Why trolley electric locomotive be choosed in mining transportation?

Why trolley electric locomotive be choosed in mining transportation?
The large and medium-sized mine auxiliary transportation system constructed in the early stage is mainly composed of the electric locomotive in the transportation main road, the mining winch in the mining area, and the small battery locomotive. It was not until the late 1970s that the development of the rail-assisted transportation system began, and no finalized product has been formed. When mine conditions permit, should we give priority to using overhead electric locomotives? Why is this, there is a small editor below for everyone to answer?

　　The main advantages of overhead line electric locomotives compared with battery locomotives are: simple structure, low cost, convenient maintenance, large transportation capacity, high speed, high electrical efficiency, and low operating cost. The investment is relatively large only in the initial construction (dedicated power supply network and rectifier equipment are required), but in the long run, the total cost of using overhead electric locomotives is much lower than that of batteries. Therefore, if the mine conditions permit, the main transportation of the mine should use overhead electric locomotives.

　　 Which parts of the power supply system of the electric locomotive for mine pits are composed and how do they form a current loop?

　　 The electric locomotive transportation and power supply system of the mine pit, including the traction converter of the electric locomotive and the traction network. The power supply system is shown in the figure.

　　The main components of the power supply system are traction converters, feeders, overhead lines (contact lines), tracks, return lines, etc.

The traction converter converts alternating current into direct current through converter equipment, and sends it from the feeder line to the overhead line through the feed point, and introduces the electric locomotive circuit through the electric locomotive collector to make the locomotive traction motor work, and then through the electric locomotive wheels, The track, return point, and return line return to the traction converter to form a complete current loop.