The application of high-voltage high-power winding asynchronous motors in electric drive systems is becoming more and more common. Direct starting will cause a large inrush current, resulting in a drop in the system voltage and affecting the normal operation of other electrical equipment in the same power grid. Liquid soft start uses liquid resistance as the medium, continuously adjusting the starting torque and starting current steplessly, so as to realize the soft start of the high-power winding motor and reduce the impact of the large high-voltage winding motor on the grid voltage and equipment during the starting process.

The author analyzes the application example of the 10kV and 3800kW winding motor of the waste heat recovery power generation project using liquid resistance technology to achieve soft start, and introduces an economical, applicable and reliable starting technology.

It is more common to use high-voltage and high-power winding asynchronous motors in various electric drive systems of production machinery, especially in fans, pumps, crushers and other units in metallurgy, mining, petrochemical and other industries. During the starting process of these high-voltage high-power motors, the starting current is too large (generally 3 to 8 times the rated current), which often causes the system voltage to drop, causing system voltage fluctuations, seriously affecting the power supply quality of the power grid, and even causing the power supply network. Downtime of other equipment affects production.