1. Brief introduction.
For a long time, wall, ground, brick, and the ball mill grinding of ceramic raw materials widely used chemical factory, it usually use simple power frequency control and easy to cause materials excessive grind. the grinding cycle is long, grinding efficiency is low, power consumption per unit product is bigger, starting current is big, the impact on the equipment and power grids is very big, machinery and equipment production and large amount of maintenance, and energy wastage is quite amazing, this will cause a lot of unnecessary trouble manufacturer and serious waste of resources, so with the development of social economy and the expansion of enterprise production, direct power frequency control of ball mill illness is exposed, seriously hindered the rapid development of industrial enterprises.
2. The principle of frequency inversion renovation
Ball mill drive mode is widely adopted at present: three phase ac motor, hydraulic coupling, gear reducer, pulley gear reducer.
Ball mill cylinder used as reducer of the pulley. When the ball mill overloading starting, motor starting current can reach more than six times the rated current. In order to alleviate the mechanical shock when starting, transmission link with hydraulic coupling, Hydraulic coupler is by controlling the working chamber to the change of moment of momentum of the working oil transfer motor drive energy.
Motor by the input shaft from the hydraulic coupler drive the active wheel rotation, to working oil acceleration, are accelerated after the work of oil to drive the hydraulic coupler driven turbo spin, the drive energy transfer to the output shaft and load. Transmission system of the hydraulic coupler buffer role when starting, the motor light load starting, to reduce the starting current, such as motor starting again after loading slowly, to achieve the smooth starting the effect of ball mill, reduce mechanical shock when starting.
Through the role of the speed regulating hydraulic coupler at work, search best work speed of ball mill, improve the efficiency of ball mill. Due to the ball mill is a constant torque load, when using hydraulic coupler speed regulation, its control efficiency is equal to the speed ratio, there is a large part of the energy is wasted in the hydraulic coupler. This causes the people to develop smooth starting, high grinding efficiency, large output, low energy consumption way of starting speed- frequency control of motor speed controller.
3. Requirement of ball mill Transform is following:
Frequency inverter work on ball mill main purpose is energy saving, the use of frequency inverter multi-speed and simple function of PLC to speed of ball mill, to optimize speed of ball mill, so as to achieve energy saving effect, energy saving rate is between 10% ~ 15%, and there is no start impact current, improve the stability of power grid.
3.1. Ball mill load fluctuations in the process of running, frequency inverter overcurrent, overload, current limiting function is strong, it can satisfy long-term stable operation in large load fluctuation.
3.2. It is very big load when ball mill load starting, generally requirement that frequency inverter torque large enough when low frequency srating.
3.3. When the inverter must satisfy the technological requirements of ball mill, extend life span of the motor and ball mill, reduce maintenance.
3.4. After transforming equipment can realize automatic control/hand movement /power frequency and fault switch other functions, and can overcome the ball mill large inertia cause recovery voltage, effectively ensure the normal operation of equipment.
3.5. Frequency conversion control system to be able to long term no fault stable operation, good environmental adaptability, high reliability.
4. inverter application examples and pictures
According to the analysis, our company design reconstruction plan as follows:
4.1. After transforming equipment has enough starting torque, meet the requirements of ball mill mix load, and ensure that equipment in variable-frequency operation conditions motor run smoothly, protect motor with constant power characteristics.
4.2. Use frequency control transform the original ball mill drive system, Insure the normal operation of the ball mill when low speed, to ensure the normal process of quality control, increase life span of ball mill and reduce maintenance time.
4.3. After transforming equipment can realize automatic control/ hand movement/power frequency and fault switch, and other functions, and can overcome the ball mill large inertia cause recovery voltage, effectively ensure the normal operation of equipment.
4.4. According to the scene of the situation, we choose powtran newest model PI500 series products, PI500 series product has the following functions, can completely meet the requirement of customers. PI500 series inverter features below:
Accurate motor parameter self learning, steady speed precision, wide speed range, low speed high torque , small torque ripple, instantaneous power failure non-stop, 40 ℃ environment temperature independent air duct design, a new generation of energy-saving operation, anti-corrosion paint coating process, the global safety certification CE/TUV, built-in adaptive PID function module, easy to use PC software, the I/O extension, built-in brake unit, support for multiple communication, high keys on the keyboard protective film, and supports a variety of installations, flange installation, removable fan. easy installation and maintenance, increases the QUICK multifunction button and select key lock function.
4.5. The modification of:
inverter model |
PI500 055F3 |
frequency inverter Series NO . |
ZPE8C0228929 |
load type |
ball mill machine |
motor rated frequency |
50HZ |
Motor power |
45kW |
Motor rated frequency |
90A |
motor rated valtage |
380V |
motor frequency speed |
960r/min |
frequency inverter working voltage |
390V |
frequency inverter working current |
78A |
frequency inverter working frequency |
50Hz | IGBT working temperature | 56 |
Grid |
402V |
Dc bus voltage |
569V |
NO grounding |
frequency inverter working mode |
Run continuously |
4.6. Here is a picture in the reconstruction of field application.
5. The effect after transforming equipment.
Using the frequency control technical to reformate ball mill drive system, to satisfy the ball mill, the characteristics of big starting torque, low speed running continuous adjustable speed of ball mill is realized. No impact current on the motor. starting current and starting torque enough, perfect protection function. Guarantee the quality of the process control, saving the maintenance cost of reconstruction after the equipment can realize automatic control, and hand movement/power frequency and fault switch and other functions, and can overcome the ball mill large inertia cause recovery voltage, effectively ensure the normal operation of equipment.