三相变四相电力变压器的差动保护原理

采用三相交四相的电力变压器可以实现四相输电方式，也可以用作电气化铁道的AT供电方式，但这种变压器的差动保护研究未见报道。根据该变压器三相侧与四相侧的电流变换关系，提出了两种简单实用的差动保护接线，并比较分析了这两种接线的优劣，给出了变压器三相侧采用三相电流互感器接成Δ形的差动保护接线方案更优的结论。

STUDY ON DIFFERENTIAL PROTECTION FOR THREE PHASE TO FOUR PHASE TRANSFORMER

The four phase power transmission can be implemented by use of three phase to four phase transformer, this kind of transformer can also be used to the AT power traction feeding system in electric railways. The report on the research of differential protection for this kind of transformer has not been seen. According to the current transferring between the three phase side and four phase side of this transformer, two simple and practical wiring schemes for differential protection are proposed and the merits and demerits of the two wiring schemes are compared. The conclusion is that the differential protection for three phase to four phase transformer with such wiring scheme is a better one, in which the three phase current transformers at the three phase side are connected in delta form.