1. IN COMBINATION IN A SWITCH, A SQUARE LOOP FERROMAGNETIC CORE, BIASING MEANS INCLUDING A BIASING WINDING COUPLED TO SAID CORE FOR SATURATING SAID CORE IN ONE HYSTERESIS REMANENT POLARITY, A FIRST SWITCHING WINDING COUPLED TO SAID CORE, A FIXED CONDUCTING RING AND A PIVOTABLY MOUNTED CONDUCTING RING BOTH COUPLED TO SAID CORE, SAID CONDUCTING RINGS BEING ADAPTED FOR RELATIVE TRANSLATION THEREBETWEEN, TWO CONTACTS, ONE OF SAID CONTACTS BEING MECHANICALLY FIXED AND THE OTHER OF SAID CONTACTS BEING JOINED TO SAID PIVOTABLY MOUNTED CONDUCTING RING.