coil on load 1402 and r load pf 1 1403 with reference to fig1 a and b the secondary coil is placed on load and current flows in the secondary coil which gives rise to a bemf induced flux which couples back to the primary causing primary current heat and losses to increase as well as altering the primary coil 39 s power factor flux flow can be compared with current in a parallel resistor circuit as shown in fig2 reluctance behaves much like resistance in that the induced magnetic field will follow the path of least reluctance r1 10 u03c9 and corresponds to the secondary cores as seen by the primary causes large flux flow r2 10 k u03c9 and corresponds to the primary core as seen by the secondary causes small flux flow fig2 shows a bi toroid transformer on load 2000 primary coil on load 2001 secondary coil 1 on load 2002 secondary coil 2 on load 2003 r load 1 2004 and r load 2 2005 fig2 shows a primary coil 2101 on load secondary coil 1 on load 2102 secondary coil 2 on load 2103 high reluctance flux path 2104 low reluctance flux path 2105 r load 1 2106 r load 2 2107 high reluctance flux path 2108 and low reluctance flux path 2109 in the dynamic situation the initial primary flux u03c6p s2 and u03c6p s1 create near saturation making the primary core a high reluctance core part as shown by the nonlinear u2018 hysteresis u2019 behavior in b h curves fig6 amp 7 counter flux u03c6p xx.