In the actual selection and application of ultra-high voltage (UHV) projects, factors such as operating environment and safety risks must be comprehensively considered. Disc-type suspension porcelain insulators are puncture-prone insulators, and deterioration occurs with increasing operating time, potentially turning into low-value or zero-value insulators. When lightning strikes or pollution flashovers occur on insulator strings containing low-value insulator discs, the power frequency follow current passing through the heads of the low-value insulator discs may cause the iron caps to explode, the insulator string to break, or even the conductor to fall to the ground-a major accident. Porcelain insulators damaged by lightning strikes with peeling glaze must be replaced.
Selection Principles: For lightly polluted areas, double-umbrella type porcelain insulators or ordinary glass insulators can be used for suspension strings, V-string strings, and tension strings. For moderately or severely polluted areas, composite insulators are generally used for suspension strings and V-string strings, while double-umbrella type porcelain insulators or ordinary glass insulators are preferable for tension strings. In areas prone to heavy icing, the performance of composite insulators deteriorates significantly after icing. Therefore, double-umbrella porcelain insulators or ordinary glass insulators are preferred, with suspension strings, V-strings, and tension strings all suitable options. In high-altitude areas, composite insulators are generally used for suspension and V-strings, while double-umbrella porcelain insulators or ordinary glass insulators are preferred for tension strings. Triple-umbrella porcelain insulators offer better resistance to pollution flashover, but their more complex structure and higher cost limit their widespread practical application compared to double-umbrella porcelain insulators.
Special Applications: Suspension grounding porcelain insulators for overhead lightning protection wires can be used in high-voltage or ultra-high-voltage transmission lines. Under normal operating voltage, the lightning protection wire is insulated from the ground, effectively reducing energy loss in the transmission line and allowing for communication. Under atmospheric overvoltage, the protective gap conducts, grounding the lightning protection wire and effectively protecting the line and equipment.
