Inrush currents associated with motor starting and transformer energizing can cause interaction problems with other loads in a facility or on the power system, particularly sags that trip loads. Protection devices can misinterpret these events as fault currents, if the devices are not properly coordinated.Coupled with the tendency of other constant power devices to increase current to make up for the reduced voltage, the inrush current may cause protection devices to trip. Energizing a transformer has the additional issue of harmonics in the inrush current, which can excite system resonances and cause dynamic overvoltages.