The formula to calculate the feeder size is:
\[ FS = \frac{2 \cdot \rho \cdot I}{V \cdot PF} \]
Where:
Let's say the resistivity (\( \rho \)) is 10 ohms per circular mil foot, the current (\( I \)) is 100 amperes, the voltage (\( V \)) is 240 volts, and the power factor (\( PF \)) is 1. Using the formula:
\[ FS = \frac{2 \cdot 10 \cdot 100}{240 \cdot 1} \]
We get:
\[ FS = \frac{2000}{240} \approx 8.33 \text{ circular mils} \]
So, the feeder size (\( FS \)) is approximately 8.33 circular mils.
Feeder size refers to the cross-sectional area of an electrical feeder wire, which is necessary to carry a certain amount of current without overheating or dropping too much voltage. It is typically measured in circular mils, which is a unit of area used specifically for wires. Proper feeder sizing is crucial for the safety and efficiency of an electrical system.
Definition: Sizing a feeder involves determining the appropriate size of the feeder conductor based on the load it will carry.
Formula: \( \text{Feeder Size} = \frac{\text{Total Load}}{\text{Voltage} \times \text{Efficiency}} \)
Example: \( \text{Feeder Size} = \frac{10000}{240 \times 0.8} \)
Definition: Calculating the feeder conductor size involves determining the appropriate wire size based on the current it will carry.
Formula: \( \text{Conductor Size} = \frac{\text{Current}}{\text{Allowable Ampacity}} \)
Example: \( \text{Conductor Size} = \frac{50}{0.8} \)
Definition: Feeder demand range calculation involves determining the demand load for a feeder based on the connected load.
Formula: \( \text{Demand Load} = \text{Connected Load} \times \text{Demand Factor} \)
Example: \( \text{Demand Load} = 15000 \times 0.75 \)
