Glass-fiber covered enameled wire is a high-performance composite conductor where a base enameled conductor (copper or aluminum) is overwrapped with a layer of fine glass fibers and subsequently impregnated with a thermosetting resin. This process combines the dielectric properties of enamel with the mechanical and thermal resilience of fiberglass.

1. Manufacturing Process:
The process is sequential and precise, designed to build a robust, unified insulation system.

• Stage 1: Base Conductor Production: The process begins with drawing high-purity copper or aluminum to the required diameter. The bare conductor is then coated through multiple passes with a base enamel—typically a polyester, polyurethane, or polyamide-imide—to form a uniform, thin insulating film. This provides the primary electrical insulation.

• Stage 2: Glass-Fiber Application: The enameled wire is then fed through a braiding, serving, or wrapping machine. Here, continuous filaments of high-temperature E-glass or similar glass fiber are applied over the enamel layer. This can be a tight braid, a unidirectional wrap, or a served layer, adding substantial mechanical armor, thermal protection, and bulk.

• Stage 3: Impregnation and Curing (The Key Step): The wrapped wire is then passed through a tank or applicator containing a compatible thermosetting varnish or resin, such as silicone, modified polyester, or epoxy. This saturates the glass-fiber layer. The wire is immediately cured in a high-temperature oven. The resin flows, gels, and hardens, permanently bonding the glass fibers to each other and to the underlying enamel. This creates a solid, monolithic sheath that is resistant to moisture, chemicals, and abrasion.

2. Primary Applications:
This dual-layer insulation grants properties superior to enamel alone: excellent thermal class (often Class 155°C to over 200°C), high dielectric strength, superb mechanical toughness, and flame retardancy. Its applications are thus demanding:

• Heavy-Duty Electric Motors and Generators: Widely used in the windings of large industrial motors (for pumps, compressors, fans), traction motors (for trains, electric vehicles), and generators. The glass-fiber layer protects against vibration, slot abrasion, and contamination.

• Dry-Type Transformers and Reactors: Essential for windings in cast resin transformers and industrial chokes, where the insulation provides the necessary creepage distance, mechanical support, and thermal endurance without liquid coolant.

• Harsh Environment Applications: Specified for motors in mining equipment, marine environments, and chemical plants where moisture, dust, and corrosive atmospheres are present.

• Material Choice Rationale: Glass-covered enameled copper wire is used for maximum efficiency and power density. Glass-covered enameled aluminum wire is selected where weight reduction and material cost are critical drivers, such as in large wind turbine generators or specific automotive components, accepting a larger conductor size for equivalent resistance.