GPO-3 Thermoset
Thermoset sheet material that consists of polyester resin with glass reinforcement
About GPO-3 Thermoset
GPO-3 is a glass reinforced thermoset polyester sheet material. GPO-3 is strong, stiff, dimensionally stable, and impact resistant. The material also has excellent electrical properties including flame, arc, and track resistance. It is widely used for electrical insulating applications. GPO-3 is also used for mechanical applications where strength, stiffness, dimensional stability, and relatively low cost are required.
Often referred to as red board, GPO-3 is widely used to fabricate durable structural and electrical insulation components. Typical uses include bus bar insulation and supports, switchgear insulation barriers, and dry-type transformer components, including core and coil blocking. The material is also commonly machined into insulation spacers and other structural electrical components used in power distribution, industrial equipment, and transportation electrical systems where reliable electrical isolation and mechanical strength are required.
Curbell supplies GPO-3 sheet, pultruded profiles, angles, channels, and dogbone rods from top manufacturers and can help navigate lead times, cut-to-size, and fabrication needs.
Tech Tip– Like many glass reinforced thermoset sheet materials, GPO-3 is somewhat abrasive on tooling during machining operations.
Length, width, thickness, and diameter tolerances vary by size, by manufacturer, brand, and grade. Custom sizes available upon request.
GPO-3 Thermoset Properties and Material Options
Glastic® UTR 1494 and 1495– Röchling’s Glastic® UTR 1494 and 1495 are glass-reinforced thermoset polyester laminates in the Glastic® GPO‑3 family, engineered for electrical insulation and structural support. Both grades are UL-recognized and meet NEMA GPO‑3 standards, with a UL 94 V‑0 flame rating and a UL temperature index of 130 °C electrical / 160 °C mechanical, making them suitable for demanding electrical and industrial applications.
Haysite H900 and H950– Haysite H900 and H950 GPO-3 laminates are UL-recognized electrical insulation materials manufactured to meet NEMA GPO-3 and MIL-I-24768/6 specifications. Both grades carry UL 94 V-0 flame ratings and are approved for use in electrical equipment requiring structural strength, arc resistance, and thermal reliability. H950 offers enhanced thermal and fire performance, including UL thermal recognition up to 160°C and validated low smoke and toxicity characteristics.
Typical Properties
Physical Properties
Mechanical Properties
Thermal Properties
Electrical Properties
Optical Properties
Other Properties
Values may vary according to brand name. Please ask your Curbell Plastics representative for more specific information about an individual brand.
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GPO-3 THERMOSET AVAILABLE ONLINE
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Fabrication & Machined Parts
Curbell supplies fabricated and machined plastic parts manufactured via CNC routing, milling, vacuum forming, die cutting, and more.
Research Materials
We carry an extensive inventory of plastic sheets, rods, tubes, film, tapes, adhesives and more from highly qualified manufacturers.
Specialized Services
We provide value for our customers with inventory programs, troubleshooting, traceability, process efficiencies, and more.
Fabrication & Machined Parts
Curbell supplies fabricated and machined plastic parts manufactured via CNC routing, milling, vacuum forming, die cutting, and more.
