Insulators are categorized by installation methods into suspension insulators and pillar insulators; by the type of insulating material used, they can be porcelain, glass, or composite (also known as synthetic) insulators; by voltage class, they are divided into low-voltage and high-voltage insulators; by environmental conditions, there are dirt-resistant insulators for polluted areas; by voltage type, there are DC insulators. Additionally, there are insulators for special purposes, such as insulating crossarms, semiconductor glaze insulators, tension insulators for distribution, reel insulators, and wiring insulators, etc. Moreover, they can be further classified into A-type insulators that cannot be punctured and B-type insulators that can be punctured, based on the possibility of insulation breakdown.