The fault features of the motor actuator and the problems that should be paid attention to in its maintenance are analyzed. A new intelligent electric actuator is introduced.
The electric actuator can be divided into two categories: straight stroke and angular stroke. It is an indispensable important equipment in the automatic control system. Its main task is to convert the control signal sent from the regulator into linear displacement or angular displacement proportionally. Drive valves, baffles, and other adjustment mechanisms to achieve automatic control, which is widely used in the field of automatic control of electric power, metallurgy, petroleum, chemical and other industrial sectors. In the past 10 years, due to extensive adoption and absorption of new technologies, new achievements, and mature experiences in microcomputer control and micro-mechanics, electric actuators have been rapidly developed. Now, microcomputer-based electric motors of the “Microcomputer + Follow-up System†structural model have been widely used. Actuator, which completes signal transmission, adjusts parameter switching, status indication, and output of control variables by the microprocessor, and enhances the flexibility of the adjustment system's performance, use, and maintenance.
First, the failure analysis of electric actuators To improve the reliability of electric actuators, it is necessary to reduce and eliminate the failure as much as possible, and in fact such failures are varied. Mainly due to a failure of a component, component/component integration factors in the system, electrical, secondary circuits, and external factors. Some faults can be solved by adjusting methods. Some faults are due to the long use time and poor accuracy. Repairs and replacement of parts are required to restore their performance. Some of them are due to poor original design and need to be improved.
1.1 Fault features of the electric actuators 1 Faults in the commissioning stage The faults of the new electric actuators are more complex and are characterized by many problems such as design, manufacture, installation and management. Common faults are severe leakage, speed is difficult to adjust and stable, dirt or oil causes the transmission mechanism to jam or malfunction. Some components are missing or loaded with wrong springs and seals. Some of them are poorly designed, improperly selected components, unsteady motion, poor positioning accuracy, etc. To deal with such failures, they should be carefully and carefully handled and eliminated one by one. 2 The characteristics of the faults that enter the normal production stage after the initial and mid-operation faults are debugged are that a small number of seals leak oil due to short-term damage to the assembly quality and material quality problems, while sticking to the wall burrs, sticky sand, The shedding of impurities and lumps causes the operation of some components to be unstable. Usually in the middle of operation, the system components/components are in the best operating state and the failure rate is low. 3 Operational failures After the electric actuators have been running for a period of time, due to the difference in working frequency and load conditions, each wearing part has worn excessively. In this stage, the fault features are poor position feedback, poor positioning accuracy, and stability. The decline in performance, the significant reduction in efficiency, and the gradual increase in failure rates. At this time, it should be fully inspected, replace failed parts, and completely repair the fault. Otherwise, it will bring a lot of inconvenience to the operators, and even seriously affect the normal regulation and control of the unit.
1.2 Sporadic, sudden failures These types of failures appear to have accidental abrupt changes in time. The failure areas and causes are more obvious. They are caused by non-human and human factors, such as poor contact of position feedback devices, brake pads wear, and "locking". , parts damage, coil burnout, seal failure and so on.
Second, the maintenance of electrical actuators Electric actuators mainly by the motor, bearings, gear transmission system and electronic components. According to the reliability data published by the US military standard MIL-HDBK-338, actuator failures are mainly concentrated on motors and bearings. In motor failure: winding failure accounts for 20%, bearing failure accounts for 45%, slip ring, brushes, commutator damage accounts for 5%, others account for 30%; in bearing failure: lubricant deteriorates, disappears for 45%, pollution Accounted for 30%, erosion accounted for 5%, mis-adjusted 5%, corrosion accounted for 5%, and others accounted for 10%. It can be seen that good maintenance management can improve the reliability and effectiveness of electric actuators. 1 Enhancing the cleanliness of lubricants The most important feature of electric actuators is the need to use lubricating oils whose viscosity varies with the oil temperature. If the viscosity is too low, the wear of the transmission components such as worms and gears will increase, which will reduce the transmission accuracy; the viscosity will be too high and the operation will be poor. The cleanliness of lubrication grease management is more difficult, the wear parts such as worms and gears, wear and aging impurities and water infiltration, internal coating off, rust, etc. will affect the cleanliness of the lubricating oil. 2 Elimination of grease leakage in a timely manner Due to the high frequency and high speed of the electric actuator, it is difficult to avoid shocks. This is an important cause of grease leakage. Once the grease leaks, it needs to be resolved in time. 3 Improve the working environment and conditions of electric actuators The reliability and lifespan of electric actuators have a direct relationship with its use conditions, the environment in which it operates, and personnel knowledge. Only by improving its working environment and conditions of use in terms of maintenance and management, and human-oriented, it is possible to extend the service life. 4 Intensive Maintenance in the Early Stage of a Fault In all failures of electric actuators, the proportion of initial failures is generally high. Initial failures are mostly caused by initial errors in design, manufacture, and installation. The discovery of these initial failures requires a certain amount of effort, and the solution also takes time. Therefore, the maintenance and management must be particularly strengthened during the initial failure period. 5 Doing Data Management to Prevent Inadvertent Failures The occasional failures of electric actuators are generally more difficult to predict. In order to prevent accidental failures, it is important to check and maintain them regularly, to master maintenance information and historical archive data at a certain stage. This is very important for accurately implementing fault diagnosis and routine maintenance. 6 Improve the professional knowledge of operation and maintenance personnel The mastery of professional knowledge of operation and maintenance personnel directly affects maintenance management. In recent years, due to the changes in the structure of the operation and maintenance personnel, they have greatly improved their knowledge of and knowledge in the electric actuators. However, there are still many operators and maintenance personnel lacking the required professional knowledge and technology. Most of the on-site operation and maintenance personnel are in an “impleminable and non-comprehensive†state for the electric actuators, which is also the weak link of maintenance and management. In order to facilitate the on-site maintenance and management of operation and maintenance personnel, it is necessary to have a sense of advancement in the design of the electric actuator system, fully taking into account the implementation of easy maintenance and management, and strive to: the system should be simplified, the simple system failure rate is low, and maintenance management Easy to use; high degree of standardization, good interchangeability, easy to repair; integrated, combined, easy to adjust, check; introduce new technologies such as fault diagnosis and positioning, fault tolerance/error correction. III. RK-Z Series Intelligent Electric Actuators 3.1 Device Overview Analysis of the use of home-made electric actuators, although certain technical indicators can be comparable with similar foreign products, reliability and stability problems have not been fundamental for a long time. Sexual solutions, the main reasons are: 1 long-term neglect of basic technology research and development; 2 domestic general-purpose parts and the quality of basic parts, but off; 3 companies on product quality control and management is not effective. In response to the above problems, Shanghai Ruikai Instrument Co., Ltd. has developed a new generation of RK-Z series of intelligent electric actuators, which has solved these defects and deficiencies. The RK-Z series intelligent electric actuator system is composed as shown in Fig. 1. The 4-20mA signal or other type of signal from the site is sent to the CPU for A/D conversion to perform arithmetic processing. At the same time, the CPU and the opening signal from the electric actuator are After comparing with the upper and lower limit setting values, the drive motor rotates. After deceleration, the output shaft is driven to make up and down displacement or angular displacement. Finally, the input signal is controlled by the electric actuator to control the displacement of the valve and other equipment. In addition, the current actual position output by the electric actuator is processed by the CPU and D/A converted, and then outputted as a 4 to 20 mA standard signal.
RK-Z series intelligent electric actuator adopts a totally enclosed and integrated structure. Equipped with a single-phase permanent magnet AC synchronous motor, it has the characteristics of small size, light weight, simple structure, small transmission inertia and large torque. The transmission system adopts the screw nut type, which has the advantages of smooth transmission, strong bearing capacity, high transmission accuracy, and self-locking ability. The internal transmission components adopt fine processing technology and strictly control the quality of each component. The actuators have imported high-grade grease before they leave the factory, and they do not need maintenance or leak out. Position feedback adopts the high-precision, high-reliability, high-resolution 0.1%, long-life conductive plastic potentiometer dedicated to the aerospace industry. With a unique mechanical design concept, the potentiometer is connected to the output shaft of the actuator, so that the displacement of the regulating valve can be accurately detected, the authenticity of the position feedback signal is ensured, and the traditional actuator feedback signal is overcome by the gear transmission device. The problem of increasing the error between the actual position of the output shaft and the feedback signal due to wear of gears. Limits and brakes are gradually approaching the electronic technology. When approaching the limit position of the valve, the speed is automatically decelerated. This realizes the “flexible full open†and “flexible full close†of the valve, eliminating the limit switch and brake pads, and solving the limit switch Failure, brake pads are easy to "lock up", and when the brakes are easy to produce large shock current burn out the motor and other difficult problems. Make full use of the microprocessor's data processing capabilities to make it a truly intelligent electric actuator. Through the 5 buttons on the control panel and 6-bit ultra-bright LED digital tube for human-machine dialogue, parameter settings and adjustments, display a clear operating status and a variety of alarm information, to bring a lot of debugging and maintenance personnel Convenience. In order to improve overall reliability, reliability design, reliability assessment, failure analysis, strict screening, aging, and other technological measures are adopted, and the movable parts are minimized, so that the MTBF value of the whole machine reaches more than 40,000 million hours. .
3.2 Device Features 1 Acceptable 0 ~ 10mA, 4 ~ 20mA, 0 ~ 5V, 1 ~ 5V and other analog signals, input signal selection, positive and negative stroke switching, and the upper and lower limit positioning adjustment, etc., without opening Cover, all debugging can be done simply by the touch buttons of the display window. 2 has a variety of control methods: input analog control, passive switch remote control internal and external 24VDC, 10mA, active 220V, 10mA AC switch remote control. 3 Advanced intelligent technology is used to control over-torque protection and over-limit protection, and mechanical torque switches and limit switches that require complex adjustments are eliminated. 4 According to the needs of the on-site system, the valve can be set at any time. 5 frequent on-off times up to 1200 times / hour. 6 Protection class: IP66.
3.3 Self-diagnosis function of the device 1 When the output shaft is displaced to 0% of the starting point of the stroke or 100% of the end of the stroke, the electric actuator will output a pair of passive normally open contacts for use by the control system. 2 When the grid voltage suddenly drops or fails, the internal control circuit of the implementing agency will keep the execution structure at the current position and automatically memorize the relevant field data of the previous instant. Once the voltage returns to normal, the actuator can automatically resume the relevant data and continue normal operation. . 3 When the mechanical parts are stuck, causing the output shaft to remain in its original position when the motor is overloaded, the control circuit will cut off the power of the motor and send an alarm signal, but still keep the opposite direction of motion. At the same time, the output is passive. Open contact pays. When the fault is removed, it automatically enters normal operation. 4 When the automatic control system fails, the state of the valve can be fully opened, closed, and maintained in place according to the process requirements. Some interlocking protection measures of the system are omitted, making operation more secure. 5 has a number of "protocol" communication capabilities, according to user requirements, you can set up other communication "RS-485" "protocol", through the communication interface, hooked up to the data bus, receive instructions from the system, data, etc., and work together.
IV. Conclusion In the automatic control system, the selection of high-quality electric actuators is very important for “life cycle costâ€. If the electric actuators are improperly selected or the quality is not over, the perfect control strategy and superb control strategy are also It is difficult to achieve the desired control effect. For this reason, the production, manufacture, and selection of highly reliable products are increasingly valued by the process control community. RK-Z series intelligent electric actuator adopts mechanical and electrical integration structure, utilizes new technologies such as microcomputer technology and electronic limit and unique mechanical design concept, with small size, light weight, large torque, high reliability, accurate positioning accuracy, and cost Low-level features. At present, several hundred sets of intelligent electric actuators have been applied in Yangshupu, Chongming, Nanshi, Gaoqiao, Luohe, Huiyuan Power Plants, and metallurgy and chemical industries. Its people-oriented design ideas, convenient maintenance and adjustment methods have been favored by field technicians and have a good application prospect.
The electric actuator can be divided into two categories: straight stroke and angular stroke. It is an indispensable important equipment in the automatic control system. Its main task is to convert the control signal sent from the regulator into linear displacement or angular displacement proportionally. Drive valves, baffles, and other adjustment mechanisms to achieve automatic control, which is widely used in the field of automatic control of electric power, metallurgy, petroleum, chemical and other industrial sectors. In the past 10 years, due to extensive adoption and absorption of new technologies, new achievements, and mature experiences in microcomputer control and micro-mechanics, electric actuators have been rapidly developed. Now, microcomputer-based electric motors of the “Microcomputer + Follow-up System†structural model have been widely used. Actuator, which completes signal transmission, adjusts parameter switching, status indication, and output of control variables by the microprocessor, and enhances the flexibility of the adjustment system's performance, use, and maintenance.
First, the failure analysis of electric actuators To improve the reliability of electric actuators, it is necessary to reduce and eliminate the failure as much as possible, and in fact such failures are varied. Mainly due to a failure of a component, component/component integration factors in the system, electrical, secondary circuits, and external factors. Some faults can be solved by adjusting methods. Some faults are due to the long use time and poor accuracy. Repairs and replacement of parts are required to restore their performance. Some of them are due to poor original design and need to be improved.
1.1 Fault features of the electric actuators 1 Faults in the commissioning stage The faults of the new electric actuators are more complex and are characterized by many problems such as design, manufacture, installation and management. Common faults are severe leakage, speed is difficult to adjust and stable, dirt or oil causes the transmission mechanism to jam or malfunction. Some components are missing or loaded with wrong springs and seals. Some of them are poorly designed, improperly selected components, unsteady motion, poor positioning accuracy, etc. To deal with such failures, they should be carefully and carefully handled and eliminated one by one. 2 The characteristics of the faults that enter the normal production stage after the initial and mid-operation faults are debugged are that a small number of seals leak oil due to short-term damage to the assembly quality and material quality problems, while sticking to the wall burrs, sticky sand, The shedding of impurities and lumps causes the operation of some components to be unstable. Usually in the middle of operation, the system components/components are in the best operating state and the failure rate is low. 3 Operational failures After the electric actuators have been running for a period of time, due to the difference in working frequency and load conditions, each wearing part has worn excessively. In this stage, the fault features are poor position feedback, poor positioning accuracy, and stability. The decline in performance, the significant reduction in efficiency, and the gradual increase in failure rates. At this time, it should be fully inspected, replace failed parts, and completely repair the fault. Otherwise, it will bring a lot of inconvenience to the operators, and even seriously affect the normal regulation and control of the unit.
1.2 Sporadic, sudden failures These types of failures appear to have accidental abrupt changes in time. The failure areas and causes are more obvious. They are caused by non-human and human factors, such as poor contact of position feedback devices, brake pads wear, and "locking". , parts damage, coil burnout, seal failure and so on.
Second, the maintenance of electrical actuators Electric actuators mainly by the motor, bearings, gear transmission system and electronic components. According to the reliability data published by the US military standard MIL-HDBK-338, actuator failures are mainly concentrated on motors and bearings. In motor failure: winding failure accounts for 20%, bearing failure accounts for 45%, slip ring, brushes, commutator damage accounts for 5%, others account for 30%; in bearing failure: lubricant deteriorates, disappears for 45%, pollution Accounted for 30%, erosion accounted for 5%, mis-adjusted 5%, corrosion accounted for 5%, and others accounted for 10%. It can be seen that good maintenance management can improve the reliability and effectiveness of electric actuators. 1 Enhancing the cleanliness of lubricants The most important feature of electric actuators is the need to use lubricating oils whose viscosity varies with the oil temperature. If the viscosity is too low, the wear of the transmission components such as worms and gears will increase, which will reduce the transmission accuracy; the viscosity will be too high and the operation will be poor. The cleanliness of lubrication grease management is more difficult, the wear parts such as worms and gears, wear and aging impurities and water infiltration, internal coating off, rust, etc. will affect the cleanliness of the lubricating oil. 2 Elimination of grease leakage in a timely manner Due to the high frequency and high speed of the electric actuator, it is difficult to avoid shocks. This is an important cause of grease leakage. Once the grease leaks, it needs to be resolved in time. 3 Improve the working environment and conditions of electric actuators The reliability and lifespan of electric actuators have a direct relationship with its use conditions, the environment in which it operates, and personnel knowledge. Only by improving its working environment and conditions of use in terms of maintenance and management, and human-oriented, it is possible to extend the service life. 4 Intensive Maintenance in the Early Stage of a Fault In all failures of electric actuators, the proportion of initial failures is generally high. Initial failures are mostly caused by initial errors in design, manufacture, and installation. The discovery of these initial failures requires a certain amount of effort, and the solution also takes time. Therefore, the maintenance and management must be particularly strengthened during the initial failure period. 5 Doing Data Management to Prevent Inadvertent Failures The occasional failures of electric actuators are generally more difficult to predict. In order to prevent accidental failures, it is important to check and maintain them regularly, to master maintenance information and historical archive data at a certain stage. This is very important for accurately implementing fault diagnosis and routine maintenance. 6 Improve the professional knowledge of operation and maintenance personnel The mastery of professional knowledge of operation and maintenance personnel directly affects maintenance management. In recent years, due to the changes in the structure of the operation and maintenance personnel, they have greatly improved their knowledge of and knowledge in the electric actuators. However, there are still many operators and maintenance personnel lacking the required professional knowledge and technology. Most of the on-site operation and maintenance personnel are in an “impleminable and non-comprehensive†state for the electric actuators, which is also the weak link of maintenance and management. In order to facilitate the on-site maintenance and management of operation and maintenance personnel, it is necessary to have a sense of advancement in the design of the electric actuator system, fully taking into account the implementation of easy maintenance and management, and strive to: the system should be simplified, the simple system failure rate is low, and maintenance management Easy to use; high degree of standardization, good interchangeability, easy to repair; integrated, combined, easy to adjust, check; introduce new technologies such as fault diagnosis and positioning, fault tolerance/error correction. III. RK-Z Series Intelligent Electric Actuators 3.1 Device Overview Analysis of the use of home-made electric actuators, although certain technical indicators can be comparable with similar foreign products, reliability and stability problems have not been fundamental for a long time. Sexual solutions, the main reasons are: 1 long-term neglect of basic technology research and development; 2 domestic general-purpose parts and the quality of basic parts, but off; 3 companies on product quality control and management is not effective. In response to the above problems, Shanghai Ruikai Instrument Co., Ltd. has developed a new generation of RK-Z series of intelligent electric actuators, which has solved these defects and deficiencies. The RK-Z series intelligent electric actuator system is composed as shown in Fig. 1. The 4-20mA signal or other type of signal from the site is sent to the CPU for A/D conversion to perform arithmetic processing. At the same time, the CPU and the opening signal from the electric actuator are After comparing with the upper and lower limit setting values, the drive motor rotates. After deceleration, the output shaft is driven to make up and down displacement or angular displacement. Finally, the input signal is controlled by the electric actuator to control the displacement of the valve and other equipment. In addition, the current actual position output by the electric actuator is processed by the CPU and D/A converted, and then outputted as a 4 to 20 mA standard signal.
RK-Z series intelligent electric actuator adopts a totally enclosed and integrated structure. Equipped with a single-phase permanent magnet AC synchronous motor, it has the characteristics of small size, light weight, simple structure, small transmission inertia and large torque. The transmission system adopts the screw nut type, which has the advantages of smooth transmission, strong bearing capacity, high transmission accuracy, and self-locking ability. The internal transmission components adopt fine processing technology and strictly control the quality of each component. The actuators have imported high-grade grease before they leave the factory, and they do not need maintenance or leak out. Position feedback adopts the high-precision, high-reliability, high-resolution 0.1%, long-life conductive plastic potentiometer dedicated to the aerospace industry. With a unique mechanical design concept, the potentiometer is connected to the output shaft of the actuator, so that the displacement of the regulating valve can be accurately detected, the authenticity of the position feedback signal is ensured, and the traditional actuator feedback signal is overcome by the gear transmission device. The problem of increasing the error between the actual position of the output shaft and the feedback signal due to wear of gears. Limits and brakes are gradually approaching the electronic technology. When approaching the limit position of the valve, the speed is automatically decelerated. This realizes the “flexible full open†and “flexible full close†of the valve, eliminating the limit switch and brake pads, and solving the limit switch Failure, brake pads are easy to "lock up", and when the brakes are easy to produce large shock current burn out the motor and other difficult problems. Make full use of the microprocessor's data processing capabilities to make it a truly intelligent electric actuator. Through the 5 buttons on the control panel and 6-bit ultra-bright LED digital tube for human-machine dialogue, parameter settings and adjustments, display a clear operating status and a variety of alarm information, to bring a lot of debugging and maintenance personnel Convenience. In order to improve overall reliability, reliability design, reliability assessment, failure analysis, strict screening, aging, and other technological measures are adopted, and the movable parts are minimized, so that the MTBF value of the whole machine reaches more than 40,000 million hours. .
3.2 Device Features 1 Acceptable 0 ~ 10mA, 4 ~ 20mA, 0 ~ 5V, 1 ~ 5V and other analog signals, input signal selection, positive and negative stroke switching, and the upper and lower limit positioning adjustment, etc., without opening Cover, all debugging can be done simply by the touch buttons of the display window. 2 has a variety of control methods: input analog control, passive switch remote control internal and external 24VDC, 10mA, active 220V, 10mA AC switch remote control. 3 Advanced intelligent technology is used to control over-torque protection and over-limit protection, and mechanical torque switches and limit switches that require complex adjustments are eliminated. 4 According to the needs of the on-site system, the valve can be set at any time. 5 frequent on-off times up to 1200 times / hour. 6 Protection class: IP66.
3.3 Self-diagnosis function of the device 1 When the output shaft is displaced to 0% of the starting point of the stroke or 100% of the end of the stroke, the electric actuator will output a pair of passive normally open contacts for use by the control system. 2 When the grid voltage suddenly drops or fails, the internal control circuit of the implementing agency will keep the execution structure at the current position and automatically memorize the relevant field data of the previous instant. Once the voltage returns to normal, the actuator can automatically resume the relevant data and continue normal operation. . 3 When the mechanical parts are stuck, causing the output shaft to remain in its original position when the motor is overloaded, the control circuit will cut off the power of the motor and send an alarm signal, but still keep the opposite direction of motion. At the same time, the output is passive. Open contact pays. When the fault is removed, it automatically enters normal operation. 4 When the automatic control system fails, the state of the valve can be fully opened, closed, and maintained in place according to the process requirements. Some interlocking protection measures of the system are omitted, making operation more secure. 5 has a number of "protocol" communication capabilities, according to user requirements, you can set up other communication "RS-485" "protocol", through the communication interface, hooked up to the data bus, receive instructions from the system, data, etc., and work together.
IV. Conclusion In the automatic control system, the selection of high-quality electric actuators is very important for “life cycle costâ€. If the electric actuators are improperly selected or the quality is not over, the perfect control strategy and superb control strategy are also It is difficult to achieve the desired control effect. For this reason, the production, manufacture, and selection of highly reliable products are increasingly valued by the process control community. RK-Z series intelligent electric actuator adopts mechanical and electrical integration structure, utilizes new technologies such as microcomputer technology and electronic limit and unique mechanical design concept, with small size, light weight, large torque, high reliability, accurate positioning accuracy, and cost Low-level features. At present, several hundred sets of intelligent electric actuators have been applied in Yangshupu, Chongming, Nanshi, Gaoqiao, Luohe, Huiyuan Power Plants, and metallurgy and chemical industries. Its people-oriented design ideas, convenient maintenance and adjustment methods have been favored by field technicians and have a good application prospect.
Different Widths,Walnut Colour Laminate Flooring,Synchronized Surface
Laminate flooring Co., Ltd. , http://www.nslaminate.com