Weak current College】 【electric actuator reliability and maintenance.

Electric actuators can be divided into straight trip itinerary and angle, it is an automatic control system indispensable equipment whose main task is the regulator for the control signal in proportion to the converted into linear displacement or angular displacement to lead the valve, regulator, bezel, etc to achieve automatic control. It is widely used in electric power, metallurgy, petroleum, chemical industry and other industrial sectors in the field of automatic control.

Over the past 10 years, due to the widespread adoption and uptake of micro-computer control, micro-mechanical, and other new technologies, new results and mature experience, electric actuator is the rapid development, has now been widely used "computer + servo system" structural model of computer type electric actuator, signaling completion of the microprocessor, tuning parameters switch, status indication, control of output, to improve performance, use and maintenance of flexibility.

First, the reliability of the electric actuator

Electric Actuator reliability refers to it within the prescribed conditions and within the time stipulated features ability to complete.

"General conditions" can be summarized as:

(1) environmental conditions: refers to electric actuator performance environmental characteristics, such as temperature, humidity, pressure, magnetic, mechanical shock, vibration, dust, etc.
(2) dynamic conditions: refers to electric actuator performance of dynamic properties.
(3) load conditions: means can affect the performance of electric actuator load characteristics, such as torque, charged object types and properties, etc.
(4) the use and maintenance conditions: electric actuator reliability only in use, and maintenance, for use and maintenance conditions, the first thing to note is the perfect use and maintenance; and second, you must require the operator to achieve the appropriate technical standards.

"Conditions" is motorized actuator reliability definition the most important and most obvious parts. Under different conditions, their reliability is a black-out specific conditions on reliability may be meaningless. The functionality of the "requirement" is the characterization of the electric actuator tasks of parameters, such as torque, on/off and time, stroke, fixed time, dead zone, etc.

Electric actuators in lifetime reliability changes is to study the basis of their reliability depends on early failure, failure of random failure and depletion. Common reliability theory (R) it a certain amount of indicators characterizing the reliability of the device, it refers to the device in the prescribed conditions and within the time stipulated features of probability. A simple and intuitive, the electric actuator industry in actual use, simply use the average time between failures (MTBF) characterization of reliability features, and as a representative of the electric actuator reliability of performance indicators.
Electric actuators for reliability in General is affected by the following main factors and influences: System selection and design, component/component, an action parameter, machinery construction, manufacturing, assembling accuracy, operation and maintenance personnel capacity, operation and maintenance programs, operation accuracy, maintenance, Assembly and construction conditions, spare performance degradation, transport and use.

To make electric actuator has many features and outstanding performance, and often had to increase the complexity of the system structure, in order to ensure the functionality and performance in use is put into practice, making the reliability problems. Because electric actuators directly control the unit's operating process, impact on the unit and power plant safety and economy, research, analysis of the reliability of the electric actuator is very important and meaningful.

2. electric actuator failure analysis

Improve the reliability of electric actuators, it is necessary to minimize and eliminate failure, but in fact this failure are many. There is a component failure, some system components/component integrated factors, some are electrical, secondary circuit and external factors. Some failure by adjusting the way you can solve, is due to the long life, poor accuracy, you need to repair and replacement parts to restore its performance, while some are the result of the original design of the desired improvement in order to exclude.

1. electric actuator failure characteristics

(1) the commissioning phase failure

New electric actuator failure problem more complicated, characterized by the design, manufacture, installation and management, and other quality issues are intertwined. Failure to reveal serious, it is difficult to adjust the speed, dirt or grease stability so that the actuator failure jam or action. Some components are missing or misplaced spring loaded, seals, but also belong to the design defect, component selection, the actions are not smooth, positioning accuracy is poor, treat such a failure, you should be patient and meticulous, careful handling, one by one.

(2) the initial and ongoing failure to run

Debugging is in normal production phase fault characteristics are: a small number of seals as Assembly quality and material quality problems in the short term damage to oil spills; originally glued in the pipe wall, the hole wall of Burr, sticky sand, impurities and dirt particles cause certain components of precariousness. General to the running of the medium-term, the system components/assemblies is best run work status, low failure rate.

(3) run late fault

Electric Actuator run time, each kind of symbol/components for the operating frequency and load conditions, all wearing parts wear out successively. Failure of this stage is characterized by a position feedback bad contact positioning accuracy is poor, and stability, efficiency significantly reduce, the failure rate has gradually increased. When should a comprehensive inspection, replacement of failure parts, make do, should not have to deal with ideas, science, strictly determined to be fully invested, repair, or may run staff a lot of trouble, even serious effects unit normal adjustment and control.

2. sporadic, sudden failure

Such a failure in time shown as incidental mutation, fault zone and causes more obvious, by non-human and human factors, such as a bad position feedback device, the brake pad wear and "ABS", Parts damaged, coil burn, seal failure, etc.

3. electric actuator maintenance

Electric Actuator primarily by the motor, bearings, gear system and electronic parts, etc. According to the United States military MIL-HDBK-338 released reliability data showed that the actuator failures are mainly concentrated in the motor and bearings, motor failure: winding failure accounts for 20%, accounting for 45% of the bearing failure, slip ring, brush and commutator damage 5%, other 30%; in bearing failure: lubricants metamorphic, vanishing 45%, 30% of the pollution, erosion, accounted for 5%-5%, 5%, the corrosion of the other 10%. Therefore, good maintenance can complement the reliability of the electric actuator, increase its effectiveness.