Insulators - Innovative solutions for substations and overhead lines

PFISTERER offers insulators for all applications in overhead line systems, substations, plant engineering, railway infrastructure and rail vehicles. The focus is on composite insulators with silicone rubber as the sheath material.

Composite insulators since 1975

PFISTERER has been producing composite insulators for more than 40 years. Our well engineered products are able to meet all challenges, as a result of continuous optimisation based on operating experience and the knowledge gained from many years of involvement in CIGRE and IEC working groups. PFISTERER has always used exclusively silicone rubber as a shield material – mainly high temperature vulcanising (HTV) silicone rubber.



  • Hydrophobic and self-cleaning
  • Lightweight
  • Impact resistant
  • Easy installation
  • Low maintenance
  • Less prone to vandalism

Three product lines

Today, PFISTERER’s portfolio comprises three main product lines: Silcosil (injection moulded), Silcosil (modular production) and Rodurflex composite insulators.


Silcosil composite insulators are manufactured in an injection moulding process. The automated continuous injection moulding (ACIM) process has been refined by PFISTERER to enable the production of insulators of any length. The ability to rotate the insulators to offset the mould seam enhances their reliability in heavily polluted environments.

Our innovative production lines have also been designed for special requirements such as the need for a longer creepage distance, insulators for compact lines, and insulators for DC applications.

Silcosil (modular)

The modular system combines the benefits of silicone rubber technology with easy adaptation for specific insulator dimensions, particularly the relationship between creepage distance and arcing distance. As an ideal complement to the production of standard insulators, the modular system is a preferred and proven alternative for DC applications that require a long creepage distance. In addition, the modular system is used for special designs and small production runs.


Rodurflex composite insulators are manufactured in a modular process. It combines the benefits of HTV silicone rubber technology with a high degree of flexibility for producing customised insulators.

PFISTERER isolators are designed in great detail and customized. Our test procedures during and after production confirm this.

The PFISTERER portfolio:

Long-rod insulators

PFISTERER insulators for overhead lines are manufactured according to international standards and customer specifications for applications in power distribution and transmission, in various load classes up to 1,500 kN. PFISTERER also designs and produces complete insulator strings.

Voltage level: up to 1,100 kV
Rod diameter: up to 63 mm
Load class: up to 1,500 kN
Flexible creepage distance dimensioning up to 55 mm/kV
End fittings compliant with IEC 60120, IEC 60471, ANSI C29.9, ANSI C29.12 and special designs

Suspension and tension towers for high voltage grids and railway grids
Insulator strings

Post insulators

PFISTERER’s product range includes insulators for vertical installation as well as post insulators with various configuration possibilities for the top and bottom fitting. Our post insulators are mainly exposed to compression, bending and torsional forces in service, and are specially designed for this.

Voltage level: up to 550 kV
Rod diameter: up to 170 mm (6.5")
Bending forces: up to 50 kNm
Flexible creepage distance dimensioning up to 55 mm/kV
Standards: DIN, IEC and ANSI flange designs

Equipment engineering
Plant and substation construction
Compact lines

Hollow insulators

PFISTERER hollow insulators are manufactured according to our customers’ requirements and in conformity with IEC, ANSI and other standards. They are used in explosion-proof switchgear, which is often exposed to adverse air pollution and weather conditions in use.

Thanks to their design and high quality materials, PFISTERER hollow core insulators withstand such conditions for many decades. Compact and lightweight, they make an essential contribution to the construction of switchgear of the highest quality and reliability.

Voltage level: up to 1,100 kV
Single-piece up to 8 m, multi-piece designs available
Maximum core rod external diameter: 580 mm
Creepage distance dimensioning up to 31 mm/kV

Equipment engineering
Plant and substation construction
Surge arresters
Cable terminations