The application of high-capacity transformers in electric power system usually causes the increase of shortcircuit current at low-or medium-voltage side because transformer’s equivalent impedance is inversely proportional to its capacity. Taking the transformers in Jinan Yaojia 220 kV-240 MV·A transformer substation for example

the characteristics and feasibility of different transformer impedance are analyzed from the aspects of technology

economics

and life cycle. The results demonstrate that in order to limit short-circuit current in bus bar in a highcapacity transformer substation

it is more economical and reasonable to choose high impedance transformer

and lower life-cycle cost can be gained compared with normal impedance transformer with current limiting reactor.