High-voltage motors generally have large power, and the impact on the power grid is very serious when they are started. Direct start, series reactor start, self-transformer step-down start, thermal resistance soft start, magnetic control soft start, and frequency conversion soft start are common Starting method, this article briefly introduces these starting methods. First, the high-voltage motor is directly started. Direct start is to directly start the motor under full voltage conditions. If the grid conditions agree, you can choose to start directly. However, in the actual production process, because of limited power grid capacity, direct launches are rarely used. When the direct start is selected, the starting current is large, which causes the voltage drop to fluctuate greatly. As for the power supply system, there is a large impact. If the voltage drop exceeds a certain value, it may cause the higher-level substation to trip. Therefore, this direct launch method is rarely used in practice. Second, the high-voltage motor series reactor is activated.The series reactor is started when the motor is started.It is serially connected to the reactor to limit and reduce the starting current and the voltage drop of the grid when the motor is started.

The reactor becomes the direct motor starting mode. Because the voltage at the motor terminal also drops during the starting process, it simply causes the starting torque to fail, and a secondary shock process will occur during the starting process. Third, high-voltage motor autotransformer start Autotransformer start refers to the use of autotransformer to reduce the starting voltage applied to the motor stator winding when the motor starts. After the motor is started, the motor is disconnected from the autotransformer to run normally under full voltage. The advantage is that different taps of the secondary side of the autotransformer can be selected to complete the step-down start according to the allowable starting current and the required starting torque, and can be used regardless of whether the stator winding of the motor uses a star connection or a delta connection. The disadvantage is that the equipment is larger and therefore more expensive. 4. Soft start of variable resistance of high-voltage motors Soft start of variable resistance includes thermal resistance and liquid resistance. It mainly shares variable pressure resistance by stringing variable liquid resistance in the circuit. With the start of the time, the voltage drop across the variable resistor is reduced, and finally the high-voltage motor starts smoothly. The variable resistance starting method has better starting characteristics during the starting process, but it is not suitable for frequent starting. V. Magnetically controlled soft starting of high voltage motors Magnetically controlled soft starting is a three-phase full reactor made in series between the power supply and the motor using the principle of magnetic amplifiers. The digital control board adjusts the exciting current of the magnetic amplifier control windings when starting.

Change the reactance value of the full reactor to adjust the voltage drop to complete the soft start of the motor. Sixth, the high-frequency motor frequency conversion soft start frequency conversion soft start is the use of thyristor elements to switch on and off the power frequency AC power through the rectifier to convert to DC power, and then the DC power conversion into frequency and voltage controllable AC The power supply, the motor, comes to the intention of starting smoothly. Now, matrix AC to AC conversion is also under development. Compared with other starting methods, frequency conversion soft starting has great advantages. Following the development of technology, it is China electric motors manufacturers the most promising high-voltage motor starting method.