Correctly distinguish inrush and internal fault has been the focus of transformer protection

Power transformer is extremely important power system equipment, transformer differential protection is the main protection. Load switching or external short circuit fault clearing voltage generated when a  power transformers  current recovery, the size of a few comparable internal fault currents. Can correctly distinguish inrush and  air circuit breaker  transformer protection has been the focus of a variety of magnetizing inrush current  Electric energy meter  method largely based on Kirchhoff's law, there is in principle a defect; several differential protection new theories, new technology also needs to be further improved in practice. With the increasing size of the power system, load tap more extensive application, which also produced a lot of problems related to.