It is installed at the output end of the inverter, which is used to limit the capacitive charging current of the inverter and the motor connecting cable, and inactivate the voltage rise rate of PWM wave output by the inverter. When the length of motor cable exceeds a certain value, it is recommended to insert a motor reactor between the inverter and the motor, which is used to compensate the recharging current of capacitor in case of the long wires. The maximum length depends on the rated value of the frequency converter and the type of the motor cable.