Insulators are categorized by installation methods, including suspended insulators and pillar insulators; by the insulation material used, they can be porcelain, glass, or composite (also known as synthetic) insulators; by voltage grade, 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; and there are various special-purpose insulators, such as insulating crossarms, semiconductor glaze insulators, tension insulators for distribution, reel insulators, and wiring insulators. Additionally, based on the possibility of insulation breakdown, they can be classified into A-type, non-breakdown insulators, and B-type, breakdown-insulators.