Research on causes of harmonic currents and solitating problem

During these days, as more electric equipments come into using and the ratio of nonlinear load increases gradually, both the type and the quantity of equipments that produce harmonic wave have increased enormously and will go on increasing consequently, the characters of Low Pressure Distribution System have chang greatly. Even if it worked with three-phase sine, three-phase line current would have non-sine aberrance and produce harmonic wave-electricity. As a result, the safe runs of electric equipments, electric fire prevention and many other new subjects come out. What´s more, the most urgent problem is the recognization of harmonic wave´s appearance and harm which should be taken serious by designers and principles-makers.