ZTSG type open ventilation variable frequency phase shifting transformer is used as multi-phase power supply for high-voltage inverter, which plays the role of rectification, phase shifting, isolation and suppression of power supply harmonics in the inverter. Cooperate with the power unit of the high-voltage frequency converter, and form an inverter with the switch cabinet and the control unit cabinet. It is widely used in electric power, metallurgy, cement, coal, petroleum, petrochemical and other fields to provide variable frequency power supply to achieve energy saving and emission reduction. According to the voltage level, there are 3kV, 36kV, 48kV, etc., the number of phases is from 6 phase, 9 phase, 12 phase up to 30 phase, 36 phase, 48 phase. The more the number of cascades, the less the harmonic content on the input side, the second time. Each group of phase-shifted windings is accurately calculated by the finite element method, and its temperature rise is calculated by simulation software to ensure the electrical stability of the transformer and provide high-quality power for the frequency conversion equipment.