S230 Series Ball Mill Special Purpose AC Drive
S230 Series Ball Mill Special Purpose AC Drive
Power Range： 30KW~500KW
V/F Control Open loop Vector Control
Characteristics of S230
S230 ball mill special Purpose ac drive is widely used in ceramics, building materials, cement and so on.
With Low frequency and high torque, rotating speed tracking precision, reliable hardware current-limiting, this could guarantee the ac drive running without tripping.
Notes: The technical regulations, wiring diagrams, performance diagrams and components of S200 series high performance ac drive are all suitable for S230
Ball mill is widely used in the ceramics industry, it is an indispensable vital production equipment in material grinding. The ball mill is usually with big power, and the working efficiency is very low, so it is the biggest power consumption equipment in ceramics industry. Energy-saving reconstruction for ball mill attaches great significance to reducing environment pollution and getting a good economic benefit.
2、Operating principle of ball mill machine
At present, ball mill common used drive: Three-phase AC motor - hydraulic coupling - gear reducer - pulley reducer.
Generally, the mill barrel is used as reducer pulley. When the mill heavy-load starts, the start current can reach six times more than the rated current. In order to alleviate the mechanical shock during starting, fluid coupling is added in transmission links. Hydraulic coupling is used to transmit the drive energy by controlling the momentum change of working chamber operating oil. Active wheel rotation is dragged by input shaft of hydraulic coupling, hydraulic oil accelerated, after acceleration, the oil drives the slave turbine rotation of the hydraulic coupling, passing the driving energy to the output shaft and load. Hydraulic coupling has the buffer function at the start in transmission system, so that the motor can start with low load, reducing the start current. After motor start, loading it little by little achieves a smooth start effect, reducing the start mechanical shock. Through the speed adjustment function of hydraulic coupling in working, it can search the optimum working speed of motor to improve the efficiency. Since the ball mill belongs to the constant torque load, its speed efficiency is equal to speed ratio, so a large part of energy is wasted in the hydraulic coupling.
3、production process of ball mill machine
Generally, ball mill operates at a fixed speed. Cylinder speed is decided by pulleys or gear reduction mechanism (also hydraulic coupler used). The rotation speed impacts directly on alumina balls and materials movement and grinding process. At different speed, balls and materials movement in cylinder body are as below:
(1)With low rotation speed, ball and materials rise with cylinder wall. When the inclination angle of ball and materials is equal to or greater than the natural one, sliding along the slope, it cannot form a sufficient gap. Small grinding effect on balls to materials, so ball mill efficiency is reduced.
(2) When the cylinder speed is a certain one between above two, the alumina balls falling along the parabola after brought to a certain height, it is greatest impact on the bottom cylinder material and highest grinding efficiency. Rotation speed at this time is known as the best working speed.
(3) If the cylinder rotation speed is high, due to the centrifugal force, the materials and alumina balls are no longer out of the cylinder wall, rotating along with it. Then the balls have no impact on the materials and grinding efficiency is very low. The minimum speed of this state is called critical speed.
Operation practice shows that the optimum rotation speed is related to the diameter of the alumina ball, armor shape, the friction coefficient between the aluminum balls and armor and other factors. General best working speed is usually 0.7-0.8 critical speed, thus, the speed has an adjustable certain range, but the range is little. The speed between real speed and optimum working speed is less than 10%, so if the ball mill uses variable frequency control searching, energy saving effect for improving grinding efficiency is also about 10%.
Operation principle for ball mill variable frequency energy-saving control system
In addition to searching the best work speed with variable frequency control , energy saving effect is achieved by improving ball mill grinding efficiency . To ensure the maximum output torque of the motor is also considered when the ball mill is designed, while in the actual production process, it is hard to reach maximum output torque. The motor is in low-loaded (not full load) operation with low power factor efficiency .At this time, through energy conservation function to reduce the inverter output voltage, automatical adjustment on output torque to match production real needs can boost the motor power factor and efficiency.
In addition, as the inverter is generally "AC - DC - AC" voltage source type, there is presence of large filter capacitor in middle DC link , which can greatly improve the network power factor on inverter input side , reduce transmission current, thereby reducing power transmission loss in line. Not only it can implement energy-saving effect, but also can reduce the capacity of the power supply system, reduce equipment investment. Or in the same network capacity, it allows multiple installation for ball mill equipment.
The following effect is achieved after installing our variable frequency energy-saving control system:
1．It eliminates the impact during start, and prolong the service life of some mechanical parts like shaft, gear box, belt and so on, which also reduce the maintenance costs.
2．The starting current would be several times lower than the original current after the ball mill is installed our frequency inverter, (for example, the original starting current of 160KW motor is higher than 1000A, the starting current with frequency inverter is 300A-350A), which achieves real soft start and the energy saving effect. With the significantly reduction of starting current, the impact to power grid and reduction of power grid voltage would be avoided, it also avoids that other electric equipment tripped or broken down because of the start of ball mill, this way, more ball mills could be installed in the same power grid capacity.
3．Milling time, grinding time and automatic stop function could be set through the frequency inverter conveniently, which makes the operation more intelligent and humanized. The energy-saving effect of ball mill special use frequency inverter could be 6%-15% usually.
6．Investment and return
Zibo is a big ceramics city, our ball mill special use frequency converter is widely used in many ceramics factories.
One customer purchased 23 pieces SVF-QM ball mill special use big power frequency converter from us, for example, one of the ball mill is 40 tons, the motor power is 160KW, the electricity consumption each month of the original ball mill is 160KW*18hours*30days=86400KW.H. Power saving rate reaches 9% after they install our ball mill special use variable frequency energy saving control system, RMB5054 (86400*9%*0.65RMB/kwh=RMB5054) electric charge could be saved each month. If each frequency inverter is RMB 55000, the investment return period is 55000/5054=10.9months, that’s to say, all investment could be taken back less than one year. The service life of frequency converter is 6-10 years usually, you could get return without any investment after the first year, annual electricity saving benefit is about RMB60000.
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