MEASUREMENTS AND COMPUTATIONS OF ELECTROMAGNETIC-FIELDS IN ELECTRIC-POWER SUBSTATIONS

The magnetic fields generated by a typical distribution substation wer e measured and calculated based on a computer model which takes into a ccount currents in the grounding systems, distribution feeder neutrals , overhead ground wires and induced currents in equipment structures a nd ground grid loops. Both measured and computed results indicate that magnetic fields ar e significantly influenced by ground currents, as well as induced currents in structures and ground system loops. All cu rrents in the network modelled were computed, based on the measured cu rrents impressed at the boundary points (ends of the conductor network ). The agreement between the measured and computed values is good. Sma ll differences were observed and are attributed mainly to uncertaintie s in the geometry of the network model and phase angles of some of the currents in the neutral conductors which were not measured in the fie ld. Further measurements, including more accurate geometrical informat ion and phase angles, are planned.