Study On Input Circuit Of Transformer Soft Starter

When power transformer is in steady state,its magnetizing current is little,and usually the magnetizing current is not more than 3%~\Q% of rated current value.But when power transformer is switched on with no load,the magnetizing current in its winding will be so high , its wave will be aberrant and at last the magnetizing current will get magnetizing inrush current. The magnetizing inrush current is harmful to power transformer ,and even more sometimes it is so high that it can cause misoperation of power transformer protection device. So the study on magnetizing inrush current is a very important reseach project in the area of power transformer protection.In this paper,the qualitative and quantitative study on magnetizing inrush current is studied on base of the lastst research native and abroad,and a computing software is developed to compute the magnetizing inrush current in power transformer by Visual C++ 6.0.Then, based on 8 bit microcontrollers smart soft starter is developed in order to avoid magnetizing inrush current.The model power transformer tests show that the result of test meets that of computing by the computing software.With the smart soft starter,when power transformer is switch on,the magnetizing inrush current is avoided.