Abstract: This paper mainly introduces the application of Schneider ATV71 inverter in the blast furnace windless system, and elaborates on the design and debugging methods of the blast furnace windless system. Keywords: Schneider inverter , system design, blast furnace windless I. Introduction to Production Process The blast furnace windless system is the main equipment of the blast furnace charging system. Its main task is to transport different types of furnace materials from the storage bins to the storage tanks at the top of the furnace. There are two main types of blast furnace charging systems: belt conveyors and inclined bridge charging cars. Generally, blast furnaces with a capacity of 3000m³ or more use belt conveyors, while those with a capacity of less than 3000m³ mainly use inclined bridge charging cars. The inclined bridge material loading machine mainly includes a material pit, a material car, an inclined bridge, and a winch. Its production process is shown in Figure 1: [align=center] Figure 1 Material Car Production Process Flowchart[/align] The inclined bridge's traveling guide rail is generally divided into three sections: the material pit section (inclination angle around 60°), the middle section (inclination angle between 45° and 60°), and the curved rail unloading section. The movement of the loading trolley on the inclined bridge consists of starting, one acceleration, high-speed operation, one deceleration, two decelerations, braking, stopping, and tipping. The control commands for the material car throughout the process are given by the material car master controller and upper and lower limit switches. To ensure equipment safety, bottom and top limit switches and an emergency pull rope switch are also generally provided. During operation, the inclined bridge material car feeder operates with two material cars alternating. When the loading trolley moves upward, the unloaded trolley moves downward. This eliminates idle travel when the motor is running, and the unloaded trolley acts as a counterweight, balancing the weight of the loaded trolley. This improves the efficiency of the drive motor, keeping it constantly powered. Compared to single-bucket hoists, this avoids the problems associated with the motor being in generator mode. II. Blast Furnace Winch System Design: The technical parameters of the blast furnace winch at Changzhi Iron and Steel Plant's No. 8 blast furnace are: maximum load capacity of the material car is 8.0t, rated load capacity is 5.5t, material car weight is 2.5t, drum diameter is 1200mm, material car travel is 86m, reducer reduction ratio is 30:1, motor: AC 380V, 220KW, speed 1480 rpm. To ensure stable blast furnace operation, the system adopts a one-in-one-outstand configuration. The frequency converter uses Schneider Electric's ATV71, and the control system uses Schneider Electric's Quantum series PLC. Signals from the operator's console enter the PLC, which processes the signals and then controls the frequency converter. There are automatic and manual modes. Automatic mode uses MODBUS communication, while manual mode uses a hard-wired connection as a backup in case of communication failure. The system schematic is shown in Figure 2. [align=center]Figure 2 Schematic diagram of the blast furnace hoisting system[/align] System parameters: 1: Frequency converter ATV71HC25N4, Pe = 250KW, Ie = 444A; 2: Incoming line reactor VW3 A4 563, Outgoing line reactor VW3 A5 107; 3: Braking unit VW3 A7 101, Braking resistor 75KW, 1.05Ω; 4: MODBUS communication card VW3 A3 302 Three: Blast Furnace Hoist Commissioning Method The blast furnace hoist charging speed curve is shown in Figure 3. In the figure, t2, t4, and t6 are speed change points, with signals provided by the charging car master controller. t8 is the charging car's upper limit point. The system has three speed settings: f1=10Hz, f2=35Hz, and f3=45Hz. At t1, when the charging car is in the charging pit section, the system issues a start command, and the frequency converter starts. At this time, the motor brake is not released, and the system current increases rapidly. When the current reaches 180-200% Ie, the PLC issues a brake release command, and the motor quickly and smoothly reaches the medium speed of 35Hz in an S-shaped acceleration pattern. At t2, the charging car master controller issues an acceleration point signal, and the charging car runs smoothly at a high speed of 45Hz in the middle section. Approaching t4, the charging car decelerates once, entering the curved track unloading section at medium speed. At t6 in the curved track unloading section, a second deceleration command is issued, and the charging car runs at a low speed of 10Hz. At time t7, a stop command is issued, and the frequency converter begins to check the speed. When the speed drops below 5Hz, the brake closes, the frequency converter begins braking, the automatic resistor engages, and the material trolley unloads into the furnace top storage tank. t8, the upper limit point of the material trolley and the lower limit signal of the descending material trolley, are the last line of defense for system protection. When these limits are reached, the output contactor of the frequency converter trips, and a brake close signal is issued simultaneously, forcing the system to stop. Each loading time is 38 seconds (coke) and 43 seconds (ore). The acceleration and deceleration times are crucial throughout the operation, as they determine the acceleration of the material trolley. If these times are too short, the wire rope of the material trolley is prone to slack when the trolley is in the material pit section; and the wire rope is prone to vibration when unloading on the curved track section. Therefore, the acceleration and deceleration ramps are generally set in an S-shape. [align=center]Figure 3 Blast Furnace Hoist Charging Speed ​​Curve[/align] Part Four: Debugging of the Blast Furnace Hoist Inverter The ATV71 inverter is a newly launched high-performance inverter from Schneider Electric, with power ranging from 0.37KW to 500KW, a scheduling range of 0-1000Hz, and an encoder speed accuracy of 1/1000, and a torque accuracy of 1/100 without the encoder. It has an overload capacity of 170% rated torque for 60s and 200% rated torque for 2s, and features high-performance vector control. It has built-in start-stop, material loading/unloading, lifting, PID regulation, master-slave control, and communication to network six different macro settings, providing users with quick programming settings for different applications. A Chinese-language graphical display terminal facilitates user programming and maintenance. The electrical schematic diagram of the hoist inverter is shown in Figure 4. Digital inputs LI1 and LI2 are for forward and reverse inputs, LI3 and LI4 are combined to provide four speed settings, but only three are actually used. LI5 is for manual/automatic selection, choosing between terminal control and communication control. LI6 is a spare. The relay outputs are used for two purposes: first, to control the main circuit contactor KM1; and second, to check the frequency. When the frequency is below 5Hz, the brake contactor is controlled. An analog current signal is output; when the current reaches 180-200% Ie, the PLC issues a brake release command. Communication control is achieved via a MODBUS communication card with the host PLC. The inverter's hardware address can be set on the MODBUS communication card, and its operating status can be observed through its indicator lights. [align=center]Figure 4 Electrical Schematic Diagram of the Hoist Inverter[/align] After setting the inverter parameters, the system's functions are first tested under no-load conditions on the middle section of the inclined bridge travel rail. After confirming the functions, a heavy-load test is then conducted on the same middle section of the inclined bridge travel rail. Finally, a load test is performed. During the test, the high speed should not be set too high; it should be determined step-by-step according to the process requirements. V: Conclusion The system has been put into operation after debugging. The system operates stably, fully meeting the process requirements, and has received positive feedback from users. References: [1] Zhang Yanbin, Application Practice of Variable Frequency Speed ​​Regulation, Machinery Industry Press [2] ATV71 Inverter Programming Manual [3] ATV71 MODBUS PLUS Communication Card User Manual