Question 2: electrical equipment failure is often manifested in what a machine tool electrical failure
In operation may be affected by unfavorable factors, such as electrical action of mechanical vibration, due to the overcurrent so that the electrical component insulation aging, arc burning, natural wear and tear, the influence of ambient temperature and humidity, the erosion of hazardous gases The quality and natural life of the components, so that the electrical line inevitably appear a variety of faults.
The electrical failure of the machine can be divided into two categories: one is the obvious appearance of the characteristics and easy to find faults, such as overheating of the motor and electrical components, smoke, fire and emit a burnt flavor; the other is not the appearance of the characteristics of the more hidden faults, most of the failures in the control circuit, such as mechanical failure, poor contact contacts, loose wiring, and damage to individual parts.
The more complex the electrical line, the greater the probability of failure. In the encounter more hidden and difficult to find the fault, often with the help of some instruments and tools. In addition, many machine tools are often mechanical, hydraulic and other joint control, so maintenance personnel are not only required to familiarize themselves with, master a certain degree of electrical knowledge, but also need to master the mechanical, hydraulic and other aspects of knowledge.
Second, the troubleshooting method
1, fault investigation of the machine tool once the failure occurs, maintenance personnel should be timely to the scene of the investigation and research in order to find the fault.
l ) to the machine operator to understand the phenomenon of failure, before and after the occurrence of the situation and the number of occurrences. Such as whether there is smoke, fire, abnormal sound and odor, whether there is improper operation and control malfunction.
2 ) to see the electrical equipment, such as observing whether the fuse fuse, there is no electrical components burned, insulation is not burned, the line is not disconnected, whether the screws are loose and so on.
3 ) Listen to the electrical components in operation with or without abnormal sound, such as the sound of fire, motor humming, etc..
4 ) Touch the electrical components and equipment with your hand to check for abnormalities such as overheating and vibration. If the temperature rises quickly, you should cut off the power supply and promptly touch the motor, transformer and solenoid coil and some other electrical components, you can find overheating components.
2, to determine the scope of the fault according to the findings of the fault, analyze the electrical schematic diagram, narrow the scope of the inspection, so as to determine the location of the fault. Then, further inspection, you can find the point of failure. Such as lighting or signal lamps do not light, it is easy to determine where the fault is the circuit, and then, in the absence of electricity with a meter (such as multimeter ohm file) to check the line where it is, you can quickly find the point of failure; and then, if the machine tool does not rotate the spindle, press the start button to observe the control of the spindle motor contactor is absorbed, if absorbed and motor does not rotate, indicating that the fault is in the main circuit; if it is not absorbed, it indicates that the fault is in the Control circuit, on the basis of this judgment, and then make further checks, you can find the fault location.
3 . Find fault points on some of the appearance of the characteristics of the fault, through the appearance of the inspection, it is easy to find fault points. But those who do not have obvious appearance characteristics of the fault. Often need to make a further search to find the point of failure. With the help of electrical instrumentation and tools, this is a very effective way to find electrical faults. Such as the ohm file with a multimeter (should be powered off), measuring the electrical components with or without short circuit, disconnection; with a multimeter voltage file, measuring the line voltage is normal; with a clamp-on ammeter to check the size of the motor's starting current; power pen to check whether there is electricity and so on. Because the machine tool has hydraulic, mechanical and other transmission devices, so when checking and judging the fault, attention should be paid to checking the hydraulic, mechanical and other aspects of the fault. The above described is to find and eliminate the general method of machine tool electrical line failure, in practice, should be applied flexibly according to the fault, and through specific practice, constantly summarize and accumulate experience.
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Question 3: What are the main causes of electrical failure? Electrical equipment in the use of the process, due to various reasons, there are often failures, which requires us to accurately find the location of the fault, and troubleshooting.
1. Characteristics of electrical equipment failure
Equipment failure is due to a variety of reasons so that the equipment damage or can not work properly, the loss of electrical function of the electrical failure. The electrical failure of the equipment usually has the following types.
1.1 Damage failure and predictive failure
Damage failure is a serious failure of the equipment has been damaged, such as filament burned out, the light bulb does not light up at all; motor winding broken, the motor can not rotate at all and so on. For this type of failure, only through the repair or replacement, and exclude the various causes of equipment damage, the fault can be eliminated.
But some of the failures, such as the decline in the brightness of the bulb, motor temperature rise is high, the equipment has not yet been damaged, can continue to use for a short time, but this will affect the normal use of equipment, and even evolve into a damaging failure.
1.2 Failure to use and performance failure
Some of the faults of the electrical equipment, although the impact of the equipment itself is not great, but can not meet the requirements of the use of this failure is called the use of faults. For example, the generator issued by the low voltage, low frequency and other faults, the generator itself does not have much impact, but can not meet the external requirements of voltage and frequency, however, the generator itself is the cause of the failure. Some faults do not affect the use, but on the equipment itself has a certain impact, or said to have a certain impact on the performance of the equipment, this type of failure is known as performance failure. For example, an increase in transformer no-load loss indicates that there are certain faults in the internal core of the transformer, which reduces the performance of the transformer itself and, at the same time, makes the transformer heat increase. However, from the point of view of external use, as long as the transformer output voltage is normal, it does not affect normal use.
1.3 Internal and external failures
Some failures of electrical equipment are caused by internal factors of the equipment, such as electromagnetic force, arcing, heating, etc., so that the structure of the electrical equipment is damaged, insulation breakdown of insulating materials. This type of failure is called internal equipment failure.
The other faults of the electrical equipment is caused by external factors, such as power supply voltage, frequency, three-phase imbalance, external forces and environmental conditions, etc., so that the formation of electrical equipment failure. This type of failure is called equipment external failure.
2. Common methods to find electrical faults
Find electrical faults, the main thing is to link theory to practice, according to the specific faults for specific analysis, but must master the basic methods of finding.
Commonly used methods to find faults in electrical equipment are the following. Detection method, empirical method, and state analysis method, analogy method, reasoning method, unit division method and graphical transformation method. Among them, the detection method is more accurate, find the process is complex, commonly used in difficult faults to accurately find; while the empirical method is relatively simple and convenient, commonly used in simple fault finding.
2.1 Empirical method
The common empirical method is more, can be summarized as follows.
2.1.1 Bouncing movable parts method
Mainly used for movable parts, such as the armature of the contactor, the pulley arm of the travel switch, buttons, switches and so on. By repeatedly bouncing the movable parts, so that the movable parts of the action is flexible, but also to make some poor contact contacts to achieve friction, to achieve the purpose of contact conduction.
For example, for a long time without the use of the control system, before the start, should be used to play pressure on the active parts of the method of all the action once, in order to eliminate the action of hysteresis and contact oxidation phenomenon, due to the environmental conditions of more dirt or moisture caused by the failure of the larger, but also should be used in this way. However, it must be noted that the spring pressure moving parts method can be used to determine the scope of the fault, but not commonly used in fault elimination, because only the use of this method, fault elimination is often incomplete, to completely eliminate the fault also need to use another measure.
2.1.2 Circuit knocking method
Circuit knocking method is basically the same as the spring pressure moving parts method, the difference between the two is that the former is carried out in the process of power outages, while the latter is mainly charged with electricity to check. Circuit knocking method can be a small rubber mallet, gently knocking the components in the work. If the circuit malfunction suddenly excluded, or the failure suddenly appeared, are shown to be struck near the component or the component itself there is poor contact phenomenon. For normal electrical equipment, generally withstand a certain amplitude ...... >>
Question 4: What are the steps in the analysis of electrical equipment fault processing Electrical troubleshooting should follow the steps
In order to avoid less detours in the secondary equipment failure to find, must be based on the characteristics of the fault phenomenon since the beginning of the calm analysis, that is to say, to be analyzed in the analysis of judgment, the comprehensive use of theory on the basis of any blind impatience, brute force are Can not solve the problem, and even the more you check the more confused. To this end, we must follow the following aspects:
1. Familiarize yourself with the circuit principle. When an equipment electrical control system failure. Do not be in a hurry to disassemble, first of all, to understand the cause of the failure of the electrical equipment, through, scope, phenomenon, familiar with the equipment and the basic working principle of the electrical system, analyze each specific circuit. Figure out the principle of the interconnection between the components and signals in the circuit of the ins and outs, carefully analyze. Combined with practical experience. After careful thought, to determine a scientific overhaul program.
2. First power after mechanical. Electrical equipment are based on the principle of electrical a mechanical, especially electromechanical instrumentation integration of advanced equipment, mechanical and electronic in the function of organic cooperation, is a whole two parts. Often the power supply failure, affecting the mechanical system, the function of many mechanical transmission components will not work. Therefore, do not be confused by the surface phenomenon, the failure of the electrical system is not all electrical problems itself, may be caused by the failure of mechanical components.
3. First simple, then complex. First, the overhaul of the failure to first use the most simple and easy to use, the day has been the most skillful way to deal with, and then use complex, precise methods. Secondly, when troubleshooting, first exclude intuitive, obvious, simple and common faults, and then exclude the higher difficulty, did not deal with the difficult faults.
4. First external inspection. After the internal processing. External means exposed to the shell of electrical equipment or seals on the outside of the various switches, buttons, jacks and indicators. Internal refers to the electrical equipment shell or seal inside the printed circuit boards, components and various connecting wires. First external debugging, after the internal processing, that is, without disassembling the electrical equipment, the use of electrical equipment panel switches, knobs, buttons and other debugging checks, compression of the scope of release. First rule out the failure caused by external components, and then overhaul the failure of the machine, try to avoid unnecessary disassembly. If necessary to dismantle, must be mechanical, electrical connection complex related components, terminals to mark, in order to prevent errors in the restoration of the installation.
5. First static test, after the dynamic measurement of "static" refers to the occurrence of faults in the absence of power, electrical equipment overhaul; "dynamic" refers to the power of the electrical equipment overhaul. Many electrical equipment failure overhaul, can not be immediately energized, if energized, it will artificially expand the scope of the failure, burn more components, resulting in undeserved losses. Therefore, before the faulty machine is energized, the first resistance measurement, take the necessary measures before energizing the overhaul.
6. First utility circuits, after the specialized circuits of any electrical system utility circuits out of order, its energy, information can not be transmitted, distributed to the specific circuits, specialized circuits, the function, performance, does not work. If the power supply of an electrical device fails, the whole system can not operate normally, to a variety of specialized circuits to transfer energy, information is impossible to achieve. Therefore, only to follow the first public circuit, after the order of specialized circuits, in order to quickly and accurately eliminate the faults of electrical equipment.
7. First overhaul of the disease, after attacking the problematic electrical equipment is often prone to the same type of failure is the "disease". As the common disease is more common, the accumulated experience is rich, so you can quickly exclude, so that you can focus your efforts and time to exclude the more rare, difficult, odd troubleshooting, simplify the steps, narrow the scope, targeting, and improve the speed of repair.
Question 5: What are the common failure analysis of electrical equipment Different uses of electrical equipment, use, maintenance, maintenance, repair will be very different.
For example, high-voltage equipment and low-voltage equipment (high-voltage, low-voltage power distribution equipment, etc.), static equipment and rotating equipment (transformers, motors, etc.), and control equipment (inverter, soft starter, servo, PLC, etc.).
For different equipment, the manufacturing manufacturer will have a corresponding user manual.
Question 6: Which are the common phenomena of electrical equipment contact failure (1) the change of electrical contact material. Electrical contact materials, especially switch contact materials, its conductivity, hardness, etc. have more stringent requirements. If the original electrical contact material is inappropriately replaced, it is bound to affect the performance of the electrical contact. Secondly, in order to make up for the defects of certain electrical contact materials, often plated on the surface of the electrical contact material with a layer of other metals, such as silver, tin, gold, etc.. In the repair process or after a long time of wear and tear, so that the plating damage or disappearance, is bound to make the electrical contact performance inferior.
(2) change in the form of electrical contact. As a result of repair or other reasons, so that the electrical contact surface is not flat or contact surface displacement and changes in direction, resulting in changes in the form of electrical contact, such as surface contact, line contact into a point contact, or point contact into a surface contact, line contact, may make the electrical contact poor.
(3) the reduction of electrical contact pressure: spring deformation, transmission mechanism is not in place, etc., so that the electrical contact pressure is reduced. This is one of the important reasons for poor electrical contact.
(4) copper - aluminum conductor direct connection caused by galvanic corrosion. Copper - aluminum conductor directly connected to each other constitutes a high potential difference between copper ions - aluminum ions of electrochemical, inevitably cause galvanic corrosion. Is more common. Running time a long time, is bound to produce electrical contact failure.
(5) poor electrical contact surface performance. Electrical contact surface, for various reasons, covered with a layer of poor conductivity of the material, such as metal oxides, sulfides, etc., its resistivity is much greater than the original metal, may also be covered in the contact surface of the dust, dirt, or oil film between the contact surface, water film, etc., the resulting formation of the surface film resistance. Its existence makes the contact connection resistance increase or cause contact resistance instability, and even destroy the normal conductivity of the electrical contact connection.
(6) electrical contact installation process does not meet the requirements. Different types of electrical contacts have different installation process requirements, not up to the specified process requirements and standards, will make the electrical contact poor.
(7) poor electrical contact leads to circuit failure The electrical contact is the weakest link in the circuit, poor electrical contact is an important cause of circuit failure. For example, the knife switch contacts loose, contacts are not in contact, the wire connection point is not good lap, wire and equipment terminal connection screws loose, tin welding point broken, often leading to circuit failure. Another example, some electrical contacts from the appearance seems to have been contacted, but the actual connection is not good. In the maintenance of electrical equipment often seem to connect the non-connection of electrical contacts called "virtual connection point". Connections are intermittent. Find the "virtual connection" is to find one of the difficulties of electrical equipment failure. Again, for example, for some low-voltage circuit, if the electrical contact resistance is much larger than the load resistance, the voltage at both ends of the load will be much lower than the operating voltage, the load can not work. In fact, it has also constituted a circuit failure.
Issue 7: electrical equipment failure is generally the cause of what the failure of electrical equipment is mostly electrical insulation breakdown, cable head explosion, etc., and without exception from the insulation weaknesses occur. The causes can be:
1, atmospheric overvoltage (lightning overvoltage).
2, operational overvoltage.
3, insulation aging (years, natural aging).
4, external damage (including water immersion, etc.), resulting in insulation damage.
5, prolonged overload.
6, poor maintenance to keep touch.
7, poor operating environment.
8, short circuit caused by small animals (such as snakes, etc.).
Question 8: Definition of electrical equipment failure Can you make the question clearer?
Question 9: What are the specific problems of electrical equipment In terms of a particular device, the failure of electrical equipment is mainly generated in the following areas:
Power supply, transformer part, switching, isolation equipment, frequency conversion, speed control equipment, power conversion equipment.
Power supply, transformer components to ensure that the heat dissipation, regular cleaning of dust, control air humidity is not too large, do not condensation. Switchgear Xiangtai Electric think mainly all kinds of buttons, relays, contactors. The use of attention can be. All are wearing parts.
Frequency conversion, speed control part of the manufacturer is generally responsible for maintenance. Maintenance is mainly for the cooling fan and clean up dust, and the working environment to maintain the power equipment are generally all kinds of motors, solenoid valves and so on. Daily maintenance is mainly to replace the bearings and coils, valve body, large motors rarely burned, because generally have frequency control, if the overcurrent will protect the shutdown.
Question 10: What are the failures of electrical equipment need to stop running 1, short-circuit failure, need to stop running.
2, the main components to heavy heat, need to stop running.
3, the hardware is seriously damaged, you need to stop running.
4, software error, has affected the normal operation of the equipment, need to stop running.
5, equipment leakage, fire, need to stop running.