Stock Code:060389
Common problems and improvement methods of power installation

The common technical problems of power installation are as follows: 1.1 bolt connection. Bolt and nut connection is the most basic assembly in the electromechanical industry. When the connection is too tight, the bolt is prone to metal fatigue under the long-term action of mechanical force and electromagnetic force, and the connection such as shear or thread sliding wire is too loose, which makes the assembly between components loose and causes accidents. For the bolt and nut connection of conductive current in electrical engineering, attention should be paid not only to its mechanical effect, but also to its electrothermal effect. The crimping is not tight, the contact resistance increases, and a vicious cycle of heating - oxidation of contact surface - increase of resistance occurs during power on, until it is seriously overheated and the joint is burned, resulting in grounding short circuit and disconnection accidents. For primary equipment and bus, parallel groove clamp, T-shaped clamp, equipment clamp and wiring of connecting wiring may cause accidents of different degrees. 1.2 vibration problems (1) pump: unbalanced rotor, large bearing clearance, friction between rotor and stator, poor concentricity between rotor and shell, etc. These are mechanical problems. (2) Motor: the rotor is unbalanced, the bearing clearance is large, and the air gap between rotor and stator is uneven. (3) Operation: the main reason is that the process operation parameters deviate too much from the rated parameters of the pump, resulting in unstable operation of the pump, such as vibration caused by too small flow controlled by the outlet valve, which requires the process to operate as close to the rated parameters of the pump as possible. 1.3 over current problem (1) pump: bearing damage, friction between rotor and shell, foreign matters in pump, etc. (2) Motor: the power is too small, the setting of overload current is too small, the line resistance is too high, and the power shortage is equal. (3) Process operation: the delivered medium exceeds the design capacity of the pump, such as high density, high viscosity and high demand. 1.4 problems of power installation equipment (1) insufficient contact pressure and contact area of moving and static contacts or improper operation during installation of disconnector may lead to electrothermal oxidation of contact surface, increase contact resistance, burn and ablate contacts, resulting in accidents. (2) If the arc contact finger and contact of the circuit breaker are not assembled correctly, and the insertion stroke, contact pressure, synchronism and opening and closing speed do not meet the requirements, the contact will overheat and the arc extinguishing time will be prolonged, resulting in the decomposition of insulating medium and the sudden increase of pressure, resulting in the explosion accident of the circuit breaker. (3) Due to careless installation and maintenance of current transformer, the primary winding is open circuit, which will produce high overvoltage and endanger the safety of personnel and equipment. (4) If the regulating device mechanism of on load voltage regulating device is assembled incorrectly, or sundries are accidentally dropped during assembly and the mechanism is stuck, accidents of different degrees will also occur. (5) Insulation damage or breakdown of main transformer. When installing the hanging core and high-voltage pipe of main transformer, sundries (such as nuts and keys, which are not rare in engineering practice), incomplete drainage in the body and casing, wrong installation of sealing device or damage during installation will greatly reduce the insulation strength of main transformer, which may lead to local insulation damage or breakdown, resulting in malignant accidents. (6) The main transformer protection refuses to operate. Short circuit and grounding accidents occur in the interior or outlet side of the main transformer, but the protection refuses to operate and the circuit breaker does not trip. The huge short-circuit current not only expands the accident state at the short circuit, but also makes the internal temperature of the main transformer rise sharply. The transformer oil vaporizes and decomposes rapidly and becomes highly explosive combustible, which may lead to the malignant accident of main transformer explosion. The emergency oil pool and other fire-fighting facilities of the main transformer are designed for this possibility. 2 improvement measures related to power equipment installation technology 2.1 strict construction organization design and selection of equipment and facilities. Construction organization design and selection of equipment and facilities are jointly studied and agreed by relevant scientific and technological personnel. Through technical calculation and checking calculation, it not only has its use value, but also ensures good economic benefits. Do not change the selected equipment arbitrarily, Otherwise, it will affect the progress of basic work. 2.2 carry out the installation work according to the predetermined plan, and each power equipment installation sequence has its scientificity. The planned queue of an equipment installation project is discharged after various considerations and technical demonstration. It has scientific basis and certain guidance. Do not change it casually, so as not to cause back work and slowdown, and the project progress is not continuous. 2.3 general layout and unified arrangement shall be made for the installation work. For large-scale installation projects, due to many equipment and installation links, there must be general layout and unified arrangement for each installation. There must be an electromechanical team leader (or deputy project manager) with unified command in the construction team to coordinate and deal with all work, brainstorm and solicit more work opinions from employees. As managers, they should know everything about the installation, know what to do next, how to do it, what materials and equipment are missing, and what problems still exist. The preparations that should be done in advance must be in place in advance, so as not to create a passive situation of shutdown and waiting for materials in the installation work. 2.4 the installation work shall have the main and secondary works with commencement conditions. Firstly, there must be power supply, secondly, there must be power source and lifting equipment (including derrick and lifting winch). In order to achieve the purpose of short-term commencement, the installation work must have primary and secondary priorities. Only when there is a reasonable arrangement for the installation of substation, pressure fan, derrick and lifting winch, and the installation work is carried out in a planned and purposeful way, can the effect of twice the result with half the effort be achieved. 2.5 construction shall be carried out in strict accordance with the design requirements. The installation of each equipment has very strict technical requirements. Only by constructing in accordance with the design technical requirements can unnecessary time loss and material consumption be reduced. The foundation of a kind of equipment is calculated and designed by the design department and constructed as required to ensure quality and safety. 2.6 the equipment shall be installed according to the conventional installation method, and each equipment shall be installed with a certain operation mode and working sequence, which shall not be eager for success and reverse the process. For example, for derrick installation, the conventional operation method is to conduct initial leveling and alignment after one layer of assembly, and then install layer by layer. After the derrick is installed, all connecting parts must be threaded with bolts one by one, tighten all connecting bolts, and conduct overall leveling and alignment. Finally, the four legs of the derrick are filled with ash for the second time. It is forbidden not to carry out initial leveling and alignment after the installation of the first floor, inaccurate leveling and alignment after the overall installation, and secondary ash filling in case of lack of parts at the connecting parts, which will bring difficulties to the installation of the upper floor, resulting in a large amount of tail work, such as bad installation, failure to fit on and failure to put on bolts, resulting in low installation quality and failure to meet the requirements of installation quality standards. 2.7 improve the overall quality of electric workers. The low quality of mechanic and electrician is the human factor causing the low installation speed and quality. During installation, the electrician must receive pre job training, master general installation knowledge and be familiar with installation standards. The parts to be leveled must be leveled, there must be one or more bolts at the connecting parts, and there must be one or more parts to wear anchor bolts; The electrician shall connect the power supply and distribution of the equipment according to the regulations and specifications, overhaul the switch and control panel of the power supply equipment in advance, and test run the equipment after connecting the power. 3 after the installation of the power on commissioning project entity, the site must be cleaned and the commissioning steps must be entered after careful inspection and preparation. The author finds out the matters needing attention in the debugging process: 3.1 must follow & ldquo; Five before five & rdquo; In principle, single machine first and then joint commissioning; Manual before automatic; First local and then remote (remote control); No load before load; Jog first and then linkage. 3.2 use & ldquo; Safety first & rdquo; The guidelines include personal safety and equipment safety. The importance of safety cannot be ignored in a hurry for success. The power transmission (reception) of all distribution panels, cabinets and equipment must be operated in strict accordance with the procedures, and & ldquo; Send (receive) power order & rdquo; System. The power transmission unit shall be responsible and arranged by a specially assigned person; Both power transmission and power reception shall be completed under the supervision of the supervisors of both parties. 3.3 form relevant project commissioning data, and require the data submitted by the construction unit to be true, accurate and complete. Some supervisors simply intervene in the commissioning process by means of patrol inspection, are not familiar with the commissioning situation and commissioning results, are skeptical about the data in the commissioning data, and often do not sign or require to reschedule the commissioning in time, resulting in data delay, distortion or waste of human and material resources, and can not reflect the side supervision role of supervision in key processes. 4. When the project meets the conditions for completion acceptance, the construction contractor shall submit the completion acceptance application form and completion report to the project supervision department after the completion of self-assessment and self inspection; The chief supervision engineer shall organize the supervision engineers of all disciplines to pre accept the completion of the project completion data and project entity quality, supervise and urge the construction unit to rectify the problems found in the inspection in time, and sign the project completion inspection application form after the project supervision department has comprehensively inspected and accepted the completion data and project entity, And submit the data evaluation report to the construction unit. For some problems that can be rectified in the future after completion acceptance and before project handover, the rejection can be handled with the consent of the installation unit, and can continue to be improved after project handover under the supervision and tracking of the supervisor.

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