Means for determining an internal condition in electrical apparatus

Claim 1

ELECTRICAL APPARATUS HAVING IN COMBINATION, AN ENCLOSING TANK OF A MAGNETIC CONDUCTING MATERIAL IN WHICH FLOWS STRAY MAGNETIC FLUX FROM SAID APPARATUS WHEN IT IS IN OPERATION, MEANS FOR INDICATING EXTERNALLY OF SAID TANK AN INTERNAL OPERATING CONDITION OF SAID APPARATUS, SAID MEANS INCLUDING A PAIR OF ELECTRIC CIRCUIT ELEMENTS MOUNTED RESPECTIVELY ON THE INSIDE AND THE OUTSIDE OF SAID TANK, SAID CIRCUIT ELEMENTS BEING INTERCONNECTED TO FORM A CLOSED LOOP CIRCUIT BY MEANS OF TWO CIRCUIT CONDUCTORS WHICH PASS FROM THE INSIDE TO THE OUTSIDE OF SAID TANK, ONE OF SAID CONDUCTORS BEING INSULATED FROM SAID TANK, THE OTHER OF SAID CONDUCTORS BEING A CONDUCTING PORTION OF SAID TANK, THE DISTANCE BETWEEN SAID CONDUCTORS WHERE THEY PASS FROM THE INSIDE TO THE OUTSIDE OF SAID TANK MEASURED IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID STRAY FLUX BEING SUFFICIENTLY SHORT THAT ANY CIRCULATING CURRENT INDUCED IN SAID CLOSED LOOP CIRCUIT BY LINKAGE WITH SAID FLUX WILL BE REDUCED BELOW A MAGNITUDE THAT PRODUCES SIGNIFICANT ERRORS IN SAID INDICATING MEANS.