280℃ Heat Resistant Polyimide Paper, Reliable Inter-Phase & Inter-Turn

This high-performance polyimide insulating paper is specially developed for winding insulation of dry-type and oil-immersed high-temperature transformers. It supports long-term continuous operation at 210℃ to 280℃, far exceeding the heat resistance limit of conventional Class H (180℃) insulation materials, classified as ultra-high heat-resistant Class C insulating substrate.

Manufactured with high-purity polyimide fiber forming technology, it integrates superior electrical insulation, mechanical strength and thermal stability. It overcomes defects of traditional aramid paper such as dielectric attenuation, dimensional shrinkage and poor oil aging resistance under high temperature, perfectly matching insulation demands of hot-spot zones in high-end power transformers.

• Thickness Range: 0.06mm ~ 0.3mm, custom slitting width available
• Dielectric Strength: ≥15kV, stable insulation performance under continuous high temperature
• Mechanical Property: Longitudinal tensile strength ≥160MPa, tear strength ＞4kN/m, flexible for automatic winding without cracking
• Thermal Endurance: Long-term service temperature 210℃–280℃, no softening, shrinkage or toxic volatilization under persistent high heat
• Chemical Resistance: Inert to transformer insulating oil, impregnating varnish, acid and alkali solvents, no pulverization or degradation after long-time immersion

• Ultra-high heat resistance: Stable long-term service at 210–280℃, resistant to instantaneous overheating impact during transformer overload, extending equipment service life greatly
• Reliable dielectric performance: Slight breakdown voltage drop under high temperature, high frequency and oil immersion, restraining space charge accumulation and partial discharge
• Outstanding mechanical toughness: High tensile & tear resistance, good flexibility for coil wrapping and interlayer lining without damage
• Low thermal shrinkage: Stable dimension under wide temperature range, no deformation after long-term high-temperature operation to secure winding insulation structure
• Flame retardant & eco-friendly: Self-extinguishing, halogen-free and zero harmful gas emission at high temperature, complying with fire safety standards for dry-type transformers

Polyimide insulating paper serves as the flexible inner-slot liner insulation, inter-turn insulation and inter-phase separator for stators.

It acts as the primary ground insulation between winding conductors and the stator core (the off-white molded insulation component shown in your hairpin flat wire stator).

1. Slot Insulation (Core Application)

   Lined between the inner wall of silicon steel stator core and copper windings, it electrically isolates conductive core lamination from winding conductors to prevent ground breakdown short circuits. Its flexible property allows perfect conformity to the irregular contour of stator slots, making it an indispensable material for hairpin flat wire motors.

2. Inter-phase Insulation

   Sandwiched between three-phase copper windings to avoid contact short-circuit between conductors of different electrical phases.

3. End Liner Cushion

   Flexible buffer mat placed at the bottom of winding overhangs to absorb vibration and prevent copper wire sharp edges from scratching and damaging wire enamel insulation film.

Core Function: Flexible conformal insulation barrier to isolate conductive circuits, tailored for narrow, bendable slot cavities.