relative humidity sensor for sensing relative humidity of air;
• a flow controller;
• and
• a device controller,
• wherein the device controller is adapted to control the source of electric potential and the flow controller in dependence on the measured electric current flowing through the electrode plates, and wherein the device controller is adapted to implement:
• a first, normal, operation mode when the measured electric current flowing through the electrode plates is below a current threshold;
• a second operation mode when the measured electric current flowing through the electrode plates is above the current threshold and the source of electric potential is controlled to reduce the electric current, wherein the flow controller is controlled to achieve a desired filtration efficiency, and wherein the measured electric current being above the current threshold is caused by a high relative humidity;
• and
• a third operation mode when the measured electric current flowing through the electrode plates is above the current threshold and the source of electric potential is controlled to reduce the electric current, wherein the flow controller is controlled to achieve the desired filtration efficiency, wherein the measured electric current being above the current threshold is caused by a level of particle deposition in the particle precipitation section, and wherein, in the third operation mode, the device controller is adapted to provide output information as an output signal indicating that cleaning or replacement of the particle precipitation section is required.