Insulation Tapes

Electrical Paper

Name: Electrical Paper
Brand: OR64

Cellulose-based dielectric insulation for transformers, cables and electrical machines

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Product

Electrical Paper

Electrical paper is a pure-cellulose insulation material made from unbleached, additive-free sulphate kraft wood pulp. Its homogeneous fibrous structure delivers high dielectric strength, excellent compatibility with insulating oils and liquids, and enough mechanical strength to withstand winding stresses and in-service operation. The properties of electrical insulation paper are governed by IEC 60641.

Bobinas de cinta de papel eléctrico kraft aislante

IEC 60641 Pure kraft cellulose, unbleached, no additives

150–180 % Oil absorption during vacuum impregnation

Turns and layers Insulation in oil-immersed transformers

65–155 g/m² Papers for high-voltage submarine cables

In application

The absence of metallic elements, sand or conductive substances ensures high resistance to folding and tearing, plus dimensional stability throughout the equipment's lifecycle. Electrical paper has no defined melting point, allowing it to withstand short-term thermal stresses up to 350°C without catastrophic degradation.

Selection guide

How to choose the right one?

Selection of the electrical paper depends on the application, the manufacturing process and the operating conditions. The main types differ in structure and mechanical properties.

Electrical paper types

Type	Structure	Main application	Characteristics
Kraft paper	Smooth, long-fibre	Conductor covering, layer insulation	High tensile strength, good impregnation
Crepe paper	Crinkled surface	Irregular geometries, complex windings	High elongation (15–300%), conformability
Presspan paper	Calendered, high density	Structural separators, barriers	Greater thickness, mechanical stiffness
DDP paper	With epoxy resin dots	Power transformer windings	Layer bonding, short-circuit strength

Selection by application

Application	Recommended type	Typical grammage	Notes
Power transformers (oil)	Kraft, DDP	25–120 g/m²	Impregnation with dielectric oil
Distribution transformers	Kraft, Crepe	40–80 g/m²	Thermal class A (105°C)
MV/HV impregnated cables	Kraft	65–155 g/m²	High dielectric strength
Motors and coils	Presspan	Variable	Thermal class B (130°C) available
Food packaging	Special kraft	Per application	Consult specific grades

Technical data

Technical specifications

Values indicated correspond to typical industry ranges per IEC 60641. Exact specifications available on request by reference.

Typical mechanical properties

Property	Kraft paper	Crepe paper	Standard
Grammage	25 – 180 g/m²	25 – 180 g/m²	IEC 60641
Thickness	0.05 – 0.50 mm	0.35 – 0.90 mm	IEC 60641
Elongation	2 – 5%	15 – 300%	IEC 60641
Tensile strength	High	Medium-High	IEC 60641

Typical electrical properties

Property	Typical value	Notes
Dielectric strength	10 – 12 kV/mm	Dry paper; improves with impregnation
Resistivity	High	Varies with moisture and impregnation
Dissipation factor	Low	Improves with oil impregnation

Thermal properties

Property	Value	Notes
Thermal class A	105°C	Continuous service, standard kraft paper
Thermal class B	130°C	Calendered presspan
Short-term resistance	Up to 350°C	No defined melting point

Composition

Property	Description
Base material	100% sulphate cellulose (kraft pulp)
Bleaching	Unbleached
Chemical additives	No additives, sizing or fillers
Conductive particles	Free of metallic elements

Degree of polymerisation (DP): The degree of polymerisation per IEC 450 characterises the paper's condition and remaining service life. New kraft paper shows DP between 1000 and 1500. During transformer operation, DP decreases progressively; end of service life is conventionally considered to occur at DP ≈ 200. Values shown are indicative. Consult exact specifications by reference and application.

Customization

Available variants

By paper type

Plain kraft — conductor covering
Crepe — high elongation for complex geometries
Presspan — structural barriers and separators

By thermal class

Class A (105°C) — standard applications
Class B (130°C) — applications with higher thermal demand

Special formats

DDP paper (Diamond Dotted Paper) — with epoxy resin dots for power-transformer windings

Supply

Delivery formats

Reels / Rolls

Width range Per customer specification

Core ID 76 mm, 152 mm (others on request)

Format Rolls, reels

Slit tapes

Width From 10 mm up to jumbo width

Format Pad, spool

Other formats and dimensions available on request. Custom slitting service available.

Applications

Application sectors

Aplicaciones típicas

Aplicación	Función del producto
Oil-immersed transformers	Insulation of conductors and between layers
Impregnated MV/HV cables	Dielectric barrier, separation
Electric motors	Slot and inter-turn insulation
Coils and windings	Layer-to-layer separation, insulation
Capacitors	Impregnated dielectric

Complements

Available transformation services

Custom slitting

Up to 1200 mm width, ±0.50 mm tolerance

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Spooling

Conversion to formats matched to the production line

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We process material from our stock or material supplied by the customer.

Need
technical advice?

Our technical team is available to help you select the optimal material for your application.

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Local stock in Barcelona · Availability on request

Electrical Paper

Electrical Paper