Taking a transformer rated 110/38.5/10.5 kV and 63 000 kVA as an example

a reactor controlled by a paralleled high-speed switch is put forward to limit the short-circuit current. The reactor is in series with the highvoltage winding of transformer. A circuit model is established to analyze the transient short-circuit currents of the windings when the three-phase short-circuit fault occurs at the location of the termination of low-voltage winding.The dynamic force

displacement and bending stress of variable impedance transformer are analyzed based on the mass-spring system. A magnetic-thermal-fluid coupled model is applied to calculate the temperature rise of the transformer windings at the short-circuit operation. The research method is applied to energy-saving transformer and the short-circuit mechanical stability and the transient temperature distribution of current-limiting reactor inputting or not are calculated. The results show that the mechanical stability and transient temperature distribution of energy-saving transformers is superior to the traditional transformer.