To isolate laterals used electrical insulating crepe paper with EKTM cross crepe (ripple), 0.44 mm thick and is supplied in rolls of a width of 1000 mm. It has a high dielectric strength (25 kV / mm in transformer oil at 90 . 5 C), oil resistance and flexibility. Another major insulation in high voltage transformers used electrical insulating board (Insulating), which are manufactured, as well as cable paper from wood pulp. Depending on the thickness of the electrical strength of insulation in the air from 7 to 15 kV / mm in a hot (90 C) transformer oil (after pre-vacuum drying and soaking in a dry transformer oil) at (100 5) C from 30 to 55 kV / mm; its dielectric permeability of 4.3-4.5.

Insulating designed to work in the oil at operating temperature of 105 C, characterized by high mechanical strength, low shrinkage after drying, resistance to stress in the direction perpendicular to the surface, as well as to the effects of surface discharges and produced five brands of AM, A, B, C, D. glass fabrics are used to mark LSMM-105/120 voltage dry-type transformers in 1000, marks LBP-120 / 130 – for the same transformers, but up to 1000 (to isolate the branches and junction). Glass fabrics produced thickness 0,12-0,24 mm in rolls of a width of 690-1140 mm. The letters I figure varnished fabrics in grades mean: A – varnished cloth, X – based on cotton, M – treatment based on an oil varnish, B – on the basis of bitumen-oil varnish, the second letter M – oil resistant, and C – based on glass, 105 – the temperature on heat resistance. Insulating tape is used for mechanical protection basic insulation of live parts. Insulating tape cotton taffeta brands of T-10-18 to T-50-39 0.25 mm thick and 10-50 mm in width and grades of kipernuyu K-S-2 to K-50-17 (with kipernym weave in " Christmas tree ") with a thickness of 0.45 mm and a width of 10-50 mm use in oil transformers.