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Method and apparatus for detecting back corona in an electrostatic filter with ordinary or intermittent DC-voltage supply

  • US 4,936,876 A
  • Filed: 11/12/1987
  • Issued: 06/26/1990
  • Est. Priority Date: 11/19/1986
  • Status: Expired due to Fees
First Claim
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1. A method for defining back corona occurrences in a dust layer precipitated on an electrostatic precipitator used in the process of cleansing flue gases from industrial plants wherein said precipitator has a section powered by a precipitator voltage and current from a DC voltage supply, said method comprising the steps ofmaking a periodic upward adjustment of the precipitator current for the DC-voltage supply until spark-over is induced in the precipitator or until a predetermined upper limit of adjustment is reached without spark-over being induced;

  • recording the precipitator voltage as a function of time;

    if the predetermined upper limit of adjustment is reached before spark-over is induced, thence blocking the precipitator current for a predetermined period of time;

    measuring a series of minimum values, i.e. trough values, of the precipitator voltage before and after spark-over or before and after said blocking period, as the case may be;

    comparing the minimum values measured before and after spark-over or before and after said blocking period in selecting the minimum value of the precipitator voltage after spark-over or after said blocking period as the second minimum value, the third minimum value or the arithmetic mean value of these two values;

    defining a back corona if the minimum value of the precipitator voltage after spark-over or said blocking period is a predetermined sensitivity factor greater than the measured minimum value of the filter voltage before spark-over or said blocking period; and

    adjusting the precipitator current downwardly when conditions defining back corona have been met.

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