Comparison of GPO3 sheet characteristics with G10 FR4 sheet

GPO-3 Sheet Introduction and Properties GPO-3 sheet is a glass fiber reinforced unsaturated polyester laminate, manu...

GPO-3 Sheet Introduction and Properties

GPO-3 sheet is a glass fiber reinforced unsaturated polyester laminate, manufactured by hot pressing fiberglass mat with polyester resin. It combines excellent electrical insulation, flame resistance, mechanical strength, and arc resistance, making it one of the most reliable insulating materials in medium and high voltage applications.

Key Properties of GPO-3

Electrical Properties

High dielectric strength: ≥ 12–14 kV/mm

Excellent arc resistance and tracking resistance (CTI ≥ 600V)

High volume resistivity: ≥ 10¹² Ω·cm

Stable insulation performance under humidity and heat

Mechanical Properties

Flexural strength: ≥ 200 MPa

Tensile strength: ≥ 120 MPa

Compressive strength: ≥ 300 MPa

Good impact resistance and dimensional stability

Easy to machine (drilling, milling, turning)

Thermal Properties

Thermal class: Class F (155 °C), up to Class H (180 °C) in special grades

Continuous operating temperature: -40 °C ~ +155 °C

Low thermal expansion and good heat resistance

Flame Retardancy & Safety

UL 94 V-0 self-extinguishing

Low smoke, low toxicity, environmentally compliant

GPO-3 vs. G10 vs. FR4

Property	GPO-3 sheet	G10 sheet	FR4 sheet
Base Material	Glass mat + unsaturated polyester resin	Woven glass cloth + epoxy resin	Woven glass cloth + epoxy resin (with flame retardant)
Reinforcement	Non-woven glass mat (random fibers)	Woven fiberglass cloth	Woven fiberglass cloth
Resin System	Polyester	Epoxy	Epoxy (brominated, flame retardant)
Mechanical Strength	Medium (good compressive, lower flexural vs. G10/FR4)	High (excellent flexural/tensile)	High (similar to G10, slightly lower due to flame retardants)
Dielectric Strength	High (≥ 12–14 kV/mm)	Very high (≥ 19–20 kV/mm)	High (≥ 17–18 kV/mm)
Tracking Resistance (CTI)	Excellent (≥ 600 V)	Moderate (≤ 300 V)	Better than G10 (≥ 400 V), not as high as GPO-3
Thermal Class	Class F (155 °C), sometimes H (180 °C)	Class F/H (155–180 °C)	Class F/H (155–180 °C)
Flammability	UL 94 V-0	Not flame-retardant (burns unless treated)	UL 94 V-0
Moisture Resistance	Good	Excellent	Excellent
Machinability	Good, easy to machine	Tougher (dense weave)	Tougher (dense weave)
Cost	Lower (economical)	Higher	Slightly lower than G10
Common Applications	Switchgear, busbar supports, barriers, arc chutes, enclosures	Structural parts, aerospace, military, precision electrical insulation	PCBs, electrical insulation, electronics, transformers

Applications of GPO-3 Sheet

Electrical Power Equipment: transformers, switchgear, RMUs, arc barriers, busbar supports

Rail Transit: flame-retardant insulation parts, structural supports

Renewable Energy: photovoltaic and wind power equipment insulation

Industrial Electrical Systems: control cabinets, distribution boxes, end plates, enclosures