The input (incoming) reactor is used at the input end of the frequency converter to protect the frequency converter from transient overvoltage effects; it also reduces surge and peak current, improves the true power factor, and improves the input current waveform. ; Inverter equipment will produce a large number of harmonics when it is working, and the input reactor can also prevent the harmonics generated by the inverter from affecting the power grid, so as to prevent the harmonics generated by the inverter from interfering with the normal operation of other electronic equipment .