Application of insulation material in transformer
The insulation level of power transformers should meet the requirements of overvoltage and long-term maximum working voltage in operation, and is related to insulation coordination. According to the requirements of the national standard GB1094.3, Zhongtian Electric Equipment Group, according to the insulation level of oil immersed power transformers, has the following requirements:
Electrical performance. In order to enable power transformers to run for a long time under rated operating voltage and withstand potential overvoltages of various power systems, the national standard “first parts of insulation coordination: definitions, principles and rules” stipulates the insulation coordination and test voltage of various voltage grade equipment in GB311.1-2012. Such as power transformer AC withstand voltage, induction withstand voltage and impact withstand voltage test.
Among them, the short-time (1min) power frequency withstand voltage test of all kinds of equipment is mainly to test the main insulation, the rated operating impulse withstand voltage can test the longitudinal insulation of transmission and transformation equipment. In order to make the long-term operation of the power transformer reliable enough, the induction pressure test is carried out on the discharge situation of the internal local defects, and the test can also be used to detect the longitudinal insulation of the transformer.
Mechanical properties. When the transformer is running normally, the mechanical stress of the winding is very small, but when the short circuit occurs, the huge short-circuit current will generate great electric force. The electric power may destroy the insulation of the transformer, such as deformation and crack, and eventually lead to the accident. So when choosing insulation materials, we must consider the effect of mechanical stress under extreme conditions.
Thermal properties. The insulation performance of insulating materials is closely related to temperature. The higher the temperature, the worse the insulation performance of insulation materials. In order to ensure insulation strength, each insulating material has a suitable maximum allowable working temperature. Under this temperature, it can be used safely for a long time, and the temperature will be aging quickly over this temperature.
Most of the tapeid materials in the oil immersed transformer belong to a grade, the national standard “second parts of the transformer of power transformer” GB1094.2 1996, GB1094.3.5-2003 power transformer; in GB/T6451-2008, there are related three phase oil immersed power transformer technical parameters and requirements. With the increase of system capacity and the increase of voltage grade, the total capacity of power transformer in power system has risen to more than nine times or even higher of the installed capacity of the generator. The stability of power transformer will affect the operation reliability of the power system.
In the process of operation, one of the main reasons for the failure of power transformers is the problem of insulation. So the analysis and research of insulation technology plays a very important role in the design, manufacture of power transformers and the safety, economy and stable operation of the power transformer. Zhongtian Electric Equipment Group is committed to the development, production and processing of insulating materials and engineering plastics. The business scope is radiated throughout the country and has a certain market position in the insulating material industry. Zhongtian Electric Equipment Group is looking forward to your cooperation!