Insulation paint aging refers to the long-term effect of electric field, temperature, mechanical force, humidity, ambient environment and other factors, so that the quality of electrical equipment insulation gradually decreases during operation and the structure gradually damages. The speed of insulation aging is closely related to the insulation structure, material, manufacturing process, operating environment, voltage, and load conditions. Insulation aging eventually leads to insulation failure and power equipment cannot continue to operate. In order to prolong the service life of power equipment, it is necessary to take appropriate measures to slow down the process of insulation aging in response to the cause of aging, during the manufacture and operation of power equipment insulation. Causes of insulation aging can be attributed to the role of electricity, thermal effects, chemical effects, mechanical force effects, humidity and so on.
According to the test, due to the combined effects of voltage rise time, cable length, and switching frequency at the output of the inverter, the peak value of the above-mentioned terminal voltage can exceed 3 kV. In addition, when a partial discharge occurs between the motor winding turns, the electrical energy stored in the distributed capacitance of the insulation becomes thermal, radiant, mechanical, and chemical energy. As a result, the entire insulation system deteriorates, and the breakdown voltage of the insulation decreases. The insulation system is broken down. Insulation accelerated aging caused by cyclic alternating stress is powered by variable frequency power supply, so that the frequency conversion motor can be started at very low frequency, low voltage, and no inrush current, and can be quickly performed by various means provided by the inverter. brake. Because the frequency conversion motor can realize the frequent starting and braking, the motor insulation is frequently under the cyclic alternating stress, which accelerates the motor insulation aging.
Problems existing in ordinary asynchronous motors due to electromagnetic excitation force, mechanical transmission, etc., become more complicated in frequency conversion motors. Various time harmonics contained in the variable frequency power supply interfere with the inherent spatial harmonics of the electromagnetic part to form various electromagnetic excitation forces. At the same time, due to the wide operating frequency range of the motor and the large change in rotational speed, resonance occurs when it is in agreement with the natural frequency of the mechanical part. Under the influence of electromagnetic excitation force and mechanical vibration, the motor insulation is subjected to more frequent cyclic alternating stress, which accelerates the aging of the motor insulation. Insulation strengthening measures for frequency conversion motor According to the above-mentioned insulation damage mechanism of frequency conversion motor, the measures to strengthen the insulation structure of variable frequency motor are: use appropriate electromagnetic wire, adopt reasonable processing technology, obtain no air gap insulation, and improve the integrity and mechanical integrity of the entire insulation structure. strength. Select the appropriate electromagnetic wire As mentioned before, the electromagnetic wire in the variable frequency motor is under the action of a large number of harmonics and high frequency pulse voltage, so that the electromagnetic wire is damaged early. Therefore, the influence of the insulation performance of the magnet wire on the reliability of the insulation structure of the variable frequency motor is particularly important.
Insulation paint materials in the process of use due to various factors of long-term effects of chemical changes and physical changes, so that electrical and mechanical properties deteriorated, known as aging, there are many factors affecting the aging of insulating materials, mainly thermal factors. If the temperature is too high during use, the aging process of the insulating material will be accelerated. Therefore, various insulating materials are provided with the limit temperature during their use, so as to delay the aging process of the insulating material and ensure the service life of the electrical product.
The type is usually divided according to the aging mechanism and aging factor.
1. Heat aging: The most basic form of aging caused by long-term heat effects.
2. Thermal oxidation aging: It is an aging form caused by the long-term effects of heat and oxygen in the air.
3. Photo-aging or photo-oxidation aging: If the insulating material is used in an outdoor environment, photo-oxidative aging occurs under the long-term effect of light and oxygen of the material, which is a main form of aging of the outdoor insulating material.
4. Ozone aging: There is ozone in the air, especially in the polluted atmosphere.
5, chemical first: material in water, solvents, acids, alkalis and other chemicals caused by the long-term effects of aging, such as hydrolysis, epoxy stress cracking and so on.
6. Biological aging: Insulating materials in the insulation of electrical products (motors, wires, etc.) are often damaged by some organisms, such as rat bites and termites, especially when microorganisms multiply in a hot and humid environment, causing decomposition of materials.
7. Fatigue: The material gradually deteriorates under the repeated action of mechanical force.
8, high-energy radiation aging; high-energy radiation, including X-ray, Y-ray, a and B particle flow, the body line and so on.
9, electrical aging: This is a unique form of aging of the insulating material. It is an aging caused by long-term effects of high voltage or high electric field strength.
10. Atmospheric aging: Actually includes aging caused by various factors that can be encountered in outdoor environments, including photooxidative aging, chemical aging, and microbial aging.
September 26, 2021
