A helicoidal guide insulating material for windings from aluminum foils, in particular for dry transformers of temperature classes f and h

摘要

An insulating material usable as an insulation for windings of aluminium foil (14) of a coil comprises a compound material comprising a porous carrier material (10) not shrinking in heat, mica paper (11) and a curable reaction resin, the material being so deformable in thickness by the pressure stresses arising during winding of the coil under tension that an intimate contact of the material with the aluminium foil (14) occurs at both sides and at all places. The quantity of resin is chosen so that a secure bonding with the foil is achieved at both sides and that the insulating material itself has a sufficiently high mechanical strength and a higher linear thermal coefficient of expansion perpendicularly to the layer direction than the aluminium foil. IMAGE