Material Selection & Properties Flashcards
7 cards from real AEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Material Selection & Properties flashcards as text
What is the primary advantage of using SF6 (sulfur hexafluoride) gas in high-voltage circuit breakers?
Answer: It has excellent arc-quenching properties and high dielectric strength
SF6 gas has superior arc-quenching capability and dielectric strength approximately 2.5 times that of air, enabling compact high-voltage switchgear designs.
In a copper-clad aluminum (CCA) conductor, what is the main functional role of the copper outer layer?
Answer: To prevent oxidation at connection points and reduce contact resistance
The copper cladding prevents the formation of high-resistance aluminum oxide at termination points, ensuring reliable low-resistance connections.
Which material property is defined as the ratio of stress to strain within the elastic limit?
Answer: Modulus of elasticity (Young's modulus)
Young's modulus (modulus of elasticity) is the ratio of tensile stress to tensile strain in the linear elastic region of a material's stress-strain curve.
Why is annealed copper used for flexible wiring applications rather than hard-drawn copper?
Answer: Annealed copper is softer and more ductile, providing greater flexibility
Annealing relieves internal stresses and reduces hardness, making copper more ductile and flexible for applications requiring repeated bending without fatigue failure.
What is the main reason fiberglass reinforced polymer (FRP) is used for utility pole crossarms instead of traditional wood?
Answer: Dimensional stability, non-conductivity, and resistance to rot and insects
FRP crossarms are electrically non-conductive, dimensionally stable, immune to rot, insect damage, and weathering, offering a longer service life than wood.
Which material phenomenon causes a conductor's effective resistance to increase at higher frequencies due to current crowding near the surface?
Answer: Skin effect
The skin effect causes alternating current to flow predominantly near the surface of a conductor, reducing the effective cross-sectional area and increasing AC resistance.
For high-temperature applications in power plant environments, which alloy family is most commonly selected due to its oxidation and creep resistance?
Answer: Nickel-based superalloys
Nickel-based superalloys maintain high strength and oxidation resistance at temperatures exceeding 1000°C, making them essential for gas turbine blades and high-temp power plant components.