Abstract: The adoption of medium voltage frequency inverter on belt conveyor is the main point of safer and more reliable usage for mine belts. Based on the application comparison of hydraulic couplers and inverters on belt conveyors, and combined with the site working of belt conveyors and inverters in Vietnam coal mine, the article introduces relevant technology of belt conveyor systems and the application of medium voltage drives on the system.
1. Introduction
Belt conveyors are widely used in mines. It is necessary to install soft starting device according to the provisions of coal mine safety regulations. And hydraulic couplers, as well as CST, are currently used as the devices in most mines.
2. Principles and characteristics of belt conveyors
After driving the hub, the belt conveyor is working by friction traction and the belt leads the objection move on the supporting roller through the tension deformation and friction. Because the belt is elastic and stores a large number of potential energy when the belt conveyor stops and runs, it is necessary to start the belt conveyor flexibly. Currently, most mines apply hydraulic couplers as the softly-starting devices, but all disadvantages are presented when driving through mark inspection and users feedback, medium voltage frequency inverters are taking the place of hydraulic couplers.
3. Advantages of medium voltage inverters
3.1 Soft starting.
The belt is driven by the motor slowly, to release storage energy slowly and reduce the impact during starting and stopping to the minimum, so it is nearly no damage to the belt;
3.2. Reduce the requirements of belt intensity.
The starting time of frequency inverter can be adjusted in the range of 1~3600s and the time of belt is set in 60~200s according to the site work. Prolonging the starting time can reduce the requirements of belt intensity and initial equipment investment.
3.3 Torque balance of motor driving.
One-for-one control and master-slave or coordinating cabinet control is available;
3.4 Belt inspection.
Inspection at the low speed is required in the belt maintenance. Any speed in the range of 0~100% of the rated speed is available at non-load state because the variable frequency speed regulating system is the AC drive system of stepless speed regulation;
3.5 Stable starting with heavy loads.
The frequency inverter can output 2.2 times of the rated torque at low frequency and is suitable for heavy load starting;
3.6 Automatic speed regulation.
The frequency inverter can adjust the belt speed automatically according to the load weight with the cooperation of coal flow sensor, not only saving the energy, but also reduce the belt abrasion;
4. Conclusions
FGI FD5000 frequency inverter which applied in belt conveyors system, not only improve the production efficiency and system reliability, but also ensure easy maintenance and safe operation. It is proved that this speed-adjusting system can control the site working with mediumer efficiency, accurate automation and less energy consumption all around the time.
