Operation at excessive magnetic flux✓Bonne réponse
Selecting a core with excessive permittivity
Explication
Saturation occurs when the magnetic flux density in the core is driven so high that its magnetic domains are already aligned and the core cannot support more flux; inductance then collapses and current rises sharply. The cause is the flux level, set by current and turns, not the operating frequency, a core with weak magnetic response, or permittivity.