When considering real transformers, the losses resulting from their operation must be included in the calculations. The losses are demonstrated in “power flows”, which make the output power of the transformer different from the input power.
Basically, there are four major loss types in power transformers:
- Copper loss: it happens by the Joule effect that occurs in the conductors of the transformer windings when traversed by the electric current.
- Foucault currents: also known as parasitic currents. These currents circulate inside the transformer core when it is subjected to a time-varying flow, causing losses by Joule effect.
- Loss by hysteresis: associated with the reorganization of the magnetic moments of the ferromagnetic material that is made the core of the transformer. Each time the hysteresis cycle is traversed, a portion of energy is expended for these magnetic moments to be realigned. To reduce this type of loss, we use materials with appropriate ferromagnetic characteristics.
- Dispersion flow: magnetic fluxes that emend with only one winding and whose trajectories are defined mainly through the air are denominated dispersion flow. These fluxes translate into a proper inductance for both coils.