Standard power Xformer and max frequency of operation

[rtarbell]

This might not be a fair question to ask because I don't have a specific transformer in mind, but I'll try to ask it anyways:

Take a standard power transformer (either EI or toroidal), 120V/240V in (depending upon what country you're in), 50/60Hz operation. I now understand that, due to the magnetic materials used in a standard power transformer, you can't use them in, say, a switchmode power supply at 100kHz.

==> Does anyone know what IS the maximum frequency you could use a standard power transformer at? If I had the equipment to do it, can I try to say, double the input frequency to 120Hz and expect normal operation?

[Elvee]

Hi,

We have to clarify some points: if you use your transformer, unmodified, on the same voltage, with just the frequency increased, you will have no problem: increasing the operating frequency also decreases the peak induction in the iron, in a proportionnal manner. This will decrease the overall losses in the iron, because these losses have a more or less exponential relationship with induction, whereas the dependence with frequency is more or less linear. The only disadvantage of operating the transformer in this way will be the increased effect of leakage inductance.

On the other hand, if you recalculate the number of turns for the new frequency, you will keep the induction constant and increase the iron losses. You may be able to reach 120Hz, or even 400Hz with good quality materials, but not further, otherwise the iron losses will become excessive and you will have to operate at a lower induction level.
LV