At present, our country's economy has entered a new stage of development. There are more and more large-scale enterprises and large-scale equipment. There are more and more applications of large motors (5000kW~60000kW). The starting methods of large motors are also receiving more and more attention.

Social development has stages. At different stages, people's means of production, production tools and daily necessities are very different. In the 1980s and 1990s, my country's economic strength was still relatively weak. At that time, small cement and small steel were developing rapidly, and the application of 1000kW to 4000kW motors was growing rapidly. Liquid starting devices that were suitable for the economic base at that time appeared. Economical and practical, it solves some problems in motor starting. It played a certain role in the economic development at that time. By the turn of the century, my country's economic strength had developed greatly, production means and production tools had also developed greatly, and motor capacity had also increased greatly. People began to be dissatisfied with the low performance of liquid starting devices, so thyristors were connected in series. The application of type (solid-state) soft starting devices began to increase, and then switching transformer type soft starting devices and magnetic saturation reactor type (magnetic control) starting devices appeared. Frequency conversion devices are increasingly used for soft starting of motors. Currently, these four products are the mainstream products in the large motor starting market, while liquid starting devices are mostly used in small (below 5000kW) motors. In addition, two old-fashioned starting methods (autotransformer and transformer-motor unit) often appear in the starting of motors below 20,000kW.

Large motor-driven equipment is generally the core equipment of an enterprise and directly affects the production status of the enterprise. Therefore, people should pay special attention to their starting. Reasonable selection of starting devices will bring great economic benefits to the enterprise. However, motor starting technology is not the core technology of an enterprise after all. Electrical workers in many enterprises have little time to study the differences between various starting methods, which often leads to inappropriate choices and sometimes even having to make a second decision. choice, causing undue losses to the enterprise. Therefore, it is very important to honestly describe the performance and differences of various starting methods. For this reason, we are trying to make some mistakes in this aspect. If there are any imperfections or inaccuracies, we hope that we will add more money and add more.