• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 66 subscribers
  • Views 4881 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Why saturation current of some inductor less than Rms current

Aneesh TS
Expert 1735 points

Hi,

Why some inductors having saturation current less than the rms current?.

The following inductor 744139 from wurth having Irms=3.4A and Isat=1A Wy it is so?

Regards

Aneesh

  • 0
    TI__Genius 9130 points
    Aneesh,

    I think is question is best directed to Wurth since this is their part and their specification.

    Bernard
  • 0
    Intellectual 540 points
    I can make a guess ...

    the data sheet rating is simply Ir not Irms (DC not AC) and is almost exclusively a function of the winding resistance.

    In order to reduce copper losses and to fully cover the core space of a toroid the wire size is maximized for the desired inductance. The current ratings are side effects of the design optimization
  • 0 in reply to Bernard Keogh
    Expert 1735 points
    Hi Bernard,

    Not only that specific Wurth inductor, if you search in digikey you can find thousands of such inductor which is having lesser Isat current than Irms.

    Aneesh
  • 0 in reply to Aneesh TS
    Genius 3295 points

    Isat is the limit for inductance. That is, the inductor's rated inductance falls out of its rated tolerance when its current reaches Isat. Specifically, the inductor's bias point has moved up along its BH curve such that it is dB/dH slope gets smaller and inductance value drops. The maximum Irms rating limits the inductor's ability to perform at high temperature. Operation of the inductor beyond its Irms rating causes the inductor core to get hot. This action reduces the core's saturation limit on its BH curve and the inductor may saturate and become an effective short, or very low inductance. Or its wire and core insulation may fail and cause a short in the windings. So what the ratings show is that you could operate your example inductor at 2 amps, however the inductance would be less than the rated inductance, say for example 50%. If want an inductor to operate at it rated inductance, use the Isat rating.