GB989221A - Improvements relating to current supply circuit arrangements - Google Patents

Abstract

989,221. Supply circuits for electrostatic precipitators; protective arrangements. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. July 6, 1961 [July 7, 1960], No. 23736/60. Heading H2H. The terminals 16, 17 of an electrostatic precipitator are supplied through a transformer 13 whose rectified primary voltage provides the excitation for a transductor 23 which in turn supplies the excitation of winding 21 of a main transductor 18, the output current of transductor 23 being normally determined by the setting of a variable ratio auto-transformer 28. When arcing occurs in the precipitator the voltage of transformer 13 falls and thus the excitation and output of transductor 23 is reduced, to produce a similar effect on transductor 18 and so further reduce the transformer voltage, this cumulative action continuing until the are can no longer maintain itself and extinguishes. Thereafter the residual magnetizing current of the transductor 18 will raise the voltage of transformer 13 to increase the excitation and output of transductor 23 and hence of transductor 18, this cumulative action continuing until the normal operating condition of the precipitator is restored. The circuit may include resistance and other elements to further improve the speed of response of the transductors and compensate for the temperature coefficient effects in their excitation windings. For any given setting of the transformer 28 the transductor 18 will pass a constant current over a range of precipitator working voltages. Typical operating characteristics for the transductors are given and discussed, Figs. 2 and 3 (not shown).