Description
GPO-3 is manufactured by impregnating random glass fiber mat with unsaturated polyester resin and curing under heat and pressure to form a rigid, dimensionally stable laminate sheet.
The material offers a balanced combination of electrical insulation, mechanical strength, arc/track resistance, and cost efficiency, often preferred over phenolic laminates in structural power-distribution components.
Grade 3 GPO-3 is typically formulated to achieve higher temperature index and improved electrical characteristics compared with lower grades, while maintaining good machinability for precision‑cut parts.
Industry‑standard GPO-3 laminates are recognized under UL systems, meeting UL 94 V‑0 flammability and aligning with NEMA LI‑1 GPO‑3 and IEC 60893 UP GM 203 requirements commonly specified by OEMs and panel builders.
Typical properties data table
| Test Report | ||||||||
| Product name: UPGM203（GPO3） Test time :2026.01 | ||||||||
| No | Test Item | Unit | Standard | Result | Test method | |||
| 1 | Flexural strength perpendicular to laminations | A:under normal conditions | MPa | ≥130 | 197 | ISO 178 | ||
| E-1/130:under 130±5℃ | ≥ 65 | 150 | ||||||
| 2 | Impact strength parallel to lamination | kJ/m2 | ≥ 40 | 54 | ISO 180 | |||
| 3 | Dielectric strength perpendicular to laminations (in oil 90±2 ℃), 2.0mm in thickness | kV/mm | ≥ 10.5 | 14.5 | IEC 60243 | |||
| 4 | Breakdown voltage parallel to laminations(in oil 90±2 ℃ ) | kV | ≥ 35 | 69 | IEC 60243 | |||
| 5 | Water absorption, 4mm in thickness |
mg | ≤ 63 | 47 | ISO 62 | |||
| 6 | Insulation resistance Impregnated in water, D-24/23 | Ω | ≥5.0×108 | 1.5×1010 | IEC 60167 | |||
| 7 | Tracking index resistance | V | ≥500 | 600 | IEC 60112 | |||
| 8 | Tracking and erosion resistance | class | 1B 2.5 | pass 1B 2.5 | IEC 60587 | |||
| 9 | Flammability | Class | FV0 | FV0 | IEC 60695 | |||
| Test result: Pass | ||||||||
Note:The product specifications provided are for reference purposes only. Please refer to the actual product for final specifications. We also offer various sizes and thicknesses to meet your specific needs. For further customization, please contact us.
Application scenarios
GPO-3 Grade 3 is widely used as a structural insulating material in low‑ and medium‑voltage switchgear, distribution boards, MCCs, and control panels, where flame resistance and electrical clearance barriers are critical.
Typical parts include phase and end barriers, busbar supports, mounting plates, terminal strips, and insulating spacers in power distribution and motor control equipment.
In power and industrial systems, GPO-3 sheets and profiles are used for busbar clamping systems, transformer and reactor component supports, and rail or channel sections that must carry mechanical loads while maintaining insulation.
The material’s good impact resistance, low water absorption, and stable dielectric properties make it suitable for humid or outdoor environments, enclosed substations, and transport equipment like rail traction panels.
GPO-3 is also selected for renewable‑energy and OEM machinery, such as inverter cabinets, wind‑turbine converters, UPS systems, battery‑energy storage racks, and elevator control units, where compact flame‑retardant insulation is required.
Because it machines well by sawing, drilling, routing, and CNC machining, producers can fabricate complex insulating shapes and brackets with tight tolerances from standard sheets and profiles.
Testing standards and compliance
Common reference standards for GPO-3 Glass Polyester Mat Grade 3 include:
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NEMA LI‑1: Grade GPO‑3 for thermoset polyester glass‑mat laminates.
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IEC 60893 (UP GM 203 / UPGM 203) for rigid insulating laminates based on unsaturated polyester resins and glass mat.
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UL 94 for flammability classification (typically V‑0 for quality GPO‑3 materials).
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ASTM D149 (dielectric strength), ASTM D495 (arc resistance), ASTM D2303 / IEC 60112 (tracking/CTI), ASTM D790 (flexural), ASTM D695 (compressive), ASTM D570 (water absorption).
For use as part of insulation systems, GPO-3 often participates in UL‑recognized insulation systems and may carry thermal index ratings per UL 746B or IEC 60085 Class F requirements.
End users should verify specific certification numbers (e.g., UL file numbers, IEC type designations) against SIDA’s datasheets and test reports for project documentation and audits.