| 摘要 |
1530137 Control circuits for electrostatic precipitators; converting LODGE-COTTRELL Ltd 25 May 1976 [6 June 1975] 24353/75 Heading H2H and H2F A power supply for an electrostatic precipitator is controlled by a circuit comprising an oscillator 25, a pair of amplifiers 26, 27 for amplifying the oscillator output pulses and a pair of pulse transformers 29, the primary windings of which are connected to the amplifier outputs and the secondary windings control the conduction of a pair of rectifiers 40, 41. The power supply is similar to that described in Specification 1,470,170 but the circuit 21 including the oscillator, the amplifiers and the pulse transformers is different. The oscillator 25 supplies pulses to the amplifiers 26, 27 at a frequency determined by a timing circuit 32, the amplifiers being controlled by a bistable circuit 28 so that one amplifier is operative whilst the other is inhibited during each half cycle of the mains supply at terminals 14. The pulses from the amplifiers are supplied to the transformers 29 to trigger the thyristors 40, 41 during alternate half-cycles of the mains supply. A feedback circuit 20 controls the circuit 21 by adjusting the firing points of the thyristors to maintain the precipitator voltage at its optimum value and a by-pass circuit 22 interrupts the power supply to the precipitator if arcing persists for four mains supply cycles. |
