The characteristics of these devices are adjusted during operation with an on-load tap changer. Lamination is introduced into these devices to minimize eddy current losses. (15[1])The open-circuit and short-circuit tests are used to determine losses in these (15[1])devices and model them as a cantilever or T-circuit after referring impedances to one side. Non-ideal versions of these devices have losses due to (*) hysteresis and non-infinite (-5[1])permeability, as well as (-5[1])copper wiring and leakage (10[1])flux. Since they rely on a (-5[1])conserved (-5[1])flow (-5[1])of magnetic flux, the (10[1])emf ratio of these devices equals the (10[1])ratio between the number of (10[1])windings the (10[1]-5[3])primary and secondary coils have around the magnetic (10[1]-5[1])core. For 10 points, (-5[1])name these devices used in power grids to step (10[2])up or step down (10[1])voltages. (10[4]0[7])■END■