New approach to Teed feeder protection using composite current and voltage signal comparison

The basis of a new approach to the problem of differential protection of Teed feeders that involves deriving differential signals which are functions of both voltages and currents measured at each feeder end are described. It is shown that this approach obviates the need for relay bias to compensate for capacitance spill current, improves the sensitivity to high resistance faults and removes uncertainties as to the dependability of protection under contingency operating and/or fault conditions