Fator de desclassificação para transformadores

Abstract

The transformer is a vital equipment for the electrical system. Due to its application in raising and lowering voltage. Its study is important in relation to its operating conditions. It is known that every transformer in operation is connected to linear loads and non-linear loads, the latter have harmonic components. Thus, with increasing non-sinusoidal loads in the system, the harmonic current level as well as the K-factor of the transformer is increased generating losses, decreasing its useful life and even being able to disable electrical equipment of the system. For this situation, its load is reduced keeping its operation under acceptable conditions. These concerns are focused primarily on the effects of harmonic distortion on the operation and life of the transformer. The derating factor for transformers is an evaluation of distorted currents in relation to the sinusoidal waveform according to the heating effects of the transformer, also known as factor K. Thus, a study is presented in order to demonstrate, by standards, the importance of the harmonic loss factor (FHL) through the recommendations in IEEE Std. C57.110-2008, of the derating factor, through UL1561 - 1994, in addition to the comparison with the European standard, according to CENELEC, in the distribution transformers.