With the development of social economy, the air separation plant becomes larger. The scale of air compressor, supercharger and other units of large air separation plant is increasing. Taking the air compressor as an example, power of the main motor has reached more than 30000 kw. For the different power grid conditions, motor configuration and motor starting mode of different users, the related electronic control design technology of air separation plant has been improved correspondingly. Here is a brief introduction to the starting mode of air compressor motor.
The starting mode of air compressor motor of large-scale air separation plant is divided into direct starting and soft starting: in order to reduce the investment of electrical equipment, after accurate calculation, the direct starting mode can be adopted for air compressor motor when the power grid conditions and equipment performance is suitable. But in reality, many users are often limited by the capacity of the power grid, so they can’t use the way of direct start.
When the motor is full voltage starting directly, the starting current will reach 4-7 times of the rated current, and the larger current will cause a sharp drop in the grid voltage, which will cause other equipment in the same grid to fail to operate normally. In addition, the torque of the motor is 2 times of the rated torque, and the larger torque will accelerate the wear of the gear and drive belt and the fatigue damage of the blades, which will affect the normal operation of the equipment. Besides, the starting current of air compressor motor during soft starting is 2-3 times of the rated current, the voltage fluctuation of power grid is about 10%, and the torque does not exceed the rated torque, which will not have a great impact on other equipment in the same power grid.
At present, the soft start of air compressor motor is widely used by most air separation users because of its advantages of reliable start and light load for energy saving. Adopting the soft start of motor and selecting the appropriate power motor according to the air compressor volume through accurate calculation can greatly reduce the energy consumption of air separation plant and fully guarantee the process performance of air separation plant.
