Analysis of Domestic 10kV Vacuum Circuit Breaker and Switchgear

0刖m vacuum circuit breakers and switchgears are more and more widely used in power systems due to their convenient maintenance, high reliability, and strong breaking capacity. In the 10kV voltage class, vacuum circuit breakers have replaced the low-oil circuit breakers. Newly built power plants and substations in Guangdong have basically used vacuum circuit breakers. The quality of homemade vacuum circuit breakers and switchgear has been significantly improved in recent years, and most manufacturers are able to make closing without bounce, reducing the overvoltage generated when the vacuum circuit breaker is closed. The market demand for vacuum circuit breakers and opening cabinets is growing rapidly, which will bring problems in production management and technical supervision.

1 Existing problems 1.1 Too many manufacturers of vacuum switchgear The current vacuum switchgear manufactured by switch manufacturers has passed technical appraisal before entering the market, but there are differences in quality after mass production, the quality of personnel, the degree of seriousness of inspection, and raw materials. The good degree of plant equipment and after-sales service have a direct impact on the quality of the product.

Too many manufacturers are rushing into the vacuum switchgear market. It is difficult for all factories to form a scale factory and make it difficult to create a well-known brand. This situation is very detrimental to the development of vacuum switchgear.

1.2 Excessive Model Numbers of Vacuum Circuit Breakers and Switchgears * Several models of vacuum circuit breakers or switchgears have not been tested for a long time since they were put into the power grid operation. Another new type of product has been produced and entered the market. This situation makes It is difficult for users to determine the vacuum circuit breaker and switchgear that are most suitable for their use.

For the operating unit, various types of vacuum circuit breakers and switchgears are operated together at the same time, which makes it difficult for operators and maintenance personnel to become familiar with and master their performance. Operation units must master the debugging skills of various circuit breakers. . Not conducive to training their own maintenance team.

1.3 vacuum interrupter leakage problems vacuum interrupter vacuum circuit breaker vacuum switch cabinet three closely linked to form a whole, the core part of the vacuum interrupter. In recent years, with the rapid increase in the use of vacuum switchgear, the vacuum interrupter has gradually exposed the problem of air leakage. This leak is a slow leak and will take a long time to discover. Leakage is caused by poor process control of the manufacturer, for example, poor adhesion and sealing of metal and ceramics or glass, or poor purification during the process of management of corrugated metal, causing corrosion in the future; vacuum interrupter manufacturers have a large market demand. With continuous expansion of production, the vacuum arc extinguishers are not stored in the factory for a long period of time, causing unqualified products to leave the factory without further inspection.

1.410kV Circuit Breaker and Switchgear Standard Uniformity Problem of Temperature Rise Test Current Value in Switchgear Cabinet Type Test: National Standard GB763-91 “Heat of AC High Voltage Apparatus in Long Term Operation” stipulates that the switchgear shall be operated at 1.0 times the rated current value. Tests, and the power department standard DL404-91 “Technical Conditions for Indoor AC High Voltage Switch Cabinet Ordering” stipulates that the switch reject shall be tested with a rated current value of 1.1 times, and the temperature rise value of each part of the switchgear shall be GB763.91, which is obviously The standard is stricter than the national standard.

(Continued on page 21.) 2.1 Limit Calculations 2.1.1 Voltage Limits and Calculation Methods The voltage limit methods can be calculated by selecting one of the following two methods from the screen menu: Curves.

Curve mode: set the voltage upper and lower limit values ​​at different intervals every day, and send the memory through the keyboard.

Calculation method: According to the real-time active load absorbed from the system, the voltage upper and lower limit values ​​are determined automatically. This method has automatic reverse voltage regulation properties. Voltage upper and lower limits are determined by the following formula: Upper voltage limit: Uu Udmax Low voltage bus voltage value corresponding to Pmax Udmin - When P=0 Low voltage bus voltage value (kV) Voltage setting Upper and lower limit width (kV) k Reverse voltage regulation Parameter Pl* real-time measured value (MW) of active power, Udmin is input from the field parameter input menu.

2.1.2 Reactive power limit (power factor) Curve mode is used to set the upper and lower limits of reactive power (power factor) limits in different daily intervals, and the memory is sent to the user through the keyboard. The time period of the limit is set to any time interval. Each time interval is accurate to the minute and can be divided into up to 15 segments per day.

2.1.3 Reactive power limit and calculation method Curve mode: Set the reactive power limit for each time period. The width of the upper and lower limits of the reactive power is preferably not less than 1.3 times the capacity of the single capacitor. The upper and lower limits of reactive power are determined by the following formula: Reactive power upper limit: Qu Qs reactive power upper and lower limit intermediate value (Mvar).

Generally speaking, the reactive power in the ideal state should be equal to zero, which means that the reactive power at this time is just balanced, then the lower limit value at this time can be zero, that is, Qt =, so that the reactive power upper limit can be calculated. .

3 Concluding remarks Through the gradual realization of voltage and reactive power automatic control at each substation, the voltage and reactive power on-site balance can be achieved in the entire regional power grid. If the main power supply at the peak, level, and valley can ensure that the system voltage is within the specified standard, the regional power grid can be manually adjusted by the voltage and reactive power integrated control device so that the bus voltage of each side of the substation is within the qualified range, so as to ensure The user's voltage is qualified.

(Continued from page 18) The inconsistency of the parallel standards has created contradictions between the implementation of the power sector and the production plant, and it is difficult for even the power sector to accurately grasp it. Some standards have not been in line with the actual situation but have not yet been cancelled. For example, the power department has already set the power frequency withstand voltage value of the 10kV switchgear to 42kV according to the actual conditions of China's 10kV power grid, and the national standard GB50150-91 "Handover test of electrical equipment installation engineering electrical equipment. Standards (implemented on July 1, 1992) still stipulate that the withstand voltage of the 10kV switch is 27kV. 2 It is recommended to control the number of vacuum switchgear manufacturers, and to those factories whose production equipment is outdated and whose technical strength cannot guarantee the quality of the switchgear. Reorganize.

The speed of developing new models of vacuum circuit breakers and switchgear should not be too fast.

The vacuum interrupter leakage problem should be given enough attention.

From the operating statistics in recent years, the leakage arc extinguishing chambers from the post-birth to the end of two years account for the majority of the total number of leakage arc extinguishing chambers. Therefore, during this period of time, the operation monitoring and test tests must be particularly strengthened. At present, the most effective way to check whether the vacuum interrupter leaks is the power frequency withstand voltage test, and the recommended test period is 3 times, half year, 1 year, and 2 years after the start of production. Pressure test, once every 2 years.

10kV circuit breakers and switchgear standards should be unified, changing the current national standard, the Department of Standards and concurrent non-uniform situation. The preparation of the standard should be based on the power sector that is familiar with the situation of the power grid. After the new standard is formulated, the old standard should be declared invalid at the same time.

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