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SF6 insulated Voltage Transformers

SF6 insulated voltage transformers are used to convert high transmission line voltages (up to 800kV) to standardized low and easily measurable values, which will be used for metering, protection and control of the high voltage system. As such, the need for accurate and reliable voltage transformation is essential.

The reliability and security of Trench gas-insulated instrument transformers is based on over 50 years of innovation with gas-insulated units operating under a wide range of environmental conditions. Voltage transformers also ensure suitable electrical insulation between high voltage and low voltage measuring equipment.

Our gas-insulated voltage transformers are compliant to the latest international safety standard requirements in terms of explosion-proof, insulating material multiple chopped ageing, seismic qualification and extreme temperature conditions.

Modern production and testing facilities guarentee not only short delivery times but also a reliable operation for many years.


More than

units of GIS & GIF instrument transformers

supplied by Trench every year.

Thousands of SF6 insulated inductive voltage transformers installed and in service for more than 50 years all over the world and in all environmental conditions are the best guarantee of the quality and reliability of our products.


  • Complete portfolio available from 72 to 800 kV
  • Meet all lEC and ANSI metering and protection classes
  • Rated primary Voltage up to 800 kV
  • Rated Secondary Voltages:
    100 V, 100:i/3 V, 100:3 V, 110 V, 110:i/3 V, …
  • Suitable also for Une Discharge use
  • Wide-range ferroresonance-free design without the use of an external damping device
  • Fully type tested according to international standards
  • Special tests are also available to meet specific customer requirements.

Product Design

  • SF6 is the main insulation medium
  • Explosion-proof design
  • External insulation with composite insulator; porcelain insulator available an request
  • External parts made of aluminum or stainless materials
  • Available to withstand:
    • Internal arc effects [according to IEC 61869 -protection stage 1]
    • Heavy seismic solicitations, according to IEC 62271, IEEE 693 and specific customers’ requests

-98Product Process

  • Optimized design to manufacturing
  • Lean manufacturing concept applied to the whole supply chain
  • Modular design allows the use of reduced numbers of components
  • Partial discharge free design and process
  • Maintenance free during a lang lifetime of more than 30 years
  • Trench Management System has been certified to ISO 9001, ISO 14001 and OHSAS 18001 standards
  • Testing laboratory accredited according DIN EN ISO/IEC 17025

Mechanical and electrical data

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