WHEN THE HIGH DC NEGATIVE POTENTIAL, APPLIED TO THE DISCHARGE ELCTRODE W.R.T. THE GROUNDED COLLECTING ELECTRODE, IS INCREASED, AT A PARTICULAR VOLTAGE THE BREAKDOWN OF THE MEDIUM TAKES PLACE, RESULTING IN THE DISCHARGE OF FREE ELECTRONS FROM THE DISCHARGE ELECTRODES. THIS PHENOMENON IS KNOWN AS ‘CORONA DISCHARGE’.
The Maximum amount value of the voltage drop that a layer of cement dust can support without break down is defined by its di-electric strength. This value is typically in the order of 15-20KV. When this value is exceeded, either the formation of Back corona or the propagation of spark across the entire electrode space results in.