Characteristics of toughened glass insulators:
1.1 Zero value self-explosion:
"Zero-value self-explosion" is the most significant feature that distinguishes glass insulators from porcelain insulators and composite insulators. This is caused by the uneven distribution of tempering stress in the glass. "Self-explosion" is a beneficial feature for transmission line inspection, because after self-explosion, all the glass of the insulator umbrella plate falls off, and the defects are obvious. When inspecting the line from the ground or by helicopter, it is easy to find the operating quality of the glass insulator. , if the glass parts are intact, everything is normal. Therefore, the product's zero-value self-explosion makes maintenance of transmission lines simple - only visual inspection is required, providing a strong guarantee for the safe operation of transmission lines.
1.2 Long lifetime:
Glass is an amorphous material in which silicate is melted at high temperature (1500°C). It has a dense structure and uniform texture. After tempering treatment (760-780°C), its surface obtains a layer of evenly distributed permanent compressive stress, and its inner layer is evenly distributed. The tensile stress, this compressive and tensile stress are collectively called the tempering internal stress, which will not decrease with the extension of the product's operating time. Therefore, there is a scientific basis for glass insulators to have a long life cycle and not easy to age.
1.3 Resistance to vibration fatigue and frost damage:
During the operation of overhead power lines, the insulators bear the action of mechanical forces such as wire load and wind force. This mechanical force is often transmitted to the insulator in the form of various vibration waves, which has a greater impact on the fatigue aging of the insulator over time. Using imitation wire vibration fatigue tests, it was measured that the electromechanical strength of glass insulators has basically remained unchanged after 15 million vibration tests, while the electromechanical strength of porcelain insulators has a significant downward trend, and the electromechanical strength of porcelain insulators has been unqualified .
It is worth mentioning that the insulator strings are connected in series with glass aerodynamic products , which is an effective measure to prevent the formation of icicles in the insulator strings and avoid ice flash accidents.
1.4 Arc resistance (large current) :
During multiple arc tests , it was found that the performance of tempered glass insulators was superior , and a larger number of porcelain insulators were damaged during the experiment .
Line operation practice shows that when struck by lightning, the surfaces of the three types of insulators (ceramic insulators, composite insulators, and glass insulators) will have burns. The glaze layer on the surface of the porcelain peels off, exposing the rough porcelain body, which easily absorbs moisture and accumulates dirt, is difficult to wipe off, and accelerates the aging of the porcelain body. Although a thin layer (thickness about 0.1~0.2mm) is peeled off on the surface of the glass insulator , the new surface is still It is a smooth glass insulator , and the mechanical and electrical properties are not damaged. As long as the arc does not burn the iron cap and steel feet, the burned glass insulator can still be used; the composite insulator cannot withstand the above-mentioned arc resistance test, that is, the arc burns the core rod and silicon When the rubber umbrella disc is damaged, the product cannot be used anymore.
1.5 No preventive testing is required :
Toughened glass insulators have the characteristic of "zero value self-explosion". The product does not need to undergo defensive tests (such as shaking insulation and withstand voltage tests) before installation. The detection of insulators running on lines can also be simplified, which not only reduces labor strength, and improves the reliability of safe operation of transmission lines.
1.6 The capacitance is large and the voltage distribution is uniform:
Toughened glass insulators have a larger main capacitance than porcelain insulators of the same grade , and the voltage distribution of the glass insulator strings is relatively uniform, which is beneficial to reducing the voltage endured by the insulators near the conductor side, improving the electrical performance of the insulator strings, and reducing the voltage of the transmission line. It is very beneficial to reduce halo loss and radio interference, and can correspondingly extend the service life of glass insulators.
1.7 Good wind and sand prevention performance :
Desert areas have harsh operating conditions such as dry weather with little rain in the morning, high surface temperatures in summer, and sandstorms. Ceramic insulators operating in such areas have serious damage to the porcelain body due to cracks in the enamel and traces of sand and dust on the surface. The core rod and silicone rubber shed of organic composite insulators cannot continue to operate after being damaged by sand. Due to the protective layer of tempered internal stress on the surface of the glass insulator, it can withstand the intense heat of the desert surface and resist the invasion of storm sand particles.
1.8 Environmentally friendly:
In the production process, glass insulators have fewer processes (10 processes, 18 processes for ceramics ) , short cycle (6 days , 19 for ceramics ) , easy to implement mechanized and automated production, easy product inspection (glass is a transparent body) and waste products can be recycled Take advantage of advantages. Currently, natural gas is used for glass melting, which is a clean energy source with high calorific value and no pollution to the atmosphere after full combustion.
The above is taken from the Journal of Electric Power Construction, Volume 30, Issue 9. " Excellent Characteristics of Tempered Glass Insulators "
Author: WANG Li-Lei, GU Hong-lian