GB1227368A - - Google Patents

Abstract

1,227,368. Automatic speed control. LENINGRADSKY METALLICHESKY ZAVOD IMENI XXII SIEZDA KPSS. Aug. 8, 1968, No. 37874/68. Heading G3R. The flow of liquid through a turbine 1 and therefore its speed is controlled by a proportional and integral feedback loop comprising a tachogenerator 2; a magnetic amplifier 33-34-55 and a hydromechanical actuator 17, the loop including a T- network 40-45 of the form shown. The speed of the turbine is measured by the tachogenerator 2, 5, 6 whose variable frequency output is applied to a tuned circuit 3, 4 giving an output in a transformer 8 when the speed deviates from a predetermined value. The output of transformer 8 is applied through a transformer 27 to a phase sensitive detector 31 the output of which is fed to the magnetic amplifier 33, 34, 35, which feeds the actuator 17. The output of the tachogenerator is also applied to a transformer 14 which provides power to the magnetic amplifier and to two potentiometers 20, 25 whose position is controlled by the actuator 17. The output of potentiometer 20 is added through transformer 21 with a speed setting value from transformer 9 to the output of transformer 8 applied to the phase detector. The output of potentiometer 35 is applied through transformer 36 and a bridge rectifier 39 to the input of the T-network 40-45. The output of the T-network is applied through a variable capacitance 46-48 to the input of the magnetic amplifier. The turbine speed is set by potentiometer 11 (driven by a motor 13), the minimum setting being set by a potentiometer 12. The inclusion of the T-network is stated to permit independant adjustment of the time constant and feedback factor of the loop while keeping their product constant. The variable capacitance 46-48 permits altering the time constant keeping the feedback factor constant; the additional capacitors 47,48 are precharged from rectifier 39 to avoid upsetting the system when changing capacitance.