Due to the iron core saturation

transformer switching in no-load situation will produce excitation inrush current

which may cause misoperation in relay protection device and overvoltage damaging equipment insulation.To research this problem

EMTP/ATP is adopted to calculate excitation inrush current of single-phase and three-phase transformer

the applicability and accuracy of saturable transformer model

BCTRAN model and Hybrid model in transformer no-load switching calculation are analyzed.And then a single-phase transformer is adopted to carry out no-load switching experiment

excitation inrush current waveforms under different switching angles and remanent magnetism are analyzed to check the accuracy of calculation results.The results show that saturable transformer model cannot consider iron core hysteresis and remanent magnetism

the deviation between calculation results and actual results is big.BCTRAN simulates hysteresis features by adding external nonlinear element

which is comparatively accurate

but the numerical waveform cannot fit experimental waveform completely.Hybrid is magnetic circuit model based on the duality principle

which can reflects the flux flow path in core column

iron yoke

and air gap better

it can simulate the amplitude and waveform of excitation inrush current more accurately

so hybrid model is recommended in transformer no-load switching calculation.