Testing and Cost Control of High-Voltage Electrical Equipment Liang Lixia (Power Technology Services Branch, Zhongshan Kaineng Group Co., Ltd., Zhongshan 528455, Guangdong, China). Finally, the role and significance of high-voltage electrical test in the process of cost control of high voltage electrical equipment and cost control process are described. High-voltage electrical equipment is an important electrical equipment in the power system. It is the premise and guarantee of safe production, transmission and transformation, control and regulation of electrical power. Different high-voltage electrical equipment has different technical characteristics and performances. Its structure is different, and its use cost is also different. The test of high-voltage electrical equipment is an important means of assessing whether the main insulation or electrical parameters of electrical equipment meet the safe operation. Before high-voltage electrical equipment is finalized and mass-produced, manufacturers must conduct a large number of high-voltage electrical tests to fully verify the applicability and reliability of high-voltage electrical equipment. This not only satisfies the need for safe operation of power systems, but also reduces equipment costs. The necessary measures to control the cost. 1 Basic requirements and test classification of high-voltage electrical equipment 1.1 Basic requirements for high-voltage electrical equipment Although various electrical equipment and current-carrying conductors have specific parameters due to their different applications, they have the common characteristics of withstand voltage and current passing. There are common basic requirements: (D) When the normal operating current passes for a long time or the short-circuit current passes for a short period of time, the heating temperature should not exceed the allowable limit; 2) It can withstand the electric power caused by the short-circuit current; 3) Has a certain level of insulation Can withstand long-term operating voltage and possible short-term over-voltage. 1.2 High-voltage electrical equipment test classification High-voltage electrical equipment test can be generally divided into 2 categories: insulation preventive experiment and electrical equipment handover test. 1.2.1 Insulation Preventive Testing Electrical equipment insulation preventive testing is an important measure to ensure the safe operation of equipment. Through tests, the equipment insulation status is grasped, hidden defects inside the insulation are discovered in time, and eliminated through inspection and repair. Severe persons must be replaced to avoid insulation breakdown during operation, resulting in irreparable damage such as power outage or equipment damage. Insulation preventive test can be divided into non-destructive test (insulation property test) and destructive test (pressure test) 2 categories: (1) non-destructive test (insulation property test) is at a lower voltage or with Other methods will not damage the insulation to measure a variety of characteristic parameters, including the measurement of insulation resistance, leakage current, dielectric loss tangent, etc., in order to determine whether the insulation inside defects. Practice has proved that this test method is effective, but at present it cannot rely solely on it to reliably judge the dielectric strength of insulation. (2) Destructive test (withstand voltage test) The voltage applied during the test is higher than the working voltage of the equipment, and the insulation test is very strict. It can expose those concentrating defects with high risk and can guarantee that the insulation has certain resistance. Electric strength, including DC withstand voltage and AC withstand voltage. The disadvantage of the withstand voltage test is that it will cause some damage to the insulation. High-voltage electrical equipment handover tests Electrical equipment handover tests In addition to partial insulation preventive tests, there are other characteristic tests, such as transformer DC resistance and transformer ratio tests, and circuit breaker loop resistance tests. In order to meet the needs of electrical installations and electrical equipment handover tests, and promote the promotion and application of new technologies for the transfer of electrical equipment, national standards GB50150-91 electrical equipment handover test standards are described in detail the content and standards of the various tests. 2 Analysis of Preventive Tests for Power Transformers Power transformers are typical of high-voltage electrical equipment and one of the most important and important substations in power systems. Here take the power transformer as an example to analyze its preventive high voltage electrical test. Power Transformer Winding Insulation Resistance Test Insulation resistance and absorption ratio or polarization index of the power transformer winding together with the bushing have high sensitivity to the insulation of the transformer as a whole. Through the insulation resistance test, concentrated defects of transformer insulation penetration can be effectively inspected, such as semi-penetrative or metallic short-circuit caused by various short-circuiting of through-holes, cracking of porcelain parts, wire-bonded shells, and copper wire bridging in the body. . Due to the low test voltage at the time of measurement, it is difficult to expose the defects, and also because the insulation resistance is related to the size of the insulation structure of the winding, the type of the insulation material, and the winding temperature. Therefore, the reliability and sensitivity of the results obtained by simply relying on the absolute value of the insulation resistance to determine the winding insulation is not high. However, for the core clips, through bolts and other components, measuring insulation resistance can often reflect the failure, this is due to the simple insulation structure of these components, a single insulating medium, under normal circumstances does not withstand voltage, insulation, more isolation, and Unlike winding insulation to withstand high voltages. Power Transformer Winding DC Resistance Test Power Transformer Winding DC Resistance Test Can effectively examine winding insulation and current loop link conditions, can expose the quality of winding welding, coil winding interturn short circuit, winding strand break or lead wire break, tap changer and wire bad contact Such as failure. At the same time, the DC resistance test can also effectively determine whether the DC resistance of each winding is balanced and whether the voltage regulator switch is correct. The long-term practice shows that the winding DC resistance test is one of the main methods to examine the transformer insulation, and even in some cases it is the only method to determine the connection status of the current loop, which is of great significance. AC withstand voltage test AC withstand voltage test can effectively identify the parameters of power transformer insulation strength and other parameters, especially for the assessment of the main insulation of the local defects, such as winding main insulation damp, cracking or loosening in the winding caused by the transport process, lead distance is not enough and winding Dirt on the insulation, etc. The disadvantage of AC withstand voltage test is that the test conditions are more stringent. For example, transformer voltage withstand tests above 35 kV and 8 000 kVA are required. Because the capacitor current is large, the rated current of the transformer with high voltage test is required to be above 100 mA. At present, such high-voltage test transformers and voltage regulators are still not popular enough, so there are not many places that can meet the test conditions. 2.4 Dielectric loss factor tg5 The test dielectric loss factor tg5 test is mainly used to check the overall deterioration of the oil quality of the transformer, oil sludge attached to the winding and serious local defects, etc., medium measurement is often subject to surface leakage and external conditions (such as disturbing electric field and atmospheric conditions ) and other factors. In the general case, tg5 is measured together with the casing, but in order to improve the accuracy of the measurement and detect the sensitivity of the defect, a decomposition test is also performed to determine the location of the defect. For example, when the transformer was pretested, it was found that one phase of the casing medium exceeded the standard, and the insulation was not qualified and the reading was low. After analysis, it was thought that it might be due to moisture. After the inspection, it was found that there was moisture at the bottom of the casing, and the casing had been dampened. After drying, the test was conducted again. All the indicators met the requirements. Measuring leakage current is similar to measuring insulation resistance, but its sensitivity is higher, and it can effectively discover local transformer defects that cannot be found in other test items. The leakage current value is related to the transformer's junction structure, temperature, and other factors. In comparison, compared with the historical data, compared with the same type of transformer data, compared with the empirical data. The dielectric loss factor tg5 and the effectiveness of the leakage current test are falling as the voltage level of the transformer increases, and as the capacity and volume increase. Therefore, the possibility of judging the insulation of windings by tg5 and leakage current is also likely to be relatively small. (We turn to page 40) The order of main vibration can find the weak point of the steel structure, and take corresponding measures to improve the structure to achieve extension. The purpose of the service life, and ultimately ensure its safety and stability. When testing the reclaimer, an objective assessment of its working conditions should be conducted, ie, determine the load form of its operation. According to this, a targeted inspection and design is carried out to ensure that the measuring points and the testing items meet the actual needs, so that the detected data can be Safe operation provides effective support. In addition, the problem with the detection is the analysis of the degree of fatigue of the steel structure, because the deformation of the steel structure is often related to the degree of fatigue, accompanied by cracks and other circumstances. The existence of this problem cannot be ignored in the test. Therefore, the fatigue evaluation of the main steel structure should also be performed according to the load conditions as a supplement to the routine test. Finally, fatigue damage should be repaired according to actual conditions to ensure safe operation. He Yongwei. Analysis of Structural Cracking of Steel Structure in Harbor Reclaimer . Lifting and transporting Li Haoyuan. The structure of modern port reclaimer rationality and reclaiming capacity of the stable lifting transport machinery, 2006 (11) He Zhongnan. Analysis and Improvement of Cracking Faults in Reclaimer Structures . Mining Machinery, 2009 (11) Li Yimin, Lu Minghui. Reasons for major accidents in reclaimers and their avoidance. Transporter Zhou Qiqun, Shao Xinjian. Steel structure design and calculation method of reclaimer Tongji University (Natural Science) 2009 (3) Fang Fang. Analysis of the main steel beam structure of reclaimed steel for large round stockpile reclaimer at the port of Wuhan University of Technology, 2008 (7) Zhang Tiejun. The problems existing in the drive mechanism of the gate bucket wheel stacker-reclaimer and the reform measures China High-tech Enterprises, 2008 Lu Minghui, Li Yimin. Development of Steel Structure Inspection Technology for Port Stacker and Reclaimer Development Yin Xingji, Ma Chunyu, and Hao Yan. Three-dimensional finite element analysis test technology and testing machine for large bucket wheel stacker and reclaimer, 2006 (3) Tong Minhui, Shen Zhuomin. Port Reclaimer Pitch Steel Structure Dynamic Characteristics Journal of Shanghai Maritime University, 2008 (1) He Luyin. Research and application of mechanical analysis of retrieving process of arm bucket wheel stacker reclaimer, Chen Jinshou. Analysis and solution of the buckling deformation of the high web of the forearm frame of bucket wheel stacker-reclaimer. The research direction: port loading and unloading equipment maintenance. (Continued from page 37.) This is mainly because the test voltages of the two tests are too low and insulation defects are difficult to fully expose. 2.5 Line Deformation Test Power transformer coil deformation refers to an irreversible change in the size or shape of the winding under the influence of electrodynamic and mechanical forces, including changes in axial and radial dimensions, transfer of the body, twisting of the winding, bulging and twisting Short circuit between. Winding deformation is a major hidden danger in the safe operation of the power system. Once the windings are deformed without being diagnosed and continue to be put into operation, it is very likely to cause accidents, and the coils will be burned if severe. Therefore, it is necessary to carry out the coil deformation test on the power transformer in order to fully grasp the information that causes the cause of the coil deformation and the hazards. The main cause of the deformation of the coil is (!) The power transformer is subjected to accidental shocks, jolts, vibrations, etc. during transportation or installation. The deformation of the coil caused by the action of the external force is more common, and it is also difficult to prevent, and the accident is large. This requires that during the transportation and installation of power transformers, collisions and vibrations should be avoided as far as possible. In particular, when the fuel tank is filled with oil, it should be noted that there must be no external force to impact the transformer and cause oil tank rupture and transformer oil spillage. (2) Short-circuit fault current impact, the electric power causes the winding to be destroyed and deformed. The generation of electric power is the result of the interaction of the short-circuit impulse current in the winding and the magnetic flux leakage. During operation, the entire winding may be twisted due to the simultaneous action of axial and radial electric forces. (3) There is a dead zone in the protection system, and the operation fails. As a result, the transformer is subjected to a stable short-circuit current for a long time, causing the winding to deform. According to the statistical results during the actual operation, the transformer that failed to timely trip due to an external short circuit accounted for approximately 30% of the short circuit damage accident when subjected to an external short circuit. Therefore, the transformer short-circuit protection system must be regularly overhauled to eliminate the fault in time so as to avoid damage. The occurrence of an accident such as a malfunction in a short circuit. 3 Impact of high-voltage electrical test on equipment cost Voltage electrical equipment is not only an important power equipment in the power system, but also a product. It also needs to face the pressure to reduce costs to obtain maximum profits and control the cost of competing with the market for the same type of products. 3.1 Definition of cost control Cost control is based on the cost management objectives established during a certain period of time. Within the scope of the responsibility of the controlling entity, before the occurrence of production costs and the formation of the company's costs, various impacts will be exerted on improving cost-effectiveness. Factors taken by the active prevention and timely adjustment measures. The following procedures are generally included: (1) Establish cost standards according to the quota, and formulate various technical measures to reduce costs accordingly. (2) implementation of standards. That is, calculation and supervision of the process of cost formation. (3) Determine the difference. Calculate the difference between actual consumption and cost indicators, analyze the extent and nature of the differences in costs, and determine the causes of the differences. (4) Eliminate differences. Excavate the potential for increasing production and save, and propose new measures to reduce costs. 3.2 Cost Control of High-Voltage Electrical Equipment The first step in cost control is to establish cost standards based on quotas and to establish technical measures to reduce costs. The formulation of this technical measure is not out of the blue, it must be based on practical and scientific basis. As far as high-voltage electrical equipment is concerned, during the equipment development process, it is necessary to continuously conduct various tests and tests on prototype products, including non-destructive insulation property tests and destructive withstand voltage tests, and only various kinds of exposures are exposed during the test process. Problems that may be encountered in actual operations can be corrected early, prevented early, and improved early. Through the accumulation and analysis of large amounts of raw data during these tests, under the principle of ensuring the applicability, safety and reliability of high-voltage electrical equipment, a series of technical measures such as new processes, new technologies, and new materials have been adopted through the improvement of design ideas. To reduce costs. At the same time, the handover test of high-voltage electrical equipment can also fully expose potential defects and damage to the equipment. The sooner these problems are discovered, the sooner they can be resolved. On the one hand, this improves the safety and reliability of the equipment, reduces the cost of equipment operation and maintenance, and more importantly, ensures the safety of the power system. 4 Conclusion High-voltage electrical test is to assess whether the main insulation or electrical parameters of high-voltage electrical equipment to meet the safe operation of an important means. High-voltage electrical tests can be divided into two categories: insulation preventive tests and electrical equipment handover tests. Different test contents can achieve different test objectives, but the ultimate goal is to ensure that high-voltage electrical equipment meets safe and reliable operation. At the same time, the high-voltage electrical test is the basis for the development of cost control measures for high-voltage electrical equipment. Through the analysis of a large amount of data in the experimental process, the purpose of reducing costs can be achieved without affecting the applicability, safety, and reliability of the equipment. Chen Huagang. Technical Question and Answer on Power Equipment Preventive Testing Beijing: China Water Conservancy and Hydropower Press, 2004 Su Jinfu. Transformer DC Resistance Test Analysis Transformer, 2005 (8) Meng Lingxin. Design Stage Cost Control Response Enterprise Technology Development, 2006, 25: Engineering Cost. 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High voltage electrical equipment test and cost control