Automation instrumentation troubleshooting - Database & Sql Blog Articles

Factory direct sales - solid capacitor - patch aluminum electrolysis, to ensure that the factory first-class goods!

In practice, instrumentation and automation faults occur in a wide range of parts, including instrumentation and automation systems, and the failures are ever-changing and random. The method of troubleshooting can only be determined according to the specific circumstances of the fault. There is no strict fixed mode, which is confusing for some maintenance personnel. In the process of troubleshooting, many detours are often taken, and even large losses are caused. Then, as an automated instrumentation worker, it is necessary to quickly identify the cause of the failure and properly and correctly handle the failure point in the event of a failure, which has a significant effect on improving labor productivity, reducing economic losses and safe production. As an automated instrumentation worker, I have been engaged in my own work for nearly 10 years, and gradually explored and summarized some experiences. In the following, I will discuss my understanding of troubleshooting with my own work and discuss with my colleagues so that I can learn from each other and promote and improve.
First, the basis of troubleshooting should thoroughly eliminate the fault, we must be clear about the cause of the fault, to quickly identify the cause of the fault, in addition to constantly accumulating experience in the work, more importantly, can theoretically analyze the reasons for the failure, Use theory to guide your work and use various methods to troubleshoot.
1. To have a certain amount of professional knowledge, many instrumentation and automation failure phenomena must rely on professional theoretical knowledge to truly understand and get through. Compared with other types of work, automated instrumentation is more theoretical, sometimes without theoretical guidance, and many jobs cannot be carried out at all. In actual work, it takes longer to get to the brain than to get started. Once you find the point of failure, the repair is relatively simple.
2. Understand the requirements of the production process for instrumentation and automation Instrumentation and automation are for production services. If you are engaged in crafts, you don't understand instrumentation and automation. Instrumentation and automation must be familiar with the requirements of the production process for instrumentation and automation. Only on this basis can the optimal control system be adopted to improve the stability and safety of equipment operation and reduce the cost of equipment operation and maintenance.
3. Proficiency in reading and understanding Drawings The automatic drawing of the instrument is in one-to-one correspondence with the actual wiring. It is the basis for improving the troubleshooting speed by being able to read and understand the drawing skillfully and familiar with the drawing method. To do this, you can have a further understanding of the equipment, and in the fault detection, you can choose an effective test point to prevent misjudgment and narrow the scope of the fault.
Second, the general method of troubleshooting has a certain theoretical basis, understand the requirements of the process automation of the instrument, and fully prepared for troubleshooting.
Effective analysis and troubleshooting points during operation also require certain means. This is the general method of troubleshooting.
1. Resistance method is a commonly used measurement method. It usually refers to a method of measuring the line and the contacts through the resistance file of the multimeter, and sometimes using a multimeter or a bridge to measure whether the resistance of the coil conforms to the standard, or measuring the mutual phase and mutual with a megger. Insulation resistance between ground and so on. (When measuring, pay attention to selecting the range. Generally, select the lower gear when measuring the path; pay attention to whether there are other circuits to avoid misjudgment; especially pay attention to the inability to measure.)
2. Voltage method Voltage method refers to the method of measuring the voltage value in the circuit by using the corresponding voltage file of the multimeter. Sometimes the voltage of the power supply and load is measured (that is, the load is always included between the two tables), and the open circuit voltage is sometimes measured to determine whether the line is normal (this method is suitable for the input point or output point of the automation module that is inconvenient to disconnect). When measuring, select the gear position of the table, select the appropriate range, and pay attention to the positive and negative polarity when measuring the DC voltage.
3. Current Method The current method is a method for determining the cause of a fault by measuring whether the current in the line meets the normal value. For the weak current signal, the current meter or the multimeter current file is often connected in the circuit for measurement; for the strong electric circuit, the clamp current meter is often used for detection.
4. Replacement method When you suspect that a device is faulty, but you are not sure, and there are substitutes, you can replace the experiment to see if the fault is eliminated.
5. Short-circuit method is applicable to low voltage, small current loops, and the method of short-circuiting the point where the fault is suspected is tested. However, it must be determined that short circuits will not cause a short circuit, and once the work does not cause harm.
6. The direct inspection method is often used to understand the cause of the fault or to have frequent faults according to experience. Then there are some special faults that can directly check the suspected fault point.
7. Instrument test method uses various instruments to measure various parameters, such as using the signal generator to receive or set the signal to observe the input and output status.
8. Step-by-step exclusion method If the system is called a communication failure and the system is not working properly, some communication lines can be gradually removed to determine the fault range and the fault point, and then further processing.
9. Adjusting the parameter method Some components in the line are not damaged, the wiring is good, just because some physical quantities are not adjusted properly (such as the PID parameters of the ingredients), so the system can not operate normally, then according to the actual situation of the field equipment Need to adjust.
10. Information help method The automation equipment has a relatively complete self-diagnosis system and application help information. Proficiency in using this information can quickly and effectively locate the fault point and win time for troubleshooting.
11. Comparison, analysis and judgment method It is based on the working principle of the system, the action procedures of the control link and the logical relationship between them, combined with the fault phenomenon, to compare, analyze and judge, reduce the measurement and inspection, and quickly judge The scope of the fault. For a simple example: a positive and negative control line, forward rotation control is normal, reverse rotation can not run, it means that the power supply, load and public line must be no problem. By analyzing and comparing and judging, it is possible to reduce the detection link, narrow down the fault range, and improve the speed of troubleshooting. It is suitable for direct judgment of partial line faults or fault points, and also throughout the troubleshooting process.
Third, the general steps to troubleshoot Although there is no fixed mode for troubleshooting, but under normal circumstances, there are still certain rules.
1. You should first fully understand the situation at the time of the failure.
1) First ask the operator in detail about the fault phenomenon of the equipment
2) Whether you notice obvious abnormalities by watching, listening, and so on.
3) Power on the test if it is confirmed that there is no danger.
Through the above understanding, the fault is accurately located. This is the basis for analyzing the fault. If the fault phenomenon is not clear, it will cause the deviation of the fault analysis.
2. Analyze the fault and determine the scope of the fault according to the fault phenomenon, combined with the principle of the automation system and the characteristics of the equipment control to determine the extent of the fault, is it an electrical fault or a network fault? Is it a fault at the input point or a fault at the output point? Is the fault of the feedback signal or the fault of the control signal? and many more.
3. Through the detection, analysis and judgment, the process of gradually reducing the fault range to eliminate faults is often the process of analyzing, detecting and judging the scope of the fault gradually. Flexibly use the above "general approach to troubleshooting" to gradually reduce the scope of the fault until the point of failure is identified.
Fourth, in the troubleshooting process to observe the following principles
1. First move the brain, then start from the determination of the fault phenomenon, to analysis, detection and judgment, we must keep a clear head. If you are strategizing and winning a thousand miles, the correct analysis can have a half-effect. Don't encounter a fault, pick up the watch and take it, pick it up and remove it. To develop a good analysis and judgment habits, each measurement must have a clear purpose, that is, what the measurement results indicate. The process of measurement is similar to the police's case-solving, can not ignore the clues, must have strict logic and powerful means of detection; the process of treatment, like a doctor to see a doctor, "the right medicine can cure the disease."
2. From the perspective of the system, a thorough and thorough analysis of the problem has some faults, and the possible reasons are various. It’s a headache, a painful foot, and sometimes it’s not a problem. This requires us to grasp the overall situation from the perspective of the system, determine a reasonable solution, and gradually eliminate until the point of failure is identified.
3. Special faults should be treated specially, for example, for certain faults, it is already clear, there is no need to check the steps step by step; there are no spare parts to replace the fault, the idea to find alternatives and so on.
4. To solve the problem thoroughly, the treatment of the fault point should be reasonable and reliable, and the fault should be eradicated.
The above is my own summary of the experience of troubleshooting the automation of the instrument. Due to the limited level, it is inevitable that there are deficiencies, and I hope to communicate with the peers and make progress together.