Starting method of the motor
Including: full voltage direct start, self coupling decompression start, Y - △ start, soft starter, frequency converter.
1、Full voltage direct start：
When both the power grid capacity and load allow full voltage direct starting, full voltage direct starting can be considered. The advantages are convenient operation and control, simple maintenance, and relatively economical. Mainly used for starting small power motors, from the perspective of energy conservation, motors larger than 11kW should not use this method.
2、Autocouple decompression starting：
Utilizing the multi tap voltage reduction of an autotransformer can not only meet the needs of different load starting, but also obtain a larger starting torque. It is a commonly used voltage reduction starting method for starting larger capacity motors. Its biggest advantage is that the starting torque is relatively high. When the winding tap is at 80%, the starting torque can reach 64% of that of direct starting. And the starting torque can be adjusted by tapping. It is still widely used today.
3、Y - △ start：
For a squirrel cage asynchronous motor with a normal operating stator winding connected in a triangular manner, if the stator winding is connected in a star shape during starting and then connected in a triangle shape after starting, it can reduce the starting current and reduce its impact on the power grid. This starting method is called star delta reduced pressure starting, or simply star delta starting (y- δ Start). When using the star delta starting method, the starting current is only one-third of the original direct starting method using the triangle connection method. If the starting current during direct starting is calculated as 6-7ie, then during star delta starting, the starting current is only 2-2.3 times. This means that when using star delta starting, the starting torque is also reduced to one-third of what it was when starting directly using the triangle connection method. Suitable for situations where there is no load or light load starting. And compared to any other vacuum starter, its structure is the simplest and the price is also the cheapest. In addition, the star delta starting method also has an advantage, which is that when the load is light, it can allow the motor to operate under the star connection method. At this point, the rated torque and load can be matched, which can improve the efficiency of the motor and save electricity consumption.
4、soft starter：
This utilizes the phase-shifting and voltage regulation principle of thyristor to achieve voltage regulation starting of electric motors, mainly used for starting control of electric motors. The starting effect is good but the cost is high. Due to the use of thyristor components, there is significant harmonic interference during the operation of the thyristor, which has a certain impact on the power grid. In addition, fluctuations in the power grid can also affect the conduction of thyristor components, especially when there are multiple thyristor devices in the same power grid. Therefore, the failure rate of thyristor components is relatively high, as it involves power electronics technology and therefore requires high maintenance technicians.
5、frequency converter：
The frequency converter is the most technologically advanced, fully functional, and effective motor control device in the field of modern motor control. It adjusts the speed and torque of the motor by changing the frequency of the power grid. Due to the involvement of power electronics technology and microcomputer technology, the cost is high and the requirements for maintenance technicians are also high. Therefore, it is mainly used in fields that require speed regulation and high speed control requirements.
[1] Edit the speed control method for this section
There are many speed control methods for electric motors, which can adapt to the requirements of different production machinery speed changes. The output power of a general electric motor varies with the speed during speed regulation. From the perspective of energy consumption, speed regulation can be roughly divided into two types:
①Keep the input power unchanged. By changing the energy consumption of the speed control device and adjusting the output power to adjust the speed of the motor.
②Control the input power of the motor to adjust its speed. Motors, electric motors, brake motors, variable frequency motors, variable speed motors, three-phase asynchronous motors, high-voltage motors, multi-speed motors, dual speed motors, and explosion-proof motors.
