G10 Epoxy Sheet: Dielectric Strength & Water Absorption Impact on Electrical Performance

Impact of Dielectric Strength and Water Absorption on the Electrical Performance of G10 In the performance evaluatio...

Impact of Dielectric Strength and Water Absorption on the Electrical Performance of G10

In the performance evaluation system of electrical insulating materials, dielectric strength and water absorption are two key indicators that determine whether a material can be used reliably and stably in electrical equipment over the long term. For G10 epoxy fiberglass sheet, these two properties directly affect its insulation reliability, safety, and service life.

1. Effect of Dielectric Strength on Electrical Performance

Dielectric strength refers to the maximum electric field intensity that a material can withstand without electrical breakdown. G10 exhibits high dielectric strength, allowing it to maintain stable insulation performance even under high-voltage conditions. This characteristic enables G10 to effectively suppress partial discharge, arc generation, and electrical breakdown.

In practical applications, the advantages of high dielectric strength are mainly reflected in:

Increasing the safety margin of electrical systems
Reducing the risk of insulation failure and short circuits
Improving operational reliability under high-voltage conditions
Extending the service life of transformers, motors, and switchgear

Therefore, G10 is particularly suitable for medium- and high-voltage electrical insulation structural and support components.

2. Effect of Water Absorption on Electrical Performance

Water absorption reflects the ability of a material to absorb moisture, which is one of the main factors causing degradation of insulation performance. G10 epoxy laminate has a relatively low water absorption rate, enabling it to maintain high insulation resistance and stable dielectric properties in humid environments, under temperature variations, or in oil-immersed conditions.

The positive effects of low water absorption on electrical performance include:
Slower reduction of insulation resistance
Lower dielectric loss
Suppressed growth of leakage current
Reduced risk of moisture-induced electrical breakdown

If the water absorption rate is too high, microscopic conductive paths may form inside the material, leading to rapid deterioration of insulation performance and even electrical failures.

3. Performance Comparison of G10 in Dry and Moist Conditions

After moisture absorption, G10 is still more stable than most engineering plastics, but its electrical performance is no longer in the optimal state.

4. Why Does Water Absorption Reduce Dielectric Strength?

From the material structure mechanism:
Moisture penetrates the interface between fiberglass and resin
Polar water molecules form conductive channels in micro-pores
The dielectric constant of water is much higher than that of epoxy resin
Local electric field distribution becomes distorted
The final result is:
Reduced effective insulation thickness + local electric field concentration → lower dielectric breakdown voltage
Therefore, moisture-absorbed G10 is more prone to partial discharge, surface tracking, electrical treeing, and dielectric breakdown.

5. Trend of Dielectric Strength Variation

Although specific values vary depending on formulation, thickness, and test methods, the trend is clear:
Dry G10: Dielectric strength remains at a high level with sufficient insulation margin
Moist G10: Dielectric strength typically decreases by about 15%–40%
The higher the humidity and temperature, the greater the reduction

6. Synergistic Effect on Electrical Performance

Through the combination of high dielectric strength and low water absorption, G10 epoxy laminate achieves long-term stable insulation performance under complex working conditions:
Not easily broken down under high voltage
Small performance degradation in humid environments
Slow aging during long-term operation
Low probability of partial discharge and insulation failure
This synergistic characteristic is a major reason why G10 is widely used in power and industrial electrical systems.

7. Conclusion

The high dielectric strength of G10 epoxy laminate provides reliable high-voltage insulation capability, while its low water absorption ensures electrical stability in humid and complex environments. Together, these two properties determine G10’s comprehensive advantages in safety, reliability, and durability in electrical insulation applications.