Material Selection & Properties Flashcards

Which property describes a material's ability to return to its original shape after the applied load is removed?

Answer: Elasticity

Elasticity is the property that allows a material to recover its original dimensions once the deforming stress is removed.

In electrical applications, which material is most commonly used for overhead transmission line conductors due to its combination of conductivity and strength?

Answer: ACSR (Aluminum Conductor Steel Reinforced)

ACSR combines the high conductivity of aluminum with the tensile strength of a steel core, making it ideal for long-span overhead transmission lines.

What does the term 'dielectric strength' refer to in electrical insulating materials?

Answer: The maximum electric field a material can withstand without breakdown

Dielectric strength is the maximum electric field intensity (V/m) that an insulating material can sustain without electrical breakdown.

Which type of corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte?

Answer: Galvanic corrosion

Galvanic corrosion occurs when two metals with different electrochemical potentials are coupled in a conductive electrolyte, causing the less noble metal to corrode faster.

For transformer core laminations, which material property is most critical to minimize energy losses?

Answer: Low hysteresis and eddy current losses

Silicon steel with low hysteresis and eddy current losses is used for transformer cores to minimize the energy dissipated as heat during each magnetization cycle.

What is the primary reason cross-linked polyethylene (XLPE) is preferred over paper-insulated lead cables (PILC) for modern underground power cables?

Answer: Higher current-carrying capacity and no need for oil maintenance

XLPE cables offer higher permissible operating temperatures, greater current-carrying capacity, and are dry-type insulation requiring no oil maintenance unlike PILC cables.

Which hardness test uses a diamond pyramid indenter and is commonly used for very hard materials or thin sections?

Answer: Vickers

The Vickers hardness test uses a square pyramid diamond indenter and can be used for a wide range of materials including very hard metals and thin coatings.