Formula Used:
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This calculation determines the length of an underground AC wire in a 1-phase 2-wire US system based on the wire's cross-sectional area, line losses, maximum voltage, phase difference, transmitted power, and material resistivity.
The calculator uses the formula:
Where:
Explanation: The formula calculates wire length by considering the relationship between power transmission, voltage, losses, and material properties.
Details: Accurate length calculation is crucial for proper cable installation, voltage drop estimation, and ensuring efficient power transmission in underground AC systems.
Tips: Enter all values in appropriate units. Ensure positive values for all parameters except phase difference which can be zero or positive. Use consistent units throughout.
Q1: Why is phase difference important in this calculation?
A: Phase difference affects the power factor, which influences the actual power being transmitted and thus impacts the length calculation.
Q2: What are typical resistivity values for common conductor materials?
A: Copper: ~1.68×10⁻⁸ Ω·m, Aluminum: ~2.82×10⁻⁸ Ω·m. Values may vary based on material purity and temperature.
Q3: How does wire area affect the calculated length?
A: Larger cross-sectional areas generally allow for longer wire lengths while maintaining acceptable voltage drop and power loss levels.
Q4: What are acceptable line loss percentages?
A: Typically, line losses should be kept below 5% of the transmitted power for efficient systems, though this varies by application.
Q5: Can this formula be used for overhead lines?
A: While the basic principles are similar, overhead lines have different considerations (temperature, sag, etc.) that may require adjustments to the formula.