What Is Aromatic (Aramid) Paper Insulation?

Published 27 Aug 2026Updated 27 Aug 20265 min readIntermediateInsulation
Quick answer — Aramid (aromatic polyamide, e.g. Nomex) paper is a high-temperature, high-strength insulation used where a higher thermal class or better mechanical/thermal endurance is needed than standard kraft paper — for example in dry-type and high-class transformers, and in the hottest spots of a liquid-filled unit. It is class H (180 C) capable and very tough.
Contents
What is aramid / aromatic paper insulation and when is it used?

What it is

Aramid paper is made from aromatic polyamide fibres and is supplied in various grades and thicknesses. It has excellent thermal (class H, 180 C) and mechanical properties.

Where it is used

Dry-type transformers and high-temperature insulation, and in liquid-filled units at the hottest spots, on lead exits, and where higher mechanical strength is needed.

Trade-off

It is more expensive than kraft or pressboard but allows a higher operating temperature and longer life, so it pays off where load and temperature are high.

References & standards

Related

Book seriesAcademy

Related manufacturers

Prolec GE (GE Vernova) · Eaton · Virginia Transformer Corp · Delta Star · WEG Transformers USA · LS Electric America

Related components

Insulation materials
Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.
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