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Questions and Answers
Why are certain conductors used for long spans of transmission lines?
Why are certain conductors used for long spans of transmission lines?
What is a characteristic of superconducting materials?
What is a characteristic of superconducting materials?
What happens to a superconducting material's resistance as temperature decreases?
What happens to a superconducting material's resistance as temperature decreases?
What is the critical temperature (𝑇𝑐) in superconductors?
What is the critical temperature (𝑇𝑐) in superconductors?
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What type of superconductors show at least some conductivity at ambient temperature?
What type of superconductors show at least some conductivity at ambient temperature?
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What happens to Type I materials at critical temperature?
What happens to Type I materials at critical temperature?
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Why do Type I metals achieve superconductivity?
Why do Type I metals achieve superconductivity?
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What is a characteristic of Type II superconductors?
What is a characteristic of Type II superconductors?
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Which of the following is an example of a superconductor?
Which of the following is an example of a superconductor?
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What happens to the resistance of a superconducting material at critical temperature?
What happens to the resistance of a superconducting material at critical temperature?
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Study Notes
Types of Conductors
- Superconductors have zero resistance to electrical current, do not release heat, sound, or other energy forms, and can transport electrons with no resistance.
- Examples of superconductors include niobium, magnesium diboride, yttrium barium copper oxide (YBa2Cu3O7), and iron pnictides.
Properties of Superconductors
- Superconductivity occurs at a specific material's critical temperature (𝑇𝑐).
- As temperature decreases, the resistance of a superconducting material gradually decreases until it reaches critical temperature, where resistance drops off, often to zero.
Classification of Superconductors
- Type I materials show some conductivity at ambient temperature, include mostly pure metals and metalloids, have low critical temperatures (0-10 K), and experience a sudden decrease in resistance and complete expulsion of magnetic fields at critical temperature.
- Type I metals achieve superconductivity through slowing down molecular activity via low temperatures.
Mechanical Properties of Electrical Conductors
- Strength: the property of a material that opposes deformation or breakdown in the presence of external forces or loads.
- Toughness: the ability of a material to absorb energy and undergo plastic deformation without fracturing, determined by the amount of energy per unit volume (J/m³).
- Hardness: the ability of a material to resist permanent shape change due to external stress.
Types of Conductors Used in Power Transmission Lines
- Common conductors used include Aluminum Alloy Conductors, All Aluminum Conductor (AAC), All Aluminum Alloy Conductor (AAAC), Aluminum Conductor Aluminum-Alloy Reinforced (ACAR), and Aluminum Conductor Steel Reinforced (ACSR).
Characteristics of AAC and AAAC Conductors
- AAC (All Aluminum Conductor): made up of concentric-lay-stranded aluminum wires, flexible, and available in different stranding patterns.
- AAAC (All Aluminum Alloy Conductor): contains a small percentage of silicon and magnesium elements, provides several benefits for overhead lines, including twice the strength of aluminum EC 1350 and a weight reduction of approximately 20% compared to ACSR conductors of equal diameter.
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Description
This quiz covers the mechanical properties of electrical conductors, including strength, toughness, hardness, and more. It is a lecture note from Ain Shams University's Faculty of Engineering.
