(A, B, C) of current source. [0017]FIG. 4 is a side view (the side with electrical connections) when seeing along a longitudinal direction of the three-phase toroidal winding of FIG. 3. [0018]FIG. 5 is a side view (the side without electrical connections) when seeing along a longitudinal direction of the three-phase toroidal winding of FIG. 3. [0019]FIG. 6 is a sectional view, showing relative pos