Geomagnetically induced currents in a Norwegian transformer station

Abstract

This report considers measurements of geomagnetically induced current (GIC) and comparison to recorded variations in the geomagnetic field (dB/dt). The GIC-sensors were installed in the neutral point of a 420 kV transformer located in Mid-Norway in 2019. The magnetometers (for dB/dt) are also located in Mid-Norway, but at another location. Recordings up to December 2021 are presented in this report. The maximum recorded GIC and dB/dt was about +/- 60 A and 14 nT/s, respectively. From linear regression, GIC is approximated to 3 times dB/dt, where GIC is measured in amps and dB/dt in nT/s. GIC is always lower than 7 times dB/dt based on the dataset with day-max values (699 points).