Chen Zujia National Electric Power Company Honorary Security Expert Guiyang 550002 Wu Yulin Guangdong Electric Power Group Corporation Guangzhou 510080 In recent years, through the safety evaluation of more than a dozen power supply companies, we found that there are some problems in the management of electrical preventive tests. The universality. The summary is summarized and recommendations for improvement are proposed. Discuss with everyone. 1 Transformer including reactor and oil-immersed transformer transformer oil total hydrocarbon hydrogen and acetylene exceeds the standard. Because transformer oil can only decompose nitrogen acetylene and other hydrocarbons when the partial discharge temperature is above 30001 or the local superheat temperature is above 1000. Compound. Therefore, through regular preventive tests, it is found that the total nitrogen or acetylene exceeds the standard, or when the standard does not exceed the standard, but the upward trend of the enthalpy indicates that partial discharge or overheating may have occurred inside the equipment, and sufficient attention should be given. Judging from the safety evaluation, the general unit can perform the precautionary procedures of the power equipment in accordance with the pre-test procedures of the original power equipment. The analysis and processing of the test values ​​are often insufficient. The following two aspects are considered to be safe and sound without exceeding the standard. If some units suddenly appear acetylene during the regular test, but do not exceed the standard 5 shells, it is considered that there is no question, let the equipment continue to operate. In fact, the appearance of acetylene indicates that partial discharge or local high temperature overheating may occur inside the equipment. For example, if a transformer in a factory has acetylene in the pre-test, it will explode the day before the inspection of the core; a trace of acetylene appears in the transformer of a factory. Check by the core in time. A partial discharge point was found. 0, and above voltage level current transformers are more common than hydrogen. In the safety evaluation, some power supply bureaus did not take measures to deal with hydrogen in time. Some units have no way to ask for nitrogen exceeding the standard. Such as a provincial power test institute regulations, if other tests are qualified. Only a single nitrogen excess can be used as a graded insulation. However, some of the foreign manufacturers have used cattle hydrogen as the only indicator for mastering and controlling internal faults of equipment. Because the dissolved gas chromatographic analysis of transformer oil is a very important technical measure to master and control the internal faults of the Asahi equipment, it is a regular test and an inspection test. Suggestions for this. If the total hydrocarbons are found in the test, acetylene exceeds the standard, or if there is an increasing trend without exceeding the standard, sufficient attention should be paid. Generally, the following measures can be taken to check the core inspection and degas the transformer oil for equipment that has exceeded the standard or has not exceeded the standard but the situation is relatively serious, such as the gas production rate is relatively fast. The equipment after the above treatment should also shorten the test period and strengthen the tracking test analysis until the gas is not generated or the gas production is no longer increased; if the current transformer generates hydrogen, if it is confirmed that the flash transformer oil quality is unqualified, it should be timely replace. The test analysis should continue to be followed after replacement. If the cause of hydrogen production cannot be determined, degassing should be performed on the basis of follow-up test analysis. Then continue to track the test analysis. Severe conditions should create conditions for the core inspection 2 transformer windings, casing and transformers 5 test idle transformer winding bushings and transformers use a large amount of insulation paper. When the water content of the insulating paper exceeds its inherent value, the equipment may be exposed to moisture. The purpose of measurement 25 is to make an accurate judgment of the insulation moisture. In addition to the different 185 allowable positions according to different equipment, the pre-test procedure also stipulates that the test measured 15 should be compared with the factory value calendar value or the last test value, and the transformer windings should be hungry. Not much dry 30; and the oily paper capacitor type bushing and current transformer set a significant increase or close to the allowable limit when the comprehensive analysis 15 and temperature and voltage relationship. When 18 5 increases with temperature, increases, or the test voltage rises to ± 125 increments exceeding ±0.3, it should not continue to operate. For electromagnetic voltage transformers, only 125 is not greater than the medium limit; The electric 1 transformers stipulate that the initial value of 185 is different from that of the girl. In the safety evaluation. Each unit attaches great importance to the limits specified in the 5 test and pre-test procedures. It seems that the comparison between the test value and the factory value or the calendar value or the previous test value is generally insufficient. For example, a power supply bureau conducts regular tests on dozens of main transformers and on-page transformers according to regulations, and records big data. It seems that there is no comparison according to regulations, and the conclusion is qualified. In the absence of comparison, there may be potential hidden dangers in the timely detection and treatment of insulation at the end of the tide. If a power plant is on the stage, although the main transformer test 185 is too large, but does not exceed the limit, it is concluded that it is qualified. In the continued operation of the casing explosion, the transformer is seriously damaged and the heavy fire accident. Since the main insulation of the capacitive bushing and the oil-paper capacitive current transformer is composed of several capacitor chains connected in series. Externally filled with insulating oil, when the equipment is damp due to poor sealing or other reasons. Water is often immersed in the capacitor core through the outer insulation. Therefore, it is more sensitive to measure the insulation resistance of the final screen to the ground at the initial stage of the damp. At the same time, it is also possible to judge the degree of insulation moisture by comparing the insulation resistance of the main insulation guide to the end screen and the outer insulation screen to the ground. Therefore, in the pre-test procedure, the capacitor-type current transformers for capacitive type and oil-paper-type current transformers should be measured during the periodic preventive test. The insulation resistance of the final screen should be measured. If it is small, the final screen should be measured. 5 shall not be greater than 2. In addition, the pre-test procedure also stipulates that the capacitance of the main insulation should be measured differently from the initial value or the factory value. If the value exceeds ±5, the cause should be ascertained. Some units of these regulations have not been implemented. Some units only have measured the insulation resistance. However, if the equipment below lOOOM is not inspected, the conclusion is qualified. , may stay, so hidden. According to the above questions, the following recommendations are proposed. The precautionary test procedure for power equipment is to summarize the technical supervision of the power sector. With more than 40 years of experience and lessons learned, I have drawn up new experimental projects and diagnostic techniques from recent years. In the case of regulatory documents, the standards and requirements of the test items 1 specified therein shall be carefully implemented. Do not arbitrarily delete or lower the standard. In order to facilitate the comparison and review of the test values ​​with the initial value of the factory values, it can be found in the current test data grid. Add the specified limit and initial or factory value, calendar year value and comparison value 5 columns. Before the test, the tester shall firstly calculate the initial value or the factory value of the apricot from the test file. In order to carry out comparative analysis on the spot after the test, it was found that the problem was dealt with in time. 5 The accuracy of the test is related to the instrument used, in addition to the technical level and experience of the tester. It is said that the 5 test can use a two-way bridge. Type testers or other instruments, like each instrument 1 does not have the precision and anti-interference ability, the measurement error is different. The values ​​measured by this flash are not the same, for the comparison. It is recommended to fix the tester and the instrument used. It is said that the 5 test is subject to high precision and is susceptible to interference from the instrument and external factors. The maximum error may be close to 0.3. Therefore, when the test value is small. If it is at 0.3, the change by contrast is slightly larger than 30, which is not a significant change. 3 The test of the on-load pressure regulating device In the safety evaluation, it was found that many units generally did not despise the test of the on-load pressure regulating device. According to the pre-test procedures, there are 6 major items and 5 small items for the test items to be carried out on this device. In the ministerial power transformer inspection guide and the operation and maintenance guide of the on-load tap-changer, the provisions and requirements for the inspection test are more detailed and specifically divided into five major items and 25 small items. For example, it is stipulated that the switching time of the contact should be measured by the DC wave during the inspection, the bridge time of the arc contact and the error of the same period are not more than the measurement of the contact resistance of each pair of contacts should be less than 500 to 0, etc. . In addition, a number of regulations have been added to the on-load tap-changer in operation, such as the insulating oil in the open and trial, every 20 months to 1 year or tap change 20004000 times at least sampling test times breakdown voltage is ten At 25 o'clock, the oil should be cleaned or oiled. The new production equipment will be converted into 5,000 core inspections in 12 years or tap change; Operate 3 loop tap-changes, etc. In the safety evaluation, we check the operation record and overhaul report of the maintenance and maintenance records of the relevant units. Only a single record has a more detailed record, but the test project is still not complete enough. In response to the above questions, the following recommendations are proposed for the transformer, the inspection and test of the on-load tap-changer should be carried out in accordance with the regulations of the operation and maintenance of the on-load tap-changer and the inspection instructions of the power transformer. It is recommended that the relevant units of the State Power Corporation shall, in accordance with the requirements of the above two ministries, revise and supplement the pre-test rules, and conduct inspection and test items. 4 Transformer Winding Deformation Test When the power transformer is in operation, a low-side side 1 short circuit or a near-field short-circuit accident occurs, the inrush current may exceed the rated current, which has a strong destructive force on the transformer, especially the domestic transformer bears this. The ability to impact is weak, often resulting in internal structures, especially severe distortion of the windings. For example, a power supply station 220150 main transformer is short-circuited at the low-voltage side outlet. The mustard insulation test and the chromatographic analysis of the transformer oil were good. However, when the winding deformation test was carried out, the internal winding showed severe deformation. After the core shield was inspected, it was found that the low-flying side winding had been closed and closed in time, and the treatment was carried out in time to avoid the heavy fire accident in which the transformer was damaged. The provisions of the winding deformation test, which were not in the intervention test procedure, caused the unit to pay insufficient attention to this test. We also found that the unit of the nail was continuously in the middle of the year due to the poor reliability of the distribution equipment including the line. Multiple quick-break over-current protection trip accidents, and some accidents occurred at the transformer exit. It seems that it has not attracted enough attention. It is generally considered that as long as the power transmission succeeds after the accident, it will be safe. According to the above experience, after the transformer outlet or near-field short-circuit accident, the winding deformation test is not likely to leave a very serious hidden danger. For this reason, it is recommended that after the main transformer has an exit or near-field short-circuit accident, in addition to various insulation tests and chromatographic analysis, the winding deformation test should be carried out in time; it is recommended that the electric power company and other relevant departments supplement the pre-test procedures. Transformer winding deformation test items! And requirements; according to the factory solution. 1 Before the power supply company did not have 4 test winding deformation test equipment, only the external unit can help the Ding, and the cost of each test is large. If the power supply bureau has more than 50 transformers, it is recommended to purchase a test instrument and test the transformer after the fault as a historical record. Convenient for future comparisons, this will play a positive role in strengthening equipment management and preventing accidents of large equipment. 5 arrester test asks the pre-test procedure to determine the specific requirements of the arrester test, in addition to the insulation resistance test, check the action of the discharge record, it is required to make the electric conduction flow of the valve arrester and the series combination in the same group before the rainy season. The difference in nonlinear factors of the component; the DC voltage applied to the metal oxide arrester, the leakage current of 1 and 0.75, 1 or less, and the active AC leakage current under the operating voltage. Although the technical tests of this item are relatively high, many units have done it, but they are not complete. The main items are as follows. For example, the metal oxide arrester only measures the full current under the voltage of the voltage in the test. The resistive current power loss is not measured and thus cannot be compared with the initial value. The test procedure stipulates that when the resistive current is increased by one time, the power shall be checked. Limitations of 51 safety guidelines and possible supplementary evaluation methods 1 Safety criteria can be given a small probability of serious grid failures, even sudden consequences, such as reversing poles and power transmission and transformation projects such as erection lines The power grid components are out of service, etc., and the safety of the system operation and the power supply to the user is directly evaluated, so that the disallowed operation mode is avoided when the operation mode is arranged and during the operation of the power grid. From the point of view of grid operation, there is no other way to replace the standard calculation procedure described in Section 4, and to evaluate the safety of the grid according to the 1 safety criterion. However, when it is necessary to take the following measures to assess the safety of the power grid not only in terms of quality, but also to make a quantitative evaluation, 1 safety standard is still limited. 1 Using the grid barrier to interrupt the power supply parameters, the frequency and duration of the overload of the grid components are considered as safety evaluation criteria; saving the impact of grid investment on power supply reliability; the frequency and duration of different grid components exiting operation exist Significant differences and the impact of the reliability of different grid components on the overall reliability level of the grid; the reliability level when the grid load and power generation conditions change drastically; compare the reliability of different substation construction schemes and grid-connected modes. At this time, it is necessary to introduce a supplementary safety evaluation method. A possible supplementary evaluation method for the above part is reliability calculation. Due to the large computational workload and high cost, the current reliability calculation is used as a supplementary evaluation method only in grid planning. 6 Conclusion 1 The safety criterion is the main means for grid planning and operation engineers to evaluate the safety of the grid under abnormal conditions. It is widely used in the German power grid as a practical evaluation standard for grid safety evaluation. Facts have proved that in order to ensure the safe and stable operation of the power system and sufficient power supply reliability, it is extremely effective to conduct safety standard assessment when planning the grid operation plan and grid operation. It is a combination of economic efficiency and safety. The construction is optimized, and the best solution is found out from various development strategies of electricity to achieve the coordination of safety and economy of the power grid. Received date 999125 connected to the 15th page test data is not compared according to the pre-test procedures, such as the electrically conductive flow of the valve arrester, the leakage current value of the metal oxide arrester, the resistive current loss, although measured, but not When compared with the initial value according to the regulations, the conclusion is qualified. Newly-operated 0, and above metal oxide arresters as required by the pre-test procedures. The secondary AC leakage current should be measured after 3 months of operation. After the semi-annual measurement, after the year of operation, the annual measurement is performed before the thunderstorm season, and some units are not implemented as required. In response to the above questions, in order to prevent the occurrence of lightning arrester explosion accidents, it is recommended to strictly implement the provisions of the pre-test procedures, and the items are not leaked, tested item by item, and compared with the initial values ​​before conclusions. Polyester Fleece Fabric,Wholesale Fabric Flannel,Polyester Flannel Fabric,Print Flannel Fabric Shaoxing Kexin Textile&Carpet Co.,Ltd , https://www.kexintextile.com