单相接地短路时故障量经变压器的传递

Transfer of Fault Through Transformer in Single-phase Short Circuit Protection

对于低压侧中性点接地的降压变压器的单相接地短路保护,许多设计手册和规范中都有保护设定值的公式,但对于公式的由来都没有详述。运用线性系统的对称分量来分析降压变压器低压侧单相接地短路时流经高压侧的故障电流,并推导手册或规范中的公式,以便更好地理解规范或设计手册中关于单相接地保护设置的规定。

For the short circuit protection of the neural earthed transform at low voltage side, there is the equation to determine the protection value in many design manuals and codes. But, there is no the detailed origin of the equation in there. In this article, by using symmetry vector of the linear system, the fault current flowing high voltage side was analyzed when short circuit in single phase earthed transformer at low voltage side was occurred, and at the same times, the equation in design manuals and codes was deducted. In this way, the regulation of setting single phase earthed protection stipulated in design manuals and codes can be better understood.