Isat is lower than Irms?

[MacIntoshCZ]

How can be Irms higher than Isat? Isnt coil unusable than?
Irms is usable current for wires than.

https://uk.farnell.com/wurth-elektronik/7443762504100/power-inductor-10uh-shielded-20a/dp/3650430?st=7443762504100

 

[ronsimpson]

The saturation current is where the inductance drops 30%.
Irms current is where the copper loss (resistance loss) is too much and the part is 50C hotter than air temperature.

At 20A the inductance is less than 1uH.

 

[Diver300]

The coil's inductance reduces to 30% at Isat.

It seems that the coil has been designed for a low resistance, so that the temperature rise is small at Isat. Making the wire larger diameter reduces the resistance losses, and increases the max Irms, but it doesn't mean that the inductor will be useful at that current.

It's a bit like having a large wire to reduce voltage drop.

 

[MacIntoshCZ]

Thanks for info. Its really helpful =)

 

[ronsimpson]

Thanks

No problem, I design inductors as part of my job. Last week I delivered one built on a 6 inch diameter form, one foot tall. 1mH and they are using it at 100A. It shows not hint of saturation.

 

[MacIntoshCZ]

No problem, I design inductors as part of my job. Last week I delivered one built on a 6 inch diameter form, one foot tall. 1mH and they are using it at 100A. It shows not hint of saturation.

I needed inductor for my pfc. From AP note i got calculcaled values: 0,4mH and 20A current peaks. I chose this core and made 36 turns. Peak magnetic induction should be .5T (20A).
Is that ok? From my perspective it works well