Feeder switch currents during load transfer

Load transfer from an overloaded feeder to a neighboring lightly loaded feeder is obtained by closing the tie switch between the two feeders, followed by opening one of the sectionalizing switches along the overloaded feeder. During such a time interval, the resulting loop operation may (under some extreme cases) result in excessive current flow through the sectionalizing switch. Such a case can lead to a potential operational problem and a hazard to utility personnel. This paper investigates a situation that can lead to currents beyond the load break rating of the switches by analyzing a simplified circuit model of a distribution feeder during load transfer. It has been determined that load transfer through line switches can be excessive when one of the two feeders is fed from a stand-alone transformer and the other from a parallel bank of the same size. The simplified analysis is verified by some field measurements.