Fault analysis and troubleshooting of electrical c

Fault analysis and troubleshooting of electrical control circuit of complex mechanical equipment (I)

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I. conditions that electrical maintenance personnel should have

realistically speaking, fault maintenance of electrical control circuit is a relatively difficult thing, and fault maintenance of complex electrical control circuit should be even more difficult

first of all, the design work always follows the trend of the times, so it can constantly abandon old technologies and components; However, maintainers should not only learn new things, but also dare not give up the old technology and methods, because as long as the equipment is in service for one day, the maintenance work must be carried out for one day

secondly, in the maintenance of electrical equipment, as a maintainer, he is always in a passive position. Because they always have big problems when they should not have problems, and the general electrical maintenance personnel cannot carry out maintenance. At this time, it is also a good time for better electrical maintenance personnel to display excellent professional skills and perform well in professional and technical status

however, as an excellent electrical maintenance personnel, they must have good professional and technical quality and rich experience accumulation, which is often accompanied by a lifetime. Because design and manufacturing may be temporary, but maintenance work is long-term. Therefore, the two magic weapons for the maintenance of complex electrical equipment are good professional quality and rich experience accumulation. Professional quality is the basis of analytical ability and processing ability; Rich maintenance experience is the guarantee of correct and rapid judgment

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therefore, to be a competent electrical maintenance personnel should have the following basic conditions and qualities:

1 With a wide range of knowledge

complex mechanical equipment is usually a combination of mechanical, electrical, hydraulic, pneumatic and other equipment. The components of complex mechanical equipment are closely related, and the failure of any part will affect the normal work of other parts. The first step of on-site maintenance is to identify the real cause and position of the fault as soon as possible according to the fault phenomenon. This is the quality that maintenance personnel must have. At the same time, it is also a requirement for maintenance personnel. It requires the maintenance personnel not only to master the professional knowledge of electrical specialty, but also to have a certain basic knowledge of mechanical transmission and structure, and the two should be organically combined. Only in this way can we quickly find out the original fault and judge the fault. In addition, in order to conduct on-site mapping of some circuits and parts during maintenance, that is to say, maintenance personnel should also have certain engineering drawing ability

2. Be good at thinking and careful in doing

complex mechanical equipment is usually expensive and plays a very important role in the enterprise. The repair and disposal must be accurate. As a maintenance personnel, we must be able to quickly find out the root cause of the failure and eliminate it by analyzing the process of the failure, aiming at various possible causes from the outside to the inside, and looking at the essence through the phenomenon. Generally speaking, for staff engaged in the maintenance of complex mechanical equipment, in a sense, they should "use their brains more and be careful with their hands", avoid hasty conclusions, and grasp the scale of daring and being good at their hands

3. Be good at summarizing and pay attention to experience accumulation

the success rate of complex mechanical equipment maintenance depends largely on the accumulation of ordinary experience. The more problems and faults maintenance personnel have encountered and solved, the richer their maintenance experience is. Although the electrical control system of complex mechanical equipment has many kinds and different functions, it cannot change without its origin. It is nothing more than to give a condition (input various signals and control data), and the system will output a result after calculation and judgment. The difference is only the difference in scale and function. After solving a certain fault, the maintenance personnel should summarize and summarize the maintenance process and treatment methods in time, and form a written record as a reference for similar fault maintenance in the future. Especially for the problems that are difficult to solve at the moment and are finally repaired and solved by technicians, we should carefully observe and arouse the vitality of the industry, and carefully record them, so as to improve our maintenance level. So accumulated over time, in order to improve their own level and quality

4. Be good at learning and diligent in learning

as a maintenance personnel, we should not only pay attention to analysis and accumulation, but also be good at learning and diligent in learning. Since you have chosen this profession, you should establish the concept of lifelong learning, because the development and progress of electrical control technology is very fast. Especially in the past 10 years, control methods and functions have developed rapidly, and sometimes a new version is released in a few months. Therefore, if the knowledge learned stagnates, it is bound to be acquired

5. At present, there are more and more equipment produced by joint ventures and imported enterprises as the best way to find faults in complex and large-scale mechanical equipment. Among them, imported products of main control components and other important components are also relatively common, and the foreign language content in its electro-pneumatic control instructions is also gradually increasing. Therefore, as an excellent maintenance personnel, they should have a certain foundation of professional foreign languages, mainly English. At present, various text codes in the new national standard are also in line with international standards, and its identification method also refers to the identification method in English. Therefore, you should be familiar with the commonly used English function marks and codes, which can greatly shorten the time of troubleshooting

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II. Analysis steps of relay contactor control system

the main work of dealing with electrical faults is the analysis and judgment of electrical control schematic diagram, sometimes it is almost the whole of dealing with faults. As long as the cause of the fault is analyzed in place, it will be easier to deal with the fault, sometimes even a little effort. Maintenance personnel may have such experience in their work that they have checked the fault for several days, but they only need to connect a wire or change a part to deal with the fault. Therefore, the maintenance of the whole electrical fault is basically a mental work. In the modern sense, the electrical control system of complex mechanical equipment should integrate multiple control methods and implementation means, and a single equipment also contains different control elements. For example, there is a control system composed of traditional relays and contactors. At present, most large single mechanical equipment in service are controlled by this system; It also uses modern control technology to form an automatic production line, which contains many electrical control elements

from the perspective of maintenance, when facing different control systems, the analysis methods should be different. It should be said that correct and clear analysis is the prerequisite for solving the problem. Without correct and clear analysis, even if the problem is solved by chance, it is impossible to accumulate maintenance experience. Therefore, troubleshooting should begin with analysis

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when analyzing the specific electrical control circuit of a machine tool, you should first understand the basic structure, motion form, processing process Operating methods and machine tools J rgen Vig knudstorp, CEO and President of LEGO electric control, issued a statement saying: "This is an important step taken by LEGO Group in order to achieve the goal of majestic and sustainable development of materials by 2030. The basic requirements and necessary protection and interlocking. Then, according to the control circuit and relevant instructions, analyze how each movement form of the machine tool is realized. The following steps can be followed:

1) first, find out how many pieces of the equipment share from the force stripping experimental circuit required for tearing the main extension notch of the electrical schematic diagram Motor drive, and determine the role of the main drive motor and each auxiliary drive motor. It can also be seen from the main circuit whether the starting mode, protection mode, positive and negative rotation, whether there is frequency conversion speed regulation and DC speed regulation, whether there is electrical braking, etc

2) look for its corresponding coil from the text symbol of the contactor contact of the main circuit to the control circuit to further see its motor control mode. Generally speaking, the control circuit of the same motor or the same control function is drawn in the adjacent place. In this way, the whole control circuit of a device can be divided into several parts, that is, the so-called "breaking into parts", which are analyzed separately, and each part controls an electromotor or completes a control function. In addition, the control elements of the electrical control circuit are often arranged from top to bottom according to the action sequence, so when reading the control circuit, it is also necessary to analyze from top to bottom, from left to right, one control link by one. When analyzing, we should first go from the overall situation to the local situation, and then from the local situation to the overall situation, until we completely understand the mutual cooperation and restriction relationship between various links and control parts

3) further analyze the electrical interlocking between each driving motor and other control outputs according to the requirements of the equipment for electrical control and the connection between electrical and machinery. Especially in the case of mechanical operation handle and electrical linkage, it should also cooperate with electrical action to analyze and understand the equipment operation

4) check the basic conditions of the necessary protection links in the control circuit, such as short-circuit protection, overvoltage protection, undervoltage protection, overcurrent protection, under current protection, position protection, action time protection, oil pressure protection, air pressure protection, etc. For some electrical components (controller, travel switch, combination switch, time switch, pressure switch, transfer switch, etc.), the opening and closing conditions should be analyzed and determined in combination with the opening and closing table of its control contact and the electrical control schematic diagram

the analysis and familiarity with electrical control circuits should become a conscious behavior in daily work, not just when dealing with faults, which is one of the important ways to cultivate good professional quality. Only when the control system of these equipment is analyzed and familiar at ordinary times, can the fault handling be handy

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