| abstract |
A direct-coupled fluxgate current sensor which is driven to hard saturation to achieve a sudden change in magnetic properties of the sensor, comprising: (a) a first closed loop core (4) of ferromagnetic material encased in a sleeve wound with a first toroidal drive winding (10), the winding for the first core (4) extending around the circumference of the first core (4); (b) a second closed loop core (6) of ferromagnetic material encased in a sleeve wound with a second toroidal drive winding (12) independent of the first winding (10), the winding (12) for the second core (6) extending around the circumference of the second core (6); and, (c) a closed loop core casing (8) which is adapted to cooperate with the first core (4) and the second core (6), the closed loop core casing (8) and the first and second cores (4),(6) being wound as a unit with a toroidal sense winding (14) independent of the first and second toroidal drive windings (10,12), the winding (14) for the closed loop core casing (8) extending around the circumference of the closed loop core casing (8). The sensor is capable of sensing toroidal magnetic fields at very low levels. |