The small inevitable difference between REG voltage and grid voltage can produce transient inrush current that
flows between the REG and the distribution system at the time of connection. The current decays to zero at an
exponential rate. Inrush current can cause a temporary voltage sag at the neighboring buses, thermal stress of the
power components, or nuisance trips of the protection systems. The severity and duration of the produced inrush current depends on the system impedance, magnitude and sign of the flux linkage of the coupling transformer, and
nonlinear magnetic saturation characteristic of the coupling transformer