First, the basis for troubleshooting electrical faults The basis for troubleshooting is the necessary conditions for troubleshooting. In order to completely eliminate the problem and solve the problems faced in the actual situation, it is necessary to find out the cause of the failure. To quickly find out the cause of the failure, in addition to constantly accumulating experience in the work, more importantly, it can be theoretically analyzed. Explain the cause of the accident, use the theory to guide your own operations, and use the basic knowledge that is mastered, and then combine it with the actual work, sometimes it will be more resilient. However, the improvement of the technical level and the accumulation of maintenance experience require a long process. Proper use and careful maintenance are the practical guarantees to prevent or avoid all failures. At the same time, as an electrical maintenance personnel in the new historical conditions, in order to better improve their ability to effectively solve practical problems and maintenance levels in practical work, they should continuously strengthen their own cultural and technical learning to adapt to the objective of contemporary enterprise development. Requirements, in order to better do their jobs and make new contributions to the development of the company. Bluetooth Speakers,Bluetooth Speaker,Portable Speakers,Mini Speaker Dongguan Guancheng Precision Plastic Manufacturing Co., Ltd. , https://www.dpowergo.com
1. Quality requirements for maintenance personnel Electrical equipment is a technology-intensive and knowledge-intensive mechatronic product. Its advanced technology, complex structure and high price often play a key role in production, so it has certain maintenance personnel. Claim. The quality of repair work depends first and foremost on the quality of the maintenance personnel. As a maintenance person, the following conditions must be met:
1 A wide range of professional knowledge. Should have a secondary education or above, master or understand the basics of computer principles, electronic technology, electrical principles, automatic control and power drag, detection technology, mechanical transmission and mechanical processing technology. You must understand electricity and understand the machine. Electricity includes both strong and weak currents; machines include mechanical, hydraulic and pneumatic technologies.
2 Diligent in learning, good at analysis. Electrical maintenance personnel should be a diligent person who not only has a wide range of knowledge, but also needs to have an in-depth understanding of the electrical system that needs to be trouble-shooted. Electrical maintenance personnel need to have an analytical mind. The cause of some faults is often not obvious. It involves various technologies of machine, electricity, liquid and gas. Therefore, it is crucial to make correct analysis and judgment in front of many numerous causes and phenomena of failure. In actual work, the time of brainstorming is longer than the time of hands-on. Once the fault point is found, the repair is relatively simple.
3 Have strong hands-on skills and practical skills. The repair of the electrical system is inseparable from the actual operation. The maintenance personnel should manually operate the repaired system, check the alarm information, check and modify the parameters, call the self-diagnosis function, and perform manual and trial operation on the machine tool; Required tools, instruments and instruments. For maintenance personnel, it is very important to be bold and daring to be hands-on and careful. The so-called "heart" is to be familiar with the situation, after the hands-on maintenance, not to be blind and ruthless; to be steady and accurate in the hands-on process.
2. Necessary technical data and technical preparation Maintenance personnel should carefully organize and read important technical information about the electrical control system. The maintenance work is done well, and the speed of troubleshooting is mainly determined by the proficiency of the maintenance personnel and the proficiency of the technical data. The following are some of the technical materials and technical preparations necessary for electrical fault repair:
1 Regarding the problem of maintenance information A common problem in the maintenance of electrical equipment is that the information is incomplete, and often only the electrical schematic of the high-voltage part or the instruction manual of the equipment. The main control system of the equipment (such as: Lincoln welder main board control schematic diagram, numerical control system numerical control device, servo drive, etc.) has very little information, at most there is only one operation manual, and the system structure, especially the circuit diagram is generally There will be no, for this reason, it will cause great difficulties for maintenance work. I think this problem can be solved from the following aspects:
a) When signing a equipment purchase contract, strive to obtain as much information as possible from the equipment supplier for future maintenance (eg, technical specifications for machine tool installation, use, operation and maintenance, including the operation panel layout of the machine tool) And its operation, the machine's electrical schematic, layout and wiring diagram. For the electrical maintenance personnel, the hydraulic circuit diagram and pneumatic circuit diagram of the machine tool are also needed.)
b) During the equipment commissioning and testing phase, the maintenance personnel use the opportunity of learning from the technicians and commissioning personnel of the equipment manufacturer to record as much as possible, collect the data, data and methods needed for various repairs, and collect the data. For future maintenance reference.
c) Information can be collected in a variety of ways, such as through related electrical magazines, technical books, through communication with peers or through Internet enquiries.
d) In routine maintenance, at the same time as inspection and repair, the faulty part of the circuit shall be mapped out, and after proofreading, the pattern of the faulty part shall be sorted out. Over time, the circuit diagram of the part that often fails will be sorted out.
e) Other technical information on components in the electrical control system, such as the list of components used in CNC equipment, spare parts lists and various general component manuals. Maintenance personnel should be familiar with all kinds of commonly used components, and if necessary, can quickly check the functions, parameters and substitute models of the components.
2 About the necessary spare parts problems For the maintenance of electrical systems, spare parts are an indispensable technical preparation means. If there are no spare parts to be exchanged or used in case of failure, it will delay the time of troubleshooting and increase the difficulty of maintenance. . Moreover, the maintenance personnel have some main control circuit boards on hand, which will bring a lot of conveniences for troubleshooting. The plate changing method can often quickly determine that some troubles occur on the circuit board, and the electrical system spare parts are configured according to In actual situations, usually some vulnerable electrical components (such as fuses of various specifications, melts, switches, brushes, and thyristor modules and printed circuit boards with different powers that are prone to failure) should be Properly configured. The management of spare parts is not discussed in detail here. Only a few solutions to the spare parts in the repair are briefly stated:
a) In the repair and maintenance, the defective components should be repaired as much as possible under certain conditions. When there are no conditions, you should also entrust a professional maintenance department with repair conditions to repair.
b) Substitution In most cases, many electrical components can be replaced by other similar specifications and types of components (eg contactors, thyristor modules, resistors, capacitors, fast-acting, Zener, triode) , FET, etc.). Maintenance personnel should master the working principle, characteristic parameters and alternative methods of related electrical components.
c) In the production and renovation, when an electrical component is broken, but the spare parts are not available, in order not to affect the production, some minor changes to the circuit may be considered, and other components are used to complete the same function. (For example: the rectifier on the main control board of an electrical control system in the spiral pipe workshop is broken. In addition to understanding the pins and functions of this integrated rectifier circuit, you can try to use another component to build a circuit to complete its existing functions. It is possible to replace damaged devices without affecting the production due to the inability to buy suitable accessories.)
3. Understand the movement form of the equipment and the specific position of the equipment and the layout of the line. When repairing the electrical equipment, first understand and master the electrical control schematic diagram of the equipment, understand the movement form of the equipment, and The questioning of the control of the electrical equipment is the basis for understanding the working principle of the electrical control of the equipment. Mastering the working principle of electrical control and comparing the electrical control features of the equipment is a very important basis for troubleshooting. For example: the CNC PC--160D plasma cutting machine electrical control system used in our company's straight seam pipe workshop includes both AC and DC control conversion, computer and plc combination, and servo drive, as well as continuous feedback control and disturbance compensation. Feedforward control, which belongs to the composite control system, summarizes the main content of the electrical control technology with certain typical, comprehensive and complex. In addition, the one-to-one correspondence between the electrical schematic and the actual wiring is the basis for improving the troubleshooting speed. By doing this, you can have a better understanding of the equipment, and can deepen the impression and perceptual knowledge, and can accurately and effectively find the test points when the fault detection means is used, to prevent misjudgment, and also to narrow the fault range. .
2. The method of detecting and eliminating electrical faults has a certain theoretical basis, masters the working principle of the equipment, and is fully prepared for troubleshooting, but in order to effectively analyze and judge in actual operation, it is easy to find out At the point of failure, it is necessary to have certain means, which is the detection means and general method required for troubleshooting.
1. Fault detection As the name implies, it is to check the measurement and make full use of the instrument to detect the equipment failure so that the position of the fault point can be judged more accurately and whether the component is damaged. Inspection of equipment failures is a common practice used by most maintenance personnel to troubleshoot and is one of the most common methods of troubleshooting. However, the commonly used methods for detecting faults generally have the following types:
1 Resistance method is a commonly used measurement method. Usually refers to the use of a multimeter's electrical barrier to measure whether the motor, circuit, contacts, etc. meet the nominal value and whether it is on or off, or use a megger to measure the insulation resistance between phase and phase, phase and ground. Wait. When measuring, pay attention to the accuracy of the range and proofreading table used. Generally, when using the resistance method, the common method is to select the low gear first. At the same time, pay attention to whether the circuit under test has a loop, and it is strictly forbidden to measure with electricity.
2 Voltage method Voltage method refers to a method of measuring the voltage value in a circuit by using the corresponding voltage block of the multimeter. Usually, when measuring, sometimes the voltage of the power source and the load is measured, and the open circuit voltage is sometimes measured to determine whether the line is normal. When measuring, pay attention to the gear of the table, select the appropriate range, generally measure the unknown AC or open circuit voltage, usually use the highest voltage of the voltage to ensure that it will not operate under high voltage and low range, so as not to damage the watch, and measure DC Attention should be paid to positive and negative polarity.
3 Current Method The current method is a method for determining whether the current in a line meets a normal value to determine the cause of the fault. For weak current circuits, it is often used to connect an ammeter or a multimeter current block in a circuit for measurement; for a strong electric circuit, a clamp-type ammeter is often used for detection.
4 Instrument test method Various instruments are used to measure various parameters, such as observing the waveform and parameter changes with an oscilloscope, in order to analyze the cause of the fault, and it is mostly used in weak current lines.
2. Trouble-shooting method By determining the location of the fault by means of detecting the fault, it is better to analyze the cause of the fault and find a solution to the problem. This is the troubleshooting method. On the basis of the judgment of equipment fault detection, it is necessary to adopt a certain method to eliminate the fault, but the commonly used methods generally have the following types:
1 The routine inspection method relies on the human sensory organs (such as: some electrical equipment has a burnt smell in use, sparking, discharging, etc.) and uses some simple instruments (such as a multimeter) to find faults. the reason. This method is the most commonly used in maintenance and is the first to be used.
2 The replacement method is to suspect that a device or circuit board is faulty, but it is not certain, and when there is a substitute, the test can be replaced to see if the fault disappears and returns to normal.
3 Direct inspection method You can directly check the suspected fault point by knowing the cause of the fault or judging the fault according to experience.
4 Step-by-step method If a short-circuit fault occurs, some lines can be gradually removed to determine the fault range and fault point.
5 Adjusting the parameter method In some cases, when a fault occurs, the components in the line are not necessarily bad, and the line contact is also good, but only due to some physical quantities (such as time, current, displacement, temperature, resistance value, feedback signal strength, etc.) Inappropriate or long-running time may cause system parameters to change due to external factors (such as interference or mechanical wear) or may not automatically correct the system value, resulting in the system not working properly, then according to the specific conditions of the equipment Make adjustments.
6 Principle analysis method According to the composition principle diagram of the control system, by tracking the signal associated with the fault, analyze and judge, find the fault point, and find out the cause of the fault. The use of this method requires maintenance personnel to have a clear understanding of how the entire system and unit circuits work.
7 Comparison, analysis, 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 links,
And quickly determine the scope of the fault. (For example, the finishing control of the spiral pipe workshop is a method of segmental control using multiple-off-site multiple-site (two-span workshop). If the master control console is normal, the power supply, load and public line are not problematic). By comparing and analyzing, it can reduce the detection link, narrow the fault range, and improve the speed of troubleshooting. It is suitable for direct determination of partial line fault ranges and fault points.
The above several commonly used methods can be used alone or in combination, and the actual fault should be applied flexibly according to the specific situation.
III. General Steps for Troubleshooting Faults There are no fixed modes, and there is no uniform standard, which varies from person to person. But under normal circumstances, there are still certain rules. Generally, when troubleshooting, the steps taken can be roughly divided into: symptom analysis → equipment inspection → determining the fault point → troubleshooting → performance observation after exclusion.
1. Symptom Analysis Symptom analysis is the process of collecting and judging all possible information about the original state of the fault. All information should be carefully analyzed before the signs of failure are disturbed. These raw information can generally be obtained from the following aspects:
1 Access the operator to obtain information on the use and changes of the equipment, the situation before and after the damage, or the situation before and after the failure. You can also learn about some similar phenomena, causes and measures taken in the past. Sometimes the operator may be unwilling or unable to explain the whole story for other reasons. Maintenance personnel should have analytical discernment and patience to get as much real raw information as possible.
2 Observations and preliminary inspections A thorough observation of equipment often leads to valuable clues. The preliminary inspection includes detection devices (for example, console indicators, display alarm information, etc.), checking the position of the operation switch, control mechanism, adjustment device, and interlocking signal device.
3 Starting the equipment Under normal circumstances, the operator should be required to start the equipment according to the normal operating procedures. If the fault is not a complete loss-making electrical control system, the test operation method can be used to start the equipment to help the maintenance personnel have a comprehensive impression of the original state of the fault.
The purpose of this phase is to collect the original information of the fault so as to analyze the existing actual situation and derive the clues that are most likely to have the fault area as a reference for the next equipment inspection. But be careful not to make premature judgments based on inaccurate signs or inadequate information.
2. Equipment Inspection A more detailed examination of the equipment based on preliminary conclusions and questions from the symptom analysis, especially those areas that are considered most likely to be faulty. It should be noted that this stage should try to avoid unnecessary disassembly of the equipment to prevent more malfunctions caused by inadvertent operation. Do not easily adjust the control device, because in general, the failure to eliminate the blind adjustment parameters will mask the symptoms, and the symptoms will reappear as the failure progresses, and may even cause more serious failures. Therefore, blindness must be avoided to prevent complications from being inadvertently handled, avoiding confusion and prolonging the time to troubleshoot.
3. Determine the fault point according to the fault phenomenon, combine the principle and control characteristics of the equipment to analyze and judge, determine the extent of the fault, is it an electrical fault or a mechanical fault? Is it a DC loop or an AC loop? Is it the main circuit or the control circuit or the auxiliary circuit? Is it the power supply part or the parameter adjustment is not suitable? Is it artificial or random? and many more. According to the symptom analysis and equipment inspection mentioned above, in the flexible use of the "general method of troubleshooting", gradually narrow the fault range until the fault point is found. In the absence of systematic diagnostic data, maintenance personnel are required to correctly divide the entire equipment or control system into small parts and then check that the inputs and outputs of these parts are normal. When determining a certain part, pay attention to the internal problems of the part and find out the point of failure.
4. Troubleshooting After determining the point of failure, whether it is repair or replacement, troubleshooting is generally much easier for electrical maintenance personnel than finding faults. However, it is generally impossible to use only a single method in the troubleshooting, and often multiple methods are used in combination.
1 In the process of troubleshooting, you should first brain, then hands-on, correct analysis can have a multiplier effect. The specifics should be followed by external external internal → first mechanical and then electrical → first static and then dynamic → first public after special → first simple and then complex → first general after the special principle. Need to pay attention to is, do not encounter a fault, pick up the watch to measure, pick up the tool to remove! To develop a good analysis and judgment habits, there is a clear purpose for each measurement, that is, what can be the result of the measurement? After identifying the component with the fault point, you should further determine the root cause of the fault. For example, when a transistor in a circuit board is burnt out, it is not enough to simply replace a transistor. It is important to find out the cause of burnout and take remedial and preventive measures.
2 In general, the sequence of actions of the equipment is the order of analysis and detection when it is excluded. According to this premise, first check the power supply, then check the line and load; first check the common circuit and then check each branch circuit; first check the main circuit and then check the control circuit; first check the easy detection part (such as each control cabinet), it is not easy to check The part of the test (such as the control device of a device).
5. After the performance observation, after the troubleshooting, the maintenance personnel should carry out further inspection before the power transmission, and confirm that the fault has been eliminated by the inspection, and then the operator will try the operation to confirm whether the equipment is running normally. The person concerned should also be informed of the issues that should be noted. It is worth noting that when repairing and then checking, try to restore the electrical control system or electrical equipment to the original, and clean the site to keep the equipment clean and hygienic. In addition, the tools, cables, etc. used by maintenance personnel must not be forgotten in the electrical cabinet of the equipment being repaired to avoid short circuit or electric shock.
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