Measurement and estimation of very fast radiated electromagnetic fields in a 245kv gas insulated substation

The transient high frequency electric and magnetic fields are generated in GIS systems during switching operations. In the present work, the measurement of magnetic fields and electric fields have been carried out at various locations of 245KV GIS (Gas insulated substation) during closing operation of disconnector switch 1(DS1) is considered. The results of measured values are compared with the estimated values. The results shows that transient electric and magnetic field values are correlate with the measured values at bus link, near current transformer (CT) and at cable termination , the calculated values are slightly deviated from the measured values when moves along with XLPE cable. This may be due to a fast attenuation rate of electromagnetic fields with distance away from the DS1. The frequency spectrum of the time varying electric field and magnetic fields at various locations are also estimated. The magnetic field at CT is exceeding standard value during transient period, which is observed in both calculated and measured cases this may leads to malfunctioning of the secondary equipment connected to CT. The above results gives a basic idea of modeling of GIS systems for the estimation of high frequency electric and magnetic fields and also helps in preparing electromagnetic chart for the particular GIS system. These results are also use full in order to prepare some precautionary protection measures to avoid malfunctioning of secondary equipment and metering equipment in a GIS systems.