Consider a magnetic circuit with constant (d.c) excitation current I0. Flux established will have fixed value with a fixed direction. Suppose this final current I0 has been attained from zero current slowly by energizing the coil from a potential divider arrangement as depicted in Figure 22.7. Let us also assume that initially the core was not magnetized. The exciting current therefore becomes a function of time till it reached the desired current I and we stopped further increasing it.
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