polymer insulator


What is polymer insulator?

Polymer insulator is a kind of insulator with polymer insulation parts, and it is also named also named composite insulators, silicone rubber insulator. Usually, the insulation parts are made of silicone rubber, Al(OH)3 and fillers. This kind of insulators have the same function of glass insulators and ceramic insulators, when applied for power systems with a voltage over 1000V.

polymer insulator

Classification of polymer insulators

When classified by how the insulators are applied, they can be classified into:

  1. Polymer suspension insulator
  2. Polymer tension insulator
  3. Polymer line post insulator
  4. Polymer station post insulator
  5. Polymer pin type insulator
  6. Polymer spacers

When classified by power system voltages, they can be classified into:

  1. High voltage insulator (< 69 kV)
  2. Medium voltage insulator (≥69 kV)
  3. Ultra High voltage insulator (≥800 kV)


Also insulators are classified by their insulation materials. There are three kinds of most popular insulators in the market now. Among them polymer insulators are become more and more popular now. Due to its advantages. 

  1. Polymer insulators
  2. Ceramic (porcelain) insulators
  3. Glass insulators

Advantages of polymer insulators

Problem Disk Ceramic Insulator Disk Glass Insulator composite long rod insulator
Lightning ♦♦
Flashover ♦♦
Bird broken ♦♦ ♦♦
Windproof ♦♦ ♦♦
String breakdown and fallen ♦♦♦ ♦♦♦ ♦♦♦
Aging ♦♦ ♦♦♦ ♦♦
Damage by force ♦♦♦
Easy for Maintainence ♦♦♦


1.    Easy to maintenance

Porcelain insulators have zero breakdown, zero detection and zero replacement problems, they need to be checked every once in a while. But polymer insulators don’t have such problems. They nearly don’t require maintenance after the installation, which greatly reduces maintenance costs.

2.     Excellent stain resistance

The good anti-pollution flashover performance of polymer insulators is an important reason for its rapid development. Pollution flashover of insulators caused by surface contamination is the main threat to the safe operation of the power grid, and is also a decisive factor in the selection of power transmission line insulators. The surface of the porcelain insulator is a high-energy surface, which forms a continuous water film after being infiltrated by water. At the same time, it is subject to pollution and is prone to pollution flashover. Therefore, manual cleaning or smearing of silicone rubber paint should be adopted in daily operation.

According to statistics, Henan Power Grid of China has experienced two large-scale pollution flashover accidents in the past twenty years. In the large-scale pollution flashover accidents in 1990 and 2001, porcelain insulators flashed 104 times, accounting for 67%; glass insulators flashed 50 times, accounting for 32%; and composite long rod polymer insulator only flashed 1 time due to ice coating, accounting for 1 %.

3.  Mechanical behavior

The axial tensile strength of the glass fiber mandrel used in polymer insulators is very high, generally above 600MPa, and the tensile strength of the latest ECR acid-resistant mandrel is above 1000MPa, which is 5 - 10 times the strength of high-quality carbon steel. But the mass per unit length of the mandrel material is much lighter than both porcelain and steel. 

4.    Anti-aging properties

Porcelain insulators have nearly a hundred years of operating experience and have strong anti-aging capabilities. For a long time after being put into operation, if zero damage does not occur, aging and replacement can be ignored. Polymer insulators belong to organic material insulators. Under the influence of the atmosphere, high and low temperature, ultraviolet rays, strong electric fields or other factors during operation, the organic materials in the shed sheath will age and deteriorate, resulting in poor insulation performance of composite insulators. Reduced, affecting the service life of composite insulators. However, from the current operating experience, the use of composite long rod polymer insulator can generally reach more than 10 years.

5.    Economic performance

According to relevant calculations, whether it is a new line or an old line update, the use of polymer insulator is more economical than porcelain insulators, and the later operation and maintenance workload of composite insulators is small, and zero-value detection is not required.