Double Film & Double Fiberglass Covered Rectangular Wire

(Common Name: Double Fiberglass & Film Lapped Rectangular Wire / Industry Abbreviation: SBEMB Wire)

Brief Introduction

Double film & double fiberglass covered rectangular wire, also widely known as double fiberglass film lapped rectangular wire, is a composite insulated magnet wire. It adopts rectangular copper or aluminum conductor as the core; the inner layer is bidirectionally lapped with two layers of polyester film or polyimide film, while the outer layer is cross-lapped oppositely with two layers of alkali-free fiberglass yarn. The wire is finally formed via repeated impregnation with high-temperature resistant insulating varnish and high-temperature baking & curing. The inner film delivers dense, high-strength insulation, and the outer fiberglass provides robust mechanical protection. Featuring reliable overall insulation, superior heat resistance and scratch resistance, it is a dedicated winding wire for high-voltage, heavy-load and high-temperature electrical equipment.

Core Features

1. Ultra-high dielectric strength Composite structure consisting of dual films, double fiberglass layers and varnish coating; breakdown voltage ≥ 8–10kV/mm, with outstanding corona resistance and partial discharge performance.

2. High thermal endurance class Common grades: Class B (155°C), Class H (180°C), Class C (200°C), Class N (220°C); polyimide film variant can withstand up to 240°C.

3. Exceptional mechanical properties Excellent scratch resistance, wear resistance, vibration resistance and shock resistance; resistant to damage during winding and assembly; tight interlayer adhesion without delamination.

4. High dimensional accuracy Regular rectangular cross-section and uniform insulation thickness, enabling high slot fill factor and favorable winding space utilization.

5. Oil & damp heat resistance Compatible with transformer oil and insulating oil environments; anti-aging and resistant to chemical corrosion for stable long-term operation.

6. Superior heat dissipation Good thermal conductivity of composite structure, suitable for high-current, high-frequency and heavy-duty operating conditions.

Structure & Manufacturing Process

• Conductor: High-precision oxygen-free rectangular copper wire / electrical rectangular aluminum wire; smooth burr-free surface, dimensional tolerance controlled within ±0.02 mm

• Inner Layer: Two layers of polyester / polyimide film lapped in opposite directions, lap ratio ≥ 25%–50%, no wrinkles or copper exposure

• Outer Layer: Two layers of alkali-free fiberglass yarn cross-lapped oppositely, coated with high-temperature resistant insulating varnish

• Curing: Multi-stage high-temperature baking to ensure full penetration and integral curing of varnish

Application Scenarios

1. High-voltage motors, traction motors, variable frequency motors: Stator & rotor windings for high voltage endurance, corona resistance and anti-vibration requirements

2. Large dry-type transformers, reactors, instrument transformers: Windings demanding high insulation, heat resistance and extreme reliability

3. New energy vehicle drive motors, wind power generators: Class H / C thermal resistance, lightweight design and long service life

4. Rail transit traction equipment, electric welding machines, industrial electric furnaces: High current, short-time overload and harsh environments

5. Special transformers, high-temperature motors, nuclear power equipment: Ultra-high temperature above 200°C, high radiation and ultra-reliable operating scenarios