LE-9204/LH-9204: UL 94 V-0 Low-Viscosity Epoxy for Transformer Coil
Impregnation & Bushings
Product Overview
LE-9204/LH-9204 is a low-viscosity, flame-retardant epoxy
system engineered for void-free impregnation of
transformer coils and high-voltage bushings. Featuring UL 94 V-0
certification and exceptional flow characteristics, it penetrates
complex winding structures to eliminate air pockets, prevent
partial discharge, and enhance dielectric strength. Ideal for VPI
processes, APG molding, or vacuum casting of dry-type transformers,
switchgear, and indoor insulation components up to 40.5 kV.
Key Features & Benefits
| Property | Advantage |
|---|
| Ultra-Low Viscosity | Deep penetration into coil windings for void-free insulation |
| Flame Safety | UL 94 V-0 certified – critical for dry-type transformers &
indoor switchgear |
| Thermal Resilience | Withstands >1,000 thermal shock cycles (-40°C to +150°C) |
| Electrical Integrity | High CTI (>600 V) and dielectric strength (>18 kV/mm) |
| Process Flexibility | Compatible with VPI, APG, and vacuum gravity casting |
| Custom Formulation | Adjust LF-630 flexibilizer (0-20 pbw) for stress reduction |
Applications
Dry-type transformers: Coil impregnation and encapsulation
Medium-voltage switchgear (up to 40.5 kV)
Bushings and insulators for indoor applications
Sensor coils and reactor windings
PCB insulation barriers
Technical Formulation
| Component | Part | Ratio (pbw) | Function |
|---|
| Epoxy Resin | LE-9204 | 100 | BPA-based liquid resin |
| Anhydride Hardener | LH-9204 | 85 | Carboxylic acid curing |
| Flexibilizer | LF-630 | 0–20 (opt.) | Reduces brittleness |
| Accelerator | LZ-622 | 0.2–1.5 | Controls cure speed |
| Silica Filler | Powder | 320–390 | Enhances mechanicals |
| Color Paste | LC Series | 3 (opt.) | Visual identification |
Cured Properties:
Viscosity (mixed): <500 mPa·s (enables deep impregnation)
UL 94 Rating: V-0
Comparative Tracking Index: >600 V
Dielectric Strength: >18 kV/mm
Thermal Shock Resistance: Passes IEC 60137 cycling tests
Processing Methods
Vacuum Pressure Impregnation (VPI):
Automatic Pressure Gelation (APG):
Vacuum Gravity Casting:
Why Choose This System?
Void Elimination: Ultra-low viscosity removes air pockets in
windings
Fire Safety: Critical UL 94 V-0 rating for indoor electrical
equipment
Flexibility Control: Tune toughness with LF-630 flexibilizer
Accelerated Curing: LZ-622 enables rapid production cycles
Industrial Compliance: Meets IEEE C57.12.01 for dry-type
transformers
Package Image
Shipment image
Example application image
