Electrical Grade Crepe Paper & Tube Manufacturer in India

Key Properties of Electrical Grade Crepe Paper

• High stretchability (10–30% crepe ratio) — conforms to bends, curves, and irregular shapes on transformer leads and bus bars without tearing, eliminating insulation gaps
• Excellent oil absorption (oil impregnation) — cellulose structure absorbs transformer oil fully during vacuum drying, increasing dielectric strength from ~10 kV/mm to up to 30 kV/mm
• High dielectric strength — reliable electrical isolation under sustained high-voltage stress in both oil-filled and dry insulation systems
• Good tensile and tear resistance — withstands the mechanical stress of hand and machine wrapping without splitting, even at high crepe ratios
• Thermal stability — retains physical and electrical properties through the thermal cycling experienced in transformer operation (typically up to 105°C continuous)
• Uniform crepe structure — consistent crinkle depth and spacing across the full roll width, ensuring predictable stretch and even insulation build-up
• Low ash content (< 1.0%) — high-purity cellulose minimises ionic contamination in transformer oil, protecting long-term insulation system performance
• Moisture-controlled — manufactured and stored to keep moisture content below 8%, preventing dielectric degradation before oil impregnation

Crepe Paper vs Kraft Paper — Which to Use?

Both electrical grade crepe paper and electrical grade kraft paper (also called press paper) are cellulose-based insulation materials used in the same transformer — but they serve different roles. Choosing the right one depends entirely on the geometry of the surface being insulated.

In a typical power transformer, both papers are used together — kraft paper for the flat winding layers, and crepe paper for all lead exits, tap changer connections, and conductor bends. They are not interchangeable — attempting to use flat kraft paper on a lead bend will result in creasing, tearing, and unacceptable insulation voids.

Crepe Paper Tubes — What They Are and Why They're Used

A crepe paper tube (also called a crepe insulation sleeve or wound paper tube) is manufactured by spirally winding multiple layers of electrical grade crepe paper around a precision mandrel under controlled tension. The finished tube is a seamless cylindrical sleeve that slides directly over a transformer lead or bus bar conductor.

• Uniform insulation thickness — a tube provides consistent wall thickness around the entire circumference of the conductor, unlike hand-wrapped tape which can vary
• Faster assembly — pre-formed tubes slide on in seconds, significantly reducing lead insulation time during transformer assembly
• Better oil impregnation — the multi-layer wound structure with slight air gaps between layers allows transformer oil to penetrate evenly through the entire wall thickness
• Mechanical protection — the rigid-yet-flexible tube structure protects lead conductors from abrasion and impact during winding and assembly
• Custom sizes — supplied to your specified inner diameter (to fit over conductor), wall thickness (to meet voltage clearance), and cut length

How Oil-Impregnated Crepe Paper Works

The oil-paper insulation system is the foundation of all oil-filled transformer design. Understanding how it works explains why the quality of the cellulose paper is so critical.

Fresh cellulose paper is hygroscopic — it absorbs moisture from the atmosphere. Moisture in insulation paper dramatically reduces dielectric strength. The transformer manufacturing process addresses this in two stages:

• Stage 1 — Vacuum drying: The fully wound and assembled transformer is placed in a vacuum oven. Heat and low pressure drive moisture out of the cellulose fibres, reducing moisture content to below 0.5%
• Stage 2 — Oil filling under vacuum: Dry, degassed transformer oil is then drawn into the tank under vacuum. The oil fills the pores of the now-dry cellulose paper, completely replacing any remaining air or moisture
• Result — oil-paper composite dielectric: The oil-saturated paper achieves dielectric strength of up to 30 kV/mm — three times higher than dry paper alone — because the oil fills every void that would otherwise become a site for partial discharge

Applications of Electrical Grade Crepe Paper

Electrical grade crepe paper is used wherever a transformer insulation system requires flexibility combined with high dielectric performance:

• Transformer lead insulation — the primary application; crepe paper tape is wound around HV and LV lead wires exiting the winding to prevent flashover at the lead-to-bushing connection
• Tap changer connections — flexible insulation at voltage tapping points where the conductor must bend through tight angles inside the tank
• Bus bar and conductor wrapping — providing a continuous, void-free insulation layer over copper or aluminium conductors of any cross-section
• Coil assembly insulation — insulating the outer surface of a wound coil, particularly at corners and edges where flat paper cannot seat flush
• Transposition insulation in CTC conductors — wrapping continuously transposed cable (CTC) conductors to prevent inter-strand short circuits
• Instrument transformer insulation — current transformers (CTs) and voltage transformers (VTs) use crepe paper for the same lead and conductor insulation purposes
• Reactor and choke winding insulation — where leads exit at angles that flat paper cannot accommodate

How ACC Insulations Manufactures Crepe Paper

The quality of electrical grade crepe paper is determined as much by the manufacturing process as by the raw material. At ACC Insulations, we control every stage:

• Raw material selection — only high-purity, sulphate-process cellulose pulp with controlled ionic impurity levels is used as the base material. This directly protects long-term transformer oil quality
• Base sheet formation — the cellulose pulp is formed into a uniform base sheet with controlled grammage (g/m²) and formation consistency across the full web width
• Creping process — the base sheet is creped against a Yankee drying cylinder using a doctor blade. Doctor blade angle, cylinder speed, and sheet tension are all precisely controlled to achieve the target crepe ratio within ±2%
• Thickness and weight control — inline gauging systems monitor thickness and basis weight continuously during production, ensuring dimensional consistency across every metre
• Slitting and rewinding — finished reels are slit to customer-specified widths and rewound to specified roll diameters and inner core diameters for direct use in transformer winding machines
• Quality testing — each batch undergoes dielectric breakdown, tensile strength, elongation, moisture content, and ash content testing before release

Standards and Compliance

• IEC 60554 — Cellulosic papers for electrical purposes (the primary international standard governing electrical insulation papers)
• IS 1576 — Indian Standard specification for electrical insulation papers
• IEC 60076-3 — Referenced for transformer insulation level and clearance requirements that the paper must support
• OEM transformer manufacturer specifications accepted — we manufacture to your design requirements

Why Choose ACC Insulations Crepe Paper?

• Consistent crepe formation — uniform wrinkle depth and spacing across every roll, not just the sampled edges
• High-purity cellulose — low ash content protects your transformer oil quality over the equipment's 25–30 year service life
• Custom roll widths and inner diameters available — for both hand wrapping and automated winding machine compatibility
• Pre-formed crepe paper tubes to your inner diameter, wall thickness, and cut length — ready to slide directly over leads
• IEC 60554 and IS 1576 compliance with batch test certificates
• Reliable supply for OEM production schedules — consistent lead times for transformer manufacturers

Industries Served

• Power transformer manufacturing (11 kV to 400 kV class)
• Distribution transformer manufacturing (up to 33 kV)
• Instrument transformer manufacturing (CT and VT)
• Reactor and choke manufacturing
• Electrical equipment OEMs requiring flexible cellulose insulation