I. Overview
Most of the existing coal belt conveyors in China generally use industrial frequency drag, and are less frequently driven by frequency converters. Due to the long-term power frequency operation of the motor coupled with the efficiency of the hydraulic coupler, the belt conveyor is very uneconomic to run; at the same time, because the motor does not have a soft start and soft stop, mechanical impact will occur and the mechanical wear will be accelerated; the belt and the liquid The wear and maintenance of the force coupler will bring a large amount of maintenance costs to the company. Increased operating costs of the company. Therefore, the frequency conversion of belt conveyors of coal mining enterprises has very realistic economic and social significance for saving social energy and increasing the economic benefits of coal mining enterprises.
Second, the working principle of the belt conveyor
The motor drives the wheel drum and runs on the friction traction belt. The belt moves the animal body on the support roller through tension deformation and friction. The belt is an elastic energy storage material, and a large amount of potential energy is stored during the stoppage and operation of the belt conveyor. This requires the belt conveyor to overcome the static friction force when it is started and should adopt a soft start method. Most domestic coal mines use hydraulic couplers to realize the soft start of the belt conveyor. When starting, the mechanical efficiency of the fluid coupling is adjusted to zero, so that the motor starts without load. Although some use the rotor series resistance to improve the starting torque and step-down no-load start method, but the starting current of the motor is still very large, not only will cause severe fluctuations in the power grid voltage, but also cause internal mechanical shock and heat, etc. phenomenon. At the same time when the hydraulic coupler is used to start the belt, due to short start-up time and large loading force, the belt is easily broken and deteriorated, and the belt is required to have high strength. Coupled with long working hours due to hydraulic coupling, the internal oil temperature rises, metal parts wear, leakage, and efficiency fluctuations, etc., and the maintenance of the equipment is difficult, the maintenance cost is high, and the environment is also polluted. It is difficult to drive the same belt with multiple motors. Solve power averages and synchronization problems.
Third, the advantages of frequency conversion
Variable frequency speed regulation is a new technology that has emerged in the past two decades. It is to adjust the motor speed by changing the frequency of the power supply. Because of its stable speed, wide speed range, and energy-saving features, it has been increasingly used. With the constant maturity of frequency control technology, the application of frequency conversion speed regulating devices on belt conveyors is also becoming more and more extensive. The PI7800 series inverters produced by Dalian Puchuan Technology have the following features:
1) The soft start of the belt conveyor system is really realized. The soft start function of the frequency converter is used to combine the soft start of the motor and the soft start of the belt conveyor. Through the slow start of the motor, the slow start of the belt conveyor is started, the energy stored inside the belt is slowly released, and the belt conveyor is The tension wave formed during the starting process is extremely small, causing almost no damage to the belt.
2) Reduce the amount of equipment maintenance. The frequency converter is an integration of electronic devices. It converts the life of a machine into the life of an electronic device, extends its service life, and greatly reduces the amount of equipment maintenance. At the same time, the frequency converter has a soft start function to achieve a soft start of the belt conveyor. During the start-up process, there is basically no impact on the machine, which also greatly reduces the maintenance of the mechanical part of the belt conveyor system. For example, if a mine belt in a coal mine in Henan Province is driven by a frequency converter, belt buckles will cost more than 10,000 yuan a year.
3) Start smoothing, large starting torque, no inrush current, can realize heavy load start.
4) Energy saving. After adopting the variable frequency drive on the belt conveyor, the power factor and system efficiency of the system are improved, which effectively saves energy.
Fourth, the specific transformation case
The application example of Shanxi Xx coal mine using universal transmission:
1. On-site inverter configuration: PI7800 250G6 660V/250KW (Z1205E19459) One.
PI7800 055G6 660V/55KW (Z1205E19457) One.
PI7800 160G6 660V/160KW (Z1205E19458) One.
All three frequency converters are used on the belt conveyor. The effect is very good. By adjusting the frequency of the frequency converter to control the amount of coal transmission, it greatly facilitates the on-site operation. Save a lot of manpower and material resources, provide enterprises with high-quality services and efficient production and energy saving, environmental protection.
2. Inverter adjustment parameters are as follows:
F04=1, frequency setting mode is terminal V2 analog input.
F05=3, the operation control mode is terminal block control.
F08=5, V/F lifting mode. The factory value is 2 and the value is appropriately adjusted depending on the start status of the load during commissioning.
F09=50, acceleration time. According to the inverter's power size and load conditions to adjust.
F10=50, deceleration time. Adjust according to the load power of the inverter.
F27=1, stop mode. Free parking option.
F54=1, motor running direction. It is easy to change the direction of the motor without changing the motor wiring.
3, inverter wiring:
4, on-site real scene
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