Vibration it can be very harmful – leading to eventual failure of the system. Consequently, one of the major reasons for vibration analysis is to predict when this type of resonance may occur and then to determine what steps to take to prevent it from occurring. As the amplitude plot shows, adding damping can significantly reduce the magnitude of the vibration. Also, the magnitude can be reduced if the natural frequency can be shifted away from the forcing frequency by changing the stiffness or mass of the system. If the system cannot be changed, perhaps the forcing frequency can be shifted
Per-unit system this, the base currents I and I are related in the opposite way that V and V are related, in that formula_31 The reason for this relation is for power conservation S = S The full load copper loss of a transformer in per-unit form is equal to the per-unit value of its resistance: formula_32 formula_33 Therefore, it may be more useful to express the resistance in per-unit form as it also represents the full-load copper loss. As stated above, there are two degrees of freedom within the per unit system that allow the engineer to specify any per unit