Crushers are widely used in mining, smelting, building materials, highways, railways, water conservancy and chemical industries and many other sectors. The crusher is mainly used for crushing various types of stones. According to different crushing principles and different product particle sizes, it can be divided into many models. Currently commonly used crushing machinery includes jaw crusher, impact crusher, winnowing crusher, hammer crusher, impact crusher, roller crusher, compound crusher, etc.
The electric charge of crushing electrical and mechanical equipment in the concentrating mill is relatively high, generally accounting for 40% to 60% of the total cost of the concentrating mill. Therefore, to improve the production efficiency of the crusher, reduce the unit energy consumption, and reduce the cost, the use of high-efficiency and energy-saving crushing equipment is the main means.
2. Working principle of the jaw crusher
The crushing method of the jaw crusher is the curved extrusion type. Its working principle is: the motor drives the belt and the pulley, and the movable jaw swings back and forth through the eccentric shaft. When the movable jaw pushes the movable jaw plate to the fixed jaw plate, the material will be crushed or chopped. When the movable jaw and the movable jaw plate retreat under the action of the eccentric shaft and the spring, the objects that have been broken into pieces are discharged from the lower discharge port of the jaw plate. With the continuous rotation of the motor, the mobile jaw of the crusher periodically crushes and discharges materials to realize mass production.
3. The problems of traditional power frequency control
(1) Low efficiency and relatively large energy consumption.
Traditional power frequency control cannot adjust the speed according to the working conditions. When the size and quantity of imported materials are different, the crusher always runs at a high speed, which will easily cause uneven crushing of materials and waste of energy.
(2) The start-up inrush current is large, which is easy to reduce the motor insulation and damage the electrical components, and the maintenance cost is high.
Most of the crushers adopt the method of power frequency direct start or self-coupled step-down method, so that the starting impulse current is large, and the requirement for the front-end transformer capacity increases. The frequent start and stop will also cause great impact and wear on the equipment, which affects the performance of motor and electrical components and shortens theirs service life.
(3) Poor automatic protection.
In the crushing process, when the stone is stuck, the current increases and the immediate protection cannot be achieved. Then the contactor will be burned out immediately. If it is serious, even the motor will be burned out, which will increase the cost of equipment maintenance.
(4) The power factor is low. Generally, the power factor is very low at a light load.
The power factor is low, and the reactive power consumption is too large, which increases the power loss inside the transformer and related electrical equipment network, and directly increases the expenditure of electricity costs. Accelerated aging of equipment will easily shorten the service life of the equipment and affect the operation of the equipment. China's electricity supply rules stipulate that all users whose power factor does not meet the above requirements will be charged additionally by the electrical industry department: power rate electricity fee (fine).
4. The characteristics and advantages of the transformation plan
Frequency conversion control technology is the most important technology of current electrical automation control. It has already played an important role in equipment control in all walks of life. It is an inevitable development trend for the application of crusher, and it will definitely become the most important and central part in the automation of crushing process control. The use of frequency conversion control technology for the crusher will bring about the following innovations:
(1) Improved power factor on the network side:
When the original motor is directly driven by the industrial frequency, the power factor is low at a light load (except for that with the compensation). After the frequency conversion speed control system is adopted, the power factor on the power supply side can be increased to more than 0.9, which can greatly reduce reactive power without a reactive power compensation equipment and meet the power grid requirements, thus further saving upstream equipment operating costs.
(2) Improve the use efficiency of the crusher, save electrical energy, reduce equipment operating costs, and ensure the progress of production tasks to the greatest extent.
The most basic and most important point of the frequency conversion speed control technology is to achieve stepless speed control that cannot be achieved by the power frequency. It can realize the speed control below the power frequency for the crusher equipment, so that the rotate speed can adapt to the best working conditions and quickly adapt to the change of load so as to ensure that the motor is running at a high efficiency with output. Mechanical losses will be further reduced, saving valuable electrical energy.
(3) Save electricity through the V/F function of frequency conversion.
Under the condition of ensuring the output torque of the motor, the V/F curve can be automatically adjusted. Reduce the output torque of the motor, reduce the input current, and achieve an energy-saving state.
(4) The motor can be soft-started, and the current does not exceed 1.2 times the rated current of the motor when starting, and the service life of the motor is prolonged.
In the entire operating range, the motor current is small when starting, and the power consumption is 80% less than starting with a contactor, and the motor can ensure stable operation. It is self-evident that the large-inertia crusher is damaged by the current impact during the traditional power frequency startup and the electrical transient during the shutdown. The frequency conversion speed control equipment has a good smooth control of the current during the startup and shutdown, which reduces the impact of starting current on the power grid, saves electricity bills, reduces the impact of starting inertia on the equipment's large inertia speed, and prolongs the service life of the equipment.
(5) Powerful protection function, strong ability to adapt to voltage fluctuations of power grid.
The general protection function of the frequency conversion speed control equipment is comprehensive. It can prevent the sudden change of the grid from damaging the motor, effectively protect the frequency converter and the motor when the grid-side power fails, and effectively prevent the fault from spreading to the grid when the motor load fails, and can protect the motor to the utmost extent. When the crusher is overloaded, it will automatically reduce the frequency to protect the normal operation of the equipment and the motor.
(6) The use of frequency conversion speed control equipment can improve the level of automation and provide a bottom solution for the factory to achieve a high degree of automation.
In the actual operation of the crusher, there are often high noise and dust, and the workers should endure high work intensity and poor working environment. If the frequency conversion speed control equipment is used, the electric transmission equipment can be placed a little far away from the ball mill, which is more convenient and safe to operate. Data monitoring can also be carried out in an environment far away from noise.
5. Concluding remarks
With its excellent performance, KE300A frequency converter greatly improves the stability and safety of the traditional jaw crusher, and reduces the maintenance work of the equipment. The control system customized for the jaw crusher integrates many safety technologies and automatic control functions, provides a complete set of electronic control solutions for the jaw crusher equipment manufacturers, and can also make the old jaw crusher rejuvenate. Since its launch, it has won unanimous praise from users, solved the problem of backward electrical control of many machinery manufacturers, and achieved good social and economic benefits.