GB819491A - Common power supply for electrostatic precipitator banks with individual section control - Google Patents

Abstract

819,491. Supply and protective arrangements for consumption apparatus. APRA PRECIPITATOR CORPORATION. July 2, 1956 [July 18, 1955], No. 20426/56. Class 38 (4). [Also in Group XXXVII] An electrostatic precipitator 12 has a plurality of compartments-illustrated by 13, 14, 15, 16 each of which is successively cleaned by means of an apparatus 38, the high voltage supply to each compartment being reduced just before the cleaning operation and removed during the cleaning operation by means of apparatus under the control of a commutator type switch 60. The high voltage supply is taken from a common power supply 40-or alternatively from a number of separate supplies-to each precipitator compartment over an individual control unit 24-27 each of which contains a triode 46 in the high voltage line, the normal operating grid bias being supplied over a line 50. As a compartment is nearing the cleaning position one of a series of contacts 60a ... 60d is made thereby energizing the requisite relay 61 which closes its contacts 62 thereby increasing the negative bias of the triode 46 and so reducing the voltage applied to the respective precipitator electrode. As the compartment reaches the cleaning position one of the contacts 60e ... 60h is made thereby energizing relay 67 and closing its contacts 68 to further increase the negative bias on the triode 46 so as to cut the triode off and remove the voltage from the precipitator electrode. Should a flashover occur within the precipitator the increase of current through the control unit associated with the compartment will cause an increase in the voltage developed across an inductor 75A in the cathode circuit of the triode 46 in the unit. This will increase the negative bias on the triode and will thus suppress the flashover. Should, however, the flashover persist the increase in voltage across a cathode resistor 75 will energize a relay 76 to close its contacts 77 to increase the grid bias to cut off the triode 46. In an alternative embodiment the triode may be replaced by a tetrode. Specification 684,024, [Group XL (a)], is referred to.