Features of Ball Mill’s Depressurization Start Mode
Source：Zhengzhou Taida Time：2018-11-09 点击率：35
Ball mill consists of motor, coupler, reducer and opinion. During running and rotation process, motor will drive and lift large gear out of ball mill and produce impetus. Owing to equipped with lining plate and stuffed with different grades steel balls, steel forge or steel rod, load will be heavy while starting. It belongs to heavy startup equipment. In order to meet load demands, ball mill is always equipped with large-power motor. Taking 110Kw asynchronous AC motor as example, rated current is 220A. It is a kind of reactive current, it will cause impact to state grid. On one hand, it will do demagnetizing function to state grid and cause voltage fluctuation. On the other hand, it will produce voltage drop to electric transmission line. Therefore, control system is a must to finish startup action.
Common startup method: direct starting, star-delta decompression startup, auto-transformer starting, soft start and frequency converter start.
Ⅰ .Direct start: This method can save cost, but needs large startup current. Generally speaking, motor with more than 18.5Kw power should be installed with startup equipment in order to reduce startup current. Therefore, direct start method only suitable for Taida intermittent ball mill (below 910 series). As for other series ball mill, in principle, it must lead a wire from startup control cabinet to control motor’s start.
Ⅱ.Star delta decompression startup: This method only suitable for decompression startup with maximum 100Kw voltage. It is mainly composed of contractor switch, start contact, time relay and complex lines. While contacting wires, six terminals should lead wires. When electrics are started, it is star connection circuit running indeed. After successful startup, change motor to delta circuit.
The star-delta start control cabinet provided by our company is equipped with a control switch, which can realize the manual and automatic start function.
When the star triangle is started, the motor winding adopts the star connection method without considering the effect of the line voltage drop caused by the motor starting current, and the voltage of the motor is 0.58 times of the delta connection voltage. This method belongs to the lowest cost method in starting the control cabinet, but this is a starting method for reducing the starting current at the expense of power. The main disadvantage is that the starting torque of the motor is only 1/3 of the full voltage starting torque.
Ⅲ.The autotransformer starts. The core of the method is an autotransformer. The output voltage of the auto-coupled buck starter can be selected according to various ratios, such as 0.6, 0.65, and 0.7. Through the autotransformer, not only can the input voltage of the motor be reduced, but also the step-down start can be realized. Moreover, the autotransformer with different transformation ratio can be selected according to the power and load condition of the motor, which is fixed 1/3 compared with the star-delta starter cabinet. Starting torque, a variety of starting torques are available on request.
Ⅳ.Fourth, soft start. The core of the soft starter is three opposite parallel thyristors, referred to as thyristors. When the motor is started using the soft starter, the output voltage of the thyristor is smoothly increased to achieve a smooth start of the motor. Compared with the first three starting modes, the motor runs smoothly when starting, the starting current is small to large, and the soft starter has a small volume and simple wiring. Most of our rotary kiln series products are recommended to be equipped with soft starter cabinets. Nowadays, most soft starters have communication interfaces and other additional functions. Of course, soft starters are recommended under the premise of investment budget.
Ⅴ.Frequency converter startup: Compared with soft startup, frequency converter startup holds complex function. Its soft startup function is stronger. To some extent, it is an updates soft startup. Main stream frequency converter changes to DC from AC, then change to AC. It provides multiple dragging mode, which can control startup current to 1.5 times of rated current. Cause less impact to equipment and holds stronger protection ability for equipment. But, its cost is the most expensive one. As a historic manufacturer, Taida Minging has provided multiple high-quality, high-efficiency ball mill, rotary kiln and calcining furnace. Taida professional technical team can provide you whole-set solutions. While guaranteeing best working effect, we can select best depressurization startup cabinet for you.