Near Resonant Coupling on EHV Circuits: I - Field Investigations

Higher voltages than anticipated and large neutral currents were measured on 345-kV shunt reactors installed at each end of a 261.4-mile 345-kV circuit operated in close parallel with a 138- kV circuit. The phenomenon existed only when the 345-kV circuit breakers at both ends were open, the line ungrounded, and either or both of the EHV shunt reactors connected. Field investigations and measurements are presented.