| 摘要 |
<p>1,241,295. Automatic power control. PLESSEY CO. Ltd. Oct.25, 1968 [Nov. 13, 1967], No. 51634/67. Heading G3R. The power dissipated by an A.C. load 12 is controlled by an arrangement including pulse producing means, e.g. a saturable reactor 1, which produces pulses at the start and finish of each half-cycle of an alternating current supplied to the load 12 through a uni-directional switch, e.g. a thyristor 10; each pulse is dropped across the series combination of a reference impedance, e.g. a fixed resistor 7, and a variable detector impedance, e.g. a thermistor 8, responsive to the power dissipated in the load, the voltage at the junction 9 between impedances 7, 8 being effective for triggering the switch 10. The pulse-producing windings 5, 6 of the saturable reactor 1 are connected in a bridge circuit with the impedances 7 and 8 so that the voltage at 9 is zero when the thermistor 8 is at the correct temperature ccrresponding to the desired load dissipation. Should the load dissipation vary, the impedance of thermistor 8 will vary accordingly and the resultant voltage pulse at 9 will control the firing of thyristor 10 to correct the deviation.</p> |
