Resistivity using Area of X-Section (2-wire Mid-point Earthed DC US) Calculator

Formula Used:

\[ \rho = \frac{A \times P_{line} \times V_m^2}{2 \times P^2 \times l} \]

Area of underground dc wire (A):

m²

Line Losses (P_line):

Maximum Voltage (V_m):

Power Transmitted (P):

Length of Wire DC (l):

Resistivity (ρ):

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1. What is Resistivity?

Resistivity is the measure of how strongly a material opposes the flow of current through them. It is a fundamental property that quantifies how strongly a given material opposes the flow of electric current.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \rho = \frac{A \times P_{line} \times V_m^2}{2 \times P^2 \times l} \]

Where:

\( \rho \) — Resistivity (Ω·m)
\( A \) — Area of underground dc wire (m²)
\( P_{line} \) — Line Losses (W)
\( V_m \) — Maximum Voltage (V)
\( P \) — Power Transmitted (W)
\( l \) — Length of Wire DC (m)

Explanation: This formula calculates the resistivity of a material based on the area of cross-section, line losses, maximum voltage, power transmitted, and length of the DC wire in a 2-wire mid-point earthed system.

3. Importance of Resistivity Calculation

Details: Accurate resistivity calculation is crucial for designing electrical systems, selecting appropriate materials for conductors, and minimizing power losses in transmission systems.

4. Using the Calculator

Tips: Enter all values in appropriate units. Area in square meters, line losses in watts, maximum voltage in volts, power transmitted in watts, and length in meters. All values must be positive and non-zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of resistivity in electrical systems?
A: Resistivity determines how much a material resists electric current flow, which affects the efficiency and performance of electrical systems.

Q2: How does wire area affect resistivity calculation?
A: Larger wire area generally results in lower resistance for the same material, but resistivity is an intrinsic property of the material itself.

Q3: What are typical resistivity values for common conductors?
A: Copper has resistivity of about 1.68×10⁻⁸ Ω·m, aluminum about 2.82×10⁻⁸ Ω·m, and silver about 1.59×10⁻⁸ Ω·m at 20°C.

Q4: How does temperature affect resistivity?
A: For most materials, resistivity increases with temperature. The relationship is often linear for small temperature changes.

Q5: Why is the 2-wire mid-point earthed system used?
A: This system provides better safety and fault protection compared to ungrounded systems, as the mid-point grounding helps limit voltage fluctuations.