| 摘要 |
<p>Detector circuit for measuring relatively strong currents including a main current transformer (1) and two substantially identical auxiliary current transformers (2, 3) where a main current (I<SUB>1</SUB>) induces magnetomotive forces in said main current transformer (1), said magnetomotive forces being counteracted by magnetomotive forces induced by a compensating current (i<SUB>1</SUB>) while at the same time the two auxiliary transformers (2, 3) are magnetised in antiphase by means of a square wave/modulation signal. Furthermore the detector circuit includes a synchronous rectifier for generating an adjusting signal for the compensating current (i<SUB>1</SUB>). According to the invention a compensating current is used for measuring current in a common winding (L3) surrounding the main transformer as well as the auxiliary transformers while at the same time a possible error signal in the shape of a voltage difference between the auxiliary transformers is used to adjust the compensating current (i<SUB>1</SUB>) by means of a negative feedback loop.</p> |
