12 October 2023

Traction Transformer Insulation Designed for the Rail Infrastructure of Tomorrow

How do Weidmann’s products withstand different thermal classes to help increase efficiency, reliability, and safety for On-Board Traction Transformers and support insulation cost optimization?

As railway electrification continues to grow rapidly in response to environmental pressures for the rail sector to use green energy, the role of traction transformers is also growing. The power systems of electrified railways rely heavily on traction transformers to provide a reliable and safe power supply while withstanding high temperatures and huge variances in load conditions.

The quality and type of transformer insulation material are significant factors in enabling traction transformers to withstand changes in temperature and load conditions. Traction transformers containing Weidmann’s insulation materials are contributing to improving electricity quality and railway transportation safety. This becomes even more significant as we move towards increasing high-speed passenger transport and loading cargo transport levels.

Thermal classes and benefits of Weidmann products

Thermal class and thermal index are used to describe insulation systems’ temperature rating in liquid-immersed transformers. Both terms describe the temperature rating of such insulation systems concerning the maximum allowable hottest spot winding temperature. Thermal Class specifically can be defined as the maximum hottest spot winding temperature under ‘Normal life expectancy loading’, which considers daily and annual load cycles.

As a transformer’s life is limited to the life of its solid insulation, many studies have taken place on different thermal upgrading methods. Developing insulation materials and components that are able to withstand different levels of temperatures (from 105°C up to 180°C) allows the manufacturer to optimize the design and cost of their transformers.

A high thermal rating product in a given insulation liquid provides several advantages:

  • Longer transformer life
  • Reduced initial and total ownership cost
  • Reduced transformer weight
  • Increased kVA output in the same footprint
  • Increased overload capacity

Choice of material and material of choice

In collaboration with Dupont, Weidmann is the leading supplier of Nomex® high-temperature thermal insulating products. This means that we cannot only offer a wider range of board and paper products suitable for on-board traction transformers but also reassure our customers that our products are rigorously tested with continuous adherence to industry standards.

Reduced size and weight

Trends in train design mean that transformer size and weight are getting smaller. Where customers need to find a solution to saving space and weight, especially in high-speed trains, Weidmann’s lightweight and high-temperature insulation products offer a unique combination of dielectric strength and mechanical support with a higher thermal capacity.

Long term reliability

Weidmann’s range of Nomex®, composite components, and cellulose papers and boards are designed to reduce lifecycle costs and provide safety benefits. By including the use of these insulation products in the design of an on-board traction transformer, not only can they offer greater power density, but they also have the ability to withstand load variations and severe overloads. In addition, our high-temperature insulating materials are highly resilient and stable, helping liquid-immersed transformers operate reliably over an extended lifetime.

The infrastructure of tomorrow

As the railway industry continues to open new lines and expand capacity, there is an increasing need for high-performance rail electrification. The success of developing the rail infrastructure while improving energy usage is largely met by finding new and innovative solutions. Weidmann’s product portfolio, comprising composite component solutions, thermally upgraded papers, Nomex® papers, and board, helps the rail industry to move towards more efficient and sustainable transport options.

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