Common causes of casing cracks are diverse, primarily including the following aspects:
Mechanical Stress
Long-Term Stress: During prolonged use, the conduit may be subjected to continuous forces from various external factors such as the weight of the conductors, wind, electromagnetic forces due to system short circuits, mechanical forces from equipment operation, and vibrations, which can lead to cracks on the surface or inside the conduit.
Improper Installation: During the installation process, excessive mechanical stress on the sleeve, such as overly tight fasteners causing excessive stress on the porcelain components, may also lead to the formation of cracks.
Section II: Temperature Fluctuations
Thermal Expansion and Contraction: The casing material will undergo thermal expansion and contraction with temperature changes. If the temperature fluctuation is significant or frequent, it may lead to stress concentration inside the casing, which in turn could cause cracking.
Extreme Temperatures: Under conditions of extreme heat or cold, the performance of casing materials may change, such as increased brittleness or reduced toughness, making cracks more likely to occur.
Chemical Erosion
Environmental Pollution: Long-term exposure of casing to the air may lead to erosion from acidic rain, salt fog, and other chemicals, resulting in degradation of material properties and the formation of cracks.
Internal Corrosion: The presence of moisture or corrosive gases within the casing can also cause corrosion to the casing material, potentially leading to cracks.
Manufacturing Defects
Material Issue: The casing may contain material defects during the manufacturing process, such as impurities and bubbles. These defects may gradually expand over time during prolonged use, forming cracks.
Manufacturing Issues: Inappropriate manufacturing processes, such as uneven firing temperatures or rapid cooling speeds, may also lead to casing cracks.
V. Other Factors
Electrical Factors: Electrical phenomena such as corona discharge and localized overheating may also cause damage to the insulating sheath, leading to cracking.
Human factors: Improper maintenance or external damage may also lead to casing cracks.
