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. The open-circuit and short-circuit tests are used to determine losses in these 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 copper wiring and leakage flux. Since they rely on a conserved flow (-5[1])of magnetic flux, the emf ratio of these devices equals the ratio between the number of windings the primary and secondary coils have around the magnetic core. For 10 points, name these devices used in power grids to step (10[1])up or step down voltages. (10[1]0[1])■END■