GB732277A - Overload protection for power supplies of an electrostatic precipitator - Google Patents

Abstract

732,277. Rectifying. AIR PREHEATER CORPORATION. Feb. 18, 1953 [Feb. 18, 1952], No. 4527/53. Class 38 (2). [Also in Group XXXVII] An electrostatic precipitator supplied by a rectifier connected to the secondary of a power transformer having a current-limiting reactor in its primary circuit, is de-energized on overload, e.g. due to a short-circuit between electrodes, by a relay responsive to excessive voltage across the reactor. In one form, Fig. 2, a potentiometer 42 is connected across the reactor 40 and the relay 31 is connected through the tapping 43 to the reactor. The contacts 32 of the relay are normally closed and so maintain energization of a contactor coil 28. On overload, the volts-drop across the reactor energizes the relay 31 and opens the circuit of coil 28 to disconnect the supply. In a modification, Fig. 3, a resistor 45 is connected in the D.C. lead of the rectifier 24 so that increased current through the resistance increases the volts-drop across the reactor. In a further form, Fig. 4 (not shown), the relay 31 is energized over a time-delay circuit, and in Fig. 5 (not shown), the electromagnetic relay 31 is replaced by thermionic relays. A cam 36 which rotates with the precipitator rotor (not shown) periodically closes contacts 38 so as to automatically reclose the contactor. The precipitator may be that of Specification 684,024, [Group XL (a)].