The problem of the high-voltage fuse of 35kv voltage transformer and its improvement plan

In the normal operation of the voltage transformer, the probability of its internal failure is very small. The high-voltage fuse is often blown because of the resonance of the voltage transformer. When the operation mode of the system changes in some way, the iron core of the voltage transformer is saturated, the inductance and capacitive reactance to the ground are equal or approximately equal, and a relatively large current is generated, causing the fuse to blow. At this time, the voltage transformer must be shut down. Replace the fuse.

 

What we are now using is a quartz sand-filled porcelain tube fuse equipped with a rain cover.

The fuse is installed in the rain cover and fixed with four screws on both sides. When replacing, you must unscrew the screws on both sides, hold the pliers in one hand to fix the nut, and the other hand to tighten the screw. Due to high-altitude operations, there are few places to focus. Such an operation is time-consuming, laborious, and dangerous. The side cover and screws are made of ordinary wrought iron, which is easy to rust and deform due to long-term sun and rain. After the screw is unscrewed, the fixed iron ring is easy to jam due to uneven force, and it is difficult to remove it. Especially in special weather, the replacement has to be postponed, which reduces the reliability of metering and protection.

To overcome the above shortcomings, we can use the rotating shaft type instead of the screw fixed type,

The fixed shaft adopts screws (pins can also be used), the nut and fixed iron ring are eliminated, and the other end of the screw is directly screwed on the side cover. During operation, only unscrew the screw at one end to open the side cover. Even if the fuse cannot be removed due to the obstruction of the connecting wire, another screw can be unscrewed, so that at most two screws can be unscrewed, and it can be done easily with only one hand.

 

To overcome corrosion, the main body of the side cover is made of steel, the outside is plated with anti-rust material (nickel-chromium alloy, etc.), and the screws are made of stainless steel.

The improvement has increased the flexibility and reliability of the high-voltage fuse, reduced the cost, and it easier to operate, creating good conditions for ensuring the safe operation of the system.

The first high-altitude test of a DC arrester on the 1100 kV Jiquan line was completed

The ±1100 kV line has 4 base towers with DC arresters installed, 3 bases are located in Gansu, and the other is located in Haiyuan County, Ningxia. The DC arresters installed on the towers are the only set of high-voltage line arresters in Ningxia Power Grid. Since a single lightning arrester weighs 3 tons and the tower is in a cornfield, the cost of using a crane to experiment is relatively high and there are significant safety hazards. For this reason, State Grid Ningxia Electric Power tried for the first time to carry out DC reference voltage and leakage current tests without removing the arrester at high altitudes.

WISHPOWER Chairman’s Message on New Year’s Day 2023

At the age of make a new start, it was the time of the new day. The clouds opened and the fog dispersed, the sun shine is in the east.
Time and space alternation, suffering with beautiful symbiosis.The winter sun is coming, at the beginning of the year, WISHPOWER sincerely wishes you: Happy New Year!
Looking back on the past year, dealing with the market and fighting the epidemic. The turbulent factors in the world order, such as the crisis in Ukraine, the impact of the epidemic and the game of great powers, have an impact on the global economy. As a foreign trade export-based enterprise, it is a difficult year. Fortunately, all Wishpower employees unite as one and make all-out efforts, and we have also made new achievements. At this beautiful moment of ring out the Old Year and ring in the New Year, on behalf of the leadership of the company, I would like to express my heartfelt thanks and high respect to all the staff!

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This year, we have made gratifying achievements. In the difficult environment affected by the epidemic, Wishpower’s market is still dominated by European and American markets, and its foreign trade performance and domestic sales are both stable and making progress. Wishpower produces more than 1.08 million pcs insulators in total. Among them, more than 730,000pcs suspension composite insulators, more than 50,000pcs post composite insulators, more than 20,000pcs railway composite insulators, more than 30,000pcs cutout fuses, more than 20,000pcs composite housing metal oxide arresters, and more than 200,000pcs other insulation products; There has been a breakthrough in the sales of post composite insulators; The company has successfully developed 10kV standardized distribution arrester and 35kV oxide arrester and obtained the third-party test report; Intelligent, automatic research and development of continuous investment, the company independent research and development of several non-standard automation equipment, reduce the labor intensity of operators and improve production efficiency.The company accepted more than 20 times of video inspection from domestic and foreign customers throughout the year, all of which met the requirements and received unanimous praise from customers.
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In this year, we strengthen the “On-site Lean Management” and “Team Quality Construction“. Wishpower continue to implement and strengthen the “7-second movement” in the whole process of production, so that employees develop a good atmosphere to improve work efficiency and benefit from time. At the same time, the company continues to optimize the organizational process, strengthen the internal training, a total of more than 30 times a year organized training, in order to improve the comprehensive quality and professional level of all employees.

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In this year, we bear in mind the management philosophy of “Cultivating Suppliers, Stabilizing Supply Chain,Win-win with Suppliers“. Wishpower always adhere to the cooperation with the strong, strict quality control, reliable suppliers, with the best quality raw materials to produce safe, reliable and life-saving power products.

In this year, we passed the audits and certifications of this industry. With the participation of all staffs, Wishpower successfully passed the annual audit of Quality, Environment, Occupational Health and Safety System, the annual audit of railway CRCC products certification, and the audit of supplier network access qualification performance review of State Grid Corporation of China, the audit of the third party appointed by foreign customers, indicating that the company’s management system is sustainable and effective, and meets the requirements of providing customers with qualified, reliable and safe products. At the same time, we will also contribute to the development of the State Grid Corporation of China.

The old year is gone, and a new one is opened. Looking ahead to the coming year of 2023, we have new expectations: WISHPOWER will continue to work in the subdivision of composite insulators, composite housing metal oxide arrester, cutout fuse, composite high voltage isolation switch, HDPE spacer, consolidate the foreign trade market, and actively explore the provincial and domestic markets. To provide customers with a full range of insulation products solutions, constantly improve the reliability and stability of products. WISHPOWER will continue to adhere to the enterprise management and development philosophy of “Work Earnestly With Responsibility, Go Forward With Sincerity “, provide customers with cost-effective products and valuable services, expand and strengthen the brand influence of WISHPOWER make the company’s work into a new level.

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On the occasion of the New Year, bless every colleague and partner, bless every employee and family, wish you in the New Year to build the future with action, faith care happiness, Thanksgiving each other, heart to broad and bright!

In the ancient capital Chang ‘an on December 30, 2022

The classification of composite fuse cutout

Fuse cutout can be divided into high voltage fuse cutout and low voltage fuse cut out according to the service voltage.  It can be divided into dropout fuse for protecting transformers and general electrical equipment,  for protecting voltage transformers, for protecting power capacitors, for protecting semiconductor components, dropout fuse for protecting motors, and dropout fuse for protecting household appliances, etc. According to the structure can be divided into open type, semi-closed type, pipe type, and jet type fuse cutout

 

The rated current of the fuse link is not equal to the rated current of the whole fuse cutout. The rated current of the fuse link shall be selected according to the load current of the protected equipment. The rated current of the fuse cutout shall be greater than the rated current of the fuse link.

Suspension insulator and post insulator test items

  1. The test items of suspension insulators and post insulators shall include the following:
  2. Measure the insulation resistance of the insulator;
  3. AC withstand voltage test of insulators.
  4. The insulation resistance value of the insulator shall meet the following requirements:
  5. The insulation resistance value of suspension insulators used for voltage levels of 330KV and below should not be less than 300MΩ; for suspension insulators used for voltage levels of 500kV, it should not be less than 500MΩ;
  6. The insulation resistance value of post insulators with voltage levels of 35kV and below shall not be lower than 500MΩ;
  7. Use Dingsheng Power DC2403 2500V insulation resistance tester to measure the insulation resistance value of insulators, which can be spot-checked at 10% of the same batch of products;
  8. Rod insulators are not subject to this test;
  9. The insulation resistance of the semiconductor glaze insulator meets the requirements of the product technical conditions.
  10. The AC withstand voltage test of the insulator shall meet the following requirements:
  11. Pillar insulators with voltage levels of 35kV and below can be carried out together after the busbar is installed. The test voltage should meet the requirements of the “Power Frequency Withstand Voltage Test Voltage Standard for High Voltage Electrical Equipment Insulation”;
  12. The AC withstand voltage test value of 35kV multi-element post insulators should meet the following requirements:

① For two glued components, each component is 50kV;

② For three glued components, each component is 34kV.

  1. The AC withstand a voltage test voltage of suspension insulators are all 60kV.

Review of Insulator Failure Modes

Composite insulators were developed 45 years ago, largely due to these defects, and were introduced on an industrial scale in the 1980s. When suppliers adjust their products through successive generations of designs based on their initial service experience, there is a learning curve, but the technology is now mature. In fact, in most countries, it is considered equivalent and interchangeable with porcelain and glass. This is an impressive achievement, especially if one thinks that 25 years ago, power engineers knew little about the technology and did not trust composite insulators.

Research on Live Cleaning Method of 500kV Post Insulator

With the increase of operating time of 500 kV substation equipment, the pollution degree of pillar insulators becomes more and more serious. The creepage of the insulators is more and more obvious, and the discharge sound increases on rainy and foggy days. Regular cleaning or emergency cleaning of insulators is an extremely effective anti-pollution flashover measure. In response to the requirements of high equipment reliability, there are fewer opportunities for power outage maintenance. At the same time, with the advancement of state maintenance work, there are fewer opportunities for equipment power outages. The hidden danger of flashover threatens the safe operation of equipment more and more seriously. To solve this contradiction, effectively improve the insulation level of the pillar insulators, clean the surface of the equipment in time, and prevent equipment pollution and flashover accidents, live cleaning has become a necessary means.

 

The layout of live equipment in the 500 kV substation is compact. The distance between some equipment is small, and there are many types of structures. When carrying out live work on high voltage equipment, safe working regulations must be strictly followed, and a sufficient safety distance can be met to ensure the personal safety of live workers. And safe operation of live equipment. To make live cleaning equipment acceptable to the user department, and to realize the live cleaning operation of high-voltage and ultra-high voltage substation equipment conveniently, safely, and reliably, the following requirements must be met: (1) The live-cleaning equipment must be miniaturized and adopted. Potential and indirect live working methods to ensure that the range of activities of the operators during live work must meet the safety distance requirements; (2) The live cleaning equipment must meet the requirements of the insulation level to ensure the personal safety of live workers and the safe operation of live equipment; ( 3) The equipment must be light, flexible, and easy to assemble to minimize the labor intensity of the operators; (4) The live cleaning equipment must be able to meet the cleaning requirements of equipment with different heights installed in the substation; (5) The cleaning equipment must be easy to operate and easy to maintain Maintenance, few vulnerable parts, long trial life.

Reasons for measuring voltage distribution of suspension insulators

Measuring the voltage distribution (or zero checks) of suspension insulators and multi-element pillar insulator strings is one of the methods to check for degraded insulators. It is carried out without power failure.

(1) Characteristics of voltage distribution on the insulator string

The voltage that each element in the suspension insulator string bears is different. This is mainly due to the capacitance between the metal part of the insulator and the ground, the cross arm or the tower, and the point wire, which makes the voltage distribution of the insulator string Very uneven. The voltage drop on the insulators closer to the wire in the insulator string increases, and the voltage on the insulators farther away from the wire gradually decreases, but the voltage drop of the insulators close to the cross-arm increases again, and the more the number of insulators, the greater the voltage distribution The more uneven.

(2) Inferior insulators and their treatment

If one or several insulators on the insulator string are degraded, the voltage distribution on each insulator along the insulator string will be different from the normal voltage distribution. If the degraded insulator has been conducting through electricity, the voltage across the insulator will be zero (called a zero-value insulator). If the insulator deteriorates, the voltage on it will be reduced, and the reduced voltage will be transferred to other insulators, especially the nearby insulators, thereby reducing the electrical withstand capability of the entire insulator string. Therefore, it should be checked and replaced in time. Commonly used tools such as resistance distribution rod, capacitance distribution rod, and spark gap inspection rod for measurement.

Hydrophobic charged detection device for composite insulators-principle and function

A new type of product that fills the gap in the field of online water-repellency testing of composite insulators in my country. The structure is simple, the operation is convenient, and the judgment is accurate. It is suitable for online detection of the hydrophobicity of 110kV and above transmission line composite insulators. It is also suitable for the hydrophobicity detection experiment and factory inspection of various composite insulators and silicone rubber. It is suitable for the water repellency detection of RTV spraying materials for magnetic insulators.

  1. Detection principle

The water-repellent state of composite insulators is judged according to the water spray classification method of the Swedish Transmission Research Institute (STRI). Based on advanced digital image processing technology, the water-repellent state of composite insulators can be objectively determined by extracting gray information such as information entropy, seed rate, the mean value of spectrum amplitude, and shape coefficient and area percentage of water droplets or water traces of hydrophobic images. judgment.

  1. Function
  • Live detection of the hydrophobicity of various composite insulators
  • Detect the hydrophobicity of silicone rubber and RTV spray materials
  • Automatic and accurate analysis of hydrophobicity level
  • Record various data and graphics of each test
  • You can query the inspection records of every string of insulators
  • Automatically judge the development trend of hydrophobicity
  • Analyze and judge the performance of pollution flashover and wet flashover resistance
  • Provide a scientific basis for maintenance and selection