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Adding capacitors to an electric power system provides well known benefits, including power factor correction, voltage support and increase of active power transfer capacity. However, the capacitor banks modify the harmonic voltages and currents in the network and give rise to current and voltage transients, stressing switching devices and sensitive loads. The first part of the paper describes measurements and studies performed before the installation of 2 x 50 MVAr capacitor banks in a 500-132 kV substation, in the Argentinian Transmission System. By measurements of harmonics content in voltage and current, the IITREE performed some studies to quantify the harmonic voltage in the 132 kV busbar and the harmonic voltages and currents in the capacitors to prevent excessive overload. Switching transients were also studied. The studies carried out with the electromagnetic transients program (EMTP) are presented. The second part of the paper deals with measurements performed after the installation of the 2 x 50 MVAr capacitor banks. These measurements were carried out to verify the harmonic levels in the busbar and in the capacitor bank, and to obtain the current and voltage switching transients. The results of measurements are compared to the ones obtained by studies and simulations.