National regulations have long stipulated that the voltage drop across the power grid during motor starting should not exceed 15%. This has led to the development of various soft starters. Generally, the starting current of a motor directly starting is 5 to 7 times its rated current. This is especially true for high-power motors, which experience significant stress on the power grid's mechanical components. Since the power supply for motors is typically selected based on the motor's rated current, excessive starting current often causes overheating of the contacts and aging of the insulation around them, a major cause of power supply failure. Due to limitations imposed by the power grid and substation distribution equipment, most high-power motors require starters. Common soft starting methods include: resistor voltage reduction, autotransformer starting, star-delta, and extended-delta starting. Autotransformer starting is the most common, but it is not suitable for frequent starting, and it is bulky, expensive, and requires extensive maintenance. The starting voltage of these methods is applied in a jump manner, which can impact the power grid and distribution equipment, damaging the motor and load equipment, affecting their lifespan, and increasing maintenance costs. With the development of computer technology and the maturity of high-power thyristor manufacturing technology, soft starting, using a computer as the control core and thyristors as the controlled object, has become possible. The basic idea is to use the computer to adjust the thyristor firing angle during startup, thereby adjusting its output voltage. This allows the voltage applied to the motor to gradually increase linearly, achieving a smooth start and minimizing the impact on the power grid until full conduction and full-voltage operation. This soft starter fundamentally solves the problem of current impact on the power grid and distribution equipment during startup. It uses weak current to control strong current, reducing the starting current and thus reducing the peak current load on the power supply, reducing motor losses, and extending the service life of mechanical transmission equipment. Smooth load acceleration reduces mechanical shock, preventing production accidents or product damage. When using the soft stop function, the load can be smoothly decelerated, eliminating the water hammer effect of pump loads. Multiple protection functions effectively prevent accidents. It is safe, reliable, small in size, low in price, and maintenance-free, providing great convenience to motor users. When conditions permit, measures to reduce starting current are often taken to improve power supply reliability and reduce motor failure rates. However, the high price of starting devices (especially for medium and high voltage motors, the price of a soft starter plus a starting switch cabinet is more than 1.5 times the price of the motor itself) and their complex structure not only increase user costs but also reduce the reliability of the electric drive system. Furthermore, the starting torque of a motor is directly proportional to the square of the starting current. When using a stator voltage reduction starting method, such as reducing the starting current from 61e to 31e, the starting torque will decrease by four times, and the starting time will increase by more than five times. Therefore, for motors requiring high starting torque and short starting time, wound-rotor motors must be used instead of squirrel-cage motors. Coal mines are a special environment that provides us with energy but also involves the safety of coal miners, thus presenting us with a new challenge—gas drainage and dewatering. Because underground mine tunnels cover a long distance, high-power fans and pumps are needed for gas drainage and dewatering. These devices are started with the help of soft starters or frequency converters. Due to the relatively high price of frequency converters, soft starters have become a more advantageous option. Electronic soft starters not only perform the basic soft-start function for motors but also integrate many protection functions, such as microprocessor-based protection against phase loss, overcurrent, short circuit, and three-phase current imbalance. This not only saves money but also makes them convenient for workers to use. The 660V soft starter used in Zhangjiakou Danhou Mine is a CMC soft starter manufactured by Xi'an Liangchi Electric Co., Ltd. The CMC soft starter offers several starting modes: current-limiting start, voltage ramp start, ramp + current-limiting start, and sudden torque start. The principle of using soft starters in coal mines is basically the same as in other applications. The soft starter uses a microcontroller to control the thyristor conduction angle, causing the voltage applied to the motor to slowly rise to the rated voltage over a set time. Simultaneously, the motor accelerates as the voltage rises until it reaches the rated speed, completing the starting process. (The peak value of the starting current and the starting time can be set through the soft starter). Its main circuit wiring diagram is shown in Figure 1. With the development of communication and fieldbus technologies, various monitoring systems in coal mines have been gradually established, allowing people to monitor and control various underground equipment from the central control room. Danhou Mine installed a soft starter control cabinet above ground, controlling the CMC-L soft starter via relay nodes of a Siemens PLC system to control the AC660V 280 kW axial flow fan used for underground ventilation. Alternatively, the CMC-S soft starter controller can be used; it is an intelligent soft starter with a visual Chinese LCD display and an RS485 interface, allowing control via fieldbus and RS485. This avoids the spark hazards caused by high current and facilitates maintenance. As shown in Figure 2, underground equipment such as fans and pumps are also included. This avoids accidents such as gas explosions caused by underground equipment, and in case of an emergency, people can promptly understand or predict the impending event through industrial Ethernet, thus greatly reducing the accident rate underground. This is a situation that the coal industry and all sectors of society hope to see.