The use of power quality standards to establish an equivalent transformer capability under harmonic loading

Abstract: Transformers which are not designed to operate under harmonic loading will experience higher than usual temperature increases in the windings due to the added harmonic current. This paper uses the IEEE 519 and NRS 048-2 power quality standards which define harmonic limits of voltage THD (Total Harmonic Distortion) and IHD (Individual Harmonic Distortion) and the IEEE C57.110 standard which uses the current harmonic information (IHD) to approximate an equivalent transformer capability, that is, a derating factor which can be used to limit the power usage on a transformer which is operating under nonlinear load conditions