Automatic Control and Safety Protection of Electric Power Drag System Shanxi Aluminum Plant Control Room (Hejin 043300, Shanxi) Yang Fengqig Li Chuanhua This paper describes the automatic control and safety protection of the electric drive system, the control principle and implementation method of the electric drive system, and the safety protection. The role is illustrated by our No. 1 roaster. Automatic control of safety interlock 1 Introduction In modern industrial production, the application of the electric drive system is very extensive. In addition to meeting the requirements of the production machine and ensuring the correct operation of the system, the electric drag system must also have Various protection devices are used to protect the grid, motors, control appliances and other electrical components, eliminating the harmful effects of abnormal work. With the improvement of the automation level and the enhancement of the computer control system, the control of the electric drive system is more safe and reliable. Output, on the computer to achieve a centralized control of the power drag system into the computer system signals are the main start-up interlock, operation interlock, motor operation signal, local centralized control *, thermal failure Qianhao and so on. The output generally has a motor start/stop, variable frequency control and so on. 3 realization of the control process Electric drive system in the computer's automatic chamber system, such as the 2 control principle for the electric drive system to anvil, the motor itself feedback: speed feedback, current feedback, voltage feedback, frequency feedback and so on. Electrical protection is divided into over-current protection, thermal protection, under-voltage protection, short-circuit protection, etc. This is the control part of the electric drive system, which is completed by electrical equipment. Computers implement other interlocking controls, security protections, and information displays. There are many ways to implement the electric drive system control on the computer, and the control schemes also have their own advantages, but most of them are implemented by programming, function blocks, and logical operations because the instrument drivers are all in a modular and device-independent way to the user. Released for users to quickly link the instrument into their own test system, making programming and configuration more convenient and reliable. Due to the different process conditions, the requirements for the electric drive system and control are also different, but in essence there is not much difference, through the signal input to start interlocking operation interlock alarm signal operation program; modular program and logic operation and screen operating. Start / stop inconsistent / alarm In order to better explain the self-gws system of the electric drive system and safety protection, a brief introduction to the blower system of No. 1 boiler in our factory. 3.1 System Components The blower system is composed of a motor, a speed reducer, and a fan. The auxiliary equipment includes an electric oil pump and a lubricating oil pump. These two pumps are used for the lubrication and cooling of the blower system. Before the start of the blower system must meet the conditions for launching Chinese instrumentation "2001.2, the motor has five conditions: front and rear bearing bush temperature, water pressure, oil pressure, undervoltage, overcurrent protection, to form a safety chain. The reducer has a lubricating oil supply signal; the fan has a vibration detection signal, a lubricating oil supply signal, an air filter signal, and a damper signal; the blower system also has an oil temperature signal, an electric dust collection inlet temperature signal, and a motor secondary start signal. These conditions determine the start and stop of the blower and complete the automatic control process in the computer. 3.2 The realization of automatic control and safety protection Some signals are not applied in the motor control, so in the logic operation, if it is OR operation, it is always 0, and the operation is always 1.1. The roaster computer system is originally the TDC2000 of HONEYWELL. The system uses the SOPL language to implement its control process. After the system is upgraded to a TPS system, a modular program is used to implement its control process. Although the implementation methods are different, the completed functions are the same. 3.2.1 Self-carving blower start conditions include: safety chain, damper closed, oil temperature, oil filter, secondary start signal, 3 lube oil flow signals, electric dust collection temperature. The operating interlocks are: 3 oil flow signals, inlet dust temperature, safety chain, and vibration signals. When the starting conditions are met, the blower can be started centrally on the computer. When one of the operating conditions does not meet the normal requirements, the blower is automatically stopped by the control of the program or modular program. Of course, the on-site control takes precedence over the centralized control. The following describes the role of each control condition: When the oil temperature is low, the lubrication effect is poor and it is forbidden to start the blower. If one of the five signals in the safety chain does not meet the conditions and the safety chain is not available, the blower cannot be started and the blower is stopped during operation. Because these five signals are serially connected, it is often important that they are just as N. The following will be introduced in the security protection. The oil flow signals (F41FS; F42FS; F43FS) are the lubricating oil signals supplied by two lube oil pumps (1603; 1604) to the reducer and fan, respectively. These three signals are both start interlock and operation interlock, as long as there is a lubrication. The oil signal disappears and cannot be recovered within 10 seconds. The blower stops automatically to prevent the speed reducer and fan from being damaged due to temperature. The damper signal must be closed before the blower starts. When the temperature of the inlet of the dust collector exceeds the temperature, the electrode plate breaks down due to excessive moisture in the air. Therefore, the blower should be stopped immediately and no air is discharged. The vibration signal is the size of the vibration of the bearing of the fan. When the vibration is reported, the blower stops automatically to prevent the fan from flying. The secondary start signal is only allowed to start the blower twice in half an hour. When the blower is started for the third time, it must be delayed for another half an hour before starting. Because the blower will start the blower many times to destroy the system in a short time. The oil filter signal prevents the lubricant from blocking the lubrication pipe. The oil temperature doubles the temperature of the lubricating oil. When the temperature is too low, the lubricating effect will be reduced. Especially in winter, the lubricating oil must be heated. 3.2.2 Security Protection The electrical protection system is divided into electrical protection and computer system protection. Electrical protection is the foundation. The computer is built on top of the electrical protection. For blowers, there are four electrical protections: undervoltage protection. , Over current protection, thermal protection and short circuit protection Computer protection includes: safety chain, operation interlock, start interlock and overall system fault stop. The following section introduces some of the functions of security protection. Undervoltage protection: When the motor is running, excessive reduction of the power supply voltage causes the motor speed to drop or even stop. At the same time, the power supply increases when the load torque is constant. In addition, the voltage drop of the motor will cause some electrical release, causing the circuit to work abnormally and possibly causing a malfunction. Therefore, it is necessary to cut off the motor power supply when the voltage drops to the minimum allowable voltage value. Over-current protection: Improper starting and excessive loads often cause large over-currents in the motor, damaging the motor and mechanical transmission components, typically 1.2 times the starting current. Thermal protection: In order to prevent the motor from being damaged due to long-term overload operation and the temperature rise of the motor M exceeds the allowable value, thermal protection is required. Short-Circuit Protection: Short-circuit currents cause electrical equipment insulation damage and generate strong electrical stresses that cause electrical damage and mechanical damage to various electrical devices in the circuit. * Safety chain: It includes undervoltage and overcurrent protection, and short circuit and Thermal protection is implemented in electrical controls. It also includes oil pressure, water pressure and bushing temperature protection. The oil pressure is the pressure of the lubricating oil pump to supply the motor bearing bushing. When the oil pressure is lower than the required pressure, the bearing bush will not supply oil and the friction will cause the bearing bush temperature to rise and burn. The bearing bush temperature and oil pressure are both protective bearings. It is a double-layer protection; the water pressure protects the inside of the motor. When the water pressure is low and the cooling effect is not achieved, the coil heats up and burns. The security chain is a string condition, and any one of the conditions does not meet the requirements. The computer system turns off the blower through self-control. This is the most important condition for the safety protection of the blower. Operation interlocking and start-up interlock protection: An automatic control process that is implemented by a program or a modular program within the computer by inputting a signal. It mainly completes the protection when the condition is not available or the signal disappears before and after the blower starts. The computer system not only guarantees the safety of the input and the transporter signals, but also the hardware and software of the computer system ensure the safety of the automatic control system. Full reliability. When an emergency occurs, the computer system will stop the site: all operating equipment. Zhongguo Instrument "2001.2
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