Influence of sampling rate on output voltage of a triphase inverter

The presence of long-term harmonic voltages, unbalance, and overvoltage conditions impose additional stress on insulating dielectric material, causing overheating resulting in reduce useful service life of power system equipment. Short-time events such as impulsive transients and switching surges having high frequency can lead to electrical tree inception, to increased partial discharges, and ultimnately to dielectric breakdown. This paper investigates the effect of sampling rates on capturing high frequency transients at the output of a triphase inverter under different loading conditions. A data acquisition system with the capability of digitizing signal upto 250 MS/s has been used. The output voltages of the triphase inverter were measured at sampling rates of (5, 10, 12.5, 25, 50, 100, 200, 250, and 500) kS/s as well as at (1, 10, 50, 100, and 250) MS/s. Although measurements were carried out at low voltages, the obtained results show the presence of high frequency transients that may be more evident in higher voltage switching systems. It is therefore imperative to monitor and analyse the impact of such high frequency transients on electrical insulation across such higher voltage AC and DC systems.