Resolving Actuator Issues in Electric Control Valves
Electric control valves play an indispensable role in automatic control systems, akin to the hands and feet of a human body. They are widely used across various industrial sectors such as power, metallurgy, petroleum, and chemical industries. The primary function of the actuator in an electric control valve is to convert control signals proportionally into linear or rotary motion to drive valve and damper mechanisms, thereby achieving automatic control. However, actuator malfunctions can occur and must be addressed promptly. This article discusses the sources, characteristics, and resolution strategies for actuator issues in electric control valves.
Actuator Classification and Fault Analysis
Actuators in electric control valves are categorized into two main types: linear (straight-stroke) and rotary (quarter-turn). Understanding these basic classifications is crucial for effective troubleshooting and resolution. Malfunctions in the actuator of an electric control valve can stem from component failure, integrated system factors, electrical issues, secondary circuit faults, or external influences. These failures can be isolated or a combination of several factors.
Fault Characteristics
1. Commissioning Phase Failures: These are complex, involving a mix of design, manufacturing, installation, and management issues. Common problems include severe leakage, unstable speed adjustment, and transmission mechanism jamming due to dirt or oil. Some components may be missing or incorrectly installed, and there might be design flaws or improper component selection leading to unstable operation and poor positioning accuracy. These issues require patient, meticulous, and careful resolution.
2. Early and Middle Operation Phase Failures: Characterized by the early failure of some seals due to assembly quality and material issues, leading to oil leakage. Additionally, debris, such as burrs or sand, adhering to pipe or hole walls can cause unstable operation. During the middle phase, system components usually operate optimally, resulting in a lower failure rate.
3. Late Operation Phase Failures: After prolonged operation, various components wear out due to differences in working frequency and load conditions. The characteristics of failures at this stage include poor contact in position feedback, poor positioning accuracy, decreased stability, significantly reduced efficiency, and an increasing failure rate. Comprehensive inspection and replacement of failed parts are necessary to prevent inconvenience to operators and potential severe impacts on the normal regulation and control of the unit.
4. Intermittent and Sudden Failures: These types of failures manifest abruptly and have clear regions and causes, resulting from both non-human and human factors. Examples include poor contact in position feedback devices, worn brake pads, "freezing" of parts, component damage, coil burnout, and seal failure.
Resolution Strategies
1. Fault Diagnosis: Accurately identifying the source of the malfunction is the first step, which may require specialized diagnostic tools and techniques.
2. Regular Maintenance: Routine inspections and maintenance can reduce the incidence of failures and extend the life of the actuator.
3. Design Improvement: For failures caused by inadequate original design, design improvements are necessary to resolve the issues.
4. Component Replacement: Timely replacement of parts that have been in use for a long time and have lost precision is essential to restore actuator performance.
5. Professional Training: Operators should receive professional training to operate and maintain electric control valves correctly, reducing human-induced failures.
The analysis and resolution of actuator issues in electric control valves are key to ensuring the stable operation of automatic control systems. By understanding the characteristics and causes of failures and adopting effective resolution strategies, the reliability and performance of the actuator can be significantly improved. Regular maintenance and professional training are equally important for preventing and reducing failures.
