Operation analysis of the temperature rise of high voltage switchboard

Abstract: Domestic JYN, KYN Handcart counter and plant joint venture production of Switchgear 8BK20 the actual temperature rise data analysis found that in the operation of switchgear for more than the average water temperature rise of the test pattern measured data. Then, from the experimental conditions, metal expansion of the effect of pressure on the fastening bolts, conductor conductivity material such as further analysis of the temperature rise exceeded. Finally, make recommendations, should be selected according to the actual situation and maintain the switchboard.
     Key words: Switchgear temperature rise type test

     With the development of grid technology and equipment to improve, 10,35 kV switchgear in the power grid system has been widely used. Switchgear and internal overheating has become a switchboard in the use of the frequently asked questions, as a result of the switch OEM confined, in some areas of heavy load, the existence of temperature rise over the counter switch problem.

     Switchgear of the temperature rise over a direct impact on safe and stable operation of equipment, and overheating is a continuous process of development, if left unchecked, will continue to intensify the degree of overheating, and pieces of insulation and the performance of equipment generated a lot of life Impact.

     At present, the power system used in switch cabinets, strictly abide by the procurement process equipment and technology policy, to ensure that the network's switchboard through the test pattern, particularly on the temperature rise of more stringent requirements. Run, the load is usually not achieve the switchboard capacity over the design, Switchgear temperature rise of the problems should not be very prominent, but the reality is not quite the case.

     Switchgear an actual temperature rise data analysis

     China-made 1.1 Handcart JYN cabinet

     A substation with type 2, with the parameters of 10kV main switchboard change the relationship between the measured temperature rise and load statistics. Switchgear for a switch plant production in Fujian, JYN1-10 type. Test temperature switchgear cabinet temperature of the surface.

     Data show that with the increase in load, the switch cabinet to speed up the rapid temperature rise. When the load close to 1900A (about Switchgear 2500A rated current 76%), particularly temperature rise, up to 47 ℃, has been sub-standard requirements (for the standard full capacity under the condition of 30 ℃), while the load is low (1200A Below), the temperature rise is not clear.

     China-made 1.2 Handcart KYN cabinet

     10kV substation of a main transformer Switchgear measured the relationship between temperature rise and load statistics, Yangzhou Switchgear for the production of a switch, KYN28-10 type, equipped with circuit breakers VD4. Temperature before the open part of the roof, switch on the counter surface temperature and tank platoon Zhumu temperature at the same time for testing.

     Data show that the mother has been ranked the highest temperature reached 100 ℃, temperature rise of 88 ℃, significantly exceeded (home waiting for the standard temperature rise of 65 ℃). As the temperature rise of the station is quite prominent, this factory for the 10kV substation Switchgear bus No. 1, 2, a new bridge to the production of steel, copper main bus schedule specifications for the replacement of 2 × TMY120 × 10 (the original specifications for the 2 × TMY100 × 10), and further improve the ventilation system.

     The improved temperature rise slightly better, but with the switch cabinet type test data provided by the deviation of temperature rise still higher.

     1.3 The joint venture plant Handcart cabinet source: www.hvsi.cn

     Switchgear factory in a joint venture, Shanghai Co., Ltd. Production of a switch, the model 8BK20, testing for the location of the switchgear cabinet appearance and internal scheduled bus home.

     Here, the temperature rise Switchgear for the time being no standard, but it should be noted that at this time does not reach the rated load capacity of 70%, but close to the maximum temperature rise. This shows that the joint venture plant products, although the situation better than the temperature rise of domestic equipment, but there are also the same temperature rise over the situation.

  Data shows that in the operation of the switchgear actual temperature rise is usually all over the level of laboratory data to measure the temperature rise. Moreover, in most cases when the temperature rise over Switchgear did not even reach full design capacity.

     2 Switchgear real reasons for Analysis of the temperature rise over

     Switchgear actual internal temperature rise, especially in connection row, and other parts of the mother, usually more than test patterns to detect high-data. There are a few reasons:

     (1) type of test data is usually measured in the laboratory to complete, not long duration, usually no more than 8h, does not have the cumulative effect of temperature rise, the same can not be sustained in the long run and heating equipment.

     (2) the expansion of the different effects of different metals. Steel bolt metal expansion coefficient than copper, aluminum smaller bus, in particular the bolt-type connector equipment, in operation with the current load and temperature changes, and its aluminum or copper and iron to the degree of expansion and contraction There are differences arising creep, that is the role of stress in the metal under the slow deformation, the creep process with the joint of the great temperature. Practice has proved that when the joint of the work of running the temperature exceeds 80 ℃, the metal joints will boom and expansion of the location of the staggered so that the contact surface to form a small gap and oxidation. When the load current decrease to lower the temperature back to the original location of the contact, due to the exposure of the oxide film covering, it is impossible for the original installation of direct contact between the metal. Every time the cycle of temperature change in the increase in contact resistance, will enable the next cycle of increasing heat, the increase in temperature and make joint working conditions deteriorate further, creating a vicious circle.

     (3) to connect parts of improper pressure on the fastening bolts. Part of the installation or maintenance staff at the conductor connected to the screw bolts that connect survivors tight as possible, this is not the case. Bus aluminum in particular, the elasticity of small, nut when the pressure reaches a certain threshold value of the pressure, if the material strength of the poor, and then continue to increase undue pressure will be part of the surface deformation caused by contact with uplift, so that instead of reducing the contact area, Contact resistance increases, thus affecting the effectiveness of contact conductor.

     (4) the choice of conductor material does not require electrical conductivity, most of the conductors belonging to the lack of purity of raw materials.

     (5) at the scene of other factors, such as the repair process may be improperly installed, such as the bus in the processing, connectivity, installation, on the bus contact surface not in place, not smooth, not smooth, no fat, such as Tu-specific power, resulting in an effective Contact area to reduce the contact resistance increases and heat.

     3 Conclusion

     Switchgear type of test temperature rise data, does not accurately reflect the operations of Switchgear actual level of temperature rise, especially in the long run relatively heavy load of switchgear, as the cumulative effect of the temperature rise for a long time, in the operation of the actual Switchgear The level of temperature rise usually have more than laboratory measured the temperature rise data. Switchgear factory on the part of the actual operation of the temperature rise has not been compromised in-depth research, such as most of the manufacturers rated for the 3150A Switchgear in accordance with the standard 2500A fans to start in the switchboard of a long period of time after the high-load operation, and then take This standard is unreasonable, the fans usually do not start, already exceeding the temperature rise.

     Therefore, the choice of switching equipment cabinets, can not blindly believe that the factory's laboratory, in running day-to-day maintenance and administration, can not be blindly applied to the laboratory data standards. Practical experience, often also very important. Only the importance of practice and constant for the actual situation analysis to solve the problem, can we really put on the safe operation of equipment, management of the Department to do it.