The loss values (no-load loss, load loss) of the transformer need to be known, as well as the load profile of the transformer or at least its average load, together with the electricity costs. The no-load loss occurs as soon as a transformer is connected to a network. The load loss has a square dependence on the load. Since the costs of the losses occur in future, the present value (PV) of the losses during the expected lifetime should be considered. Different methods exist. The most common one is the total cost of ownership (TOC) approach, which will be recognized by the new upcoming transformer standards. ABB is providing an easy-to-use, free access web tool for TCO analysis.