The function of the position locator is to compare the control signal with the feedback signal of the valve position in the field and then output it to the actuator; the actuator will drive the single-phase motor to rotate according to the signal sent by the position locator, and the position of the valve will follow the reducer. The change occurs and the motor stops when the difference between the valve position feedback signal and the control signal is smaller than the dead zone of the positioner. At this point, the one motion process ends.
This type of electric actuator has been operating for nylon 66 salt company for nearly five years. Due to its great control, the use of the situation has repeatedly affected the long-term stable operation of the process. Therefore, understand its working principle and familiarity. It is necessary to have a fault phenomenon and master its daily maintenance. Its working principle diagram is as follows:
S1, S2: Travel limit micro switch S3, S4: Torque limit micro switch RT: Overheat protection switch When the actuator power is turned on, the AC contactors K1 and K2 are energized and the contacts K1-1 and K2-1 are self-acting Switch on. When the control signal is greater than the feedback signal, the position locator sends a signal to make terminals 20 and 15 connected, then the motor rotates in a forward direction, drives the reducer to run, and the cam also rotates (causes the feedback signal to increase); S1 breaks when overtraveling On, K1 loses power, K1-1 turns off, and the motor stalls. In the moment of over-torque occurred during the rotation, S3 is turned on, and relay K3 is closed to make K3-2 pull in and K3 is locked. At the same time, normally closed contact K3-1 is cut off, K1 loses power, and the motor stops. When the control signal is smaller than the feedback signal, the position locator sends a signal, 20 and 16 are turned on, the motor is reversed, and the principle of the action process is the same as above.
The rotation of the reducer is finally driven by the cam to rotate the single-conducting conductive plastic potentiometer, and the current transformer TAM2 outputs a 4-20mADC feedback signal to perform the remote transmission instruction.
Electric actuator failure analysis
Performance
Whether the electric actuator can operate reliably and whether it can fulfill the specified function within the specified time and under the specified conditions, the key lies in its performance index. The performance index is generally expressed by MTBF, which contains some important parameters such as basic error, hysteresis, damping, dead zone, etc. These parameters reflect the performance of the electric actuator to some extent.
Main performance indicators and current problems
The technical parameters of this kind of electric actuator include: 1 input channel, 250 ohm resistance, 1% basic error, 1.5% hysteresis, 0.5% to 3% dead zone, and no disturbance in damping characteristics. .
Although some of the technical parameters of such electric actuators can be compared with foreign counterparts, due to the imperfections of domestic production companies, there are several drawbacks:
(1) Ignoring the research and development of basic technologies (2) The quality of general components is not high (3) The quality management of enterprises is lax. Due to the above drawbacks, there are still many failures in the operation of electric actuators. , Here's a detailed introduction.
Early failure analysis operation
The initial period of operation is the run-in period. The failures that occur during this period are more complex and the reasons are also manifold, such as selection problems, design and manufacturing problems, or installation and environmental issues. For example, if the torque is too small, it may affect the speed of adjustment or even cannot be adjusted at all. There are several practical applications: design does not pay attention to the solid connection between the connecting rod and the actuator, there is a phenomenon of shedding; installation of the power line and signal line use the same threading pipe, resulting in large signal interference; nearby unshielded large The motor equipment has an impact on the stable operation of the actuator's motor; the position locator's insurance selection is too large, causing damage to its internal choke coils. For these problems, we must observe them in time and find and handle them in time to avoid unnecessary losses.
Middle run
In the middle period of operation, the overall performance of the electric actuators also shifts from the break-in period to the adaptation period, which is more stable at this time. The problems that arise are mostly caused by quality problems in individual electronic components. Such as position current transformer TAM2, intermediate contactors K1, K2, over-torque micro-switches, etc., in addition to timely response to the manufacturer, but also do statistical work, pay attention to prepare more spare parts, as replacement .
Late run
In the later stages of operation, the aging of components and the wear of transmission components begin to become extremely serious. Such as the motor coil aging caused by reduced insulation, unstable operation; motor lubrication is not good to reduce the stability of the operation; positioner's comparative coil aging or position current converter aging to reduce the positioning accuracy; reducer drive parts wear and tear resulting in the motor can not Adjustments, etc., should be checked periodically to prevent major failures. It is also necessary to prepare for the preparation of the station.
Of course, among all the fault factors, the objective factors also have a certain proportion, such as artificial stamping in the actual operation, stuck process flaps, and erroneous operation of the process. 4. Maintenance Based on the actual experience of on-site maintenance personnel, maintenance of electric actuators should adopt different key maintenance measures according to their different usage periods. We usually need to make the following points.
Regular lubrication
Motors and transmission components of electric actuators need to be lubricated with oil, and the viscosity of the oil changes with the temperature of the oil. The viscosity is too low, the wear of gears and other transmission components increases; the viscosity is too high and the action is poor. Therefore, regular lubrication can extend its service life.
Improve the operating environment
In order to ensure the reliability of the electric actuator, it must be ensured that it operates in a suitable operating environment and avoids the occurrence of circuit short-circuits or other faults caused by other environmental factors such as environmental humidity.
Periodic inspection
Regular inspection, timely detection of hidden accidents in operation, to eliminate them in the bud, at least for the search for factors that help the failure, to avoid detours.
Manage fault accounting
Each fault that has been dealt with must be recorded in detail, including fault phenomena, fault analysis and search procedures, fault causes, treatment methods, and preventive measures. This will not only provide reference value for similar problems in the future, but also improve the level of finding fault factors through the fault curve and achieve a multiplier effect.
Strengthen the technical training and learning of maintenance personnel
For the staff of the thermoelectric station, timely technical training and learning can help them eliminate psychological stress factors, improve skill levels, and ultimately achieve the goal that everyone can handle common faults.
to sum up
In general, after nearly 5 years of actual maintenance, the current status quo shows that the use of electric actuators in nylon 66 salt company is quite satisfactory. Of course, from the perspective of facilitating maintenance, professional designers are expected to fully consider the convenience of on-site maintenance and management when designing the electric actuator system, such as simplifying the system as much as possible, reducing the failure rate, realizing on-line debugging, and standardizing the components used. Highly-featured, easy-to-repair; proper introduction of fault-tolerance/error-correction functions, etc., as a result, the maintenance work of electric actuators will become easier, and their use in industry will become more and more widespread.
This type of electric actuator has been operating for nylon 66 salt company for nearly five years. Due to its great control, the use of the situation has repeatedly affected the long-term stable operation of the process. Therefore, understand its working principle and familiarity. It is necessary to have a fault phenomenon and master its daily maintenance. Its working principle diagram is as follows:
S1, S2: Travel limit micro switch S3, S4: Torque limit micro switch RT: Overheat protection switch When the actuator power is turned on, the AC contactors K1 and K2 are energized and the contacts K1-1 and K2-1 are self-acting Switch on. When the control signal is greater than the feedback signal, the position locator sends a signal to make terminals 20 and 15 connected, then the motor rotates in a forward direction, drives the reducer to run, and the cam also rotates (causes the feedback signal to increase); S1 breaks when overtraveling On, K1 loses power, K1-1 turns off, and the motor stalls. In the moment of over-torque occurred during the rotation, S3 is turned on, and relay K3 is closed to make K3-2 pull in and K3 is locked. At the same time, normally closed contact K3-1 is cut off, K1 loses power, and the motor stops. When the control signal is smaller than the feedback signal, the position locator sends a signal, 20 and 16 are turned on, the motor is reversed, and the principle of the action process is the same as above.
The rotation of the reducer is finally driven by the cam to rotate the single-conducting conductive plastic potentiometer, and the current transformer TAM2 outputs a 4-20mADC feedback signal to perform the remote transmission instruction.
Electric actuator failure analysis
Performance
Whether the electric actuator can operate reliably and whether it can fulfill the specified function within the specified time and under the specified conditions, the key lies in its performance index. The performance index is generally expressed by MTBF, which contains some important parameters such as basic error, hysteresis, damping, dead zone, etc. These parameters reflect the performance of the electric actuator to some extent.
Main performance indicators and current problems
The technical parameters of this kind of electric actuator include: 1 input channel, 250 ohm resistance, 1% basic error, 1.5% hysteresis, 0.5% to 3% dead zone, and no disturbance in damping characteristics. .
Although some of the technical parameters of such electric actuators can be compared with foreign counterparts, due to the imperfections of domestic production companies, there are several drawbacks:
(1) Ignoring the research and development of basic technologies (2) The quality of general components is not high (3) The quality management of enterprises is lax. Due to the above drawbacks, there are still many failures in the operation of electric actuators. , Here's a detailed introduction.
Early failure analysis operation
The initial period of operation is the run-in period. The failures that occur during this period are more complex and the reasons are also manifold, such as selection problems, design and manufacturing problems, or installation and environmental issues. For example, if the torque is too small, it may affect the speed of adjustment or even cannot be adjusted at all. There are several practical applications: design does not pay attention to the solid connection between the connecting rod and the actuator, there is a phenomenon of shedding; installation of the power line and signal line use the same threading pipe, resulting in large signal interference; nearby unshielded large The motor equipment has an impact on the stable operation of the actuator's motor; the position locator's insurance selection is too large, causing damage to its internal choke coils. For these problems, we must observe them in time and find and handle them in time to avoid unnecessary losses.
Middle run
In the middle period of operation, the overall performance of the electric actuators also shifts from the break-in period to the adaptation period, which is more stable at this time. The problems that arise are mostly caused by quality problems in individual electronic components. Such as position current transformer TAM2, intermediate contactors K1, K2, over-torque micro-switches, etc., in addition to timely response to the manufacturer, but also do statistical work, pay attention to prepare more spare parts, as replacement .
Late run
In the later stages of operation, the aging of components and the wear of transmission components begin to become extremely serious. Such as the motor coil aging caused by reduced insulation, unstable operation; motor lubrication is not good to reduce the stability of the operation; positioner's comparative coil aging or position current converter aging to reduce the positioning accuracy; reducer drive parts wear and tear resulting in the motor can not Adjustments, etc., should be checked periodically to prevent major failures. It is also necessary to prepare for the preparation of the station.
Of course, among all the fault factors, the objective factors also have a certain proportion, such as artificial stamping in the actual operation, stuck process flaps, and erroneous operation of the process. 4. Maintenance Based on the actual experience of on-site maintenance personnel, maintenance of electric actuators should adopt different key maintenance measures according to their different usage periods. We usually need to make the following points.
Regular lubrication
Motors and transmission components of electric actuators need to be lubricated with oil, and the viscosity of the oil changes with the temperature of the oil. The viscosity is too low, the wear of gears and other transmission components increases; the viscosity is too high and the action is poor. Therefore, regular lubrication can extend its service life.
Improve the operating environment
In order to ensure the reliability of the electric actuator, it must be ensured that it operates in a suitable operating environment and avoids the occurrence of circuit short-circuits or other faults caused by other environmental factors such as environmental humidity.
Periodic inspection
Regular inspection, timely detection of hidden accidents in operation, to eliminate them in the bud, at least for the search for factors that help the failure, to avoid detours.
Manage fault accounting
Each fault that has been dealt with must be recorded in detail, including fault phenomena, fault analysis and search procedures, fault causes, treatment methods, and preventive measures. This will not only provide reference value for similar problems in the future, but also improve the level of finding fault factors through the fault curve and achieve a multiplier effect.
Strengthen the technical training and learning of maintenance personnel
For the staff of the thermoelectric station, timely technical training and learning can help them eliminate psychological stress factors, improve skill levels, and ultimately achieve the goal that everyone can handle common faults.
to sum up
In general, after nearly 5 years of actual maintenance, the current status quo shows that the use of electric actuators in nylon 66 salt company is quite satisfactory. Of course, from the perspective of facilitating maintenance, professional designers are expected to fully consider the convenience of on-site maintenance and management when designing the electric actuator system, such as simplifying the system as much as possible, reducing the failure rate, realizing on-line debugging, and standardizing the components used. Highly-featured, easy-to-repair; proper introduction of fault-tolerance/error-correction functions, etc., as a result, the maintenance work of electric actuators will become easier, and their use in industry will become more and more widespread.
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