Real Electric was invited to participate in the seminar on power transformers and arresters
On the afternoon of July 18, 2018, I went to Wuhan on behalf of the company to participate in the quality analysis and technical seminar of power transformers and arresters held on July 19 and 20. The meeting was prepared by the Chinese Academy of Electric Power, during which it was held with Tektronix and Yang Gong. Peers, increased their knowledge and learned a lot.
At 9:00 on July 19, the meeting began on time. First, the host introduced the leaders and guests and the welcome speech. Then the leaders of the electric power industry electrical quality inspection and testing center reported on the quality supervision and spot check of power transformers and arresters:
First, the power transformer
China's distribution transformer industry has a low barrier to entry, so the overall technical level is not high, there are many manufacturers in the industry, and the market competition is fierce. The meeting analyzed the domestic industry distribution, industry status, product application prospects and development trends. The two key points for the future development of the distribution transformer industry will be energy-saving oil-immersed transformers and amorphous alloy transformers.
Power transformer quality inspection report: In 2017, according to the national standards and international standards of power transformer products, such as product standards, method standards, performance standards and performance standards, this sampling has checked 8 items: 1) winding resistance measurement; 2) voltage ratio Measurement and connection group label verification; 3) short-circuit impedance and load loss measurement; 4) no-load current and no-load loss measurement; 5) temperature rise test; 6) external pressure test, induction withstand voltage test; 7) partial discharge Measurement (dry change only); 8) Lightning impulse test. This time, we sampled 48 products from 48 companies in 13 provinces and cities. Among them, 45 of the 45 companies were qualified, and 3 of the 3 were unqualified. The sampling rate of the products was 93.8%. The unqualified items were: no-load current and no-load loss measurement, temperature rise test and local Discharge measurement.
The results of the sampling test show that the average sampling pass rate of power transformer products is relatively low, reflecting that the product quality of some enterprises is insufficient, and production control management needs to be strengthened. Sampling should be strictly enforced! (Sampling situation, quality problem analysis, see Annex I "Transformer Product Quality Status Analysis Report")
Second, metal oxide arrester
The arrester products have been sampled for 7 project characteristics: 1) power frequency reference voltage test; 2) DC reference voltage test; 3) 0.75 times DC reference voltage leakage current test; 4) sealing test; 5) nominal discharge current residual voltage test ; 6) square wave impulse current withstand test; 7) high current impulse withstand test. This time, 13 batches of products from 13 companies in 7 provinces and cities were sampled. Two of the two companies were unqualified, and the sampling rate of the products was 86.7%. The unqualified items were: nominal discharge current residual pressure test and high current impact tolerance test. Among them, the pass rate of small and medium-sized enterprises is relatively low, and will be the focus of spot checks in the future. (Sampling situation, quality problem analysis, see Annex II, "Lightning arrester product quality status analysis report")
The Power Industry Quality Inspection and Testing Center of the Power Industry clearly pointed out that the relevant sampling inspection supervision work of the State Grid will be strengthened in the future, and the product quality requirements will become more and more strict!
At 11 o'clock in the morning, Mr. Jiang Kai from Huazhong University of Science and Technology spoke about the progress and challenges in the research and development of advanced electrical materials. The new conductive materials include: 1) nanomaterials; 2) superconducting materials; 3) carbon fiber reinforced composite wires; 4) electrical contact materials. There are also new applications for insulation and magnetic materials in current production and future trends. Subsequently, this conference organizer: CLP Supreme Certification Body, introduces the development history of the organization, and sincerely provides quality services to manufacturers who need certification.
In the afternoon meeting, we arranged technical seminars for transformer companies and lightning arresters. The seminars were held in different halls. I participated in the technical seminar of transformers.
At 2 o'clock in the afternoon, Zhang Shuzhen first talked about some parts of the Chinese Standard Law. Then, Shi Guangyu, an engineer from Fujian Electric Power Research Institute, explained the causes and countermeasures of axial instability after transformer short circuit. The report pointed out that the force between coils will increase tens of times after transformer short circuit, which will cause deformation inside and outside the transformer. When manufacturing, it is necessary to avoid the looseness of the coil when winding. It is necessary to fix the coil and reduce the relative displacement between the coils to improve the short-circuit resistance of the transformer.
After a short break, Zhang Gong of Shanghai Confidence Electric explained the research on the key technologies and measures to improve the short-circuit resistance of the transformer. The current transformer has four coil shapes: circular, elliptical, oblong and rectangular. Among them, the circular coil is evenly stressed, and its short-circuit resistance is the best when a short circuit occurs, but the circular coil volume is relatively large, and the elliptical coil scheme is the best solution. Then the senior experts of the transformer explained the design and process of the three-dimensional coil core transformer. Because the afternoon meeting agenda is more professional, I can't understand it thoroughly in the future. In the future work, I will continue to learn and digest.
Before the end of the afternoon meeting, the personnel of the Electrical Equipment Quality Inspection and Testing Center of the Power Industry explained the difference between the GB/T1094.3-2017 standard on the transformer and the 2013 standard. The subsequent transformer production and inspection standards should be implemented according to the 2017 version. See Annex III ("GBT1094.3-2017 Power Transformer Part III")
On the morning of July 20th, Mr. Meng visited us together with the president of Henan Transformer Industry and the Gonggong of Xuji Transformer. They learned from them that Fidelity Seiko has a proven short-circuit test. The new drawings, if necessary, can contact the general manager of Fidelity. There are some other technical and industry information. In the afternoon, I returned to Xuchang with Meng.
This time I went out to study, I gained a lot of knowledge, learned a lot of knowledge, and in the future work, I must continue to learn and work better.
Annex I, Analysis Report on Quality Status of Transformer Products
Annex II: Analysis report on the quality status of arrester products
Annex III, GBT1094.3-2017 Power Transformer Part III
Contributed by: Marketing Center - Yang Yabing
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