Application of EPGC308 in Dry-Type Transformers

Application of EPGC308 in Dry-Type Transformers EPGC308  epoxy fiberglass sheet (also commonly referred to as G11-H)...

Application of EPGC308 in Dry-Type Transformers

EPGC308  epoxy fiberglass sheet (also commonly referred to as G11-H) is a high-performance epoxy glass cloth laminated sheet. It serves as a critical Class H (180°C) insulation structural material in dry-type transformers. It is manufactured by impregnating alkali-free glass cloth with a specialized high-Tg(Glass Transition Temperature) epoxy resin system under high heat and pressure.

1. Key Application Areas in Dry-Type Transformers

Due to its superior mechanical and dielectric properties, EPGC308 is machined into various essential components:
Insulation Spacers and Bracing Bars: Used to maintain ventilation ducts between coil layers or windings. They ensure structural integrity under high voltage and mechanical vibration while meeting stringent flame-retardant and arc-resistance requirements.
End Rings and Pressure Plates: Applied at the ends of transformer coils for fixation and axial clamping, effectively withstanding the short-circuit electrodynamic forces generated during operation.
Lead Supports and Fasteners: Used to secure high-voltage leads, providing robust phase-to-phase and phase-to-ground insulation.
Slot Wedges and Custom Contoured Parts: Utilized as structural supports for coil positioning in specialized transformer or reactor designs.

2. Core Performance Advantages

High Thermal Stability: Specifically designed for Class H (180°C) continuous service, with a
typically ranging from 180°C to 200°C. It maintains high mechanical rigidity at elevated temperatures without softening or deformation.
Excellent Mechanical Strength: Compared to standard EPGC203 (Class F), EPGC308 retains significantly higher strength at operational temperatures (typically
50% retention at 180°C).
Superior Dielectric Properties: It offers high dielectric strength (parallel to laminations) and low dissipation factors. Even in high-humidity environments, its insulation resistance remains extremely stable (often exceeding).
Flame Retardancy and Chemical Resistance: Generally compliant with the UL94 V-0 flammability rating and exhibits strong resistance to acids, alkalis, and transformer oils.

3. Material Selection by Voltage Rating

In practical engineering, selection depends on the voltage class:

10kV (Distribution Transformers): EPGC308 is used for high-end units, though EPGC203 (G11) may be used for standard Class F designs to balance cost.
35kV Class (Medium-to-High Voltage): EPGC308 is highly recommended for phase barriers and high-voltage lead clamps. Its high
helps minimize outgassing, which is crucial for controlling Partial Discharge (PD) levels.
110kV+ or Special Reactors: EPGC308 is the preferred choice for structural members subjected to extreme thermal and mechanical stresses.