IEC 60394-1: Impregnated Fabrics for Electrical Purposes — The “Paper” Standard in Transformer and Motor Insulation

Transformer Insulation Paper Is Not Ordinary Paper — It Is Vacuum-Impregnated Cellulose or Aramid Fibre

IEC 60394-1:1972 specifies impregnated fabrics for electrical purposes. The “insulation paper” used in transformers and motors is actually specialty cellulose (Kraft) or aramid (Nomex) fibre thin-layer material, vacuum-impregnated with oil or resin to fill inter-fibre micro-voids and eliminate partial discharge initiation sites. Unimpregnated paper ages rapidly from air discharge in micro-voids under HV.

TNLab — The transformation of transformer insulation paper from wood to finished product determines the transformer life ceiling.