Abstract: This article introduces the research results and practical experience of applying CNC technology to the transformation of the electrical control system of mine hoists in Yanzhou mining area, which has considerable reference value.
Keywords: coal mine; hoist; CNC technology
Chinese Library Classification Number: TD679 Document Identification Code: B
introduction
The hoisting process at the mine entrance is a crucial link in the coal mine production process. Vertical shaft hoists are responsible for hoisting materials and personnel, and are one of the key electromechanical equipment in coal mines. Their safe and reliable operation plays a vital role in mine production and safety, affecting not only the mine's production capacity but also the lives of miners. Due to the high technical requirements of hoist manufacturing, its electrical drive and control have always been an important research area in the electrical drive industry worldwide. With the development of production and technological advancements, the safety and reliability of mine hoisting systems have become increasingly prominent, leading to higher demands on hoist electrical control systems, including humanized and intelligent design and structural forms. The Yanzhou Mining Area has accumulated considerable experience in the long-term operation of hoist electrical control equipment, but has also discovered some imperfections in the new equipment after CNC technology upgrades. In recent years, coal mines under Yanzhou Mining (Group) Co., Ltd. have conducted extensive research and practice in applying CNC technology to the transmission and control upgrades of mine hoists, achieving good results in the field. Further in-depth research and technological upgrades are necessary to further improve the hoist CNC system. Their experience is of considerable reference value to their domestic counterparts.
1. Research on CNC Retrofitting of Mine Hoists
Shandong University of Science and Technology and Nantun Coal Mine of Yanzhou Coal Mining (Group) Co., Ltd. conducted research on the CNC transformation of old-type mine hoists that are still widely used in China.
The CNC hoist system in a mine mainly consists of a main control system, drive control system, braking system, monitoring system, and shaft signal system. Its safety circuit design primarily uses hardware safety circuits. When the drive control, braking, monitoring, shaft signal system, and other systems with critical status signals that communicate with the main control system require adjustment of the safety circuit, the main control's safety circuit (software safety circuit) will activate and send an adjustment command to the relay safety circuit. The hoist system design generally uses the hardware relay safety circuit as the final and most fundamental protection link. The safety circuit follows the design principle of closing when energized and disconnecting when de-energized to ensure that the safety circuit can adjust under any abnormal conditions, ensuring the safe operation of the hoist.
(1) Travel Correction
The CNC mine hoist uses a main control system to receive pulse signals from a pulse converter connected to the drum shaft, counts the pulses, and then calculates the hoisting position and speed values. During the hoisting process, factors such as wire rope creep, elongation, rope slippage, and changes in the main drum liner can affect the hoist's operation, causing deviations in the counting results. To prevent the calculated travel from deviating from the actual position of the skip or cage due to variable factors during hoist operation, a hoist travel correction function is implemented.
① Precise stroke correction. When the hoisting skip encounters the shaft position magnetic switch during its upward movement, the hoisting height at the switch location is written into the PLC's high-speed counting module to achieve stroke correction. To compensate for the unreliability of the magnetic switch's operation, the system sets multiple stroke position correction switches at different heights. If one switch malfunctions while the other position switches still provide precise correction, the correction value before the position switch is changed without altering the magnetic switch position to achieve a small-range adjustment of the final position. This addresses the impact of changes in the hoisting rope length due to various reasons on the hoist's condition.
② Position switch status check. This is a preventative measure for the hoist's stroke correction function, primarily used to check the operation of the shaft position switches during the downward movement of the skip or cage. If the same position switch malfunctions twice consecutively, the automatic and manual hoisting modes are automatically locked, alerting the hoist operator to switch to inspection mode for maintenance.
③ Automatic correction of calculation coefficients. This mainly involves tracking and detecting changes in the thickness of the main drum friction pad and calculating the stroke of a single pulse. When the hoist is operating in automatic mode and running stably for more than 10 minutes, if the stroke value at a certain fixed position exceeds or falls below a certain error range of the actual stroke value at that position, the calculation coefficient correction function will be automatically activated to reduce the stroke calculation error caused by inaccurate calculation coefficients.
(2) Zero-speed closed-loop control
The most common problems with hoists are brake opening, speed start-up, and stopping during operation. When the hoist brakes open, both the speed and current loops of the control system are closed. However, the lag in these loops causes the hoist to drop in the opposite direction during brake opening. If a current input value is given to the current loop before brake opening begins, the drive unit outputs a step current at the start of brake opening to suppress the sinking of the heavy-load skip or cage. Throughout the brake opening process, the drive unit's output current follows the downward force acting on the main drum to achieve force balance. Once the working brake reaches the brake release pressure, the speed input is engaged, achieving automatic brake opening control. Similarly, after completing the lifting stroke, a zero-speed closed-loop control function is used, ensuring the hoist remains in a zero-speed closed-loop control state throughout the entire brake closing and stopping process, resolving issues such as inaccurate stopping or reversing during stopping.
(3) Current regulator
The current negative feedback control employs a PI regulator with voltage adapter feedforward control and discontinuous current feedforward control. The current PI regulator is a proportional-integral regulator, with two integral coefficients set for continuous and discontinuous current regulation, respectively, to eliminate the adverse effect of discontinuous current causing softened control performance. The actual back EMF is calculated by the program, filtered, and compared with the voltage filter value when the converter is unloaded. The result is added to the output of the current regulator as a condition for generating the delay angle, forming voltage-adaptive feedforward control, so that the converter's output voltage follows the back EMF changes. If the back EMF increases, the ratio becomes larger, the delay angle decreases, and the output voltage value increases; conversely, the smaller the ratio, the smaller the output voltage. With voltage-adaptive feedforward control, the control of the converter's output voltage is enhanced. In continuous current operation, current control involves the PI regulator, voltage-adaptive feedforward, and discontinuous current feedforward. The more severe the discontinuity, the larger the discontinuous current feedforward control, resulting in better control performance for the hoist.
(4) Overweight control
① Loading control. If the metering bin is full, the conveyor and feeder will stop operating, and loading into the skip will be restricted. Since the feeder's feed rate is relatively stable, the loading rate can be controlled by controlling the feeder's operating time.
② Lifting Control. A constant speed range of 0.5–1 m is designed before the initial acceleration of the hoist as an accurate hoisting current detection zone. If the detected current exceeds a certain range of the normal hoisting current, the hoist is prohibited from lifting; if the detected current is less than a certain range of the normal hoisting current, it can be determined that the downward-moving skip is not empty, and the quantitative bin is only allowed to load onto the skip after one hoisting cycle; during the initial acceleration phase of the hoist, regardless of which overcurrent protection device is activated, the hoist will implement safety braking.
2. CNC technology upgrade of the main shaft hoisting system at Dongtan Coal Mine
The friction hoist in the main shaft of the Dongtan Coal Mine of Yanzhou Coal Mining (Group) Co., Ltd. is driven by a low-speed DC motor with a rated power of 1700kW. The hoist's electrical control and hydraulic braking systems are products from the Swedish company ASEA in the mid-1970s, and the shaft signaling system is a relay-controlled digital display and voice system. The electrical control equipment and braking system were severely aged, with a high failure rate and poor operational reliability, resulting in annual maintenance and spare parts costs of 400,000 yuan. The mine has upgraded the hoist using CNC technology, and its actual operating condition is good.
(1) Fully digital drive system
① Armature Section. The hoist armature drive system consists of four Siemens 6-pulse four-quadrant fully digital SIMO-REG6RA70DCMASTER rectifier units, connected in series (2 in series and parallel) to form the hoist armature drive system. Each DCMASTER unit outputs a rated current of 1500A and a rated rectified voltage of DC 400V. This drive system features closed-loop control of armature current, torque control, and armature commutation. It communicates with the hoist main control system via Profibus fieldbus and is equipped with comprehensive protection functions, including overvoltage protection, undervoltage protection, overcurrent protection, current setpoint and feedback value error protection, DC circuit insulation protection, cabinet cooling airflow detection protection, and fuse status monitoring, ensuring the safe and reliable operation of the hoist.
② Excitation section. The hoist constant excitation system consists of one SIMOREG6RA70DCMASTER unit, which provides 127A, 90V DC power to generate a constant magnetic field; the maximum output current is 280A, and the same protection functions as the armature section can be selected as needed.
(2) Electrical control system
The main control system consists of an S7400 PLC and an FM458 to realize the functions of improving process control and hoist monitoring. The FM458 is used to control and optimize the speed loop and position loop of the hoist.
① PLC Redundancy System. The hoist is controlled in an open-loop manner by a SIMATIC S7400 PLC system. Digital and analog inputs/outputs are connected via ET200 distributed remote terminals installed locally on the equipment, and communication with the main PLC is achieved through a PROFIBUS bus. The ET200 remote I/O is installed in the low-voltage cabinet, braking system control box, gate box, and signal cabinet, significantly reducing the number of cables and the probability of wire breaks and short circuits, making the system safer and more reliable. A dual PLC system, consisting of CPU416 and CPU414, forms two independent PLC systems that constitute a safety loop. This integrates monitoring of all fault signals related to personnel, equipment, and material safety. Signal data acquisition and protection both use a two-wire system. The calculation results of the two systems monitor each other. If a safety fault occurs or the monitoring results differ, the safety loop is triggered and an alarm is sounded. The electrical control system classifies faults into three categories: Category I faults immediately initiate mechanical safety braking and issue an audible and visual alarm; Category II faults first initiate electrical braking, then apply safety braking to stop the hoist; Category III faults allow the hoist to complete the current cycle, and after stopping, a working brake is applied. Operation cannot resume until the fault is resolved.
② Closed-loop control system. The monitoring system, centered on the FM458-1DP (process control module), achieves closed-loop control of the hoist's speed and position loops, as well as stroke process monitoring. The position closed-loop control accuracy is ±10mm throughout the entire hoisting cycle; the speed closed-loop control accuracy is ±1%. It features continuous speed monitoring, point-by-point speed monitoring, and monitoring of sudden changes in position and speed. Throughout the hoisting process, it continuously controls and monitors the hoisting speed, achieving smooth changes in acceleration and deceleration, reducing impact on the wire rope and other mechanical equipment. It optimizes the hoisting process by automatically selecting different deceleration points based on the hoisting speed, minimizing hoisting time.
(3) Hydraulic braking system
The "Constant Deceleration ST3-D" disc brake system provided by SMIMA consists of a shared oil tank, valve assembly, electric variable pump, various sensors, six pairs of BE100 disc brakes, and piping, and has an independent hydraulic-electric control system. The electric variable pump has a flow rate of 40 L/min and a working oil pressure of 14.4 MPa, with a positive pressure of 100 kN per pair of disc brakes. Pressurized oil charges the accumulator. Under the main working pressure, the brake spring is compressed, achieving a specified gap (2-3 mm) between the brake shoe and the brake disc. When the working pressure is reached, the pump flow rate decreases to maintain the operating level.
① Single tank, dual system. This means that two independent electric variable pumps and two independent valve systems share one oil tank, with one system in operation and the other on standby. The two electric variable pumps can be switched by changing the selector switch on the hydraulic control panel; the two valve circuits can be switched by operating the manual directional valve connected to the main oil inlet line, which greatly reduces the impact of braking system failure on production.
② A hydraulic-electric control system is composed of two sets of S7-300 PLCs and ET200 remote I/O. Dual-channel control technology is adopted to continuously monitor various valves, pressure switches, temperature control switches, disc brakes, and other components of the braking system in real time, ensuring the safety and reliability of the braking system.
③ During safety braking, the hoist can be safely stopped at a constant deceleration rate, reducing the impact on the drums and wire ropes. In the event of constant deceleration braking failure, it automatically switches to constant torque braking to ensure safe braking of the hoist.
④ Driver's control panel and human-machine interface (HMI) display. The driver's control panel is equipped with a depth indicator with coarse and fine display, speed and brake control handles, buttons, switches, indicator lights, signals, armature ammeter, excitation ammeter, speedometer, accelerometer, torque meter, hydraulic pressure gauge, and other operation-related components. The HMI and display use Siemens WinCC software to monitor the computer, enabling real-time monitoring of position, speed, etc. It also allows for position and speed protection experiments, such as overspeed protection, rope slip protection, system A/B speed difference monitoring, and system A/B position difference monitoring, by modifying set parameters.
⑤ Hoisting Signal System. This system possesses comprehensive signaling capabilities and connects to the hoist's monitoring system via both network and hard-wired connections. The signaling system uses an S7-300 PLC as its core controller, installed in the signal cabinet inside the control room, and serves as a slave station for the hoist monitoring system. One ET200 remote I/O unit is installed on each of the upper and lower wellhead signal control consoles. The PLC in the control room monitors and controls all hoisting signals and wellhead facility status online. LED displays are located in the control room, at the upper wellhead, and at the lower wellhead for real-time display of hoisting signals and status information, as well as audio audible feedback.
3. CNC technology upgrade of the hoist electrical control system at Xinglongzhuang Coal Mine
The Xinglongzhuang Coal Mine of Yanzhou Coal Mining (Group) Co., Ltd. has two HSVE2.8 type 6-rope friction hoists, imported from Sweden in the 1970s, installed in both the main and auxiliary shafts. Both are powered by thyristors and powered by DC externally excited motors. Their electrical control system is a speed regulation system with reversible magnetic field, no circulating current logic, and dual closed-loop speed and current control. The two hoists in the main shaft use double skips for hoisting raw coal. In the auxiliary shaft, hoist #1 has two double-layer, four-car cages; hoist #2 has two cages, one a double-layer, four-car cage and the other a counterweight, used for hoisting personnel, gangue, and materials. After decades of use, the hoists have reached their service life, experiencing frequent failures. Spare parts for the electrical control components are scarce and very expensive (some manufacturers no longer produce spare parts), making maintenance and repair difficult. In response to the extremely unsuitable conditions for mine production, the mine and ABB upgraded the electrical control equipment of four hoists, replacing them with AC110 controllers and DCF600 AC numerical control systems.
(1) Upgrade the electromechanical control system.
① Modification of the main electrical control circuit. The magnetic field commutation was changed to armature commutation to avoid impacts during startup, deceleration, and shutdown, thereby reducing equipment damage.
② Replace with a new generation of monitors. Install one encoder each on the main motor, hoisting wire rope, and main shaft to provide signals to the HMS monitor, reduce errors, and prevent sudden stops caused by inconsistent or large errors between the detection signals of one encoder and the other two encoders, effectively ensuring safe hoisting.
③ The control panel is equipped with an additional bypass operation mode. Its function is to allow the hoist to continue operating when certain system faults occur. This fault selection allows the emergency drive system to take over control from the main control system, enabling the hoist to continue operating; when a ground fault is detected in the shaft signal system power supply, the fault selection sends a signal to the main control system to bypass the ground fault, allowing the system to continue operating.
④ Braking Control and Braking System. Braking control is changed to two modes: constant torque and constant deceleration. Constant torque emergency braking is an open-loop braking control mode that performs emergency braking according to a preset braking time and sequence, used for main shaft hoisting with a constant load. The braking process is independent of the actual load state. Constant deceleration braking control achieves semi-closed-loop control of braking and deceleration by detecting the actual speed value during the braking process (converted to deceleration). It only controls the decrease in hydraulic pressure during braking but prevents it from rising. That is, it detects when the emergency braking speed reaches a predetermined value and maintains the pressure at a constant deceleration level. This is used for auxiliary shafts with large load variations and personnel hoisting.
⑤ The braking system is equipped with two hydraulic stations. This reduces braking force and prevents hydraulic components from rupturing, such as hoses, or similar malfunctions. All spare brakes can be easily connected to another hydraulic station. Any modifications to the brake clamp piping are subject to comparison with the selection commands provided by the limit switch monitor and the HST screen.
(2) Problems that exist after the renovation.
① Once the hoist is running, the selector switch cannot be used for any other selections. Because the operating mode cannot be changed after startup, if the operator discovers an abnormality during automatic operation and cannot brake to stop, only emergency braking can be applied, with potentially serious consequences. Therefore, manual operation must be used when loading or unloading personnel, and semi-automatic operation is strictly prohibited. The semi-automatic mode can only be used under normal filling conditions in the auxiliary shaft's dual tanks. If the filling conditions do not meet the requirements for semi-automatic operation, the wellhead signalman must immediately contact the operator to cancel the semi-automatic mode. It would be even safer if it could be improved to automatically switch to working braking and stop the machine in abnormal situations.
② High-voltage switchgear malfunctions and converter tripping faults. These are common faults after the upgrade. When a high-voltage switchgear malfunction occurs, it's difficult to reset and restart from the control panel; a local reset at the high-voltage switchgear is required, often repeating several times. When a high-voltage switchgear trips, the converter usually trips as well. This is because the fault signal, while being sent to the main control system, also triggers the safety circuit via a relay connected in series, causing the converter to trip and stop abruptly. Currently, this is only resolved by resetting or repeatedly resetting.
4. CNC technology upgrade of the electrical control system for the auxiliary shaft hoisting machine at Beisu Coal Mine
The 2JK-3/20 single-rope winding hoist at the No. 2 auxiliary shaft of Beisu Coal Mine, Yanzhou Coal Mining (Group) Co., Ltd., was put into operation in 1990. It is equipped with a JR1510-10 motor, 400kW, 6kV, and uses TKD AC electrical control. With the research, development, and application of CNC DC speed regulation technology in the electrical control systems of mine hoists in my country, the mine upgraded its original electrical control system, replacing the dynamic braking with thyristor low-frequency braking and replacing the original relay logic with PLC logic. However, serious problems still existed during operation after this upgrade. Therefore, they adopted CNC technology to replace analog control, completely solving the problems of unsatisfactory AC drive speed regulation performance, numerous peripheral hardware components, and poor stability in mine hoists, thus achieving automated hoisting.
The upgraded system uses the TS3A electrical control system, offering manual, inspection, layer-changing, and semi-automatic operation modes. The hoist is equipped with major protections against overwind, overspeed in the constant speed section, overspeed in the deceleration section, overspeed throughout the entire range, synchronous over-limit, loading/unloading failure, emergency stop, encoder failure, motor over-temperature trip, rectifier failure trip, fast-opening trip, emergency stop, excitation failure, operating procedure failure, hydraulic system failure, low-voltage power supply system failure, fan auxiliary system failure, computer system failure, slack rope failure, and drive failure. The software safety circuit consists of two S7-400 sets, plus one independent relay safety circuit. The hydraulic station uses constant torque control. The hoist room houses one rectifier transformer, one reactor, and one DC fast circuit breaker. The main rectifier cabinet contains one SIEMENS 6RA70 rectifier to power the armature circuit of the DC motor. Power supply uses parallel 6-pulse thyristors for armature commutation and also provides excitation power. The hoist control console has two inlet control handles, one for speed setting and the other for brake setting. An ET200M remote substation is installed within the console. The display screen shows the main status and major fault indicators. The disc depth indicator and digital depth indicator are equipped with armature current, excitation current, digital speed, acceleration, working valve current, and brake oil pressure gauges. The main control cabinet contains two S7-400 systems with redundant functions, responsible for the hoist's program control, stroke control, status monitoring, and various protection functions, respectively. The auxiliary cabinet contains a relay safety circuit and an ET200M. The armature circuit's adjustment functions include setting the speed setpoint, freely selecting the actual speed signal, automatic speed adjustment, automatic armature current adjustment, a ramp function generator, torque limiting, current limiting, a pre-controller, and a triggering device. Stroke monitoring includes automatic generation of the hoist envelope and monitoring of position and speed throughout the hoisting process, achieving point-by-point speed protection. The system's stroke control accuracy does not exceed ±20mm.
5. Upgrade of CNC automation system for auxiliary shaft hoist at Yangcun Coal Mine
The hoist at the Yangcun Coal Mine of Yanzhou Coal Mining (Group) Co., Ltd. was originally equipped with an AC asynchronous motor driven TKD system, which used relay contact logic control and analog adjustable gate closed-loop regulation with a magnetic amplifier as the core. Speed regulation was achieved by switching the rotor resistance of the AC motor. However, the regulation accuracy was difficult to guarantee, and the stability and linearity were poor. Moreover, the equipment was aging, affecting the safe production of the mine. Therefore, they decided to upgrade it and, with the support of China University of Mining and Technology and Yanzhou Coal Mining (Group) Co., Ltd., developed a numerical control automation system for the hoist.
(1) Scope of technical transformation of control system.
The application of PLCs in the retrofitting of AC hoists mainly manifests in replacing relay logic with PLC logic; replacing magnetic amplifiers with electronic circuits for regulating and controlling adjustable brakes and dynamic braking; replacing the master controller with simple contact coupling; and processing speed signals with electronic circuits. These technologies improve hoist performance to some extent, but problems remain: excessive peripheral hardware fails to fully utilize the PLC software's capabilities, making the device prone to malfunctions and instability; the simple coupling of the master controller results in poor reliability and can easily lead to major errors in start-up control; the addition of intermediate active links for speed detection can easily cause speed monitoring errors; too few critical points such as deceleration points are set, leaving hidden dangers; and the lack of a good adjustment and control program results in unsatisfactory speed regulation performance. Compared with AC asynchronous motor drives, DC motor drives in mine hoists offer better speed regulation performance, do not require additional drive devices, and are easier to automate. The renovation involves removing the TKD electrical control system, AC motors, and signal control equipment, replacing them with a new DC speed control automation system. This includes developing a fully digital automated auxiliary shaft hoisting electrical control system consisting of a high-voltage switchgear, rectifier transformer, armature rectifier cabinet, driver control console, PLC cabinet, low-voltage distribution cabinet, and upper-level monitoring computer. The system will use DC motors and replace one set of PLC control signal control equipment.
(2) Improve the key technologies of electromechanical control systems.
① Power System Design. Two 6kV incoming lines from the mine's 35kV substation are manually switched. One 6kV high-voltage switchgear is housed in the hoist room. The high-voltage switchgear uses vacuum circuit breakers and is equipped with instantaneous trip, overcurrent, undervoltage, and loss-of-voltage trip protection functions. Two 380V incoming lines serve as low-voltage power supply circuits, manually switched. The low-voltage distribution cabinet has multiple outputs, responsible for powering the hoist's electrical control and signal systems, mainly supplying power to auxiliary equipment such as the main cooling fan, brake hydraulic station, and lubrication station, as well as the system's required DC24V, DC15V, DC110V, DC220V, AC220V, and AC110V control power supplies.
② Drive System. The hoist room is equipped with one rectifier transformer. The main circuit of the DC motor uses one main rectifier cabinet with a built-in SIEMENS 6RA70 rectifier. The armature circuit of the DC motor uses thyristor 6-pulse power supply for armature commutation. The 6RA70 SIEMENS 6RA70 DCMASTER series rectifier is a fully digital compact rectifier, with a three-phase input power supply, providing armature and excitation power for the variable speed DC drive, stabilizing the armature current from 15 to 2000A. Open-loop and closed-loop drive control and communication functions are implemented by two powerful microprocessors. The drive control function is implemented through parameters provided by the software program blocks. Based on the hoist stroke control requirements, the PLC performs speed curve and protection curve calculations, synthesizing them into a speed setpoint output. Speed control is completed by the 6RA70 device, with a circular transition at the speed inflection point to reduce mechanical shock. Speed feedback is achieved using an independent 5000 pulses per revolution encoder. The current regulator is a PI regulator with independently settable P amplification values and adjustable integral time. The actual current value is detected by the current transformer on the three-phase AC side, and after passing through the load resistor, rectification, analog-to-digital conversion, it is sent to the current regulator. The output of the current regulator forms the control angle of the trigger device, and the pre-controller also acts on the trigger device. The pre-controller of the current regulation loop is used to improve the dynamic response of the regulation system. The allowable rise time of the current regulation loop is 6-9 ms. The pre-control and current setpoint are related to the motor EMF. The current pre-feed function is realized through the current pre-controller. The 6RA70 master station completes the response to speed control, enabling the hoist to start smoothly.
③ Hoist Control System. The control panel has two handles, one for speed setting and the other for brake setting. The control panel display includes main status indicator lights, main fault indicator lights, a disc-type depth indicator and a digital depth indicator, an armature ammeter, an excitation ammeter, and a speedometer. The control panel also includes an ET200M remote substation. The main control cabinet contains two S7-400 systems. The main PLC implements program control, stroke control protection, status monitoring, and various protections for the hoist. The PLC automatically generates the hoist envelope, enabling position and speed monitoring throughout the hoisting process, and providing point-by-point speed protection. The system stroke control error is ≤±20mm. If one main unit fails, the other unit will be activated as an emergency start. The system has a main S7-400 soft safety circuit to complete all system protections; a secondary S7-400 soft safety circuit to complete the system's stroke protection; and a relay-driven hardware safety circuit to complete critical system protections. The hoist control process program adopts a modular structure, with main functions including manual, inspection, and leveling operation modes to meet the needs of the auxiliary shaft hoisting process. Based on the characteristics of this hoist, they organically combined operation and settings to integrate the drive system and hoisting system, and designed protections to reduce system impact during system development, torque start-up and shutdown.
④ Human-Machine Interaction. The host computer uses a 17″ LCD display. The host computer displays a full view of the hoist status, signal system information, fault information, hoist drive information, high-voltage power supply, low-voltage power distribution, hydraulic braking system diagram, hoisting network diagram, etc., intuitively displaying the current information and historical data of the hoisting system. The host monitoring program can perform graphical process monitoring, data acquisition and management, and supervision and control.
⑤ Signal and Loading Quantity Control System. The PLC main shaft hoisting signal and loading quantity control system is suitable for environments without gas, coal dust, or explosion hazards. It features audible and visual alarms, digital display, signal memory; emergency stop alarm; signal interlocking; signal command and start-up circuit interlocking, emergency stop and safety circuit interlocking, preventing start-up signals from being issued if the positioning equipment is not functioning properly; emergency stop memory and signal self-protection; hoisting count memory and hoisting command storage; hoisting category display; and a hot standby simple marker signal system.
(3) Effects of the renovation.
Practical application demonstrates that: Because the hardware circuits utilize large-scale and very large-scale integrated circuits, there are fewer components, the structure is simpler, there are fewer points of failure, and reliability is higher; the hardware adopts a modular structure connected by a bus, and the control algorithm and system control are implemented in software, making it configurable, allowing for functional expansion and flexible operation; the hardware operating status can be reflected through software, and the software operation status can also be monitored through hardware; both hardware and software faults can be directly reflected through indicators, facilitating maintenance; equipped with a microprocessor, the entire control function and speed regulation algorithm are completed in software, resulting in high control precision and good stability; the CNC DC drive system has high operating efficiency and low power consumption, saving a significant amount of energy and reducing maintenance costs; this system can generate an "S"-shaped curve, reducing impact on the system and protecting the smoothness of system operation; this achievement easily enables digital communication and networking with other systems, transmitting system operating parameters and operating status to the network for modern management.
Main references:
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[2] Li Weisheng, Liu Xiangnan. Application of CNC technology to upgrade and improve electromechanical control system [J]. Coal Mine Electromechanical, 2007, 28(3):61-63
[3] Ma Lianxia. Discussion on the operation experience and technical transformation of the old and new generations of HSVE multi-strength friction hoists in Sweden [J]. Coal Mine Modernization, 2009, 18(4): 117-118
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