Hi, I had modeled a simple transformer with Maxwell 3D (one closed iron and 2 coils), all seems all right except the output voltage, I have only 300 mV and I must have 12V ! I join the files, if someone can help me ? A strange thing is the StrandedLoss which up to 350 kW !!! where's come from this ? V1=12V V2=300mV Coil1=1000 turns Coil2=1000 turns Regards Edit: I have increase the secondary resistor : 1000 Ohms and the voltage is good. But when I want to place a small value for resistor (5 Ohms) for example, the voltage is very low ! someone has an idea where come from the problem ?