Thanks for replay.
As you see at the attachmend, there is a formula in the IEC 354 for hot spot temperature(Qh) calculation. But this formula is so complex and i couldn't find out a function that indicates power curve(depends K) referring to hot spot and the other variables at the formula...
That's a great comminity here.
Now I have a problem with ambient temperature rise. Let's describe the problem. For the power transformers the power of transformer is related with ambient temperature. And IEC 354 shows how it is calculate for a transformer . But its so complex and I couldn't...