Ferrite Inductor DCApril 19th Fact-of-the-Day
Direct current can have large effects on the inductance of chokes, filters and transformers wound on ferrite cores. Because of that, it generally is best to provide another path for direct current where it is practical to do so. It is important to determine how much effect direct current will have on inductance and then adjust the number of turns of otherwise compensate where a direct current shunt-path is not practical. Very small values of direct current may slightly increase inductance, but larger direct current values will significantly decrease inductance. Where large DC current cannot be avoided, such as where a ferrite-core inductor is used as power supply filter component, a ferrite core air-gap will reduce the effect of the direct current on the inductance. Or course, the air-gap also will reduce the inductance, but the result will be an inductance that changes less with DC current changes. ©2005 Martek International All rights reserved.
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