Step-down starting method of Weifang Chenxing power generator set with three-phase asynchronous motor

When choosing a generator set to drive a motor, many people are often confused. How can I choose a generator set? Can a 1kW motor be started with a generator set of the same power? Weifang Chenxing Power Equipment Co., Ltd. has been focusing on diesel generator sets for 6 years, and will give you answers.

1. Full voltage start, that is, direct start, that is, start under rated voltage. The starting current of this method is very large, which can reach 4 to 7 times the rated current. Weifang Chenxing Power Equipment Co., Ltd. reminds you that the starting power of a single motor should not exceed 30% of the capacity of the power distribution generator set.

2. The phase asynchronous motor has two types: direct start and reduced voltage start.

1) Direct starting means starting under rated voltage. The starting current of this method is very large, which can reach 4 to 7 times the rated current. Weifang Chenxing Power Equipment Co., Ltd. reminds you that the starting power of a single motor should not exceed 30% of the capacity of the distribution transformer.

2) Decreased voltage start Use the starting device to reduce the voltage, and then add it to the motor. When the motor speed rises to a certain value, it will be switched to the rated voltage for operation. Weifang Chenxing Power Equipment Co., Ltd. reminds you that although this method can reduce the starting current, the torque of the motor is proportional to the square of the voltage, and the starting torque of the motor is therefore reduced, so it is only suitable for cage motors. No-load or light-load starting occasions. Generally, the commonly used methods of reducing voltage start are as follows:

(1) Star-delta step-down starting: When starting, connect the three-phase stator windings in a star shape to limit the starting current. When the speed is close to the rated speed, switch to a triangle to make the motor run at full voltage. Weifang Chenxing Power Equipment Co., Ltd. reminds you that with this starting method, the starting current is small, and the starting torque is also small, so it is generally suitable for delta connection and small capacity motors for no-load or light-duty operation. Load start. It can also be started frequently.

(2) Autotransformer step-down start: Connect the high-voltage side of the autotransformer to the power grid and the low-voltage side to the motor. When starting, the autotransformer tap is used to reduce the voltage of the motor. When the speed rises to a certain value, the autotransformer is automatically cut off, and the motor is connected to the power supply and runs normally under full voltage. In this starting method, the tap position of the autotransformer can be selected to adjust the terminal voltage of the motor, and the starting torque is larger than the star-delta step-down starting. Weifang Chenxing Power Equipment Co., Ltd. reminds you that the autotransformer has a large investment and is not allowed to start frequently. It is only suitable for large-capacity motors connected in star or delta.

(3) Yanbian triangle step-down starting: When starting, the stator windings are connected to the Yanbian triangle to reduce the starting current. After the motor starts, it is switched to a triangle to make the motor run under full voltage. This starting method can obtain starting torques of different values ??by adjusting the tap ratio of the stator winding, thereby overcoming the disadvantages of low star-delta starting voltage and small starting torque. It is suitable for motors with intermediate taps in the stator winding, and can also be used for frequent starting. Rotor circuit is connected in series with resistance to start. When starting, a resistance is connected in series in the rotor circuit to make a star connection to reduce the starting current and increase the starting torque, so that the motor can obtain better starting performance. Weifang Chenxing Power Equipment Co., Ltd. reminds you that this starting method is only suitable for wire wound asynchronous motors.