Several Industrial units - cement, steel and power plants - had installed Electrostatic Precipitators (ESPs) for emission control. These systems had been designed for earlier emission norms of about 150 mg/Nm3. the revised norms for Pollution Control Boards are at stringent level of about 30 mg/Nm3. In addition industries also have to deal with changes in process inputs, inferior quality coal and increase in capacity which causes higher pollution. Installing a new ESP is costly and in most of the cases unfeasible due to limited space available in the plant. Add to these the costs of long shutdowns and production loss.