1 Answer
To calculate the **current in an 11 kV line**, you need to know **two key things**:
1. **The power being transmitted (in kW or MW)**
2. **The type of connection (single-phase or three-phase)**
---
## Formula for Current Calculation
Assuming it's a **three-phase system**, which is common for 11 kV lines, the current can be calculated using the formula:
$$
I = \frac{P}{\sqrt{3} \cdot V \cdot \cos\phi}
$$
Where:
* $I$ = Line current (in Amperes)
* $P$ = Power in watts (W) or kilowatts (kW), or megawatts (MW)
* $V$ = Line voltage in volts (11 kV = 11,000 V)
* $\cos\phi$ = Power factor (typically 0.8 to 1 for power transmission)
* $\sqrt{3} \approx 1.732$
---
### Example 1: 1 MW Load at 11 kV with 0.9 Power Factor
Let’s say you're transmitting **1 MW (1000 kW)** of power at **11 kV**, and your **power factor is 0.9**.
$$
I = \frac{1000 \times 10^3}{\sqrt{3} \cdot 11000 \cdot 0.9}
$$
$$
I = \frac{1000000}{1.732 \cdot 11000 \cdot 0.9} \approx \frac{1000000}{17139.6} \approx 58.35 \text{ A}
$$
So, the **current is approximately 58.35 A**.
---
### Example 2: 5 MW Load at 11 kV with 0.85 PF
$$
I = \frac{5 \times 10^6}{\sqrt{3} \cdot 11000 \cdot 0.85} = \frac{5000000}{1.732 \cdot 11000 \cdot 0.85}
$$
$$
I = \frac{5000000}{16184.1} \approx 308.85 \text{ A}
$$
---
## For Single-phase (less common in HV):
Use:
$$
I = \frac{P}{V \cdot \cos\phi}
$$
---
## Important Notes:
* **11 kV lines are almost always three-phase**.
* The **power factor ($\cos\phi$)** varies with the load (typically 0.8–1.0 for transmission).
* The **line voltage is line-to-line voltage** in three-phase calculations.
* If the load is given in **kVA**, you can directly use:
$$
I = \frac{S}{\sqrt{3} \cdot V}
$$
Where $S$ = apparent power in kVA.
---
### Want a calculator or chart for common values? I can provide one. Would that help?
1. **The power being transmitted (in kW or MW)**
2. **The type of connection (single-phase or three-phase)**
---
## Formula for Current Calculation
Assuming it's a **three-phase system**, which is common for 11 kV lines, the current can be calculated using the formula:
$$
I = \frac{P}{\sqrt{3} \cdot V \cdot \cos\phi}
$$
Where:
* $I$ = Line current (in Amperes)
* $P$ = Power in watts (W) or kilowatts (kW), or megawatts (MW)
* $V$ = Line voltage in volts (11 kV = 11,000 V)
* $\cos\phi$ = Power factor (typically 0.8 to 1 for power transmission)
* $\sqrt{3} \approx 1.732$
---
### Example 1: 1 MW Load at 11 kV with 0.9 Power Factor
Let’s say you're transmitting **1 MW (1000 kW)** of power at **11 kV**, and your **power factor is 0.9**.
$$
I = \frac{1000 \times 10^3}{\sqrt{3} \cdot 11000 \cdot 0.9}
$$
$$
I = \frac{1000000}{1.732 \cdot 11000 \cdot 0.9} \approx \frac{1000000}{17139.6} \approx 58.35 \text{ A}
$$
So, the **current is approximately 58.35 A**.
---
### Example 2: 5 MW Load at 11 kV with 0.85 PF
$$
I = \frac{5 \times 10^6}{\sqrt{3} \cdot 11000 \cdot 0.85} = \frac{5000000}{1.732 \cdot 11000 \cdot 0.85}
$$
$$
I = \frac{5000000}{16184.1} \approx 308.85 \text{ A}
$$
---
## For Single-phase (less common in HV):
Use:
$$
I = \frac{P}{V \cdot \cos\phi}
$$
---
## Important Notes:
* **11 kV lines are almost always three-phase**.
* The **power factor ($\cos\phi$)** varies with the load (typically 0.8–1.0 for transmission).
* The **line voltage is line-to-line voltage** in three-phase calculations.
* If the load is given in **kVA**, you can directly use:
$$
I = \frac{S}{\sqrt{3} \cdot V}
$$
Where $S$ = apparent power in kVA.
---
### Want a calculator or chart for common values? I can provide one. Would that help?