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What is property of porosity and temperature change in insulating materials?
Less, less affected
Less, highly affected
High, highly affected
High, less affected
Less, less affected
High-quality electrical insulating materials require low porosity and stability against temperature variations. Low porosity ensures that the material does not absorb moisture, which would otherwise degrade its dielectric strength and increase leakage current, while stability ensures that the material properties remain relatively constant during thermal fluctuations.
High-quality electrical insulating materials require low porosity and stability against temperature variations. Low porosity ensures that the material does not absorb moisture, which would otherwise degrade its dielectric strength and increase leakage current, while stability ensures that the material properties remain relatively constant during thermal fluctuations.
VbтАЛ=EbтАЛтЛЕd тАФ where VbтАЛ is breakdown voltage, EbтАЛ is dielectric strength, and d is thickness.
╧╡rтАЛ(T) тАФ relative permittivity as a function of temperature; ideal insulators have dTd╧╡rтАЛтАЛтЙИ0.
Porosity directly influences the absorption of gases and liquids; high porosity leads to increased permittivity and dielectric loss. Thermal stability is characterized by a low temperature coefficient of dielectric properties. When a material is 'less affected' by temperature, it maintains a stable breakdown voltage and insulation resistance across its operating range.
Low porosity prevents the ingress of moisture, which significantly reduces the insulation resistance.
Thermal stability is critical to prevent thermal runaway in high-voltage applications.
Insulating materials must possess high mechanical strength and chemical inertness alongside these electrical properties.
Higher reliability in humid environments
Consistent performance under fluctuating load conditions
Materials with extremely low porosity can sometimes be more brittle
High-performance insulating materials often involve complex manufacturing processes
High-voltage transformer oil paper insulation
Switchgear bushings and ceramic insulators
Cable insulation for power distribution
Insulating materials like porcelain and specialized synthetic polymers are preferred because they exhibit minimal water absorption and stable dielectric constants.
Options B, C, and D are incorrect because high porosity leads to moisture absorption and being 'highly affected' by temperature would lead to unstable insulation performance under operational stress.
A is correct тАФ High-quality insulators must have low porosity to avoid moisture absorption and remain less affected by temperature to ensure operational stability.
In competitive exams, always link 'porosity' with 'moisture absorption' and 'temperature' with 'thermal stability' when evaluating dielectric materials.