I made the BH curve of a ferrite core transformer and an iron core transformer with a 2V and 20Hz sine wave in input and saw that the BH curve of the iron core transformer is a bit larger than the other one.

What does that mean? What happens if I increase the frequency for each case?

Thanks !

  • \$\begingroup\$ high BH ferrite using MgZn can store energy better at high f but saturate at low f. While CRGOS cores are magnetized with 10% rated current to couple far greater energy than the reactive energy stored, The cores are also high capacitance of > 1uF per lamination in series.so rt(L/C) impedance levels are low at low f. high saturation levels of 6T (cheap) to 12T ($) allow far more energy transfer in most cases \$\endgroup\$ Mar 9, 2019 at 18:28
  • \$\begingroup\$ 1uF for a large surface area lamination with silicate insulation coating (1m^2) whereas ferrite L/C ratio is much higher. CRGOS can also be down to 0.1W/kg loss but typically <0.3. The CRGOS imaginary permeability of iron core rises sharply with f while the real part of mu drops sharply after 1kHz \$\endgroup\$ Mar 9, 2019 at 18:45
  • \$\begingroup\$ Thanks for helping but I'm not sure to get everything you said ! I'm still a student. \$\endgroup\$
    – Xeruth
    Mar 9, 2019 at 18:46
  • \$\begingroup\$ Try loading each core and see the effects from impedance. for secondary max power vs f and primary current using the same turns ratios. But use a voltage source like an Audio Power Amp otherwise if using a 50 Ohm Sig Gen observe the input impedance (attenuation) with AC current applied from 50 Ohms with higher V \$\endgroup\$ Mar 9, 2019 at 18:52
  • \$\begingroup\$ en.wikipedia.org/wiki/… \$\endgroup\$ Mar 9, 2019 at 18:55

1 Answer 1


In general a transformer with an Iron core has a higher saturation flux density so you can get away with a smaller core, or fewer turns in a low frequency design. Iron cores do suffer from circulating currents in the core however which makes them lossy at high frequencies. Iron cores are often laminated to reduce this effect.

Ferrite cores will saturate at a lower flux density but has lower losses at high frequencies as they have much higher resistance.

  • \$\begingroup\$ Good answer, without drowning us in abstract math equations. \$\endgroup\$
    – user105652
    Mar 9, 2019 at 19:52
  • 2
    \$\begingroup\$ It's perhaps worth mentioning metal powder cores here, which are kind of a best-of-both-worlds, but can be prohibitively expensive compared to ferrite or steel laminate. \$\endgroup\$
    – Hearth
    Mar 9, 2019 at 20:10

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