Method for controlling electrostatic precipitator

Abstract

There is disclosed a method for controlling an electrostatic precipitator which includes discharging electrodes and collecting electrodes and which is supplied with a rectified secondary high voltage from a high voltage generating apparatus connected to an AC source. The rectified secondary voltage is applied to the electrostatic precipitator by alternating an on-load period of a fixed time length corresponding to one or two cycles of the AC source and an off-load period of variable time length. In such an application of voltage, a voltage application compulsory pause period corresponding to at least 10 cycles of the AC source is provided at a suitable interval, and as a reference voltage for back ionization detection, there is detected the bottom value of the secondary voltage in the first on-load period just after each compulsory pause period. Further, there is detected the voltage of an odd-numbered bottom in each on-load period after the above compulsory pause period and until the next compulsory pause period, so as to compare the detected bottom voltage with the reference voltage and to adjust the time length of the next off-load period the time corresponding to one cycle of the AC source on the basis of the result of the comparison.